Features • High Performance, Low Power AVR ® 8-bit Microcontroller • Advanced RISC Architecture – 131 Powerful Instructions - Most Single Clock Cycle Execution – 32 x 8 General Purpose Working Registers – Fully Static Operation – Up to 1 MIPS Throughput per MHz – On-chip 2-cycle Multiplier • Data and Non-Volatile Program Memory – 8K Bytes of In-System Programmable Program Memory Flash • Endurance: 10,000 Write/Erase Cycles • Lock bits protection • Optional 2k Bytes Boot Code Section with Independent Lock Bits • In-System Programming by On-chip Boot Program • True Read-While-Write Operation – 512 Bytes of In-System Programmable EEPROM, • 4 bytes page size – 256Bytes Internal SRAM • On Chip Debug support (debugWIRE) • Peripheral Features – One 12-bit High Speed PSC (Power Stage Controllers with extended PSC2 features) • Non overlapping inverted PWM output pins with flexible Dead-Time • Variable PWM duty cycle and frequency • Synchronous update of all PWM registers • Enhanced resolution mode (16 bits) • Additional register for ADC synchronization • Input capture • Four output pins and output matrix – One 12-bit High Speed PSC (Power Stage Controller) • Auto Stop function for event driven PFC implementation • Non overlapping inverted PWM output pins with flexible Dead-Time • Variable PWM duty cycle and frequency • Synchronous update of all PWM registers • Enhanced resolution mode (16 bits) • Input capture – One 16-bit simple General purpose Timer/Counter – 10-bit ADC • up to 11 single ended channels and 1 fully differential ADC channel pair • Programmable gain (5x, 10x, 20x, 40x on differential channel) • Internal reference voltage – One 10-bit DAC – Three Analog Comparator with • Resistor-Array to adjust comparison voltage • DAC to adjust comparison voltage – One SPI – 3 External interrupts – Programmable Watchdog Timer with Separate On-Chip Oscillator 8-bit Microcontroller with 8K Bytes InSystem Programmable Flash AT90PWM81 7734P–AVR–08/10 • Special Microcontroller Features – Low Power Idle, Noise Reduction, and Power Down Modes – Power On Reset and Programmable Brown Out Detection – Flag Array in bit-programmable I/O space (3 bytes) – In-System Programmable via SPI Port – Internal low power Calibrated RC Oscillator (8 or 1-MHz, low jitter) – On chip PLL for fast PWM (32, 48, 64-MHz) and CPU (12, 16 MHz); PLL source RC & XTAL – Dynamic clock switch – Temperature sensor • Operating Voltage: 2.7V - 5.5V • Operating Temperature: – -40°C to +105°C or -40°C to +125°C • Operating Speed – 5V : 16 MHz core, 64 MHz PLL – 3.3V : 12 MHz core, 48 MHz PLL 1. Products Configuration The different product configurations are described per Table 1-1. Table 1-1. 2 PWM81 configurations Package SO20 QFN32 Pins 20 32 Flash size 8k 8k EEPROM size 512 512 RAM size 256 256 PSC 12 bits with extended features 1 1 PSC 12 bits 1 1 Timer 8 bits - - Timer 16 bits 1 1 ADC inputs 8 11 Amplifiers for ADC 1 1 Temperature sensor 1 1 Analog Comparators 3 3 DAC 1 1 DAC amplifiers - - UART/DALI - - SPI 1 1 AT90PWM81 7734P–AVR–08/10 AT90PWM81 2. Pin Configurations Figure 2-1. 20 Pin Packages 3 7734P–AVR–08/10 NC (PSCINr/ACMP1M/XTAL2) PE2 (PSCOUTR0/PSCINrB) PD1 (ADC0/ACMP1) PD2 (ADC1/ACMP2_OUT) PD3 (ADC2/ACMP2M/PSCOUTR1) PB3 (ADC3/ACMPM/MOSI) PB4 NC 9 10 11 12 13 14 15 16 32 31 30 29 28 27 26 25 AT90PWM81 QFN 32 5*5 NC (ACMP3_OUT_A/SS/CLKO) PD0 (PSCOUT20) PB1 (INT0/PSCOUT21) PB2 VCC GND (ACPM1_OUT/PSCIN2/XTAL1) PE1 NC 4 PB7 (ADC9/PSCOUT22/ICP1) PD7 (ADC10/PSCINrA) PB6 (ADC8/MISO/ACMP3) PD6 (AMP0+) NC PB0 (PSCOUT23/T1/ACMP3_OUT) PE0 (RESET/OCD/INT2) NC Figure 2-2. 32-Pin Packages 1 2 3 4 5 6 7 8 24 23 22 21 20 19 18 17 NC PD5 (AMP0-/ADC7) PE3/AREF/ADC6 AGND AVCC PB5 (ADC5/INT1/SCK/ACMP2) PD4 (PSCIN2A/ACMP3M/ADC4) NC AT90PWM81 7734P–AVR–08/10 AT90PWM81 Table 2-1. : Alternate functions description MNEMONIC NAME, FUNCTION & ALTERNATE FUNCTION GND Ground: 0V reference AGND Analog Ground: 0V reference for analog part VCC Power Supply: AVCC Analog Power Supply: This is the power supply voltage for analog part For a normal use this pin must be connected. AREF Analog Reference : reference for analog converter. This is the reference voltage of the A/D converter. As output, can be used by external analog CLKO System Clock Output RESET# OCD Reset Input On Chip Debug I/O XTAL1 XTAL Input XTAL2 XTAL Output MISO SPI Master In Slave Out MOSI SPI Master Out Slave In SCK SPI Clock SS SPI Slave Select INTn External interrupt n Tn Timer n clock input PSCOUTxn PSCx output n PSCINx PSCx Digital Input PSCOUT0n PSC reduced output n PSCINr PSC reduced Digital Input ACMPn Analog Comparator n Positive Input ACMPMn Analog Comparator n Negative Input ACMPM Negative input for analog comparators ACOMPn_OUT Analog Comparator n Output AMPn- Analog Differential Amplifier n Input Channel AMPn+ Analog Differential Amplifier n Input Channel ADCn Analog Converter Input Channel n 5 7734P–AVR–08/10 Table 2-2. Port PB0 PE0 PD0 PB1 PB2 VCC GND PE1 PE2 Pin out description SO 20 QFN32 pins pins GP 1 30 T1 2 31 RESET# OCD, INT2 NA 2 CLKO, SS 3 3 4 4 INT0 5 5 Power Supply 6 6 Ground 7 7 XTAL1 8 10 XTAL2 PD1 9 PD2 10 PD3 NA PB3 11 PB4 12 PD4 NA PB5 13 AVCC 14 AGND 15 16 PD5 17 PD6 18 PB6 19 PD7 NA PB7 20 2.1 2.1.1 11 12 13 14 15 18 19 20 21 22 23 26 27 28 29 PSC PSCOUT23 Analog ACMP3_OUT ACMP3_OUT_A PSCOUT20 PSCOUT21 PSCIN2 PSCINr PSCOUTR0, PSCINrB PSCOUTR1 MOSI PSCIN2A INT1, SCK Analog Supply Analog Ground AREF, Analog Ref ACMP1_OUT ACMP1M ADC0 ADC1 ADC2 ADC3 ADC4 ADC5 ADC6 ADC7 MISO ICP1 ADC PSCINrA PSCOUT22 ADC8 ADC10 ADC9 ACMP1 ACMP2_OUT ACMP2M ACMPM ACMP3M ACMP2 AMP0AMP0+ ACMP3 Pin Descriptions VCC Digital supply voltage. 2.1.2 GND Ground. 2.1.3 Port B (PB7..PB0) Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port B output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up resistors are activated. The Port B pins are tri-stated when a reset condition becomes active, even if the clock is not running. Port B also serves the functions of various special features of the AT90PWM81 as listed on Table 9-3 on page 73. 6 AT90PWM81 7734P–AVR–08/10 AT90PWM81 2.1.4 Port D (PD7..PD0) Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port D output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated. The Port D pins are tri-stated when a reset condition becomes active, even if the clock is not running. Port D also serves the functions of various special features of the AT90PWM81 as listed on Table 9-6 on page 76 2.1.5 Port E (P32..0) RESET/ XTAL1/ XTAL2/AREF Port E is an 4-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port E output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port E pins that are externally pulled low will source current if the pull-up resistors are activated. The Port E pins are tri-stated when a reset condition becomes active, even if the clock is not running. If the RSTDISBL Fuse is programmed, PE0 is used as an I/O pin. Note that the electrical characteristics of PE0 differ from those of the other pins. If the RSTDISBL Fuse is unprogrammed, PE0 is used as a Reset input. A low level on this pin for longer than the minimum pulse length will generate a Reset, even if the clock is not running. The minimum pulse length is given in Table 7-1 on page 50. Shorter pulses are not guaranteed to generate a Reset. Depending on the clock selection fuse settings, PE1 can be used as input to the inverting Oscillator amplifier and input to the internal clock operating circuit. Depending on the clock selection fuse settings, PE2 can be used as output from the inverting Oscillator amplifier. The various special features of Port E are elaborated in Table 9-9 on page 78 and Section “Clock Systems and their Distribution”, page 27. 2.1.6 AVCC AVCC is the supply voltage pin for the A/D Converter. It should be externally connected to VCC, even if the ADC is not used. If the ADC is used, it should be connected to VCC through a lowpass filter. 7 7734P–AVR–08/10 3. AVR CPU Core 3.1 Introduction This section discusses the AVR core architecture in general. The main function of the CPU core is to ensure correct program execution. The CPU must therefore be able to access memories, perform calculations, control peripherals, and handle interrupts. 3.2 Architectural Overview Figure 3-1. Block Diagram of the AVR Architecture Data Bus 8-bit Flash Program Memory Program Counter Status and Control 32 x 8 General Purpose Registrers Control Lines Direct Addressing Instruction Decoder Indirect Addressing Instruction Register Interrupt Unit SPI Unit Watchdog Timer ALU Analog Comparator I/O Module1 Data SRAM I/O Module 2 I/O Module n EEPROM I/O Lines In order to maximize performance and parallelism, the AVR uses a Harvard architecture – with separate memories and buses for program and data. Instructions in the program memory are executed with a single level pipelining. While one instruction is being executed, the next instruction is pre-fetched from the program memory. This concept enables instructions to be executed in every clock cycle. The program memory is In-System Reprogrammable Flash memory. 8 AT90PWM81 7734P–AVR–08/10 AT90PWM81 The fast-access Register File contains 32 x 8-bit general purpose working registers with a single clock cycle access time. This allows single-cycle Arithmetic Logic Unit (ALU) operation. In a typical ALU operation, two operands are output from the Register File, the operation is executed, and the result is stored back in the Register File – in one clock cycle. Six of the 32 registers can be used as three 16-bit indirect address register pointers for Data Space addressing – enabling efficient address calculations. One of the these address pointers can also be used as an address pointer for look up tables in Flash program memory. These added function registers are the 16-bit X-, Y-, and Z-register, described later in this section. The ALU supports arithmetic and logic operations between registers or between a constant and a register. Single register operations can also be executed in the ALU. After an arithmetic operation, the Status Register is updated to reflect information about the result of the operation. Program flow is provided by conditional and unconditional jump and call instructions, able to directly address the whole address space. Most AVR instructions have a single 16-bit word format. Every program memory address contains a 16- or 32-bit instruction. Program Flash memory space is divided in two sections, the Boot Program section and the Application Program section. Both sections have dedicated Lock bits for write and read/write protection. The SPM (Store Program Memory) instruction that writes into the Application Flash memory section must reside in the Boot Program section. During interrupts and subroutine calls, the return address Program Counter (PC) is stored on the Stack. The Stack is effectively allocated in the general data SRAM, and consequently the Stack size is only limited by the total SRAM size and the usage of the SRAM. All user programs must initialize the SP in the Reset routine (before subroutines or interrupts are executed). The Stack Pointer (SP) is read/write accessible in the I/O space. The data SRAM can easily be accessed through the five different addressing modes supported in the AVR architecture. The memory spaces in the AVR architecture are all linear and regular memory maps. A flexible interrupt module has its control registers in the I/O space with an additional Global Interrupt Enable bit in the Status Register. All interrupts have a separate Interrupt Vector in the Interrupt Vector table. The interrupts have priority in accordance with their Interrupt Vector position. The lower the Interrupt Vector address, the higher is the priority. The I/O memory space contains 64 addresses for CPU peripheral functions as Control Registers, SPI, and other I/O functions. The I/O Memory can be accessed directly, or as the Data Space locations following those of the Register File, 0x20 - 0x5F. In addition, the AT90PWM81 has Extended I/O space from 0x60 - 0xFF in SRAM where only the ST/STS/STD and LD/LDS/LDD instructions can be used. 3.3 ALU – Arithmetic Logic Unit The high-performance AVR ALU operates in direct connection with all the 32 general purpose working registers. Within a single clock cycle, arithmetic operations between general purpose registers or between a register and an immediate are executed. The ALU operations are divided into three main categories – arithmetic, logical, and bit-functions. Some implementations of the architecture also provide a powerful multiplier supporting both signed/unsigned multiplication and fractional format. See the “Instruction Set” section for a detailed description. 3.4 Status Register The Status Register contains information about the result of the most recently executed arithmetic instruction. This information can be used for altering program flow in order to perform conditional operations. 9 7734P–AVR–08/10 Note that the Status Register is updated after all ALU operations, as specified in the Instruction Set Reference. This will in many cases remove the need for using the dedicated compare instructions, resulting in faster and more compact code. The Status Register is not automatically stored when entering an interrupt routine and restored when returning from an interrupt. This must be handled by software. The AVR Status Register – SREG – is defined as: Bit 7 6 5 4 3 2 1 0 I T H S V N Z C Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 SREG • Bit 7 – I: Global Interrupt Enable The Global Interrupt Enable bit must be set to enabled the interrupts. The individual interrupt enable control is then performed in separate control registers. If the Global Interrupt Enable Register is cleared, none of the interrupts are enabled independent of the individual interrupt enable settings. The I-bit is cleared by hardware after an interrupt has occurred, and is set by the RETI instruction to enable subsequent interrupts. The I-bit can also be set and cleared by the application with the SEI and CLI instructions, as described in the instruction set reference. • Bit 6 – T: Bit Copy Storage The Bit Copy instructions BLD (Bit LoaD) and BST (Bit STore) use the T-bit as source or destination for the operated bit. A bit from a register in the Register File can be copied into T by the BST instruction, and a bit in T can be copied into a bit in a register in the Register File by the BLD instruction. • Bit 5 – H: Half Carry Flag The Half Carry Flag H indicates a Half Carry in some arithmetic operations. Half Carry Is useful in BCD arithmetic. See the “Instruction Set Description” for detailed information. • Bit 4 – S: Sign Bit, S = N ⊕ V The S-bit is always an exclusive or between the negative flag N and the Two’s Complement Overflow Flag V. See the “Instruction Set Description” for detailed information. • Bit 3 – V: Two’s Complement Overflow Flag The Two’s Complement Overflow Flag V supports two’s complement arithmetic. See the “Instruction Set Description” for detailed information. • Bit 2 – N: Negative Flag The Negative Flag N indicates a negative result in an arithmetic or logic operation. See the “Instruction Set Description” for detailed information. • Bit 1 – Z: Zero Flag The Zero Flag Z indicates a zero result in an arithmetic or logic operation. See the “Instruction Set Description” for detailed information. • Bit 0 – C: Carry Flag The Carry Flag C indicates a carry in an arithmetic or logic operation. See the “Instruction Set Description” for detailed information. 10 AT90PWM81 7734P–AVR–08/10 AT90PWM81 3.5 General Purpose Register File The Register File is optimized for the AVR Enhanced RISC instruction set. In order to achieve the required performance and flexibility, the following input/output schemes are supported by the Register File: • One 8-bit output operand and one 8-bit result input • Two 8-bit output operands and one 8-bit result input • Two 8-bit output operands and one 16-bit result input • One 16-bit output operand and one 16-bit result input Figure 3-2 shows the structure of the 32 general purpose working registers in the CPU. Figure 3-2. AVR CPU General Purpose Working Registers 7 0 Addr. R0 0x00 R1 0x01 R2 0x02 … R13 0x0D General R14 0x0E Purpose R15 0x0F Working R16 0x10 Registers R17 0x11 … R26 0x1A R27 0x1B X-register Low Byte X-register High Byte R28 0x1C Y-register Low Byte R29 0x1D Y-register High Byte R30 0x1E Z-register Low Byte R31 0x1F Z-register High Byte Most of the instructions operating on the Register File have direct access to all registers, and most of them are single cycle instructions. As shown in Figure 3-2, each register is also assigned a data memory address, mapping them directly into the first 32 locations of the user Data Space. Although not being physically implemented as SRAM locations, this memory organization provides great flexibility in access of the registers, as the X-, Y- and Zpointer registers can be set to index any register in the file. 3.5.1 The X-register, Y-register, and Z-register The registers R26..R31 have some added functions to their general purpose usage. These registers are 16bit address pointers for indirect addressing of the data space. The three indirect address registers X, Y, and Z are defined as described in Figure 3-3. Figure 3-3. The X-, Y-, and Z-registers 15 X-register XH 7 R27 (0x1B) 15 XL 0 7 0 0 R26 (0x1A) YH YL 0 11 7734P–AVR–08/10 Y-register 7 0 R29 (0x1D) Z-register 7 0 R28 (0x1C) 15 ZH 7 0 ZL 7 R31 (0x1F) 0 0 R30 (0x1E) In the different addressing modes these address registers have functions as fixed displacement, automatic increment, and automatic decrement (see the instruction set reference for details). 3.6 Stack Pointer The Stack is mainly used for storing temporary data, for storing local variables and for storing return addresses after interrupts and subroutine calls. The Stack Pointer Register always points to the top of the Stack. Note that the Stack is implemented as growing from higher memory locations to lower memory locations. This implies that a Stack PUSH command decreases the Stack Pointer. The Stack Pointer points to the data SRAM Stack area where the Subroutine and Interrupt Stacks are located. This Stack space in the data SRAM must be defined by the program before any subroutine calls are executed or interrupts are enabled. The Stack Pointer must be set to point above 0x100. The Stack Pointer is decremented by one when data is pushed onto the Stack with the PUSH instruction, and it is decremented by two when the return address is pushed onto the Stack with subroutine call or interrupt. The Stack Pointer is incremented by one when data is popped from the Stack with the POP instruction, and it is incremented by two when data is popped from the Stack with return from subroutine RET or return from interrupt RETI. The AVR Stack Pointer is implemented as two 8-bit registers in the I/O space. The number of bits actually used is implementation dependent. Note that the data space in some implementations of the AVR architecture is so small that only SPL is needed. In this case, the SPH Register will not be present. Bit Read/Write Initial Value 3.7 15 14 13 12 11 10 9 8 SP15 SP14 SP13 SP12 SP11 SP10 SP9 SP8 SPH SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0 SPL 7 6 5 4 3 2 1 0 R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Instruction Execution Timing This section describes the general access timing concepts for instruction execution. The AVR CPU is driven by the CPU clock clkCPU, directly generated from the selected clock source for the chip. No internal clock division is used. Figure 3-4 shows the parallel instruction fetches and instruction executions enabled by the Harvard architecture and the fast-access Register File concept. This is the basic pipelining concept to obtain up to 1 MIPS per MHz with the corresponding unique results for functions per cost, functions per clocks, and functions per power-unit. 12 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 3-4. The Parallel Instruction Fetches and Instruction Executions T1 T2 T3 T4 clkCPU 1st Instruction Fetch 1st Instruction Execute 2nd Instruction Fetch 2nd Instruction Execute 3rd Instruction Fetch 3rd Instruction Execute 4th Instruction Fetch Figure 3-5 shows the internal timing concept for the Register File. In a single clock cycle an ALU operation using two register operands is executed, and the result is stored back to the destination register. Figure 3-5. Single Cycle ALU Operation T1 T2 T3 T4 clkCPU Total Execution Time Register Operands Fetch ALU Operation Execute Result Write Back 3.8 Reset and Interrupt Handling The AVR provides several different interrupt sources. These interrupts and the separate Reset Vector each have a separate program vector in the program memory space. All interrupts are assigned individual enable bits which must be written logic one together with the Global Interrupt Enable bit in the Status Register in order to enable the interrupt. Depending on the Program Counter value, interrupts may be automatically disabled when Boot Lock bits BLB02 or BLB12 are programmed. This feature improves software security. See the section “Memory Programming” on page 247 for details. The lowest addresses in the program memory space are by default defined as the Reset and Interrupt Vectors. The complete list of vectors is shown in “Interrupts” on page 61. The list also determines the priority levels of the different interrupts. The lower the address the higher is the priority level. RESET has the highest priority, and next is PSC2 CAPT – the PSC2 Capture Event. The Interrupt Vectors can be moved to the start of the Boot Flash section by setting the IVSEL bit in the MCU Control Register (MCUCR). Refer to “Interrupts” on page 61 for more information. The Reset Vector can also be moved to the start of the Boot Flash section by programming the BOOTRST Fuse, see “Boot Loader Support – Read-WhileWrite Self-Programming” on page 232. 3.8.1 Interrupt Behavior When an interrupt occurs, the Global Interrupt Enable I-bit is cleared and all interrupts are disabled. The user software can write logic one to the I-bit to enable nested interrupts. All enabled interrupts can then interrupt the current interrupt routine. The I-bit is automatically set when a Return from Interrupt instruction – RETI – is executed. 13 7734P–AVR–08/10 There are basically two types of interrupts. The first type is triggered by an event that sets the interrupt flag. For these interrupts, the Program Counter is vectored to the actual Interrupt Vector in order to execute the interrupt handling routine, and hardware clears the corresponding interrupt flag. Interrupt flags can also be cleared by writing a logic one to the flag bit position(s) to be cleared. If an interrupt condition occurs while the corresponding interrupt enable bit is cleared, the interrupt flag will be set and remembered until the interrupt is enabled, or the flag is cleared by software. Similarly, if one or more interrupt conditions occur while the Global Interrupt Enable bit is cleared, the corresponding interrupt flag(s) will be set and remembered until the Global Interrupt Enable bit is set, and will then be executed by order of priority. The second type of interrupts will trigger as long as the interrupt condition is present. These interrupts do not necessarily have interrupt flags. If the interrupt condition disappears before the interrupt is enabled, the interrupt will not be triggered. When the AVR exits from an interrupt, it will always return to the main program and execute one more instruction before any pending interrupt is served. Note that the Status Register is not automatically stored when entering an interrupt routine, nor restored when returning from an interrupt routine. This must be handled by software. When using the CLI instruction to disable interrupts, the interrupts will be immediately disabled. No interrupt will be executed after the CLI instruction, even if it occurs simultaneously with the CLI instruction. The following example shows how this can be used to avoid interrupts during the timed EEPROM write sequence. Assembly Code Example in r16, SREG ; store SREG value cli ; disable interrupts during timed sequence sbi EECR, EEMWE ; start EEPROM write sbi EECR, EEWE out SREG, r16 ; restore SREG value (I-bit) C Code Example char cSREG; cSREG = SREG; /* store SREG value */ /* disable interrupts during timed sequence */ _CLI(); EECR |= (1<<EEMWE); /* start EEPROM write */ EECR |= (1<<EEWE); SREG = cSREG; /* restore SREG value (I-bit) */ When using the SEI instruction to enable interrupts, the instruction following SEI will be executed before any pending interrupts, as shown in this example. Assembly Code Example sei ; set Global Interrupt Enable sleep; enter sleep, waiting for interrupt ; note: will enter sleep before any pending ; interrupt(s) 14 AT90PWM81 7734P–AVR–08/10 AT90PWM81 C Code Example _SEI(); /* set Global Interrupt Enable */ _SLEEP(); /* enter sleep, waiting for interrupt */ /* note: will enter sleep before any pending interrupt(s) */ 3.8.2 Interrupt Response Time The interrupt execution response for all the enabled AVR interrupts is four clock cycles minimum. After four clock cycles the program vector address for the actual interrupt handling routine is executed. During this four clock cycle period, the Program Counter is pushed onto the Stack. The vector is normally a jump to the interrupt routine, and this jump takes three clock cycles. If an interrupt occurs during execution of a multi-cycle instruction, this instruction is completed before the interrupt is served. If an interrupt occurs when the MCU is in sleep mode, the interrupt execution response time is increased by four clock cycles. This increase comes in addition to the start-up time from the selected sleep mode. A return from an interrupt handling routine takes four clock cycles. During these four clock cycles, the Program Counter (two bytes) is popped back from the Stack, the Stack Pointer is incremented by two, and the I-bit in SREG is set. 15 7734P–AVR–08/10 4. Memories This section describes the different memories in the AT90PWM81. The AVR architecture has two main memory spaces, the Data Memory and the Program Memory space. In addition, the AT90PWM81 features an EEPROM Memory for data storage. All three memory spaces are linear and regular. 4.1 In-System Reprogrammable Flash Program Memory The AT90PWM81 contains 8K bytes On-chip In-System Reprogrammable Flash memory for program storage. Since all AVR instructions are 16 or 32 bits wide, the Flash is organized as 4K x 16. For software security, the Flash Program memory space is divided into two sections, Boot Program section and Application Program section. The Flash memory has an endurance of at least 10,000 write/erase cycles. The AT90PWM81 Program Counter (PC) is 12 bits wide, thus addressing the 4K program memory locations. The operation of Boot Program section and associated Boot Lock bits for software protection are described in detail in “Boot Loader Support – Read-While-Write Self-Programming” on page 232. “Memory Programming” on page 247 contains a detailed description on Flash programming in SPI or Parallel programming mode. Constant tables can be allocated within the entire program memory address space (see the LPM – Load Program Memory. Timing diagrams for instruction fetch and execution are presented in “Instruction Execution Timing” on page 12. Figure 4-1. Program Memory Map Program Memory 0x0000 Application Flash Section Boot Flash Section 0x0FFF 4.2 SRAM Data Memory Figure 4-2 shows how the AT90PWM81 SRAM Memory is organized. 16 AT90PWM81 7734P–AVR–08/10 AT90PWM81 The AT90PWM81 is a complex microcontroller with more peripheral units than can be supported within the 64 locations reserved in the Opcode for the IN and OUT instructions. For the Extended I/O space from 0x60 - 0xFF in SRAM, only the ST/STS/STD and LD/LDS/LDD instructions can be used. The lower 512 data memory locations address both the Register File, the I/O memory, Extended I/O memory, and the internal data SRAM. The first 32 locations address the Register File, the next 64 location the standard I/O memory, then 160 locations of Extended I/O memory, and the next 256 locations address the internal data SRAM. The five different addressing modes for the data memory cover: Direct, Indirect with Displacement, Indirect, Indirect with Pre-decrement, and Indirect with Post-increment. In the Register File, registers R26 to R31 feature the indirect addressing pointer registers. The direct addressing reaches the entire data space. The Indirect with Displacement mode reaches 63 address locations from the base address given by the Yor Z-register. When using register indirect addressing modes with automatic pre-decrement and post-increment, the address registers X, Y, and Z are decremented or incremented. The 32 general purpose working registers, 64 I/O Registers, 160 Extended I/O Registers, and the 256 bytes of internal data SRAM in the AT90PWM81 are all accessible through all these addressing modes. The Register File is described in “General Purpose Register File” on page 11. Figure 4-2. Data Memory Map Data Memory 32 Registers 64 I/O Registers 160 Ext I/O Reg. Internal SRAM (256 x 8) 0x0000 - 0x001F 0x0020 - 0x005F 0x0060 - 0x00FF 0x0100 0x01FF 4.2.1 SRAM Data Access Times This section describes the general access timing concepts for internal memory access. The internal data SRAM access is performed in two clkCPU cycles as described in Figure 4-3. 17 7734P–AVR–08/10 Figure 4-3. On-chip Data SRAM Access Cycles T1 T2 T3 clkCPU Address Compute Address Address valid Write Data WR Read Data RD Memory Access Instruction 4.3 Next Instruction EEPROM Data Memory The AT90PWM81 contains 512 bytes of data EEPROM memory. It is organized as a separate data space, in which single bytes can be read and written. The EEPROM has an endurance of at least 100,000 write/erase cycles. The access between the EEPROM and the CPU is described in the following, specifying the EEPROM Address Registers, the EEPROM Data Register, and the EEPROM Control Register. For a detailed description of SPI and Parallel data downloading to the EEPROM, see “Serial Downloading” on page 261, and “Parallel Programming Parameters, Pin Mapping, and Commands” on page 252 respectively. 4.3.1 EEPROM Read/Write Access The EEPROM Access Registers are accessible in the I/O space. The write access time for the EEPROM is given in Table 4-2. A self-timing function, however, lets the user software detect when the next byte can be written. If the user code contains instructions that write the EEPROM, some precautions must be taken. In heavily filtered power supplies, VCC is likely to rise or fall slowly on power-up/down. This causes the device for some period of time to run at a voltage lower than specified as minimum for the clock frequency used. For details on how to avoid problems in these situations seeSee “Preventing EEPROM Corruption” on page 25. In order to prevent unintentional EEPROM writes, a specific write procedure must be followed. Refer to the description of the EEPROM Control Register for details on this. When the EEPROM is read, the CPU is halted for four clock cycles before the next instruction is executed. When the EEPROM is written, the CPU is halted for two clock cycles before the next instruction is executed. 18 AT90PWM81 7734P–AVR–08/10 AT90PWM81 4.3.2 The EEPROM Address Registers – EEARH and EEARL Bit Read/Write Initial Value 15 14 13 12 11 10 9 – – – – – – – 8 EEAR8 EEARH EEAR7 EEAR6 EEAR5 EEAR4 EEAR3 EEAR2 EEAR1 EEAR0 EEARL 7 6 5 4 3 2 1 0 R/W R R R R R R R R/W R/W R/W R/W R/W R/W R/W R/W 0 0 0 0 0 0 0 X X X X X X X X X • Bits 15..9 – Reserved Bits These bits are reserved bits in the AT90PWM81 and will always read as zero. • Bits 8..0 – EEAR8..0: EEPROM Address The EEPROM Address Registers – EEARH and EEARL specify the EEPROM address in the 512 bytes EEPROM space. The EEPROM data bytes are addressed linearly between 0 and 511. The initial value of EEAR is undefined. A proper value must be written before the EEPROM may be accessed. 4.3.3 The EEPROM Data Register – EEDR Bit 7 6 5 4 3 2 1 0 EEDR7 EEDR6 EEDR5 EEDR4 EEDR3 EEDR2 EEDR1 EEDR0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 EEDR • Bits 7..0 – EEDR7.0: EEPROM Data For the EEPROM write operation, the EEDR Register contains the data to be written to the EEPROM in the address given by the EEAR Register. For the EEPROM read operation, the EEDR contains the data read out from the EEPROM at the address given by EEAR. 4.3.4 The EEPROM Control Register – EECR Bit 7 6 5 4 3 2 1 0 NVMBSY EEPAGE EEPM1 EEPM0 EERIE EEMWE EEWE EERE Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value X X X X 0 0 X 0 EECR • Bits 7 – NVMBSY: Non-volatile memory busy The NVMBSY bit is a status bit that indicates that the NVM memory (FLASH, EEPROM, Lock-bits) is busy programming. Once a program operation is started, the bit will be set and it remains set until the program operation is completed. Bits 6 – EEPAGE: EEPROM page access (multiple bytes access mode) Writing EEPAGE to one enables the multiple bytes access mode. That means that several bytes can be programmed simultaneously into the EEPROM. When the EEPAGE bit has been written to one, the EEPAGE bit remains set until an EEPROM program operation is completed. Alternatively the bit is cleared when the temporary EEPROM buffer is flushed in software (see EEPMn bits description). Any write to EEPAGE while EEPE is one will be ignored. See Section “Program multiple bytes in one Atomic operation”, page 21 for details on how to load data into the temporary EEPROM page and the usage of the EEPAGE bit. 19 7734P–AVR–08/10 • Bits 5..4 – EEPM1 and EEPM0: EEPROM Programming Mode Bits The EEPROM Programming mode bit setting defines which programming action that will be triggered when writing EEWE. It is possible to program data in one atomic operation (erase the old value and program the new value) or to split the Erase and Write operations in two different operations. The Programming times for the different modes are shown in Table 4-1. While EEWE is set, any write to EEPMn will be ignored. During reset, the EEPMn bits will be reset to 0b00 unless the EEPROM is busy programming. Table 4-1. EEPROM Mode Bits EEPM1 EEPM0 Programming Time 0 0 3.4 ms Erase and Write in one operation (Atomic Operation) 0 1 1.8 ms Erase Only 1 0 1.8 ms Write Only 1 1 – Operation Flush temporary EEPROM page buffer • Bit 3 – EERIE: EEPROM Ready Interrupt Enable Writing EERIE to one enables the EEPROM Ready Interrupt if the I bit in SREG is set. Writing EERIE to zero disables the interrupt. The EEPROM Ready interrupt generates a constant interrupt when EEWE is cleared. The interrupt will not be generated during EEPROM write or SPM. • Bit 2 – EEMWE: EEPROM Master Write Enable The EEMWE bit determines whether setting EEWE to one causes the EEPROM to be written. When EEMWE is set, setting EEWE within four clock cycles will write data to the EEPROM at the selected address If EEMWE is zero, setting EEWE will have no effect. When EEMWE has been written to one by software, hardware clears the bit to zero after four clock cycles. See the description of the EEWE bit for an EEPROM write procedure. • Bit 1 – EEWE: EEPROM Write Enable The EEPROM Write Enable Signal EEWE is the write strobe to the EEPROM. When address and data are correctly set up, the EEWE bit must be written to one to write the value into the EEPROM. The EEMWE bit must be written to one before a logical one is written to EEWE, otherwise no EEPROM write takes place. The following procedure should be followed when writing the EEPROM (the order of steps 3 and 4 is not essential): 1. Wait until EEWE becomes zero. 2. Wait until SPMEN (Store Program Memory Enable) in SPMCSR (Store Program Memory Control and Status Register) becomes zero. 3. Write new EEPROM address to EEAR (optional). 4. Write new EEPROM data to EEDR (optional). 5. Write a logical one to the EEMWE bit while writing a zero to EEWE in EECR. 6. Within four clock cycles after setting EEMWE, write a logical one to EEWE. The EEPROM can not be programmed during a CPU write to the Flash memory. The software must check that the Flash programming is completed before initiating a new EEPROM write. Step 2 is only relevant if the software contains a Boot Loader allowing the CPU to program the Flash. If the Flash is never being updated by the CPU, step 2 can be omitted. See “Boot Loader Support – Read-While-Write Self-Programming” on page 232 for details about Boot programming. 20 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Caution: An interrupt between step 5 and step 6 will make the write cycle fail, since the EEPROM Master Write Enable will time-out. If an interrupt routine accessing the EEPROM is interrupting another EEPROM access, the EEAR or EEDR Register will be modified, causing the interrupted EEPROM access to fail. It is recommended to have the Global Interrupt Flag cleared during all the steps to avoid these problems. When the write access time has elapsed, the EEWE bit is cleared by hardware. The user software can poll this bit and wait for a zero before writing the next byte. When EEWE has been set, the CPU is halted for two cycles before the next instruction is executed. • Bit 0 – EERE: EEPROM Read Enable The EEPROM Read Enable Signal EERE is the read strobe to the EEPROM. When the correct address is set up in the EEAR Register, the EERE bit must be written to a logic one to trigger the EEPROM read. The EEPROM read access takes one instruction, and the requested data is available immediately. When the EEPROM is read, the CPU is halted for four cycles before the next instruction is executed. The user should poll the EEWE bit before starting the read operation. If a write operation is in progress, it is neither possible to read the EEPROM, nor to change the EEAR Register. The calibrated Oscillator is used to time the EEPROM accesses. Table 4-2 lists the typical programming time for EEPROM access from the CPU. Table 4-2. Symbol EEPROM write (from CPU) 4.3.5 EEPROM Programming Time. Number of Calibrated RC Oscillator Cycles Typ Programming Time 26368 3.3 ms Program multiple bytes in one Atomic operation It is possible to write multiple bytes into the EEPROM. Before initiating a programming (erase/write), the data to be written has to be loaded into the temporary EEPROM page buffer. Writing EEPAGE to one enables a load operation. When EEPAGE bit is written to one, the temporary EEPROM page buffer is ready for loading. To load data into the temporary EEPROM page buffer, the address and data must be written into EEARL and EEDR respectively. Note that the data is loaded when EEDR is updated. Therefore, the address must be written before data. This operation is repeated until the temporary EEPROM page buffer is filled up or until all data to be written have been loaded. The number of bytes that is loaded must not exceed the temporary EEPROM page size before performing a program operation. Note that it is not possible to write more than one time to each byte in the temporary EEPROM page buffer before executing a program operation. If the same byte is written multiple times, the content in the temporary EEPROM page will be bit wise AND between the written data (i.e. if 0xaa and 0x55 is loaded to the same byte, the result will be 0x00). The temporary EEPROM buffer will be ready for new data after the program operation has completed. Alternatively, the temporary EEPROM buffer is flushed and ready for new data by writing EEPE (within four cycles after EEMPE is written) if the EEPMn bits are 0b11. When the temporary EEPROM buffer is flushed, the EEPAGE bit will be cleared. Loading data into the temporary EEPROM buffer takes three CPU clock cycles. If EEDR is written while EEPAGE is set, the CPU is halted to ensure that the operation takes three cycles. 21 7734P–AVR–08/10 The order the different bits and registers should be accessed is: 1 Write EEPAGE in EECR (loading of temporary EEPROM buffer is enabled) 2 Write the address bits needed to address bytes within a page into EEARL 3 Write data to EEDR 4 Repeat 2 and 3 above until the buffer is filled up or until all data is loaded 5 Write the remaining address bits into EEARH:EEARL a. Select which programming mode that should be executed (EEPMn bits). Write the EEPE bit in EECR (within four cycles after EEMPE has been written) to start a program operation. The temporary EEPROM page buffer will auto-erase after program operation is completed. OR b. If an error situation occurred and the loading should be terminated by software: Write EEPM1:0 to 0b11 and trigger the flushing by writing EEPE (within four cycles after EEMPE has been written). 4.4 Fuse Bits The AT90PWM81 has three Fuse bytes. Table 4-3 - Table 4-5 describe briefly the functionality of all the fuses and how they are mapped into the Fuse bytes. Note that the fuses are read as logical zero, “0”, if they are programmed. Table 4-3. Extended Low Fuse Byte Extended Fuse Byte Description Default Value PSC2RB 7 PSC2 Reset Behavior 1 PSC2RBA 6 PSC2 Reset Behavior for OUT22 & 23 1 PSCRRB 5 PSC Reduced Reset Behavior 1 PSCRV 4 PSCOUT & PSCOUTR Reset Value 1 PSCINRB 3 PSC & PSCR Inputs Reset Behavior 1 BODLEVEL2(1) 2 Brown-out Detector trigger level 1 (unprogrammed) BODLEVEL1 (1) 1 Brown-out Detector trigger level 0 (programmed) BODLEVEL0 (1) 0 Brown-out Detector trigger level 1 (unprogrammed) Notes: 22 Bit No 1. See Table 7-2 on page 52 for BODLEVEL Fuse decoding AT90PWM81 7734P–AVR–08/10 AT90PWM81 Table 4-4. Fuse High Byte High Fuse Byte Description Default Value 7 External Reset Disable 1 (unprogrammed) DWEN 6 debugWIRE Enable 1 (unprogrammed) SPIEN(2) 5 Enable Serial Program and Data Downloading 0 (programmed, SPI programming enabled) WDTON(3) 4 Watchdog Timer Always On 1 (unprogrammed) EESAVE 3 EEPROM memory is preserved through the Chip Erase 1 (unprogrammed), EEPROM not reserved BOOTSZ1 2 Select Boot Size (see Table 113 for details) 0 (programmed)(4) BOOTSZ0 1 Select Boot Size (see Table 113 for details) 0 (programmed)(4) BOOTRST 0 Select Reset Vector 1 (unprogrammed) RSTDISBL Notes: Bit No (1) 1. See “Alternate Functions of Port E” on page 78 for description of RSTDISBL Fuse. 2. The SPIEN Fuse is not accessible in serial programming mode. 3. See “Watchdog Timer Configuration” on page 59 for details. 4. The default value of BOOTSZ1..0 results in maximum Boot Size.. Table 4-5. Low Fuse Byte Fuse Low Byte Description Default Value 7 Divide clock by 8 0 (programmed) 6 Clock output 1 (unprogrammed) SUT1 5 Select start-up time 1 (unprogrammed)(1) SUT0 4 Select start-up time 0 (programmed)(1) CKSEL3 3 Select Clock source 0 (programmed)(2) CKSEL2 2 Select Clock source 0 (programmed)(2) CKSEL1 1 Select Clock source 1 (unprogrammed)(2) CKSEL0 0 Select Clock source 0 (programmed)(2) CKDIV8(4) CKOUT Note: (3) Bit No 1. The default value of SUT1..0 results in maximum start-up time for the default clock source. See Table 5-4 on page 30 for details. 2. The default setting of CKSEL3..0 results in internal RC Oscillator @ 8 MHz. See Table 5-1 on page 28 for details. 3. The CKOUT Fuse allows the system clock to be output on PORTD0. See “Clock Output Buffer” on page 34 for details. 4. See “System Clock Prescaler” on page 38 for details. The status of the Fuse bits is not affected by Chip Erase. Note that the Fuse bits are locked if Lock bit1 (LB1) is programmed. Program the Fuse bits before programming the Lock bits. 23 7734P–AVR–08/10 4.4.1 Code examples The following code examples show one assembly and one C function for writing to the EEPROM. The examples assume that interrupts are controlled (e.g. by disabling interrupts globally) so that no interrupts will occur during execution of these functions. The examples also assume that no Flash Boot Loader is present in the software. If such code is present, the EEPROM write function must also wait for any ongoing SPM command to finish. Assembly Code Example EEPROM_write: ; Wait for completion of previous write sbic EECR,EEWE rjmp EEPROM_write ; Set up address (r18:r17) in address register out EEARH, r18 out EEARL, r17 ; Write data (r16) to data register out EEDR,r16 ; Write logical one to EEMWE sbi EECR,EEMWE ; Start eeprom write by setting EEWE sbi EECR,EEWE ret C Code Example void EEPROM_write (unsigned int uiAddress, unsigned char ucData) { /* Wait for completion of previous write */ while(EECR & (1<<EEWE)) ; /* Set up address and data registers */ EEAR = uiAddress; EEDR = ucData; /* Write logical one to EEMWE */ EECR |= (1<<EEMWE); /* Start eeprom write by setting EEWE */ EECR |= (1<<EEWE); } 24 AT90PWM81 7734P–AVR–08/10 AT90PWM81 The next code examples show assembly and C functions for reading the EEPROM. The examples assume that interrupts are controlled so that no interrupts will occur during execution of these functions. Assembly Code Example EEPROM_read: ; Wait for completion of previous write sbic EECR,EEWE rjmp EEPROM_read ; Set up address (r18:r17) in address register out EEARH, r18 out EEARL, r17 ; Start eeprom read by writing EERE sbi EECR,EERE ; Read data from data register in r16,EEDR ret C Code Example unsigned char EEPROM_read(unsigned int uiAddress) { /* Wait for completion of previous write */ while(EECR & (1<<EEWE)) ; /* Set up address register */ EEAR = uiAddress; /* Start eeprom read by writing EERE */ EECR |= (1<<EERE); /* Return data from data register */ return EEDR; } 4.4.2 Preventing EEPROM Corruption During periods of low VCC, the EEPROM data can be corrupted because the supply voltage is too low for the CPU and the EEPROM to operate properly. These issues are the same as for board level systems using EEPROM, and the same design solutions should be applied. An EEPROM data corruption can be caused by two situations when the voltage is too low. First, a regular write sequence to the EEPROM requires a minimum voltage to operate correctly. Secondly, the CPU itself can execute instructions incorrectly, if the supply voltage is too low. EEPROM data corruption can easily be avoided by following this design recommendation: Keep the AVR RESET active (low) during periods of insufficient power supply voltage. This can be done by enabling the internal Brown-out Detector (BOD). If the detection level of the internal BOD does not match the needed detection level, an external low VCC reset Protection circuit can be used. If a reset occurs while a write operation is in progress, the write operation will be completed provided that the power supply voltage is sufficient. 25 7734P–AVR–08/10 4.5 I/O Memory The I/O space definition of the AT90PWM81 is shown in “Register Summary” on page 298. All AT90PWM81 I/Os and peripherals are placed in the I/O space. All I/O locations may be accessed by the LD/LDS/LDD and ST/STS/STD instructions, transferring data between the 32 general purpose working registers and the I/O space. I/O registers within the address range 0x00 - 0x1F are directly bitaccessible using the SBI and CBI instructions. In these registers, the value of single bits can be checked by using the SBIS and SBIC instructions. Refer to the instruction set section for more details. When using the I/O specific commands IN and OUT, the I/O addresses 0x00 - 0x3F must be used. When addressing I/O registers as data space using LD and ST instructions, 0x20 must be added to these addresses. The AT90PWM81 is a complex microcontroller with more peripheral units than can be supported within the 64 location reserved in Opcode for the IN and OUT instructions. For the Extended I/O space from 0x60 0xFF in SRAM, only the ST/STS/STD and LD/LDS/LDD instructions can be used. For compatibility with future devices, reserved bits should be written to zero if accessed. Reserved I/O memory addresses should never be written. Some of the status flags are cleared by writing a logical one to them. Note that, unlike most other AVR’s, the CBI and SBI instructions will only operate on the specified bit, and can therefore be used on registers containing such status flags. The CBI and SBI instructions work with registers 0x00 to 0x1F only. The I/O and peripherals control registers are explained in later sections. 4.6 General Purpose I/O Registers The AT90PWM81 contains four General Purpose I/O Registers. These registers can be used for storing any information, and they are particularly useful for storing global variables and status flags. The General Purpose I/O Registers, within the address range 0x00 - 0x1F, are directly bit-accessible using the SBI, CBI, SBIS, and SBIC instructions. 4.6.1 General Purpose I/O Register 0 – GPIOR0 Bit 4.6.2 7 6 5 4 3 2 1 GPIOR07 GPIOR06 GPIOR05 GPIOR04 GPIOR03 GPIOR02 GPIOR01 GPIOR00 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 0 7 6 5 4 3 2 1 GPIOR17 GPIOR16 GPIOR15 GPIOR14 GPIOR13 GPIOR12 GPIOR11 GPIOR10 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 0 GPIOR1 General Purpose I/O Register 2 – GPIOR2 Bit 26 GPIOR0 General Purpose I/O Register 1 – GPIOR1 Bit 4.6.3 0 7 6 5 4 3 2 1 GPIOR27 GPIOR26 GPIOR25 GPIOR24 GPIOR23 GPIOR22 GPIOR21 GPIOR20 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 GPIOR2 AT90PWM81 7734P–AVR–08/10 AT90PWM81 5. System Clock and Clock Options The AT90PWM81 provides a large number of clock sources. Those can be divided in two categories: internal and external. After reset, CKSEL Fuses select one clock source. Once the device is running, software clock switching is available on any other clock sources. Some hardware controls are provided for clock switching management but some specific procedures must be observed. Some settings may lead the user to program the device in an inadequate configuration. 5.1 Clock Systems and their Distribution Figure 5-1 presents the principal clock systems in the AVR and their distribution. All of the clocks may not be active at a given time. In order to reduce power consumption, the clocks from modules not being used can be halted by using different sleep modes or by using features of the dynamic clock switch (“Power Management and Sleep Modes” on page 44 or “Dynamic Clock Switch” on page 35). The clock systems are detailed below. Figure 5-1. Clock Distribution PSC2/PSCR General I/O Modules ADC CPU Core Flash and EEPROM RAM clk ADC clk I/O clk CPU AVR Clock Control Unit clk FLASH CLK PLL PLL Reset Logic Watchdog Timer Source Clock CLK PLL /4 Prescaler PLL Input Multiplexer CKOUT Fuse CLKO Watchdog Clock Clock switch External Clock (Crystal Oscillator) XTAL1 Watchdog Oscillator Calibrated RC Oscillator XTAL2 27 7734P–AVR–08/10 5.1.1 CPU Clock – clkCPU The CPU clock is routed to parts of the system concerned with operation of the AVR core. Examples of such modules are the General Purpose Register File, the Status Register and the Data memory holding the Stack Pointer. Halting the CPU clock inhibits the core from performing general operations and calculations. 5.1.2 I/O Clock – clkI/O The I/O clock is used by the majority of the I/O modules, like Timer/Counter. The I/O clock is also used by the External Interrupt module, but note that some external interrupts are detected by asynchronous logic, allowing such interrupts to be detected even if the I/O clock is halted. 5.1.3 Flash Clock – clkFLASH The Flash clock controls operation of the Flash interface. The Flash clock is usually active simultaneously with the CPU clock. 5.1.4 PLL Clock – clkPLL The PLL clock allows the PSC modules to be clocked directly from a 64/32 MHz clock. A 16 MHz clock is also derived for the CPU. 5.1.5 ADC Clock – clkADC The ADC is provided with a dedicated clock domain. This allows halting the CPU and I/O clocks in order to reduce noise generated by digital circuitry. This gives more accurate ADC conversion results. 5.2 Clock Sources The device has the following clock source options, selectable by Flash Fuse bits (default) or by the CLKSELR register (dynamic clock switch circuit) as shown below. The clock from the selected source is input to the AVR clock generator, and routed to the appropriate modules. Device Clocking Options Select(1) , PLL source and PE1 and PE2 functionality Table 5-1. CKSEL3..0 (3) CSEL3..0 (4) PE1 PE2 RC Osc 0000 CLKI I/O PLL / 4 RC Osc 0001 I/O I/O Calibrated Internal RC Oscillator 8 MHz RC Osc RC Osc 0010 I/O I/O Internal 128 kHz RC Oscillator (WD) WD N/A 0011 I/O I/O PLL output divided by 4 / PLL driven by External Crystal/Ceramic Resonator PLL / 4 Ext Osc 0100 XTAL1 XTAL2 PLL output divided by 4/ PLL driven by External clock PLL / 4 Ext Clk 0101 CLKI I/O Calibrated Internal RC Oscillator 1MHz RC Osc N/A 0110 I/O I/O External Crystal/Ceramic Resonator (3.0 - 8.0 MHz) Ext Osc Ext Osc 0111 b XTAL1 XTAL2 External Crystal/Ceramic Resonator (0.9 - 3.0 MHz) Ext Osc RC Osc 1000 b XTAL1 XTAL2 External Crystal/Ceramic Resonator (0.9 - 3.0 MHz) Ext Osc RC Osc 1001 b XTAL1 XTAL2 External Crystal/Ceramic Resonator (3.0 - 8.0 MHz) Ext Osc RC Osc 1010 b XTAL1 XTAL2 External Crystal/Ceramic Resonator (3.0 - 8.0 MHz) Ext Osc RC Osc 1011 b XTAL1 XTAL2 Device Clocking Option System Clock PLL Input External Clock Ext Clk PLL output divided by 4 : 16 MHz driven by internal RC 28 (2) AT90PWM81 7734P–AVR–08/10 AT90PWM81 Device Clocking Options Select(1) , PLL source and PE1 and PE2 functionality Table 5-1. CKSEL3..0 (3) CSEL3..0 (4) PE1 PE2 RC Osc 1100 b XTAL1 XTAL2 Ext Osc RC Osc 1101 b XTAL1 XTAL2 External Crystal/Ceramic Resonator (8.0 - 16.0 MHz) Ext Osc RC Osc 1110 b XTAL1 XTAL2 External Crystal/Ceramic Resonator (8.0 - 16.0 MHz) Ext Osc RC Osc 1111 b XTAL1 XTAL2 Device Clocking Option System Clock PLL Input External Crystal/Ceramic Resonator (3.0 - 8.0 MHz) Ext Osc External Crystal/Ceramic Resonator (3.0 - 8.0 MHz) Note: (2) 1. For all fuses “1” means unprogrammed while “0” means programmed. 2. PLL must be driven by a nominal 8 MHz clock source 3. Flash Fuse bits. 4. CLKSELR register bits. 5. Ext Osc : External Osc 6. RC Osc : Internal RC Oscillator (1 MHz or 8 MHz) 7. WD : Internal Watch Dog RC Oscillator 128 kHz 8. Ext Clk : External Clock Input The various choices for each clocking option is given in the following sections. When the CPU wakes up from Power-down, or when a new clock source is enabled by the dynamic clock switch circuit, the selected clock source is used to time the start-up, ensuring stable oscillator operation before instruction execution starts. When the CPU starts from reset, there is an additional delay allowing the power to reach a stable level before commencing normal operation. The Watchdog Oscillator is used for timing this real-time part of the start-up time. The number of WDT Oscillator cycles used for each time-out is shown in Table 5-2. Table 5-2. 5.2.1 Number of Watchdog Oscillator Cycles Typ. Time-out Number of Cycles 4 ms 512 64 ms 8K (8,192) Default Clock Source The device will always starts up from reset using the clock source defined by CKSEL Fuses the start-up time defined by SUT Fuses. This configuration is latched in CLKSELR register at reset. The device will always starts up at Power-on using the clock source defined by CLKSELR register (CSEL3..0 and CSUT1:0). The device is shipped with CKSEL Fuses = 0010 b, SUT Fuses = 10 b, and CKDIV8 Fuse programmed. The default clock source setting is therefore the Internal RC Oscillator running at 8 MHz with longest start-up time and an initial system clock prescaling of 8. This default setting ensures that all users can make their desired clock source setting using an In-System or High-voltage Programmer. This set-up must be taken into account when using ISP tools. 5.2.2 Calibrated Internal RC Oscillator By default, the Internal RC OScillator provides an approximate 8.0 MHz clock or a 1 MHz clock. Though voltage and temperature dependent, this clock can be very accurately calibrated by the user. 29 7734P–AVR–08/10 The switch between 8 MHz and 1 MHz is done by the CKRC81 bit in MCUCR register. See “MCU Control Register – MCUCR” on page 41 for more details.The RC oscillator can be accessed by two CKSEL or CSEL configurations. At reset, the CKRC81 bit is initialised with the value compatible with CKSEL value (1 for CKSEL3..0 = 0110, 0 for all other values). The RC oscillator is active for any CKSEL3..0 or CSEL3..0 configuration where it is used as system clock or PLL source clock. The RC oscillator is diabled in the following CKSEL3..0 or CSEL3..0 cases: • 0011 (128k oscillator) • 0100, 0101 (PLL/4 system clock driven by external clock or oscillator) • 1100,1101 (External oscillator) The device is shipped with the CKDIV8 Fuse programmed. See “System Clock Prescaler” on page 38 for more details. This clock may be selected as the system clock by programming the CKSEL Fuses or CSEL field as shown in Table 5-1. If selected, it will operate with no external components. During reset, hardware loads the calibration byte into the OSCCAL Register and thereby automatically calibrates the RC Oscillator.The accuracy of this calibration is shown as Factory calibration in Table 24-1 on page 277. By changing the OSCCAL register from SW, see “OSCCAL – Oscillator Calibration Register” on page 38, it is possible to get a higher calibration accuracy than by using the factory calibration. The accuracy of this calibration is shown as User calibration in Table 24-1 on page 277 When this Oscillator is used as the chip clock, the Watchdog Oscillator will still be used for the Watchdog Timer and for the Reset Time-out. For more information on the pre-programmed calibration value, see the section “Calibration Byte” on page 252. Table 5-3. Internal Calibrated RC Oscillator Operating Modes(1)(3) Frequency Range(2) (MHz) CKSEL3..0 7.6 - 8.4 0010 (4) 0.95 - 1.05 Notes: 0010 1. The device is shipped with this option selected. 2. The frequency ranges are preliminary values. Actual values are TBD. 3. If 8 MHz frequency exceeds the specification of the device (depends on VCC), the CKDIV8 Fuse can be programmed in order to divide the internal frequency by 8. 4. Switch between 8 MHz and 1 MHz is done by CKRC81 bit in MCUCR register. When this Oscillator is selected, start-up times are determined by the SUT Fuses as shown in Table 5-4 on page 30. Table 5-4. Start-up times for the internal calibrated RC Oscillator clock selection Power Conditions Start-up Time from Power-down BOD enabled 6 CK Fast rising power 6 CK Slowly rising power 6 CK Additional Delay from Reset (VCC = 5.0V) (1) 14CK + 4.1 ms Reserved Note: 00 14CK 14CK + 65 ms SUT1..0 (2) 01 10 11 1. If the RSTDISBL fuse is programmed, this start-up time will be increased to 14CK + 4.1 ms to ensure programming mode can be entered. 2. The device is shipped with this option selected. 30 AT90PWM81 7734P–AVR–08/10 AT90PWM81 5.2.2.1 5.2.3 RC Oscillator calibration at Factory The RC oscillator is calibrated at 3V, 25°C for an 8MHz target frequency with an Accuracy +/- 1%. The corresponding value OSCAL (@Amb.) is stored in the signature row and automatically loaded in the OSCAL register at reset. The RC oscillator is monitored at 105°C or 125°C (versus Product version) with an accuracy within +/- 5% limits. 128 KHz Internal Oscillator The 128 KHz internal Oscillator is a low power Oscillator providing a clock of 128 KHz. The frequency is nominal at 3V and 25°C. This clock may be select as the system clock by programming CKSEL Fuses or CSEL field as shown in Table 5-1 on page 28. When this clock source is selected, start-up times are determined by the SUT Fuses or by CSUT field as shown in Table 5-5. Table 5-5. Start-up Times for the 128 kHz Internal Oscillator (1) SUT1..0 CSUT1..0(4) Start-up Time from Power-down Additional Delay from Reset 00 6 CK 14CK 01 6 CK 14CK + 4 ms Fast rising power 10 6 CK 14CK + 64 ms Slowly rising power 11 Notes: Recommended Usage BOD enabled Reserved 1. Flash Fuse bits 2. CLKSELR register bits 5.2.4 Crystal Oscillator XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier which can be configured for use as an On-chip Oscillator, as shown in Figure 5-2. Either a quartz crystal or a ceramic resonator may be used. C1 and C2 should always be equal for both crystals and resonators. The optimal value of the capacitors depends on the crystal or resonator in use, the amount of stray capacitance, and the electromagnetic noise of the environment. Some initial guidelines for choosing capacitors for use with crystals are given in Table 5-6. For ceramic resonators, the capacitor values given by the manufacturer should be used. Figure 5-2. Crystal Oscillator Connections C2 C1 XTAL2 XTAL1 GND 31 7734P–AVR–08/10 The Oscillator can operate in three different modes, each optimized for a specific frequency range. The operating mode is selected by CKSEL3..1 fuses or by CSEL3..1 field as shown in Table 5-6. Table 5-6. Crystal Oscillator Operating Modes (1) CKSEL3..1 CSEL3..1(2) Frequency Range (MHz) Recommended Range for Capacitors C1 and C2 for Use with Crystals (pF) 100(3) 0.4 - 0.9 – 101 0.9 - 3.0 12 - 22 110 3.0 - 8.0 12 - 22 111 8.0 - 16.0 12 - 22 Notes: 1. Flash Fuse bits. 2. CLKSELR register bits. 3. This option should not be used with crystals, only with ceramic resonators. The CKSEL0 Fuse together with the SUT1..0 Fuses or CSEL0 together with CSUT1..0 field select the start-up times as shown in Table 5-7. Table 5-7. Start-up Times for the Crystal Oscillator Clock Selection CKSEL0(1) CSEL0(2) SUT1..0(1) CSUT1..0(2) Start-up Time from Power-down and Power-save Additional Delay from Reset (Vcc = 5.0V) 0 00 258 CK(3) 14CK + 4.1 ms Ceramic resonator, fast rising power 0 01 258 CK(3) 14CK + 65 ms Ceramic resonator, slowly rising power 0 10 1K (1024) CK(4) 14CK Ceramic resonator, BOD enabled 0 11 1K (1024)CK(4) 14CK + 4.1 ms Ceramic resonator, fast rising power 1 00 1K (1024)CK(4) 14CK + 65 ms Ceramic resonator, slowly rising power 1 01 16K (16384) CK 14CK 1 10 16K (16384) CK 14CK + 4.1 ms Crystal Oscillator, fast rising power 1 11 16K (16384) CK 14CK + 65 ms Crystal Oscillator, slowly rising power Notes: Recommended Usage Crystal Oscillator, BOD enabled 1. Flash Fuse bits. 2. CLKSELR register bits. 3. These options should only be used when not operating close to the maximum frequency of the device, and only if frequency stability at start-up is not important for the application. These options are not suitable for crystals. 4. These options are intended for use with ceramic resonators and will ensure frequency stability at startup. They can also be used with crystals when not operating close to the maximum frequency of the device, and if frequency stability at start-up is not important for the application. 32 AT90PWM81 7734P–AVR–08/10 AT90PWM81 5.2.5 External Clock To drive the device from this external clock source, CLKI should be driven as shown in Figure 5-3. To run the device on an external clock, the CKSEL Fuses or CSEL field must be programmed as shown in Table 5-1 on page 28. Figure 5-3. External Clock Drive Configuration External Clock Signal CLKI (XTAL1) GND When this clock source is selected, start-up times are determined by the SUT Fuses or CSUT field as shown in Table 5-8. Table 5-8. Start-up Times for the External Clock Selection SUT1..0(1) CSUT1..0(2) Start-up Time from Power-down Additional Delay from Reset 00 6 CK 14CK 01 6 CK 14CK + 4 ms Fast rising power 10 6 CK 14CK + 64 ms Slowly rising power 11 Notes: Recommended Usage BOD enabled Reserved 1. Flash Fuse bits. 2. CLKSELR register bits. Note that the System Clock Prescaler can be used to implement run-time changes of the internal clock frequency while still ensuring stable operation. Refer to “System Clock Prescaler” on page 38 for details. 5.2.6 PLL To generate high frequency and accurate PWM waveforms, the ‘PSC’s need high frequency clock input. This clock is generated by a PLL. To keep all PWM accuracy, the frequency factor of PLL must be configured by software.. The internal PLL in AT90PWM81 generates a clock frequency multiplied from nominally 8 MHz input. The source of the 8 MHz PLL input clock can be selected from three possible sources (See the Figure 5-4 on page 34) : • Internal RC Oscillator • Crystal oscillator • External clock The internal PLL is enabled only when the PLLE bit in the register PLLCSR is set. The bit PLOCK from the register PLLCSR is set when PLL is locked. When selected as clock source by fuse, the PLL multiplication factor is initialized at the value of 6, compatible with a 3V supply. 33 7734P–AVR–08/10 The PLL is locked on the source oscillator which must remains close to 8 MHz to assure proper lock of the PLL. Both internal RC Oscillator and PLL are switched off in Power-down and Standby sleep modes Table 5-9. Start-up Times when the PLL is selected as system clock CKSEL3..0 SUT1..0 Start-up Time from Power-down Additional Delay from Reset (VCC = 5.0V) 00 1K CK 14CK 01 1K CK 14CK + 4 ms 10 1K CK 14CK + 64 ms 11 16K CK 14CK 00 16K CK 14CK 01 16K CK 14CK + 4 ms 10 16K CK 14CK + 4 ms 11 16K CK 14CK + 64 ms 00 1K CK 14CK 01 1K CK 14CK + 4 ms 10 1K CK 14CK + 64 ms Clock Source 0100 External Crystal or resonator 0101 0001 External Clock Figure 5-4. Internal RC Oscillator PCK Clocking System OSCCAL CKSEL3..0 PLLE PLLF3..0 PLOCK Lock Detector RC OSCILLATOR 8 MHz PLL *N CLK PLL DIVIDE BY 4 CK SOURCE XTAL1 XTAL2 5.2.7 34 OSCILLATORS Clock Output Buffer The device can output the system clock on the CLKO pin. To enable the output, the CKOUT Fuse or COUT bit of CLKSELR register has to be programmed. This mode is suitable when the chip clock is used to drive other circuits on the system. Note that the clock will not be output during reset and the normal operation of I/O pin will be overridden when the fuses are programmed. Any clock source can be selected when the clock is output on CLKO. If the System Clock Prescaler is used, it is the divided system clock that is output. AT90PWM81 7734P–AVR–08/10 AT90PWM81 5.3 5.3.1 Dynamic Clock Switch Features AT90PWM81 provides a powerful dynamic clock switch that allows users to turn on and off clocks of the device on the fly. The built-in de-glitching circuitry allows clocks to be enabled or disabled asynchronously. This enables efficient power management schemes to be implemented easily and quickly. In a safety application, the dynamic clock switch circuit may continuously monitor the external clock fails. The AT90PWM81 provides one register for Clock Fuse substitution (CLKSELR) and one register to control the dynamic clock switch circuit (CLKCSR). The watchdog is used to monitor external clock source if needed. The control of the dynamic clock switch circuit must be supervised by software. The low level control is performed by hardware through the CLKCSR register. The features are: • Safe commands, to avoid unintentional commands, a special write procedure must be followed to change the CLKCSR register bits (See “CLKCSR – Clock Control & Status Register” on page 41.): • Exclusive action, the actions are controlled by a decoding (command table). The main commands of the dynamic clock switching are: – ‘Disable Clock Source’, – ‘Enable Clock Source’, – ‘Request for Clock Availability’, – ‘Clock Source Switching’, – ‘Recover System Clock Source’. • Status, a status on the availability of the enabled clock and the code recovering of clock source used to drive the system clock are provided. 5.3.2 Fuses substitution During reset, bits of the Low Fuse Byte are latched in the CLKSELR register. The content of this register can operate as well as the Low Fuse Byte. CKSEL3..0, SUT1..0 and CKOUT fuses are substituted as shown in Figure 5-5 on page 35 and replaced respectively by CSEL3..0, CSUT1:0 and COUT. 5.3.3 Clock Source Selection The available codes of clock source is given are in Table 5-1 on page 28. Fuses substitution and Clock Source Selection CKSEL[3..0] CSEL[3..0] CSUT[1..0] COUT Default CLKSEL[3..0] SUT[1..0] CKOUT Reset R/W Reg. Register: CLKSELR Internal Data Bus Fuse: Fuse Low Byte ( ) SCLKRq * SEL Decodeur Figure 5-5. SEL-0 SEL-1 SEL-2 SEL-n Selected Configuration SUT[1..0] ( ) SCLKRq * : Command of Clock Control & Status Register SEL Encodeur CKOUT EN-0 EN-1 EN-2 Clock Switch Current Configuration EN-n 35 7734P–AVR–08/10 When ‘Enable/Disable Clock Source’, ‘Request for Clock Availability’ or ‘Clock Source Switching’ command is entered, the selected configuration provided by the CLKSELR register is latched for each targeted clock source. ‘Recover System Clock Source’ command enables the code recovering of clock source used to drive the system clock. The CKSEL field of CLKSELR register is then updated with this code. There is no information on the SUT used or status on CKOUT. Because the selected configuration is latched at clock source level, it is possible to enable many clock sources at a given time (ex: the internal RC oscillator for system clock + an oscillator with external crystal). The user’s software has the responsibility of this management. ‘Request for Clock Availability’ command returns the working order of the clock source addressed. The status is set in the CLKRDY bit of CLKCSR register 5.3.4 Enable/Disable Clock Source ‘Enable Clock Source’ command selects and enables the clock source provided by the setting of CLKSELR register (CSEL3..0 and CSUT1:0). CSEL field will select the clock source and CSUT field will select the start-up time (as CKSEL and SUT fuse bits do it). To be sure that a clock source has been enabled, it will be better to perform a ‘Request for Clock Availability’ command after the ‘Enable Clock Source’ command. ‘Disable Clock Source’ command disables the clock source provided by the setting of CLKSELR register (only CSEL3..0). If the clock source is the one that is used to drive the system clock, the command is not taken into account. 5.3.5 Clock Availability ‘Request for Clock Availability’ command enables an oscillation-counting of the selected source clock, CSEL3..0. The count is provided by CSUT1..0. The clock is declared ready (CLKRDY = 1) when the count is finished. This flag remains unchanged up to a new count. The CLKRDY flag is reset when the count starts. To perform this checking, the CKSEL and CSUT fields should not change all long the operation is running. Two usages are possible: 5.3.6 1. Clock stability before switching Once the new clock source is selected, the count procedure is running. The user (code) should wait for the setting of the CLKRDY flag in CLKSCR register before to perform a switching. 2. Clock available on request AT any time, the user (code) can ask for the availability of a clock source. The user (code) can request it writing the appropriate command in the CLKSCR register. A full status on clock sources then can be done. Clock Switching To drive the system clock, the user can switch from the current clock source to the following ones (one of them is the current clock source): 1. 2. 3. 4. 5. Calibrated internal RC oscillator 8.0/1.0 MHz, Internal watchdog oscillator 128 kHz, External clock, External Crystal/Ceramic Resonator PLL output divided by four. The clock switching is performed in a sequence of commands. First, the user (code) must make sure that the new clock source is running. Then the switching command can be entered. At the end, the user (code) 36 AT90PWM81 7734P–AVR–08/10 AT90PWM81 can stop the previous clock source. It will be better to run this sequence once the interrupts disabled. The user (code) has the responsibility of the clock switching sequence. Here is a “light” C-code that describes such a sequence of commands. C Code Example void ClockSwiching (unsigned char clk-number, unsigned char sut) { #define #define #define #define CLOCK-RECOVER CLOCK-ENABLE CLOCK-SWITCH CLOCK-DISABLE 0x05 0x02 0x04 0x01 unsigned char previous-clk, temp; // Disable interrupts asm ("cli"); temp = SREG; // “Recover System Clock Source” command CLKCSR = 1 << CLKCCE; CLKCSR = CLOCK-RECOVER; previous-clk = CLKSELR & 0x0F; // “Enable Clock Source” command CLKSELR = ((sut << 4 ) & 0x30) | (clk-number & 0x0F); CLKCSR = 1 << CLKCCE; CLKCSR = CLOCK-ENABLE; // Wait for clock availability while ((CLKCSR & (1 << CLKRDY)) == 0); // “Clock Source Switching” command CLKCSR = 1 << CLKCCE; CLKCSR = CLOCK-SWITCH; // Wait for effective switching while (1){ CLKCSR = 1 << CLKCCE; CLKCSR = CLOCK-RECOVER; if ((CLKSELR & 0x0F) == (clk-number & 0x0F)) break; } // “Disable Clock Source” command CLKSELR = previous-clk; CLKCSR = 1 << CLKCCE; CLKCSR = CLOCK-DISABLE; // Re-enable interrupts SREG = temp; asm ("sei"); } Warning: In the AT90PWM81, only one among the external clock sources can be enabled at a given time and it is not possible to switch from external clock to external oscillator as both sources share one pin. Also, it is not possible to switch the synchronization source of the PLL when the sytem clock is PLL/4. See Table 5-1 on page 28 to identify these cases. As they are two CSEL adresses to access the Calibrated internal RC oscillator 8.0/1.0 MHz, the change between the two frequencies is not allowed by the clock switching features. The CKRC81 bit in MCUCR register must be used for this purpose. 37 7734P–AVR–08/10 5.4 5.4.1 System Clock Prescaler Features The AT90PWM81 system clock can be divided by setting the Clock Prescaler Register – CLKPR. This feature can be used to decrease power consumption when the requirement for processing power is low. This can be used with all clock source options, and it will affect the clock frequency of the CPU and all synchronous peripherals. clkI/O, clkADC, clkCPU, and clkFLASH are divided by a factor as shown in Table 510 on page 39. 5.4.2 Switching Time When switching between prescaler settings, the System Clock Prescaler ensures that no glitches occur in the clock system and that no intermediate frequency is higher than neither the clock frequency corresponding to the previous setting, nor the clock frequency corresponding to the new setting. The ripple counter that implements the prescaler runs at the frequency of the undivided clock, which may be faster than the CPU’s clock frequency. Hence, it is not possible to determine the state of the prescaler – even if it were readable, and the exact time it takes to switch from one clock division to another cannot be exactly predicted. From the time the CLKPS values are written, it takes between T1 + T2 and T1 + 2*T2 before the new clock frequency is active. In this interval, 2 active clock edges are produced. Here, T1 is the previous clock period, and T2 is the period corresponding to the new prescaler setting. 5.5 5.5.1 Register Description OSCCAL – Oscillator Calibration Register Bit Read/Write Initial Value 7 6 5 4 3 2 1 0 CAL7 CAL6 CAL5 CAL4 CAL3 CAL2 CAL1 CAL0 R/W R/W R/W R/W R/W R/W R/W R/W OSCCAL Device Specific Calibration Value • Bits 7:0 – CAL7:0: Oscillator Calibration Value The Oscillator Calibration Register is used to trim the Calibrated Internal RC Oscillator to remove process variations from the oscillator frequency. The factory-calibrated value is automatically written to this register during chip reset, giving an oscillator frequency of 8.0 MHz at 25°C. The application software can write this register to change the oscillator frequency. The oscillator can be calibrated to any frequency in the range 7.6 - 8.4 MHz within ± 1% accuracy. Calibration outside that range is not guaranteed. Note that this oscillator is used to time EEPROM and Flash write accesses, and these write times will be affected accordingly. If the EEPROM or Flash are written, do not calibrate to more than 8.8 MHz. Otherwise, the EEPROM or Flash write may fail. The CAL7..0 bits are used to tune the frequency within the selected range. A setting of 0x00 gives the lowest frequency in that range, and a setting of 0x7F gives the highest frequency in the range. Incrementing CAL7..0 by 1 will give a frequency increment of less than 0.5% in the frequency range 7.6 - 8.4 MHz. 38 AT90PWM81 7734P–AVR–08/10 AT90PWM81 5.5.2 CLKPR – Clock Prescaler Register Bit 7 6 5 4 3 2 1 0 CLKPCE – – – CLKPS3 CLKPS2 CLKPS1 CLKPS0 Read/Write R/W R R R R/W R/W R/W R/W Initial Value 0 0 0 0 CLKPR See Bit Description • Bit 7 – CLKPCE: Clock Prescaler Change Enable The CLKPCE bit must be written to logic one to enable change of the CLKPS bits. The CLKPCE bit is only updated when the other bits in CLKPR are simultaneously written to zero. CLKPCE is cleared by hardware four cycles after it is written or when the CLKPS bits are written. Rewriting the CLKPCE bit within this time-out period does neither extend the time-out period, nor clear the CLKPCE bit. • Bits 6:4 – Res: Reserved Bits These bits are reserved bits in the AT90PWM81 and will always read as zero. • Bits 3:0 – CLKPS3:0: Clock Prescaler Select Bits 3 - 0 These bits define the division factor between the selected clock source and the internal system clock. These bits can be written run-time to vary the clock frequency to suit the application requirements. As the divider divides the master clock input to the MCU, the speed of all synchronous peripherals is reduced when a division factor is used. The division factors are given in Table 5-10. To avoid unintentional changes of clock frequency, a special write procedure must be followed to change the CLKPS bits: 1. Write the Clock Prescaler Change Enable (CLKPCE) bit to one and all other bits in CLKPR to zero. 2. Within four cycles, write the desired value to CLKPS while writing a zero to CLKPCE. Interrupts must be disabled when changing prescaler setting in order not to disturb the procedure. The CKDIV8 Fuse determines the initial value of the CLKPS bits. If CKDIV8 is unprogrammed, the CLKPS bits will be reset to “0000”. If CKDIV8 is programmed, CLKPS bits are reset to “0011”, giving a division factor of eight at start up. This feature should be used if the selected clock source has a higher frequency than the maximum frequency of the device at the present operating conditions. Note that any value can be written to the CLKPS bits regardless of the CKDIV8 Fuse setting. The Application software must ensure that a sufficient division factor is chosen if the selected clock source has a higher frequency than the maximum frequency of the device at the present operating conditions. The device is shipped with the CKDIV8 Fuse programmed. Table 5-10. Clock Prescaler Select CLKPS3 CLKPS2 CLKPS1 CLKPS0 Clock Division Factor 0 0 0 0 1 0 0 0 1 2 0 0 1 0 4 0 0 1 1 8 0 1 0 0 16 0 1 0 1 32 0 1 1 0 64 0 1 1 1 128 39 7734P–AVR–08/10 Table 5-10. 5.5.3 Clock Prescaler Select (Continued) CLKPS3 CLKPS2 CLKPS1 CLKPS0 Clock Division Factor 1 0 0 0 256 1 0 0 1 Reserved 1 0 1 0 Reserved 1 0 1 1 Reserved 1 1 0 0 Reserved 1 1 0 1 Reserved 1 1 1 0 Reserved 1 1 1 1 Reserved PLL Control and Status Register – PLLCSR Bit 7 6 5 4 3 2 1 0 $29 ($29) – – PLLF3 PLLF2 PLLF1 PLLF0 PLLE PLOCK Read/Write R R R/W R/W R/W R/W R/W R Initial Value 0 0 0 1 0 0 0/1 0 PLLCSR • Bit 7..3 – Res: Reserved Bits These bits are reserved bits in the AT90PWM81 and always read as zero. • Bit 5..2-– PLLF: PLL Factor The PLLF bits is used to select the multiplication factor of the PLL . Table 5-11. PLLF3..0 PLL multiplication factor N+2 7-F Reserved 6 8 64 5 7 56 4 6 48 3 5 40 2 4 32 0-1 Note: 40 PLL frequency MHz Reserved PLLF3 is used for debug purpose (must be wired) AT90PWM81 7734P–AVR–08/10 AT90PWM81 • Bit 1 – PLLE: PLL Enable When the PLLE is set, the PLL is started and if not yet started the internal RC Oscillator is started as PLL reference clock. If PLL is selected as a system clock source the value for this bit is always 1. • Bit 0 – PLOCK: PLL Lock Detector When the PLOCK bit is set, the PLL is locked to the reference clock, and it is safe to enable CLKPLL for PSC. The time to lock is specified in Table 5-9 on page 34. 5.5.4 MCU Control Register – MCUCR Bit 7 6 5 4 3 2 1 – – – PUD RSTDIS CKRC81 IVSEL IVCE Read/Write R R R R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0/1(1) 0 0 0 Notes: 0 MCUCR 1. V alue is Initialized with the fuse CKSEL2 2. Value is initialized with fuses CKSEL3..0 (1 when CKSEL3..0= 0110, 0 in all other cases) • Bit 2– CKRC81: Frequency Selection of the calibrated 8/1 MHz RC Oscillator Thanks to CKRC81 in MCUCR Sfr, the typical frequency of the calibrated RC oscillator is changed. – When the CKRC81 bit is written to zero, the RC oscillator frequency is 8 MHz. – When the CKRC81 bit is written to one, the RC oscillator frequency is 1 MHz. 5.5.5 Note: This be only can be changed only when the RC oscillator is enabled. Note: When the RC oscillator is used as the PLL source, CKRC81 must not be written to 1. Note: If the RC oscillator is disabled, this bit is cleared by hardware CLKCSR – Clock Control & Status Register Bit 7 6 5 4 3 2 1 0 CLKCCE – – CLKRDY CLKC3 CLKC2 CLKC1 CLKC0 Read/Write R/W R R R R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 CLKCSR • Bit 7 – CLKCCE: Clock Control Change Enable The CLKCCE bit must be written to logic one to enable change of the CLKCSR bits. The CLKCCE bit is only updated when the other bits in CLKCSR are simultaneously written to zero. CLKCCE is cleared by hardware four cycles after it is written or when the CLKCSR bits are written. Rewriting the CLKCCE bit within this time-out period does neither extend the time-out period, nor clear the CLKCCE bit. • Bits 6:5 – Res: Reserved Bits These bits are reserved bits in the AT90PWM81 and will always read as zero. • Bits 4 – CLKRDY: Clock Ready Flag This flag is the output of the ‘Clock Availability’ logic. This flag is reset once the ‘Request for Clock Availability’ command is entered. It is set when ‘Clock Availability’ logic confirms that the (selected) clock is running and is stable. The delay from the request and the flag setting is not fixed, it depends on the clock start-up time, the clock frequency and, of course, if the clock is alive. The user’s has itself to do the difference between ‘no_clock_signal’ and ‘clock_signal_not_yet_available’. 41 7734P–AVR–08/10 • Bits 3:0 – CLKC3:0: Clock Control Bits 3 - 0 These bits define the command to provide to the ‘Clock Switch’ module. The special write procedure must be followed to change the CLKC bits (See ”Bit 7 – CLKCCE: Clock Control Change Enable” on page 41.). 1. Write the Clock Control Change Enable (CLKCCE) bit to one and all other bits in CLKCSR to zero. 2. Within 4 cycles, write the desired value to CLKCSR register while clearing CLKCCE bit. Interrupts should be disabled when setting CLKCSR register in order not to disturb the procedure. Table 5-12. Clock command list. Clock Command 5.5.6 CLKC3..0 No command 0000 b Disable clock source 0001 b Enable clock source 0010 b Request for clock availability 0011 b Clock source switch 0100 b Recover system clock source code 0101 b CKOUT command 0111 b No command 1xxx b Clock Selection Register - CLKSELR Bit 7 6 5 4 3 2 1 0 - COUT CSUT1 CSUT0 CSEL3 CSEL2 CSEL1 CSEL0 Read/Write R R/W R/W R/W R/W R/W R/W R/W Initial Value 0 CKOUT fuse SUT1..0 fuses CLKSELR CKSEL3..0 fuses • Bit 7– Res: Reserved Bit This bit is reserved bit in the AT90PWM81 and will always read as zero. • Bit 6 – COUT: Clock Out The COUT bit is initialized with CKOUT Fuse bit. The COUT bit is only used in case of ‘CKOUT’ command. Refer to Section 5.2.7 ”Clock Output Buffer” on page 34 for using. In case of ‘Recover System Clock Source’ command, COUT it is not affected (no recovering of this setting). • Bits 5:4 – CSUT1:0: Clock Start-up Time CSUT bits are initialized with the values of SUT Fuse bits. In case of ‘Enable/Disable Clock Source’ command, CSUT field provides the code of the clock start-up time. Refer to subdivisions of Section 5.2 ”Clock Sources” on page 28 for code of clock start-up times. In case of ‘Recover System Clock Source’ command, CSUT field is not affected (no recovering of SUT code). 42 AT90PWM81 7734P–AVR–08/10 AT90PWM81 • Bits 3:0 – CSEL3:0: Clock Source Select CSEL bits are initialized with the values of CKSEL Fuse bits. In case of ‘Enable/Disable Clock Source’, ‘Request for Clock Availability’ or ‘Clock Source Switch’ command, CSEL field gets back the code of the clock source. Refer to Table 5-1 on page 28 and subdivisions of Section 5.2 ”Clock Sources” on page 28 for clock source codes. In case of ‘Recover System Clock Source’ command, CSEL field receives the code of the clock source used to drive the Clock Control Unit as described in Figure 5-1 on page 27. 43 7734P–AVR–08/10 6. Power Management and Sleep Modes Sleep modes enable the application to shut down unused modules in the MCU, thereby saving power. The AVR provides various sleep modes allowing the user to tailor the power consumption to the application’s requirements. 6.1 Sleep Modes Figure 5-1 on page 27 presents the different clock systems in the AT90PWM81, and their distribution. The figure is helpful in selecting an appropriate sleep mode. Table 6-1 shows the different sleep modes, their wake up sources. Table 6-1. Active Clock Domains and Wake-up Sources in the Different Sleep Modes. clkPLL Main Clock Source Enabled INT3..0 PSC SPM/EEPROM Ready ADC WDT Other/O X X X X X X X X X X X X X X(2) X X X X ADC Noise Reduction Powerdown Standby(1) Notes: Wake-up Sources clkADC Idle Oscillators clkIO Sleep Mode clkFLASH clkCPU Active Clock Domains X X(2) X X(2) X 1. Only recommended with external crystal or resonator selected as clock source. 2. Only level interrupt. To enter any of the five sleep modes, the SE bit in SMCR must be written to logic one and a SLEEP instruction must be executed. The SM2, SM1, and SM0 bits in the SMCR Register select which sleep mode (Idle, ADC Noise Reduction, Power-down or Standby) will be activated by the SLEEP instruction. See Table 6-2 on page 47 for a summary. If an enabled interrupt occurs while the MCU is in a sleep mode, the MCU wakes up. The MCU is then halted for four cycles in addition to the start-up time, executes the interrupt routine, and resumes execution from the instruction following SLEEP. The contents of the register file and SRAM are unaltered when the device wakes up from sleep. If a reset occurs during sleep mode, the MCU wakes up and executes from the Reset Vector. 6.2 Idle Mode When the SM2..0 bits are written to 000, the SLEEP instruction makes the MCU enter Idle mode, stopping the CPU but allowing SPI, Analog Comparator, ADC, Timer/Counters, Watchdog, and the interrupt system to continue operating. This sleep mode basically halt clkCPU and clkFLASH, while allowing the other clocks to run. Idle mode enables the MCU to wake up from external triggered interrupts as well as internal ones like the Timer Overflow interrupts. If wake-up from the Analog Comparator interrupt is not required, the Analog Comparator can be powered down by clearing the ACnEN bit in the Analog Comparator Control and Sta- 44 AT90PWM81 7734P–AVR–08/10 AT90PWM81 tus Register – ACnCON. This will reduce power consumption in Idle mode. If the ADC is enabled, a conversion starts automatically when this mode is entered. 6.3 ADC Noise Reduction Mode When the SM2..0 bits are written to 001, the SLEEP instruction makes the MCU enter ADC Noise Reduction mode, stopping the CPU but allowing the ADC, the External Interrupts, Timer/Counter (if their clock source is external - T0 or T1) and the Watchdog to continue operating (if enabled). This sleep mode basically halts clkI/O, clkCPU, and clkFLASH, while allowing the other clocks to run. This improves the noise environment for the ADC, enabling higher resolution measurements. If the ADC is enabled, a conversion starts automatically when this mode is entered. Apart from the ADC Conversion Complete interrupt, only an External Reset, a Watchdog Reset, a Brown-out Reset, a Timer/Counter interrupt, an SPM/EEPROM ready interrupt, an External Level Interrupt on INT2:0 can wake up the MCU from ADC Noise Reduction mode. 6.4 Power-down Mode When the SM2..0 bits are written to 010, the SLEEP instruction makes the MCU enter Power-down mode. In this mode, the External Oscillator is stopped, while the External Interrupts and the Watchdog continue operating (if enabled). Only an External Reset, a Watchdog Reset, a Brown-out Reset, a PSC Interrupt, an External Level Interrupt on INT2:0 can wake up the MCU. This sleep mode basically halts all generated clocks, allowing operation of asynchronous modules only. Note that if a level triggered interrupt is used for wake-up from Power-down mode, the changed level must be held for some time to wake up the MCU. Refer to “External Interrupts” on page 82 for details. When waking up from Power-down mode, there is a delay from the wake-up condition occurs until the wake-up becomes effective. This allows the clock to restart and become stable after having been stopped. The wake-up period is defined by the same CKSEL fuses that define the Reset Time-out period, as described in “Clock Sources” on page 28. 6.5 Standby Mode When the SM2..0 bits are 110 and an external crystal/resonator clock option is selected, the SLEEP instruction makes the MCU enter Standby mode. This mode is identical to Power-down with the exception that the Oscillator is kept running. From Standby mode, the device wakes up in six clock cycles. 6.6 Power Reduction Register The Power Reduction Register, PRR, provides a method to stop the clock to individual peripherals to reduce power consumption. The current state of the peripheral is frozen and the I/O registers can not be read or written. Resources used by the peripheral when stopping the clock will remain occupied, hence the peripheral should in most cases be disabled before stopping the clock. Waking up a module, which is done by clearing the bit in PRR, puts the module in the same state as before shutdown. A full predictable behavior of a peripheral is not guaranteed during and after a cycle of stopping and starting of its clock. So its recommended to stop a peripheral before stopping its clock with PRR register. Module shutdown can be used in Idle mode and Active mode to significantly reduce the overall power consumption. In all other sleep modes, the clock is already stopped. 6.7 Minimizing Power Consumption There are several issues to consider when trying to minimize the power consumption in an AVR controlled system. In general, sleep modes should be used as much as possible, and the sleep mode should be 45 7734P–AVR–08/10 selected so that as few as possible of the device’s functions are operating. All functions not needed should be disabled. In particular, the following modules may need special consideration when trying to achieve the lowest possible power consumption. 6.7.1 Analog to Digital Converter If enabled, the ADC will be enabled in all sleep modes. To save power, the ADC should be disabled before entering any sleep mode. When the ADC is turned off and on again, the next conversion will be an extended conversion. Refer to “CROSS REFERENCE REMOVED” for details on ADC operation. 6.7.2 Analog Comparator When entering Idle mode, the Analog Comparator should be disabled if not used. When entering ADC Noise Reduction mode, the Analog Comparator should be disabled. In other sleep modes, the Analog Comparator is NOT automatically disabled, so it should be disabled if not used However, if the Analog Comparator is set up to use the Internal Voltage Reference as input, the Analog Comparator should be disabled in all sleep modes. Otherwise, the Internal Voltage Reference will be enabled, independent of sleep mode. Refer to “Analog Comparator” on page 194 for details on how to configure the Analog Comparator. 6.7.3 Brown-out Detector If the Brown-out Detector is not needed by the application, this module should be turned off. If the Brown-out Detector is enabled by the BODLEVEL Fuses, it will be enabled in all sleep modes, and hence, always consume power. In the deeper sleep modes, this will contribute significantly to the total current consumption. Refer to “Brown-out Detection” on page 52 for details on how to configure the Brown-out Detector. 6.7.4 Internal Voltage Reference The Internal Voltage Reference will be enabled when needed by the Brown-out Detection, the Analog Comparator or the ADC. If these modules are disabled as described in the sections above, the internal voltage reference will be disabled and it will not be consuming power. When turned on again, the user must allow the reference to start up before the output is used. If the reference is kept on in sleep mode, the output can be used immediately. Refer to “Internal Voltage Reference” on page 54 for details on the startup time. 6.7.5 Watchdog Timer If the Watchdog Timer is not needed in the application, the module should be turned off. If the Watchdog Timer is enabled, it will be enabled in all sleep modes, and hence, always consume power. In the deeper sleep modes, this will contribute significantly to the total current consumption. Refer to “Watchdog Timer” on page 55 for details on how to configure the Watchdog Timer. 6.7.6 Port Pins When entering a sleep mode, all port pins should be configured to use minimum power. The most important is then to ensure that no pins drive resistive loads. In sleep modes where both the I/O clock (clkI/O) and the ADC clock (clkADC) are stopped, the input buffers of the device will be disabled. This ensures that no power is consumed by the input logic when not needed. In some cases, the input logic is needed for detecting wake-up conditions, and it will then be enabled. Refer to the section “I/O-Ports” on page 66 for details on which pins are enabled. If the input buffer is enabled and the input signal is left floating or have an analog signal level close to VCC/2, the input buffer will use excessive power. 46 AT90PWM81 7734P–AVR–08/10 AT90PWM81 For analog input pins, the digital input buffer should be disabled at all times. An analog signal level close to VCC/2 on an input pin can cause significant current even in active mode. Digital input buffers can be disabled by writing to the Digital Input Disable Registers (DIDR1 and DIDR0). Refer to “Digital Input Disable Register 1– DIDR1” and “Digital Input Disable Register 0 – DIDR0” on page 202 and page 221 for details. 6.7.7 6.8 6.8.1 On-chip Debug System If the On-chip debug system is enabled by OCDEN Fuse and the chip enter sleep mode, the main clock source is enabled, and hence, always consumes power. In the deeper sleep modes, this will contribute significantly to the total current consumption. Register description Sleep Mode Control Register – SMCR The Sleep Mode Control Register contains control bits for power management. Bit 7 6 5 4 3 2 1 0 – – – – SM2 SM1 SM0 SE Read/Write R R R R R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 SMCR • Bits 3..1 – SM2..0: Sleep Mode Select Bits 2, 1, and 0 These bits select between the five available sleep modes as shown in Table 6-2. Table 6-2. Note: Sleep Mode Select SM2 SM1 SM0 Sleep Mode 0 0 0 Idle 0 0 1 ADC Noise Reduction 0 1 0 Power-down 0 1 1 Reserved 1 0 0 Reserved 1 0 1 Reserved 1 1 0 Standby(1) 1 1 1 Reserved 1. Standby mode is only recommended for use with external crystals or resonators. • Bit 1 – SE: Sleep Enable The SE bit must be written to logic one to make the MCU enter the sleep mode when the SLEEP instruction is executed. To avoid the MCU entering the sleep mode unless it is the programmer’s purpose, it is recommended to write the Sleep Enable (SE) bit to one just before the execution of the SLEEP instruction and to clear it immediately after waking up. 6.8.2 Power Reduction Register - PRR Bit 7 6 5 4 3 2 1 0 PRPSC2 - PRPSCR PRTIM1 - PRSPI - PRADC Read/Write R/W R R/W R/W R R/W R R/W Initial Value 0 0 0 0 0 0 0 0 PRR 47 7734P–AVR–08/10 • Bit 7 - PRPSC2: Power Reduction PSC2 Writing a logic one to this bit reduces the consumption of the PSC2 by stopping the clock to this module. When waking up the PSC2 again, the PSC2 should be re initialized to ensure proper operation. • Bit 6 - Reserved • Bit 5 - PRPSCR: Power Reduction PSC reduced Writing a logic one to this bit reduces the consumption of the PSCR by stopping the clock to this module. When waking up the PSCR again, the PSCR should be re initialized to ensure proper operation. • Bit 4 - PRTIM1: Power Reduction Timer/Counter1 Writing a logic one to this bit reduces the consumption of the Timer/Counter1 module. When the Timer/Counter1 is enabled, operation will continue like before the setting of this bit. • Bit 3 - Reserved • Bit 2 - PRSPI: Power Reduction Serial Peripheral Interface Writing a logic one to this bit reduces the consumption of the Serial Peripheral Interface by stopping the clock to this module. When waking up the SPI again, the SPI should be re initialized to ensure proper operation. • Bit 1 - Reserved • .Bit 0 - PRADC: Power Reduction ADC Writing a logic one to this bit reduces the consumption of the ADC by stopping the clock to this module. The ADC must be disabled before using this function. The analog comparator cannot use the ADC input MUX when the clock of ADC is stopped. 48 AT90PWM81 7734P–AVR–08/10 AT90PWM81 7. System Control and Reset 7.1 System Control overview 7.1.1 Resetting the AVR During reset, all I/O Registers are set to their initial values, and the program starts execution from the Reset Vector. The instruction placed at the Reset Vector must be a JMP – Absolute Jump – instruction to the reset handling routine. If the program never enables an interrupt source, the Interrupt Vectors are not used, and regular program code can be placed at these locations. This is also the case if the Reset Vector is in the Application section while the Interrupt Vectors are in the Boot section or vice versa. The circuit diagram in Figure 7-1 shows the reset logic. Table 7-1 defines the electrical parameters of the reset circuitry. The I/O ports of the AVR are immediately reset to their initial state when a reset source goes active. This does not require any clock source to be running. After all reset sources have gone inactive, a delay counter is invoked, stretching the internal reset. This allows the power to reach a stable level before normal operation starts. The time-out period of the delay counter is defined by the user through the SUT and CKSEL Fuses. The different selections for the delay period are presented in “Clock Sources” on page 28. 7.1.2 Reset Sources The AT90PWM81 has four sources of reset: • Power-on Reset. The MCU is reset when the supply voltage is below the Power-on Reset threshold (VPOT). • External Reset. The MCU is reset when a low level is present on the RESET pin for longer than the minimum pulse length. The external reset pin can be disabled in 2 ways: – By the RSTDISBL fuse. In this case , the SPI programming is disabled – By software using the RSTDIS bit in MCUCR register. In this case , the SPI programming is still active at power up time. • Watchdog Reset. The MCU is reset when the Watchdog Timer period expires and the Watchdog is enabled. • Brown-out Reset. The MCU is reset when the supply voltage VCC is below the Brown-out Reset threshold (VBOT) and the Brown-out Detector is enabled. 49 7734P–AVR–08/10 Figure 7-1. Reset Logic DATA BUS PORF BORF EXTRF WDRF MCU Status Register (MCUSR) Power-on Reset Circuit Brown-out Reset Circuit BODLEVEL [2..0] Pull-up Resistor Spike Filter RSTDIS Watchdog Oscillator Clock Generator CK Delay Counters TIMEOUT CKSEL[3:0] SUT[1:0] Table 7-1. Symbol VPOT Reset Characteristics(1) Parameter Typ. Max. Units Power-on Reset Threshold Voltage (rising) 1.4 2.3 V Power-on Reset Threshold Voltage (falling)(2) 1.3 2.3 V 0.85Vcc V VRST RESET Pin Threshold Voltage tRST Minimum pulse width on RESET Pin Notes: Condition Min. 0.2Vcc 400 ns 1. Values are guidelines only.. 2. The Power-on Reset will not work unless the supply voltage has been below VPOT (falling) 7.1.3 Power-on Reset A Power-on Reset (POR) pulse is generated by an On-chip detection circuit. The detection level is defined in Table 7-1. The POR is activated whenever VCC is below the detection level. The POR circuit can be used to trigger the start-up Reset, as well as to detect a failure in supply voltage. A Power-on Reset (POR) circuit ensures that the device is reset from Power-on. Reaching the Power-on Reset threshold voltage invokes the delay counter, which determines how long the device is kept in RESET after VCC rise. The RESET signal is activated again, without any delay, when VCC decreases below the detection level. 50 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 7-2. MCU Start-up, RESET Tied to VCC VCC RESET VPOT VRST tTOUT TIME-OUT INTERNAL RESET Figure 7-3. MCU Start-up, RESET Extended Externally VCC VPOT RESET TIME-OUT VRST tTOUT INTERNAL RESET 7.1.4 External Reset An External Reset is generated by a low level on the RESET pin. Reset pulses longer than the minimum pulse width (see Table 7-1) will generate a reset, even if the clock is not running. Shorter pulses are not guaranteed to generate a reset. When the applied signal reaches the Reset Threshold Voltage – VRST – on its positive edge, the delay counter starts the MCU after the Time-out period – tTOUT – has expired. Figure 7-4. External Reset During Operation CC 51 7734P–AVR–08/10 7.1.5 Brown-out Detection AT90PWM81 has an On-chip Brown-out Detection (BOD) circuit for monitoring the VCC level during operation by comparing it to a fixed trigger level. The trigger level for the BOD can be selected by the BODLEVEL Fuses. The trigger level has a hysteresis to ensure spike free Brown-out Detection. The hysteresis on the detection level should be interpreted as VBOT+ = VBOT + VHYST/2 and VBOT- = VBOT VHYST/2. Table 7-2. BODLEVEL Fuse Coding(1)(2) BODLEVEL 2..0 Fuses Min VBOT 111 Max VBOT Units Forbidden, BOD must be enabled 110 4.5 V 101 ( default configuration) 2.7 V 100 3.9 4.3 4.6 V 011 4.4 V 010 4.2 V 001 2.8 V 000 Notes: Typ VBOT 2.5 2.7 2.9 V 1. VBOT may be below nominal minimum operating voltage for some devices. For devices where this is the case, the device is tested down to VCC = VBOT during the production test. This guarantees that a BrownOut Reset will occur before VCC drops to a voltage where correct operation of the microcontroller is no longer guaranteed. The test is performed using BODLEVEL = 010 for Low Operating Voltageand BODLEVEL = 101for High Operating Voltage. 2. Values are guidelines only. Table 7-3. Brown-out Characteristics(1) Symbol Parameter VHYST Brown-out Detector Hysteresis 70 mV tBOD Min Pulse Width on Brown-out Reset 2 µs Notes: Min. Typ. Max. Units 1. Values are guidelines only. When VCC decreases to a value below the trigger level (VBOT- in Figure 7-5), the Brown-out Reset is immediately activated. When VCC increases above the trigger level (VBOT+ in Figure 7-5), the delay counter starts the MCU after the Time-out period tTOUT has expired. The BOD circuit will only detect a drop in VCC if the voltage stays below the trigger level for longer than tBOD given in Table 7-3. 52 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 7-5. Brown-out Reset During Operation VCC VBOT+ VBOT- RESET tTOUT TIME-OUT INTERNAL RESET 7.1.6 Watchdog Reset When the Watchdog times out, it will generate a short reset pulse of one CK cycle duration. On the falling edge of this pulse, the delay timer starts counting the Time-out period tTOUT. Refer to page 55 for details on operation of the Watchdog Timer. Figure 7-6. Watchdog Reset During Operation CC CK 7.2 7.2.1 System Control registers MCU Status Register – MCUSR The MCU Status Register provides information on which reset source caused an MCU reset. Bit 7 6 5 4 3 2 1 – – – – WDRF BORF EXTRF 0 PORF Read/Write R R R R R/W R/W R/W R/W Initial Value 0 0 0 0 See Bit Description MCUSR • Bit 3 – WDRF: Watchdog Reset Flag This bit is set if a Watchdog Reset occurs. The bit is reset by a Power-on Reset, or by writing a logic zero to the flag. 53 7734P–AVR–08/10 • Bit 2 – BORF: Brown-out Reset Flag This bit is set if a Brown-out Reset occurs. The bit is reset by a Power-on Reset, or by writing a logic zero to the flag. • Bit 1 – EXTRF: External Reset Flag This bit is set if an External Reset occurs. The bit is reset by a Power-on Reset, or by writing a logic zero to the flag. • Bit 0 – PORF: Power-on Reset Flag This bit is set if a Power-on Reset occurs. The bit is reset only by writing a logic zero to the flag. To make use of the Reset flags to identify a reset condition, the user should read and then reset the MCUSR as early as possible in the program. If the register is cleared before another reset occurs, the source of the reset can be found by examining the reset flags. 7.2.2 MCU Control Register – MCUCR Bit 7 6 5 4 3 2 1 – – – PUD RSTDIS CKRC81 IVSEL 0 IVCE Read/Write R R R R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 MCUCR • Bit 3– RSTDIS: Reset Pin Disable Thanks to RSTDIS in MCUCR Sfr, the reset function can be disabled, leaving this pin for functional purpose. – When the RSTDIS bit is written to zero, the reset signal is active. – When the RSTDIS bit is written to one, the reset signal is inactive. 7.3 Internal Voltage Reference AT90PWM81 features an internal bandgap reference. This bandgap reference is used for Brown-out Detection and can be used as analog input for the analog comparators or the ADC. The internal voltage reference for the DAC and/or the ADC and the comparators is derived from this bandgap voltage. see “On Chip voltage Reference and Temperature sensor overview” on page 189 The Vref voltage is configured thanks to the REFS1 and REFS0 bits in the ADMUX register; see “ADC Multiplexer Register – ADMUX” on page 216 7.3.1 Bandgap and Internal Voltage Reference Enable Signals and Start-up Time The bandgap and the internal voltage reference characteristics is given on Table 7-4. To save power, the reference is not always turned on. The bandgap and the internal reference is on during the following situations: 1. When the BOD is enabled (by programming the BODLEVEL [2..0] Fuse). 2. When the internal reference is selected (REFS1 = 1) 3. When the bandgap reference is connected to the Analog Comparator. 4. When the ADC is enabled. Thus, when the BOD is not enabled, after enabling the ADC, comparator or the internal reference, the user must always allow the reference to start up before the output from the Analog Comparator or ADC or 54 AT90PWM81 7734P–AVR–08/10 AT90PWM81 DAC is used. To reduce power consumption in Power-down mode, the user can avoid the four conditions above to ensure that the reference is turned off before entering Power-down mode. 7.3.2 Voltage Reference Characteristics Table 7-4. Symbol Parameter Condition Min. Typ. Max. Units VBG Bandgap reference voltage 1.1 V tBG Bandgap reference start-up time 40 µs IBG Bandgap reference current consumption 15 µA Note: 7.4 Internal Voltage Reference Characteristics(1) 1. Values are guidelines only. Watchdog Timer AT90PWM81 has an Enhanced Watchdog Timer (WDT). The main features are: • Clocked from separate On-chip Oscillator • 3 Operating modes – Interrupt – System Reset – Interrupt and System Reset • Selectable Time-out period from 1ms to 8s • Possible Hardware fuse Watchdog always on (WDTON) for fail-safe mode Figure 7-7. Watchdog Timer OSC/8K OSC/2K OSC/4K OSC/1K OSC/128 OSC/256 OSC/512 128 KHz OSCILLATOR WDP3 MCU RESET WDIF INTERRUPT WDIE The Watchdog Timer (WDT) is a timer counting cycles of a separate on-chip 128 kHz oscillator. The WDT gives an interrupt or a system reset when the counter reaches a given time-out value. In normal operation mode, it is required that the system uses the WDR - Watchdog Timer Reset - instruction to restart the counter before the time-out value is reached. If the system doesn't restart the counter, an interrupt or system reset will be issued. 55 7734P–AVR–08/10 In Interrupt mode, the WDT gives an interrupt when the timer expires. This interrupt can be used to wake the device from sleep-modes, and also as a general system timer. One example is to limit the maximum time allowed for certain operations, giving an interrupt when the operation has run longer than expected. In System Reset mode, the WDT gives a reset when the timer expires. This is typically used to prevent system hang-up in case of runaway code. The third mode, Interrupt and System Reset mode, combines the other two modes by first giving an interrupt and then switch to System Reset mode. This mode will for instance allow a safe shutdown by saving critical parameters before a system reset. The “Watchdog Timer Always On” (WDTON) fuse, if programmed, will force the Watchdog Timer to System Reset mode. With the fuse programmed the System Reset mode bit (WDE) and Interrupt mode bit (WDIE) are locked to 1 and 0 respectively. To further ensure program security, alterations to the Watchdog set-up must follow timed sequences. The sequence for clearing WDE and changing time-out configuration is as follows: 1. In the same operation, write a logic one to the Watchdog change enable bit (WDCE) and WDE. A logic one must be written to WDE regardless of the previous value of the WDE bit. 2. Within the next four clock cycles, write the WDE and Watchdog prescaler bits (WDP) as desired, but with the WDCE bit cleared. This must be done in one operation. The following code example shows one assembly and one C function for turning off the Watchdog Timer. The example assumes that interrupts are controlled (e.g. by disabling interrupts globally) so that no interrupts will occur during the execution of these functions. Assembly Code Example(1) 56 AT90PWM81 7734P–AVR–08/10 AT90PWM81 WDT_off: ; Turn off global interrupt cli ; Reset Watchdog Timer wdr ; Clear WDRF in MCUSR in r16, MCUSR andi r16, (0xff & (0<<WDRF)) out MCUSR, r16 ; Write logical one to WDCE and WDE ; Keep old prescaler setting to prevent unintentional time-out lds r16, WDTCSR ori r16, (1<<WDCE) | (1<<WDE) sts WDTCSR, r16 ; Turn off WDT ldi r16, (0<<WDE) sts WDTCSR, r16 ; Turn on global interrupt sei ret C Code Example(1) void WDT_off(void) { __disable_interrupt(); __watchdog_reset(); /* Clear WDRF in MCUSR */ MCUSR &= ~(1<<WDRF); /* Write logical one to WDCE and WDE */ /* Keep old prescaler setting to prevent unintentional time-out */ WDTCSR |= (1<<WDCE) | (1<<WDE); /* Turn off WDT */ WDTCSR = 0x00; __enable_interrupt(); } Note: 1. The example code assumes that the part specific header file is included. Note: If the Watchdog is accidentally enabled, for example by a runaway pointer or brown-out condition, the device will be reset and the Watchdog Timer will stay enabled. If the code is not set up to handle the Watchdog, this might lead to an eternal loop of time-out resets. To avoid this situation, the application software should always clear the Watchdog System Reset Flag (WDRF) and the WDE control bit in the initialisation routine, even if the Watchdog is not in use. The following code example shows one assembly and one C function for changing the time-out value of the Watchdog Timer. 57 7734P–AVR–08/10 Assembly Code Example(1) WDT_Prescaler_Change: ; Turn off global interrupt cli ; Reset Watchdog Timer wdr ; Start timed sequence lds r16, WDTCSR ori r16, (1<<WDCE) | (1<<WDE) sts WDTCSR, r16 ; -- Got four cycles to set the new values from here - ; Set new prescaler(time-out) value = 64K cycles (~0.5 s) ldi r16, (1<<WDE) | (1<<WDP2) | (1<<WDP0) sts WDTCSR, r16 ; -- Finished setting new values, used 2 cycles - ; Turn on global interrupt sei ret C Code Example(1) void WDT_Prescaler_Change(void) { __disable_interrupt(); __watchdog_reset(); /* Start timed equence */ WDTCSR |= (1<<WDCE) | (1<<WDE); /* Set new prescaler(time-out) value = 64K cycles (~0.5 s) */ WDTCSR = (1<<WDE) | (1<<WDP2) | (1<<WDP0); __enable_interrupt(); } Note: 1. The example code assumes that the part specific header file is included. Note: The Watchdog Timer should be reset before any change of the WDP bits, since a change in the WDP bits can result in a time-out when switching to a shorter time-out period; 7.4.1 Watchdog Timer Control Register - WDTCSR Bit 7 6 5 4 3 2 1 0 WDIF WDIE WDP3 WDCE WDE WDP2 WDP1 WDP0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 X 0 0 0 WDTCSR • Bit 7 - WDIF: Watchdog Interrupt Flag This bit is set when a time-out occurs in the Watchdog Timer and the Watchdog Timer is configured for interrupt. WDIF is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, WDIF is cleared by writing a logic one to the flag. When the I-bit in SREG and WDIE are set, the Watchdog Time-out Interrupt is executed. 58 AT90PWM81 7734P–AVR–08/10 AT90PWM81 • Bit 6 - WDIE: Watchdog Interrupt Enable When this bit is written to one and the I-bit in the Status Register is set, the Watchdog Interrupt is enabled. If WDE is cleared in combination with this setting, the Watchdog Timer is in Interrupt Mode, and the corresponding interrupt is executed if time-out in the Watchdog Timer occurs. If WDE is set, the Watchdog Timer is in Interrupt and System Reset Mode. The first time-out in the Watchdog Timer will set WDIF. Executing the corresponding interrupt vector will clear WDIE and WDIF automatically by hardware (the Watchdog goes to System Reset Mode). This is useful for keeping the Watchdog Timer security while using the interrupt. To stay in Interrupt and System Reset Mode, WDIE must be set after each interrupt. This should however not be done within the interrupt service routine itself, as this might compromise the safety-function of the Watchdog System Reset mode. If the interrupt is not executed before the next time-out, a System Reset will be applied. Table 7-5. Watchdog Timer Configuration (1) WDTON Note: WDE WDIE Mode Action on Time-out 0 0 0 Stopped None 0 0 1 Interrupt Mode Interrupt 0 1 0 System Reset Mode Reset 0 1 1 Interrupt and System Reset Mode Interrupt, then go to System Reset Mode 1 x x System Reset Mode Reset 1. For the WDTON Fuse “1” means unprogrammed while “0” means programmed. • Bit 4 - WDCE: Watchdog Change Enable This bit is used in timed sequences for changing WDE and prescaler bits. To clear the WDE bit, and/or change the prescaler bits, WDCE must be set. Once written to one, hardware will clear WDCE after four clock cycles. • Bit 3 - WDE: Watchdog System Reset Enable WDE is overridden by WDRF in MCUSR. This means that WDE is always set when WDRF is set. To clear WDE, WDRF must be cleared first. This feature ensures multiple resets during conditions causing failure, and a safe start-up after the failure. • Bit 5, 2..0 - WDP3..0: Watchdog Timer Prescaler 3, 2, 1 and 0 The WDP3..0 bits determine the Watchdog Timer prescaling when the Watchdog Timer is running. The different prescaling values and their corresponding time-out periods are shown in Table 7-6 on page 60. 59 7734P–AVR–08/10 . Table 7-6. Watchdog Timer Prescaler Select WDP3 WDP2 WDP1 WDP0 Number of WDT Oscillator Cycles Typical Time-out at VCC = 5.0V 0 0 0 0 2K (2048) cycles 16 ms 0 0 0 1 4K (4096) cycles 32 ms 0 0 1 0 8K (8192) cycles 64 ms 0 0 1 1 16K (16384) cycles 0.125 s 0 1 0 0 32K (32768) cycles 0.25 s 0 1 0 1 64K (65536) cycles 0.5 s 0 1 1 0 128K (131072) cycles 1.0 s 0 1 1 1 256K (262144) cycles 2.0 s 1 0 0 0 512K (524288) cycles 4.0 s 1 0 0 1 1024K (1048576) cycles 8.0 s 1 0 1 0 1K (1024) cycles 8ms 1 0 1 1 512 cycles 4 ms 1 1 0 0 256 cycles 2 ms 1 1 0 1 128 cycles 1 ms 1 1 1 0 1 1 1 1 Reserved 60 AT90PWM81 7734P–AVR–08/10 AT90PWM81 8. Interrupts This section describes the specifics of the interrupt handling as performed in AT90PWM81. For a general explanation of the AVR interrupt handling, refer to “Reset and Interrupt Handling” on page 13. 8.1 Interrupt Vectors in AT90PWM81 Table 8-1. Reset and Interrupt Vectors Vector No. Program Address 1 0x0000 2 0x0001 PSC2 CAPT PSC2 Capture Event 3 0x0002 PSC2 EC PSC2 End Cycle 4 0x0003 PSC2 EEC PSC2 End of Enhanced Cycle 5 0x0004 PSCr CAPT PSC reduced Capture Event 6 0x0005 PSCr EC PSC reduced End Cycle 7 0x0006 PSCr EEC PSC reduced End of Enhanced Cycle 8 0x0007 ANACOMP 0 Analog Comparator 0 9 0x0008 ANACOMP 1 Analog Comparator 1 10 0x0009 ANACOMP 2 Analog Comparator 2 11 0x000A INT0 External Interrupt Request 0 12 0x000B TIMER1 CAPT Timer/Counter1 Capture Event 13 0x000C TIMER1 OVF Timer/Counter1 Overflow 14 0x000D ADC ADC Conversion Complete 15 0x000E INT1 External Interrupt Request 1 16 0x000F SPI, STC SPI Serial Transfer Complete 17 0x0010 INT2 External Interrupt Request 2 18 0x0011 WDT Watchdog Time-Out Interrupt 19 0x0012 EE READY EEPROM Ready 20 0x0013 SPM READY Store Program Memory Ready 21 0x0014 22 0x0015 Notes: Source RESET Interrupt Definition External Pin, Power-on Reset, Brown-out Reset, Watchdog Reset, and Emulation AVR Reset 1. When the BOOTRST Fuse is programmed, the device will jump to the Boot Loader address at reset, see “Boot Loader Support – Read-While-Write Self-Programming” on page 232. 2. When the IVSEL bit in MCUCR is set, Interrupt Vectors will be moved to the start of the Boot Flash Section. The address of each Interrupt Vector will then be the address in this table added to the start address of the Boot Flash Section. Table 8-2 shows reset and Interrupt Vectors placement for the various combinations of BOOTRST and IVSEL settings. If the program never enables an interrupt source, the Interrupt Vectors are not used, and 61 7734P–AVR–08/10 regular program code can be placed at these locations. This is also the case if the Reset Vector is in the Application section while the Interrupt Vectors are in the Boot section or vice versa. Table 8-2. Reset and Interrupt Vectors Placement in AT90PWM81(1) BOOTRST IVSEL Reset Address Interrupt Vectors Start Address 1 0 0x000 0x001 1 1 0x000 Boot Reset Address + 0x001 0 0 Boot Reset Address 0x001 0 1 Boot Reset Address Boot Reset Address + 0x001 Note: 1. The Boot Reset Address is shown in Table 20-7 on page 246. For the BOOTRST Fuse “1” means unprogrammed while “0” means programmed. The most typical and general program setup for the Reset and Interrupt Vector Addresses in AT90PWM81 is: Address Labels Code Comments 0x000 rjmp RESET ; Reset Handler 0x001 rjmp PSC2_CAPT ; PSC2 Capture event Handler 0x002 rjmp PSC2_EC ; PSC2 End Cycle Handler 0x003 rjmp PSC2_EEC ; PSC2 End Enhanced Cycle Handler 0x004 rjmp PSCR_CAPT ; PSCr Capture event Handler 0x005 rjmp PSCR_EC ; PSC0 End Cycle Handler 0x006 rjmp PSCR_EEC ; PSCr End Enhanced Cycle Handler 0x007 rjmp ANA_COMP_0 ; Analog Comparator 0 Handler 0x008 rjmp ANA_COMP_1 ; Analog Comparator 1 Handler 0x009 rjmp ANA_COMP_2 ; Analog Comparator 2 Handler 0x00A rjmp EXT_INT0 ; IRQ0 Handler 0x00B rjmp TIM1_CAPT ; Timer1 Capture Handler 0x00C rjmp TIM1_OVF ; Timer1 Overflow Handler 0x00D rjmp ADC ; ADC Conversion Complete Handler 0x00E rjmp EXT_INT1 ; IRQ1 Handler 0x00F rjmp SPI_STC ; SPI Transfer Complete Handler 0x010 rjmp EXT_INT2 ; IRQ2 Handler 0x011 rjmp WDT ; Watchdog Timer Handler 0x012 rjmp EE_RDY ; EEPROM Ready Handler 0x013 rjmp SPM_RDY ; Store Program Memory Ready Handler 0x014 rjmp 0x015 rjmp 0x016 rjmp 0x017 rjmp 0x018 rjmp 0x019 rjmp 0x01A rjmp 0x01B rjmp 0x01C rjmp 0x01F rjmp ; 62 AT90PWM81 7734P–AVR–08/10 AT90PWM81 0x020RESET: ldi r16, high(RAMEND); Main program start 0x021 out SPH,r16 0x022 ldi 0x023 0x024 out sei 0x025 ... r16, low(RAMEND) SPL,r16 ; Enable interrupts <instr> ... ... ; Set Stack Pointer to top of RAM xxx ... When the BOOTRST Fuse is unprogrammed, the Boot section size set to 2K bytes and the IVSEL bit in the MCUCR Register is set before any interrupts are enabled, the most typical and general program setup for the Reset and Interrupt Vector Addresses in AT90PWM81 is: Address Labels Code Comments 0x000 RESET: ldi 0x001 out r16,high(RAMEND); Main program start SPH,r16 0x002 ldi r16,low(RAMEND) 0x003 0x004 out sei SPL,r16 0x005 <instr> ; Set Stack Pointer to top of RAM ; Enable interrupts xxx ; .org 0xC01 0xC01 rjmp PSC2_CAPT ; PSC2 Capture event Handler 0xC02 rjmp PSC2_EC ; PSC2 End Cycle Handler ... ... ... ; 0xC1F rjmp SPM_RDY ; Store Program Memory Ready Handler When the BOOTRST Fuse is programmed and the Boot section size set to 2K bytes, the most typical and general program setup for the Reset and Interrupt Vector Addresses in AT90PWM81 is: Address Labels Code Comments .org 0x001 0x001 rjmp PSC2_CAPT ; PSC2 Capture event Handler 0x002 rjmp PSC2_EC ; PSC2 End Cycle Handler ... ... ... ; 0x01F rjmp SPM_RDY ; Store Program Memory Ready Handler ; .org 0xC00 0xC00 RESET: ldi r16,high(RAMEND); Main program start 0xC01 out SPH,r16 0xC02 ldi r16,low(RAMEND) 0xC03 0xC04 out sei SPL,r16 0xC05 <instr> ; Set Stack Pointer to top of RAM ; Enable interrupts xxx When the BOOTRST Fuse is programmed, the Boot section size set to 2K bytes and the IVSEL bit in the MCUCR Register is set before any interrupts are enabled, the most typical and general program setup for the Reset and Interrupt Vector Addresses in AT90PWM81 is: Address Labels Code Comments ; 63 7734P–AVR–08/10 .org 0xC00 0xC00 rjmp RESET ; Reset handler 0xC01 rjmp PSC2_CAPT ; PSC2 Capture event Handler 0xC02 rjmp PSC2_EC ; PSC2 End Cycle Handler ... ... ... ; 0xC1F rjmp SPM_RDY ; Store Program Memory Ready Handler ; 0xC20 RESET: ldi 0xC21 out r16,high(RAMEND); Main program start SPH,r16 0xC22 ldi r16,low(RAMEND) 0xC23 0xC24 out sei SPL,r16 0xC25 <instr> ; Set Stack Pointer to top of RAM ; Enable interrupts xxx 8.1.1 Moving Interrupts Between Application and Boot Space The MCU Control Register controls the placement of the Interrupt Vector table. 8.1.2 MCU Control Register – MCUCR Bit 7 6 5 4 3 2 1 0 – – – PUD RSTDIS CKRC81 IVSEL IVCE Read/Write R R R R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 MCUCR • Bit 1 – IVSEL: Interrupt Vector Select When the IVSEL bit is cleared (zero), the Interrupt Vectors are placed at the start of the Flash memory. When this bit is set (one), the Interrupt Vectors are moved to the beginning of the Boot Loader section of the Flash. The actual address of the start of the Boot Flash Section is determined by the BOOTSZ Fuses. Refer to the section “Boot Loader Support – Read-While-Write Self-Programming” on page 232 for details. To avoid unintentional changes of Interrupt Vector tables, a special write procedure must be followed to change the IVSEL bit: a. Write the Interrupt Vector Change Enable (IVCE) bit to one. b. Within four cycles, write the desired value to IVSEL while writing a zero to IVCE. Interrupts will automatically be disabled while this sequence is executed. Interrupts are disabled in the cycle IVCE is set, and they remain disabled until after the instruction following the write to IVSEL. If IVSEL is not written, interrupts remain disabled for four cycles. The I-bit in the Status Register is unaffected by the automatic disabling. Note: If Interrupt Vectors are placed in the Boot Loader section and Boot Lock bit BLB02 is programmed, interrupts are disabled while executing from the Application section. If Interrupt Vectors are placed in the Application section and Boot Lock bit BLB12 is programed, interrupts are disabled while executing from the Boot Loader section. Refer to the section “Boot Loader Support – Read-While-Write Self-Programming” on page 232 for details on Boot Lock bits. • Bit 0 – IVCE: Interrupt Vector Change Enable The IVCE bit must be written to logic one to enable change of the IVSEL bit. IVCE is cleared by hardware four cycles after it is written or when IVSEL is written. Setting the IVCE bit will disable interrupts, as explained in the IVSEL description above. See Code Example below. 64 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Assembly Code Example Move_interrupts: ; Enable change of Interrupt Vectors ldi r16, (1<<IVCE) out MCUCR, r16 ; Move interrupts to Boot Flash section ldi r16, (1<<IVSEL) out MCUCR, r16 ret C Code Example void Move_interrupts(void) { /* Enable change of Interrupt Vectors */ MCUCR = (1<<IVCE); /* Move interrupts to Boot Flash section */ MCUCR = (1<<IVSEL); } 65 7734P–AVR–08/10 9. 9.1 I/O-Ports Introduction All AVR ports have true Read-Modify-Write functionality when used as general digital I/O ports. This means that the direction of one port pin can be changed without unintentionally changing the direction of any other pin with the SBI and CBI instructions. The same applies when changing drive value (if configured as output) or enabling/disabling of pull-up resistors (if configured as input). Each output buffer has symmetrical drive characteristics with both high sink and source capability. All port pins have individually selectable pull-up resistors with a supply-voltage invariant resistance. All I/O pins have protection diodes to both VCC and Ground as indicated in Figure 9-1. Refer to “Electrical Characteristics(1)” on page 273 for a complete list of parameters. Figure 9-1. I/O Pin Equivalent Schematic Rpu Pxn Logic Cpin See Figure "General Digital I/O" for Details All registers and bit references in this section are written in general form. A lower case “x” represents the numbering letter for the port, and a lower case “n” represents the bit number. However, when using the register or bit defines in a program, the precise form must be used. For example, PORTB3 for bit no. 3 in Port B, here documented generally as PORTxn. The physical I/O Registers and bit locations are listed in “Register Description for I/O-Ports”. Three I/O memory address locations are allocated for each port, one each for the Data Register – PORTx, Data Direction Register – DDRx, and the Port Input Pins – PINx. The Port Input Pins I/O location is read only, while the Data Register and the Data Direction Register are read/write. However, writing a logic one to a bit in the PINx Register, will result in a toggle in the corresponding bit in the Data Register. In addition, the Pull-up Disable – PUD bit in MCUCR disables the pull-up function for all pins in all ports when set. Using the I/O port as General Digital I/O is described in “Ports as General Digital I/O”. Most port pins are multiplexed with alternate functions for the peripheral features on the device. How each alternate function interferes with the port pin is described in “Alternate Port Functions” on page 71. Refer to the individual module sections for a full description of the alternate functions. Note that enabling the alternate function of some of the port pins does not affect the use of the other pins in the port as general digital I/O. 66 AT90PWM81 7734P–AVR–08/10 AT90PWM81 9.2 Ports as General Digital I/O The ports are bi-directional I/O ports with optional internal pull-ups. Figure 9-2 shows a functional description of one I/O-port pin, here generically called Pxn. Figure 9-2. General Digital I/O(1) PUD Q D DDxn Q CLR WDx RESET 1 Q Pxn D 0 PORTxn Q CLR WPx DATA BUS RDx RESET WRx RRx SLEEP SYNCHRONIZER D Q L Q D RPx Q PINxn Q clk I/O PUD: PULLUP DISABLE SLEEP: SLEEP CONTROL clkI/O : I/O CLOCK Note: 9.2.1 WDx: RDx: WRx: RRx: RPx: WPx: WRITE DDRx READ DDRx WRITE PORTx READ PORTx REGISTER READ PORTx PIN WRITE PINx REGISTER 1. WRx, WPx, WDx, RRx, RPx, and RDx are common to all pins within the same port. clkI/O, SLEEP, and PUD are common to all ports. Configuring the Pin Each port pin consists of three register bits: DDxn, PORTxn, and PINxn. As shown in “Register Description for I/O-Ports” on page 80, the DDxn bits are accessed at the DDRx I/O address, the PORTxn bits at the PORTx I/O address, and the PINxn bits at the PINx I/O address. The DDxn bit in the DDRx Register selects the direction of this pin. If DDxn is written logic one, Pxn is configured as an output pin. If DDxn is written logic zero, Pxn is configured as an input pin. If PORTxn is written logic one when the pin is configured as an input pin, the pull-up resistor is activated. To switch the pull-up resistor off, PORTxn has to be written logic zero or the pin has to be configured as an output pin The port pins are tri-stated when reset condition becomes active, even if no clocks are running. 67 7734P–AVR–08/10 If PORTxn is written logic one when the pin is configured as an output pin, the port pin is driven high (one). If PORTxn is written logic zero when the pin is configured as an output pin, the port pin is driven low (zero). 9.2.2 Toggling the Pin Writing a logic one to PINxn toggles the value of PORTxn, independent on the value of DDRxn. Note that the SBI instruction can be used to toggle one single bit in a port. 9.2.3 Switching Between Input and Output When switching between tri-state ({DDxn, PORTxn} = 0b00) and output high ({DDxn, PORTxn} = 0b11), an intermediate state with either pull-up enabled {DDxn, PORTxn} = 0b01) or output low ({DDxn, PORTxn} = 0b10) must occur. Normally, the pull-up enabled state is fully acceptable, as a high-impedant environment will not notice the difference between a strong high driver and a pull-up. If this is not the case, the PUD bit in the MCUCR Register can be set to disable all pull-ups in all ports. Switching between input with pull-up and output low generates the same problem. The user must use either the tri-state ({DDxn, PORTxn} = 0b00) or the output high state ({DDxn, PORTxn} = 0b11) as an intermediate step. Table 9-1 summarizes the control signals for the pin value. Table 9-1. 9.2.4 68 Port Pin Configurations DDxn PORTxn PUD (in MCUCR) I/O Pull-up 0 0 X Input No Default configuration after Reset. Tri-state (Hi-Z) 0 1 0 Input Yes Pxn will source current if ext. pulled low. 0 1 1 Input No Tri-state (Hi-Z) 1 0 X Output No Output Low (Sink) 1 1 X Output No Output High (Source) Comment Reading the Pin Value Independent of the setting of Data Direction bit DDxn, the port pin can be read through the PINxn Register bit. As shown in Figure 9-2, the PINxn Register bit and the preceding latch constitute a synchronizer. This is needed to avoid metastability if the physical pin changes value near the edge of the internal clock, but it also introduces a delay. Figure 9-3 shows a timing diagram of the synchronization when reading an externally applied pin value. The maximum and minimum propagation delays are denoted tpd,max and tpd,min respectively. AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 9-3. Synchronization when Reading an Externally Applied Pin value SYSTEM CLK INSTRUCTIONS XXX XXX in r17, PINx SYNC LATCH PINxn r17 0x00 0xFF t pd, max t pd, min Consider the clock period starting shortly after the first falling edge of the system clock. The latch is closed when the clock is low, and goes transparent when the clock is high, as indicated by the shaded region of the “SYNC LATCH” signal. The signal value is latched when the system clock goes low. It is clocked into the PINxn Register at the succeeding positive clock edge. As indicated by the two arrows tpd,max and tpd,min, a single signal transition on the pin will be delayed between ½ and 1½ system clock period depending upon the time of assertion. When reading back a software assigned pin value, a nop instruction must be inserted as indicated in Figure 9-4. The out instruction sets the “SYNC LATCH” signal at the positive edge of the clock. In this case, the delay tpd through the synchronizer is 1 system clock period. Figure 9-4. Synchronization when Reading a Software Assigned Pin Value SYSTEM CLK r16 INSTRUCTIONS 0xFF out PORTx, r16 nop in r17, PINx SYNC LATCH PINxn r17 0x00 0xFF t pd The following code example shows how to set port B pins 0 and 1 high, 2 and 3 low, and define the port pins from 4 to 7 as input with pull-ups assigned to port pins 6 and 7. The resulting pin values are read back 69 7734P–AVR–08/10 again, but as previously discussed, a nop instruction is included to be able to read back the value recently assigned to some of the pins. Assembly Code Example(1) ... ; Define pull-ups and set outputs high ; Define directions for port pins ldi r16, (1<<PB7)|(1<<PB6)|(1<<PB1)|(1<<PB0) ldi r17, (1<<DDB3)|(1<<DDB2)|(1<<DDB1)|(1<<DDB0) out PORTB, r16 out DDRB, r17 ; Insert nop for synchronization nop ; Read port pins in r16, PINB ... C Code Example unsigned char i; ... /* Define pull-ups and set outputs high */ /* Define directions for port pins */ PORTB = (1<<PB7)|(1<<PB6)|(1<<PB1)|(1<<PB0); DDRB = (1<<DDB3)|(1<<DDB2)|(1<<DDB1)|(1<<DDB0); /* Insert nop for synchronization*/ _NOP(); /* Read port pins */ i = PINB; ... Note: 9.2.5 1. For the assembly program, two temporary registers are used to minimize the time from pull-ups are set on pins 0, 1, 6, and 7, until the direction bits are correctly set, defining bit 2 and 3 as low and redefining bits 0 and 1 as strong high drivers. Digital Input Enable and Sleep Modes As shown in Figure 9-2, the digital input signal can be clamped to ground at the input of the schmitt-trigger. The signal denoted SLEEP in the figure, is set by the MCU Sleep Controller in Power-down mode, and Standby mode to avoid high power consumption if some input signals are left floating, or have an analog signal level close to VCC/2. SLEEP is overridden for port pins enabled as external interrupt pins. If the external interrupt request is not enabled, SLEEP is active also for these pins. SLEEP is also overridden by various other alternate functions as described in “Alternate Port Functions” on page 71. If a logic high level (“one”) is present on an Asynchronous External Interrupt pin configured as “Interrupt on Rising Edge, Falling Edge, or Any Logic Change on Pin” while the external interrupt is not enabled, the corresponding External Interrupt Flag will be set when resuming from the above mentioned sleep modes, as the clamping in these sleep modes produces the requested logic change. 70 AT90PWM81 7734P–AVR–08/10 AT90PWM81 9.3 Alternate Port Functions Most port pins have alternate functions in addition to being general digital I/Os. Figure 9-5 shows how the port pin control signals from the simplified Figure 9-2 can be overridden by alternate functions. The overriding signals may not be present in all port pins, but the figure serves as a generic description applicable to all port pins in the AVR microcontroller family. Figure 9-5. Alternate Port Functions(1) PUOExn PUOVxn 1 PUD 0 DDOExn DDOVxn 1 Q D DDxn 0 Q CLR WDx PVOExn RESET RDx 1 1 Pxn Q 0 D 0 PORTxn PTOExn Q CLR DIEOExn DATA BUS PVOVxn WPx DIEOVxn RESET WRx 1 0 RRx SLEEP SYNCHRONIZER D SET Q RPx Q D PINxn L CLR Q CLR Q clk I/O DIxn AIOxn PUOExn: Pxn PULL-UP OVERRIDE ENABLE PUOVxn: DDOExn: DDOVxn: PVOExn: PVOVxn: DIEOExn: Pxn PULL-UP OVERRIDE VALUE Pxn DATA DIRECTION OVERRIDE ENABLE Pxn DATA DIRECTION OVERRIDE VALUE Pxn PORT VALUE OVERRIDE ENABLE Pxn PORT VALUE OVERRIDE VALUE Pxn DIGITAL INPUT-ENABLE OVERRIDE ENABLE DIEOVxn: Pxn DIGITAL INPUT-ENABLE OVERRIDE VALUE SLEEP: SLEEP CONTROL PTOExn: Pxn, PORT TOGGLE OVERRIDE ENABLE Note: PUD: PULLUP DISABLE WDx: RDx: RRx: WRx: RPx: WPx: clkI/O: DIxn: AIOxn: WRITE DDRx READ DDRx READ PORTx REGISTER WRITE PORTx READ PORTx PIN WRITE PINx I/O CLOCK DIGITAL INPUT PIN n ON PORTx ANALOG INPUT/OUTPUT PIN n ON PORTx 1. WRx, WPx, WDx, RRx, RPx, and RDx are common to all pins within the same port. clkI/O, SLEEP, and PUD are common to all ports. All other signals are unique for each pin. Table 9-2 summarizes the function of the overriding signals. The pin and port indexes from Figure 9-5 are not shown in the succeeding tables. The overriding signals are generated internally in the modules having the alternate function. 71 7734P–AVR–08/10 Table 9-2. Generic Description of Overriding Signals for Alternate Functions Signal Name Full Name Description PUOE Pull-up Override Enable If this signal is set, the pull-up enable is controlled by the PUOV signal. If this signal is cleared, the pull-up is enabled when {DDxn, PORTxn, PUD} = 0b010. PUOV Pull-up Override Value If PUOE is set, the pull-up is enabled/disabled when PUOV is set/cleared, regardless of the setting of the DDxn, PORTxn, and PUD Register bits. DDOE Data Direction Override Enable If this signal is set, the Output Driver Enable is controlled by the DDOV signal. If this signal is cleared, the Output driver is enabled by the DDxn Register bit. DDOV Data Direction Override Value If DDOE is set, the Output Driver is enabled/disabled when DDOV is set/cleared, regardless of the setting of the DDxn Register bit. PVOE Port Value Override Enable If this signal is set and the Output Driver is enabled, the port value is controlled by the PVOV signal. If PVOE is cleared, and the Output Driver is enabled, the port Value is controlled by the PORTxn Register bit. PVOV Port Value Override Value If PVOE is set, the port value is set to PVOV, regardless of the setting of the PORTxn Register bit. PTOE Port Toggle Override Enable If PTOE is set, the PORTxn Register bit is inverted. DIEOE Digital Input Enable Override Enable If this bit is set, the Digital Input Enable is controlled by the DIEOV signal. If this signal is cleared, the Digital Input Enable is determined by MCU state (Normal mode, sleep mode). DIEOV Digital Input Enable Override Value If DIEOE is set, the Digital Input is enabled/disabled when DIEOV is set/cleared, regardless of the MCU state (Normal mode, sleep mode). DI Digital Input This is the Digital Input to alternate functions. In the figure, the signal is connected to the output of the schmitt trigger but before the synchronizer. Unless the Digital Input is used as a clock source, the module with the alternate function will use its own synchronizer. AIO Analog Input/Output This is the Analog Input/output to/from alternate functions. The signal is connected directly to the pad, and can be used bidirectionally. The following subsections shortly describe the alternate functions for each port, and relate the overriding signals to the alternate function. Refer to the alternate function description for further details. 9.3.1 MCU Control Register – MCUCR Bit 7 6 5 4 3 2 1 – – – PUD RSTDIS CKRC81 IVSEL 0 IVCE Read/Write R R R R/W RW R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 MCUCR • Bit 4 – PUD: Pull-up Disable When this bit is written to one, the pull-ups in the I/O ports are disabled even if the DDxn and PORTxn Registers are configured to enable the pull-ups ({DDxn, PORTxn} = 0b01). Se 72 AT90PWM81 7734P–AVR–08/10 AT90PWM81 9.3.2 Alternate Functions of Port B The Port B pins with alternate functions are shown in Table 9-3. Table 9-3. Port Pin Port B Pins Alternate Functions Alternate Functions PB7 PSCOUT22 Output ICP1 (Timer/Counter1 Input Capture Pin ) ADC9 (Analog Input Channel 9) PB6 MISO (SPI Master In Slave Out) ACMP3 (Analog Comparator 3 Positive Input ) ADC8 (Analog Input Channel 8) PB5 ADC5 (Analog Input Channel 5) ACMP2 (Analog Comparator 2 Positive Input) INT1(External Interrupt 1 Input) SCK (SPI Clock) PB4 MOSI (SPI Master Out Slave In) ADC3 (Analog Input Channel 3) ACMPM reference for analog comparators PB3 PSCOUTR1 Output . ADC2 (Analog Input Channel 2) ACMP2M (Analog Comparator 2 Negative Input) PB2 INT0 (External Interrupt 0 Input) PSCOUT21 OutpuT PB1 PSCOUT20 output PB0 T1counter source. PSCOUT23 Output ACMP3_OUT( Analog Comparator3 Output) The alternate pin configuration is as follows: • PSCOUT22/ICP1/ADC9 – Bit 7 PSCOUT22: Output 2 of PSC 2 ICP1 – Input Capture Pin1: This pin can act as an input capture pin for Timer/Counter1. ADC9, Analog to Digital Converter, input channel 9. • MISO/ACMP3/ADC8– Bit 6 MISO: Master Data input, Slave Data output pin for SPI channel. When the SPI is enabled as a master, this pin is configured as an input regardless of the setting of DDB0. When the SPI is enabled as a slave, the data direction of this pin is controlled by DDB0. When the pin is forced to be an input, the pull-up can still be controlled by the PORTB0 and PUD bits. ACMP3, Analog Comparator 3 Positive Input. Configure the port pin as input with the internal pull-up switched off to avoid the digital port function from interfering with the function of the Analog Comparator. ADC8, Analog to Digital Converter, input channel 8. 73 7734P–AVR–08/10 • ADC5/ACMP2/INT1/SCK – Bit 5 ADC5, Analog to Digital Converter, input channel 5. ACMP2, Analog Comparator 2 Positive Input. Configure the port pin as input with the internal pull-up switched off to avoid the digital port function from interfering with the function of the Analog Comparator. INT1, External Interrupt source 1. This pin can serve as an external interrupt source to the MCU. SCK: Master Clock output, Slave Clock input pin for SPI channel. When the SPI is enabled as a slave, this pin is configured as an input regardless of the setting of DDD4. When the SPI is enabled as a master, the data direction of this pin is controlled by DDD4. When the pin is forced to be an input, the pull-up can still be controlled by the PORT bit. • MOSI/ADC3/ACMPM– Bit 4 MOSI: SPI Master Data output, Slave Data input for SPI channel. When the SPI is enabled as a slave, this pin is configured as an input regardless of the setting of DDB1 When the SPI is enabled as a master, the data direction of this pin is controlled by DDB1. When the pin is forced to be an input, the pull-up can still be controlled by the PORTB1 and PUD bits. ADC3, Analog to Digital Converter, input channel 3. ACMPM, Analog Comparators Negative Input. Configure the port pin as input with the internal pull-up switched off to avoid the digital port function from interfering with the function of the Analog Comparator. • PSCOUTR1/ADC2/ACMP2M– Bit 3 PSCOUTR1: Output 1 of PSCR. ADC2, Analog to Digital Converter, input channel 2. ACMP2M, Analog Comparator 2 Negative Input. Configure the port pin as input with the internal pull-up switched off to avoid the digital port function from interfering with the function of the Analog Comparator. • INT0/PSCOUT21 – Bit 2 INT0, External Interrupt source 0. This pin can serve as an external interrupt source to the MCU. PSCOUT21: Output 1 of PSC 2. • PSCOUT20 – Bit 1 PSCOUT20: Output 0 of PSC 2. • T1/PSCOUT23/ACMP3_OUT – Bit 0 T1, Timer/Counter1 counter source. PSCOUT23: Output 3 of PSC 2. ACMP3_OUT, Analog Comparator3 Output. 74 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Table 9-4 and Table 9-5 relates the alternate functions of Port B to the overriding signals shown in Figure 9-5 on page 71. Table 9-4. Signal Name Overriding Signals for Alternate Functions in PB7..PB4 PB7/PSCOUT22/ ICP1/ADC9 PB6/MISO/ ACMP3/ADC8 PB5/ADC5/ ACMP2/INT1/SCK PB4/MOSI/ADC 3/ACMPM PUOE PUOV DDOE DDOV PVOE PVOV DIEOE DIEOV DI AIO Table 9-5. Signal Name Overriding Signals for Alternate Functions in PB3..PB0 PB3/PSCOUTR1/ ADC2/ACMP2M PB2/PSCOUTR1/ ADC2/ACMP2M PB1/ PSCOUT20 PB0/T1/PSCOUT2 3/ACMP3_OUT PUOE PUOV DDOE DDOV PVOE PVOV DIEOE DIEOV DI AIO The alternate pin configuration is as follows 75 7734P–AVR–08/10 9.3.3 Alternate Functions of Port D The Port D pins with alternate functions are shown in Table 9-6. Table 9-6. Port Pin Port D Pins Alternate Functions Alternate Function PD7 ADC10 (Analog Input Channel 10) PCSINrA (PSCR first Alternate Digital Input ) PD6 AMP0+ (Analog Differential Amplifier 0 Input Channel ) PD5 AMP0- (Analog Differential Amplifier 0 Input Channel ) ADC7 (Analog Input Channel 7) PD4 ACMP3M (Analog Comparator 3 Negative Input) ADC4 (Analog Input Channel 4) PCSIN2A (PSC 2 Digital Input) PD3 ADC1 (Analog Input Channel 1) ACMP2_OUT (Analog Comparator 2 Output) PD2 ADC0 (Analog Input Channel 0) ACMP1 (Analog Comparator 1 Positive Input) PD1 PSCOUTR0 Output 0 PCSINrB (PSCR Second Alternate Digital Input) PD0 ACMP3_OUT_A (Analog Comparator 2 Alternate Output) CLKO ( System Clock) SS ( SPI Slave Select) The alternate pin configuration is as follows: • ADC10/PSCINrA – Bit 7 ADC10, Analog to Digital Converter, input channel 10. PCSINrA, PSCR First Alternate Digital Input. • APM0+ – Bit 6 AMP0+, Analog Differential Amplifier 0 Positive Input Channel. • AMP0-/ADC7 – Bit 5 AMP0-, Analog Differential Amplifier 0 Negative Input Channel. ADC7, Analog to Digital Converter, input channel 7. • ACMP3M/ADC4/PSCIN2A – Bit 4 ACMP3M, Analog Comparator 3 Negative Input. Configure the port pin as input with the internal pull-up switched off to avoid the digital port function from interfering with the function of the Analog Comparator. ADC4, Analog to Digital Converter, input channel 4. PCSIN2A, PSC 2 Alternate Digital Input. 76 AT90PWM81 7734P–AVR–08/10 AT90PWM81 • ADC1/ACMP2_OUT, Bit 3 ADC1, Analog to Digital Converter, input channel 1. ACMP2_OUT, Analog Comparator 2 Output. • ADC0/ACMP1, Bit 2 ADC0, Analog to Digital Converter, input channel 0. ACMP1, Analog Comparator 1 Positive Input. Configure the port pin as input with the internal pull-up switched off to avoid the digital port function from interfering with the function of the Analog Comparator. • PSCOUTR0/PSCINrB – Bit 1 PSCOUTR0: Output 0 of PSCR. PCSINrB, PSCR Second Alternate Digital Input. • ACMP3_OUT_A/SS/CLKO – Bit 0 ACMP2_OUT_A, Analog Comparator 2 Alternate Output. SS: Slave Port Select input. When the SPI is enabled as a slave, this pin is configured as an input regardless of the setting of DDDn. As a slave, the SPI is activated when this pin is driven low. When the SPI is enabled as a master, the data direction of this pin is controlled by DDDn. When the pin is forced to be an input, the pull-up can still be controlled by the PORTDn bit. CLKO, Divided System Clock: The divided system clock can be output on this pin. The divided system clock will be output if the CKOUT Fuse is programmed, regardless of the PORTDn and DDDn settings. It will also be output during reset. Table 9-7 and Table 9-8 relates the alternate functions of Port D to the overriding signals shown in Figure 9-5 on page 71. Table 9-7. Signal Name Overriding Signals for Alternate Functions PD7..PD4 PD7/ ADC10/ PSCINrA PD6/APM0+ PD5/AMP0/ADC7 PD4/ACMP3M/ ADC2/PSCIN2A PUOE PUOV DDOE DDOV PVOE PVOV DIEOE DIEOV DI AIO 77 7734P–AVR–08/10 Table 9-8. Signal Name Overriding Signals for Alternate Functions in PD3..PD0 PD3/ADC1/ ACMP2_OUT PD2/ADC0/ ACMP1 PD1/PSCOUTR0/ PSCINrB PD0/ACMP2_OUT/ SS/CLKO PUOE PUOV DDOE DDOV PVOE PVOV DIEOE DIEOV DI AIO 9.3.4 Alternate Functions of Port E The Port E pins with alternate functions are shown in Table 9-9. Table 9-9. Port Pin Port E Pins Alternate Functions Alternate Function PE2 XTAL2: XTAL Output ACMP1M (Analog Comparator 1 Negative Input) PCSINr (PSCR Digital Input) PE1 XTAL1: XTAL Input PCSIN2 (PSC 2 Digital Input) ACMP1_OUT (Analog Comparator 1 Output.) PE0 RESET (Reset Input) OCD (On Chip Debug I/O) INT2 (External Interrupt 2 Input) The alternate pin configuration is as follows: • AREF/ADC6, Bit 3 AREF: Analog reference voltage. See Table 17-3 on page 217 for the definition of this pin. ADC6, Analog to Digital Converter, input channel 6. This pin can only be used as a digital output pin. It cannot be read as a digital input. • XTAL2/ACMP1M/PSCINr – Bit 2 XTAL2: Chip clock Oscillator pin 2. Used as clock pin for crystal Oscillator or Low-frequency crystal Oscillator. When used as a clock pin, the pin can not be used as an I/O pin. 78 AT90PWM81 7734P–AVR–08/10 AT90PWM81 ACMP1M, Analog Comparator 1 Negative Input. Configure the port pin as input with the internal pull-up switched off to avoid the digital port function from interfering with the function of the Analog Comparator. PCSINr, PSCR Digital Input. • XTAL1/PSCIN2/ACMP1_OUT – Bit 1 XTAL1: Chip clock Oscillator pin 1. Used for all chip clock sources except internal calibrated RC Oscillator. When used as a clock pin, the pin can not be used as an I/O pin. PCSIN2, PSC 2 Digital Input. ACMP1_OUT, Analog Comparator 1 Output. • RESET/OCD/INT2 – Bit 0 RESET, Reset pin: When the RSTDISBL Fuse is programmed, this pin functions as a normal I/O pin, and the part will have to rely on Power-on Reset and Brown-out Reset as its reset sources. When the RSTDISBL Fuse is unprogrammed, the reset circuitry is connected to the pin, and the pin can not be used as an I/O pin. If PE0 is used as a reset pin, DDE0, PORTE0 and PINE0 will all read 0. INT2, External Interrupt source 2. This pin can serve as an External Interrupt source to the MCU. Table 9-10 relates the alternate functions of Port E to the overriding signals shown in Figure 9-5 on page 71. Table 9-10. Signal Name Overriding Signals for Alternate Functions in PE2..PE0 PE2/XTAL2/ACM P1M/PSCINr PE1/XTAL1/PSCI N2/ ACMP1_OUT PE0/RESET/OCD/ INT2 PUOE PUOV DDOE DDOV PVOE PVOV DIEOE DIEOV DI AIO 79 7734P–AVR–08/10 9.4 9.4.1 Register Description for I/O-Ports Port B Data Register – PORTB Bit 9.4.2 7 6 5 4 3 2 1 0 PORTB7 PORTB6 PORTB5 PORTB4 PORTB3 PORTB2 PORTB1 PORTB0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 Port B Data Direction Register – DDRB Bit 9.4.3 7 6 5 4 3 2 1 0 DDB7 DDB6 DDB5 DDB4 DDB3 DDB2 DDB1 DDB0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 7 6 5 4 3 2 1 0 PINB7 PINB6 PINB5 PINB4 PINB3 PINB2 PINB1 PINB0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value N/A N/A N/A N/A N/A N/A N/A N/A 7 6 5 4 3 2 1 0 PORTD7 PORTD6 PORTD5 PORTD4 PORTD3 PORTD2 PORTD1 PORTD0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 7 6 5 4 3 2 1 0 DDD7 DDD6 DDD5 DDD4 DDD3 DDD2 DDD1 DDD0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 7 6 5 4 3 2 1 0 PIND7 PIND6 PIND5 PIND4 PIND3 PIND2 PIND1 PIND0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value N/A N/A N/A N/A N/A N/A N/A N/A PIND Port E Data Register – PORTE Bit 80 DDRD Port D Input Pins Address – PIND Bit 9.4.7 PORTD Port D Data Direction Register – DDRD Bit 9.4.6 PINB Port D Data Register – PORTD Bit 9.4.5 DDRB Port B Input Pins Address – PINB Bit 9.4.4 PORTB 7 6 5 4 3 2 1 0 – – – – – PORTE2 PORTE1 PORTE0 Read/Write R R R R R R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 PORTE AT90PWM81 7734P–AVR–08/10 AT90PWM81 9.4.8 Port E Data Direction Register – DDRE Bit 9.4.9 7 6 5 4 3 2 1 0 – – – – – DDE2 DDE1 DDE0 Read/Write R R R R R R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 0 DDRE Port E Input Pins Address – PINE Bit 7 6 5 4 3 2 1 – – – – – PINE2 PINE1 PINE0 Read/Write R R R R R R/W R/W R/W Initial Value 0 0 0 0 0 N/A N/A N/A PINE 81 7734P–AVR–08/10 10. External Interrupts The External Interrupts are triggered by the INT2:0 pins. Observe that, if enabled, the interrupts will trigger even if the INT2:0 pins are configured as outputs. This feature provides a way of generating a software interrupt. The External Interrupts can be triggered by a falling or rising edge or a low level. This is set up as indicated in the specification for the External Interrupt Control Registers – EICRA (INT2:0). When the external interrupt is enabled and is configured as level triggered, the interrupt will trigger as long as the pin is held low. Note that recognition of falling or rising edge interrupts on INT2:0 requires the presence of an I/O clock, described in “Clock Systems and their Distribution” on page 27. The I/O clock is halted in all sleep modes except Idle mode. Note that if a level triggered interrupt is used for wake-up from Power-down mode, the changed level must be held for some time to wake up the MCU. This makes the MCU less sensitive to noise. The changed level is sampled twice by the Watchdog Oscillator clock. The period of the Watchdog Oscillator is 1 µs (nominal) at 5.0V and 25°C. The frequency of the Watchdog Oscillator is voltage dependent as shown in the “Electrical Characteristics(1)” on page 273. The MCU will wake up if the input has the required level during this sampling or if it is held until the end of the start-up time. The start-up time is defined by the SUT fuses as described in “System Clock and Clock Options” on page 27. If the level is sampled twice by the Watchdog Oscillator clock but disappears before the end of the start-up time, the MCU will still wake up, but no interrupt will be generated. The required level must be held long enough for the MCU to complete the wake up to trigger the level interrupt. 10.0.1 External Interrupt Control Register A – EICRA Bit 7 6 5 4 3 2 1 0 - - ISC21 ISC20 ISC11 ISC10 ISC01 ISC00 Read/Write R R R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 EICRA • Bits 7..0 – ISC21, ISC20 – ISC01, ISC00: External Interrupt 2 - 0 Sense Control Bits The External Interrupts 3 - 0 are activated by the external pins INT2:0 if the SREG I-flag and the corresponding interrupt mask in the EIMSK is set. The level and edges on the external pins that activate the interrupts are defined in Table 10-1. Edges on INT3..INT0 are registered asynchronously.The value on the INT2:0 pins are sampled before detecting edges. If edge or toggle interrupt is selected, pulses that last longer than one clock period will generate an interrupt. Shorter pulses are not guaranteed to generate an interrupt. Observe that CPU clock frequency can be lower than the XTAL frequency if the XTAL divider is enabled. If low level interrupt is selected, the low level must be held until the completion of the currently executing instruction to generate an interrupt. If enabled, a level triggered interrupt will generate an interrupt request as long as the pin is held low. Interrupt Sense Control(1) Table 10-1. ISCn1 ISCn0 0 0 The low level of INTn generates an interrupt request. 0 1 Any logical change on INTn generates an interrupt request 1 0 The falling edge between two samples of INTn generates an interrupt request. 1 1 The rising edge between two samples of INTn generates an interrupt request. Note: 82 Description 1. n = 3, 2, 1 or 0. When changing the ISCn1/ISCn0 bits, the interrupt must be disabled by clearing its Interrupt Enable bit in the EIMSK Register. Otherwise an interrupt can occur when the bits are changed. AT90PWM81 7734P–AVR–08/10 AT90PWM81 10.0.2 External Interrupt Mask Register – EIMSK Bit 7 6 5 4 3 2 1 - - - - - INT2 INT1 0 IINT0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 EIMSK • Bits 2..0 – INT2 – INT0: External Interrupt Request 3 - 0 Enable When an INT2 – INT0 bit is written to one and the I-bit in the Status Register (SREG) is set (one), the corresponding external pin interrupt is enabled. The Interrupt Sense Control bits in the External Interrupt Control Register – EICRA – defines whether the external interrupt is activated on rising or falling edge or level sensed. Activity on any of these pins will trigger an interrupt request even if the pin is enabled as an output. This provides a way of generating a software interrupt. 10.0.3 External Interrupt Flag Register – EIFR Bit 7 6 5 4 3 2 1 - - - - - INTF2 INTF1 0 IINTF0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 EIFR • Bits 2..0 – INTF2 - INTF0: External Interrupt Flags 3 - 0 When an edge or logic change on the INT2:0 pin triggers an interrupt request, INTF2:0 becomes set (one). If the I-bit in SREG and the corresponding interrupt enable bit, INT2:0 in EIMSK, are set (one), the MCU will jump to the interrupt vector. The flag is cleared when the interrupt routine is executed. Alternatively, the flag can be cleared by writing a logical one to it. These flags are always cleared when INT2:0 are configured as level interrupt. 83 7734P–AVR–08/10 11. Reduced 16-bit Timer/Counter1 The 16-bit Timer/Counter unit allows accurate program execution timing (event management). The main features are: • • • • • 11.1 Clear Timer on Compare Match (Auto Reload) One Input Capture Unit Input Capture Noise Cancelerr External Event Counter Two independent interrupt Sources (TOV1, ICF1) Overview Most register and bit references in this section are written in general form. A lower case “n” replaces the Timer/Counter number, and a lower case “x” replaces the Output Compare unit channel. However, when using the register or bit defines in a program, the precise form must be used, i.e., TCNT1 for accessing Timer/Counter1 counter value and so on. A simplified block diagram of the 16-bit Timer/Counter is shown in Figure 11-1. For the actual placement of I/O pins, refer to “Pin out description” on page 6. CPU accessible I/O Registers, including I/O bits and I/O pins, are shown in bold. The device-specific I/O Register and bit locations are listed in the “16-bit Timer/Counter Register Description” on page 96. The PRTIM1 bit in “Power Reduction Register” on page 45 must be written to zero to enable Timer/Counter1 module. 84 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 11-1. 16-bit Timer/Counter Block Diagram(1) Count Clear TOVn (Int.Req.) Control Logic clk Tn Clock Select Edge Detector TOP Tn BOTTOM (Ckio ) Timer/Counter TCNTn = =0 DATA BUS Fixed TOP Values ( From Analog Comparator Ouput ) ICFn (Int.Req.) Edge Detector ICRn Noise Canceler ICPn TCCRnB Note: 11.1.1 AC1ICE 1. Refer toTable 2-1 on page 5 for Timer/Counter1 pin placement and description. Registers The Timer/Counter (TCNT1), and Input Capture Register (ICR1) are all 16-bit registers. Special procedures must be followed when accessing the 16-bit registers. These procedures are described in the section “Accessing 16-bit Registers” on page 86. The Timer/Counter Control Registers (TCCR1A/B) are 8-bit registers and have no CPU access restrictions. Interrupt requests (abbreviated to Int.Req. in the figure) signals are all visible in the Timer Interrupt Flag Register (TIFR1). All interrupts are individually masked with the Timer Interrupt Mask Register (TIMSK1). TIFR1 and TIMSK1 are not shown in the figure. The Timer/Counter can be clocked internally, or by an external clock source on the T1 pin. The Clock Select logic block controls which clock source and edge the Timer/Counter uses to increment (or decrement) its value. The Timer/Counter is inactive when no clock source is selected. The output from the Clock Select logic is referred to as the timer clock (clkT1). The Input Capture Register can capture the Timer/Counter value at a given external (edge triggered) event on either the Input Capture pin (ICP1). The Input Capture unit includes a digital filtering unit (Noise Canceler) for reducing the chance of capturing noise spikes. The TOP value, or maximum Timer/Counter value, can in some modes of operation be defined by the ICR1 Register, or by a set of fixed values. 85 7734P–AVR–08/10 11.1.2 Definitions The following definitions are used extensively throughout the section: 11.2 BOTTOM The counter reaches the BOTTOM when it becomes 0x0000. MAX The counter reaches its MAXimum when it becomes 0xFFFF (decimal 65535). TOP The counter reaches the TOP when it becomes equal to the highest value in the count sequence. The TOP value can be assigned to be one of the fixed values: 0x00FF, 0x01FF, or 0x03FF, or to the value stored in the ICR1 Register. The assignment is dependent of the mode of operation. Accessing 16-bit Registers The TCNT1, and ICR1 are 16-bit registers that can be accessed by the AVR CPU via the 8-bit data bus. The 16-bit register must be byte accessed using two read or write operations. Each 16-bit timer has a single 8-bit register for temporary storing of the high byte of the 16-bit access. The same temporary register is shared between all 16-bit registers within each 16-bit timer. Accessing the low byte triggers the 16-bit read or write operation. When the low byte of a 16-bit register is written by the CPU, the high byte stored in the temporary register, and the low byte written are both copied into the 16-bit register in the same clock cycle. When the low byte of a 16-bit register is read by the CPU, the high byte of the 16-bit register is copied into the temporary register in the same clock cycle as the low byte is read. To do a 16-bit write, the high byte must be written before the low byte. For a 16-bit read, the low byte must be read before the high byte. The following code examples show how to access the 16-bit Timer Registers assuming that no interrupts updates the temporary register. The same principle can be used directly for accessing the ICR1 Registers. Note that when using “C”, the compiler handles the 16-bit access. 86 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Assembly Code Examples(1) ... ; Set TCNT1 to 0x01FF ldi r17,0x01 ldi r16,0xFF out TCNT1H,r17 out TCNT1L,r16 ; Read TCNT1 into r17:r16 in r16,TCNT1L in r17,TCNT1H ... C Code Examples(1) unsigned int i; ... /* Set TCNT1 to 0x01FF */ TCNT1 = 0x1FF; /* Read TCNT1 into i */ i = TCNT1; ... Note: 1. The example code assumes that the part specific header file is included. For I/O Registers located in extended I/O map, “IN”, “OUT”, “SBIS”, “SBIC”, “CBI”, and “SBI” instructions must be replaced with instructions that allow access to extended I/O. Typically “LDS” and “STS” combined with “SBRS”, “SBRC”, “SBR”, and “CBR”. The assembly code example returns the TCNT1 value in the r17:r16 register pair. It is important to notice that accessing 16-bit registers are atomic operations. If an interrupt occurs between the two instructions accessing the 16-bit register, and the interrupt code updates the temporary register by accessing the same or any other of the 16-bit Timer Registers, then the result of the access outside the interrupt will be corrupted. Therefore, when both the main code and the interrupt code update the temporary register, the main code must disable the interrupts during the 16-bit access. The following code examples show how to do an atomic read of the TCNT1 Register contents. Reading any of the OCR1A/B or ICR1 Registers can be done by using the same principle. Assembly Code Example(1) 87 7734P–AVR–08/10 TIM16_ReadTCNT1: ; Save global interrupt flag in r18,SREG ; Disable interrupts cli ; Read TCNT1 into r17:r16 in r16,TCNT1L in r17,TCNT1H ; Restore global interrupt flag out SREG,r18 ret C Code Example(1) unsigned int TIM16_ReadTCNT1( void ) { unsigned char sreg; unsigned int i; /* Save global interrupt flag */ sreg = SREG; /* Disable interrupts */ _CLI(); /* Read TCNT1 into i */ i = TCNT1; /* Restore global interrupt flag */ SREG = sreg; return i; } Note: 1. The example code assumes that the part specific header file is included. For I/O Registers located in extended I/O map, “IN”, “OUT”, “SBIS”, “SBIC”, “CBI”, and “SBI” instructions must be replaced with instructions that allow access to extended I/O. Typically “LDS” and “STS” combined with “SBRS”, “SBRC”, “SBR”, and “CBR”. The assembly code example returns the TCNT1 value in the r17:r16 register pair. 88 AT90PWM81 7734P–AVR–08/10 AT90PWM81 The following code examples show how to do an atomic write of the TCNT1 Register contents. Writing any of the OCR1A/B or ICR1 Registers can be done by using the same principle. Assembly Code Example(1) TIM16_WriteTCNT1: ; Save global interrupt flag in r18,SREG ; Disable interrupts cli ; Set TCNT1 to r17:r16 out TCNT1H,r17 out TCNT1L,r16 ; Restore global interrupt flag out SREG,r18 ret C Code Example(1) void TIM16_WriteTCNT1( unsigned int i ) { unsigned char sreg; unsigned int i; /* Save global interrupt flag */ sreg = SREG; /* Disable interrupts */ _CLI(); /* Set TCNT1 to i */ TCNT1 = i; /* Restore global interrupt flag */ SREG = sreg; } Note: 1. The example code assumes that the part specific header file is included. For I/O Registers located in extended I/O map, “IN”, “OUT”, “SBIS”, “SBIC”, “CBI”, and “SBI” instructions must be replaced with instructions that allow access to extended I/O. Typically “LDS” and “STS” combined with “SBRS”, “SBRC”, “SBR”, and “CBR”. The assembly code example requires that the r17:r16 register pair contains the value to be written to TCNT1. 11.2.1 11.3 Reusing the Temporary High Byte Register If writing to more than one 16-bit register where the high byte is the same for all registers written, then the high byte only needs to be written once. However, note that the same rule of atomic operation described previously also applies in this case. Timer/Counter Clock Sources The Timer/Counter can be clocked by an internal or an external clock source. The clock source is selected by the Clock Select logic which is controlled by the Clock Select (CS12:0) bits located in the Timer/Counter control Register B (TCCR1B). 89 7734P–AVR–08/10 11.3.1 External Clock Source An external clock source applied to the T1/T0 pin can be used as Timer/Counter clock (clkT1/clkT0). The T1/T0 pin is sampled once every system clock cycle by the pin synchronization logic. The synchronized (sampled) signal is then passed through the edge detector. Figure 11-2 shows a functional equivalent block diagram of the T1/T0 synchronization and edge detector logic. The registers are clocked at the positive edge of the internal system clock (clkI/O). The latch is transparent in the high period of the internal system clock. The edge detector generates one clkT1/clkT0 pulse for each positive (CSn2:0 = 7) or negative (CSn2:0 = 6) edge it detects. Figure 11-2. T1/T0 Pin Sampling D Tn Q D Q D Tn_sync (To Clock Select Logic) Q LE clk I/O Synchronization Edge Detector The synchronization and edge detector logic introduces a delay of 2.5 to 3.5 system clock cycles from an edge has been applied to the T1/T0 pin to the counter is updated. Enabling and disabling of the clock input must be done when T1/T0 has been stable for at least one system clock cycle, otherwise it is a risk that a false Timer/Counter clock pulse is generated. Each half period of the external clock applied must be longer than one system clock cycle to ensure correct sampling. The external clock must be guaranteed to have less than half the system clock frequency (fExtClk < fclk_I/O/2) given a 50/50% duty cycle. Since the edge detector uses sampling, the maximum frequency of an external clock it can detect is half the sampling frequency (Nyquist sampling theorem). However, due to variation of the system clock frequency and duty cycle caused by Oscillator source (crystal, resonator, and capacitors) tolerances, it is recommended that maximum frequency of an external clock source is less than fclk_I/O/2.5. An external clock source can not be prescaled. 11.4 Counter Unit The main part of the 16-bit Timer/Counter is the programmable 16-bit bi-directional counter unit. Figure 11-3 shows a block diagram of the counter and its surroundings. Figure 11-3. Counter Unit Block Diagram DATA BUS (8-bit) TOVn (Int.Req.) TEMP (8-bit) Clock Select Count TCNTnH (8-bit) TCNTnL (8-bit) Clear Control Logic clk Tn Edge Detector Tn TCNTn (16-bit Counter) ( Ckio ) TOP 90 BOTTOM AT90PWM81 7734P–AVR–08/10 AT90PWM81 Signal description (internal signals): Count Increment TCNT1 by 1. Clear Clear TCNT1 (set all bits to zero). clkT1 Timer/Counter clock. TOP Signalize that TCNT1 has reached maximum value. BOTTOM Signalize that TCNT1 has reached minimum value (zero). The 16-bit counter is mapped into two 8-bit I/O memory locations: Counter High (TCNT1H) containing the upper eight bits of the counter, and Counter Low (TCNT1L) containing the lower eight bits. The TCNT1H Register can only be indirectly accessed by the CPU. When the CPU does an access to the TCNT1H I/O location, the CPU accesses the high byte temporary register (TEMP). The temporary register is updated with the TCNT1H value when the TCNT1L is read, and TCNT1H is updated with the temporary register value when TCNT1L is written. This allows the CPU to read or write the entire 16-bit counter value within one clock cycle via the 8-bit data bus. It is important to notice that there are special cases of writing to the TCNT1 Register when the counter is counting that will give unpredictable results. The special cases are described in the sections where they are of importance. Depending on the mode of operation used, the counter is cleared, incremented, or decremented at each timer clock (clkT1). The clkT1 can be generated from an external or internal clock source, selected by the Clock Select bits (CS12:0). When no clock source is selected (CS12:0 = 0) the timer is stopped. However, the TCNT1 value can be accessed by the CPU, independent of whether clkT1 is present or not. A CPU write overrides (has priority over) all counter clear or count operations. The counting sequence is determined by the setting of the Waveform Generation mode bit (WGM13) located in the Timer/Counter Control Registers B ( TCCR1B). The Timer/Counter Overflow Flag (TOV1) is set according to the mode of operation selected by the WGM13 bit. TOV1 can be used for generating a CPU interrupt. 11.5 Input Capture Unit The Timer/Counter incorporates an Input Capture unit that can capture external events and give them a time-stamp indicating time of occurrence. The external signal indicating an event, or multiple events, can be applied via the ICP1 pin or alternatively, via the analog-comparator unit. The time-stamps can then be used to calculate frequency, duty-cycle, and other features of the signal applied. Alternatively the timestamps can be used for creating a log of the events. The Input Capture unit is illustrated by the block diagram shown in Figure 11-4. The elements of the block diagram that are not directly a part of the Input Capture unit are gray shaded. The small “n” in register and bit names indicates the Timer/Counter number. 91 7734P–AVR–08/10 Figure 11-4. Input Capture Unit Block Diagram DATA BUS (8-bit) TEMP (8-bit) ICRnH (8-bit) WRITE ICPnA ICRnL (8-bit) TCNTnH (8-bit) ICRn (16-bit Register) TCNTnL (8-bit) TCNTn (16-bit Counter) ICNC ICES Noise Canceler Edge Detector ICFn (Int.Req.) When a change of the logic level (an event) occurs on the Input Capture pin (ICP1), alternatively on the Analog Comparator output (ACO), and this change confirms to the setting of the edge detector, a capture will be triggered. When a capture is triggered, the 16-bit value of the counter (TCNT1) is written to the Input Capture Register (ICR1). The Input Capture Flag (ICF1) is set at the same system clock as the TCNT1 value is copied into ICR1 Register. If enabled (ICIE1 = 1), the Input Capture Flag generates an Input Capture interrupt. The ICF1 Flag is automatically cleared when the interrupt is executed. Alternatively the ICF1 Flag can be cleared by software by writing a logical one to its I/O bit location. Reading the 16-bit value in the Input Capture Register (ICR1) is done by first reading the low byte (ICR1L) and then the high byte (ICR1H). When the low byte is read the high byte is copied into the high byte temporary register (TEMP). When the CPU reads the ICR1H I/O location it will access the TEMP Register. The ICR1 Register can only be written when using a Waveform Generation mode that utilizes the ICR1 Register for defining the counter’s TOP value. In these cases the Waveform Generation mode (WGM13) bits must be set before the TOP value can be written to the ICR1 Register. When writing the ICR1 Register the high byte must be written to the ICR1H I/O location before the low byte is written to ICR1L. For more information on how to access the 16-bit registers refer to “Accessing 16-bit Registers” on page 86. 11.5.1 Input Capture Trigger Source The main trigger source for the Input Capture unit is the Input Capture pin (ICP1). Timer/Counter1 can alternatively use the Analog Comparator output as trigger source for the Input Capture unit. The Analog Comparator is selected as trigger source by setting the Analog Comparator Input Capture (AC1ICE) bit in the Analog Comparator Extended Control Register (AC1ECON). Be aware that changing trigger source can trigger a capture. The Input Capture Flag must therefore be cleared after the change. 92 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Both the Input Capture pin (ICP1) and the Analog Comparator 1 output (AC1O) inputs are sampled using the same technique as for the T1 pin (SeeFigure 11-2 on page 90). The edge detector is also identical. However, when the noise canceler is enabled, additional logic is inserted before the edge detector, which increases the delay by four system clock cycles. Note that the input of the noise canceler and edge detector is always enabled unless the Timer/Counter is set in a Waveform Generation mode that uses ICR1 to define TOP. An Input Capture can be triggered by software by controlling the port of the ICP1 pin. 11.5.2 Noise Canceler The noise canceler improves noise immunity by using a simple digital filtering scheme. The noise canceler input is monitored over four samples, and all four must be equal for changing the output that in turn is used by the edge detector. The noise canceler is enabled by setting the Input Capture Noise Canceler (ICNC1) bit in Timer/Counter Control Register B (TCCR1B). When enabled the noise canceler introduces additional four system clock cycles of delay from a change applied to the input, to the update of the ICR1 Register. The noise canceler uses the system clock and is therefore not affected by the prescaler. 11.5.3 Using the Input Capture Unit The main challenge when using the Input Capture unit is to assign enough processor capacity for handling the incoming events. The time between two events is critical. If the processor has not read the captured value in the ICR1 Register before the next event occurs, the ICR1 will be overwritten with a new value. In this case the result of the capture will be incorrect. When using the Input Capture interrupt, the ICR1 Register should be read as early in the interrupt handler routine as possible. Even though the Input Capture interrupt has relatively high priority, the maximum interrupt response time is dependent on the maximum number of clock cycles it takes to handle any of the other interrupt requests. Using the Input Capture unit in any mode of operation when the TOP value (resolution) is actively changed during operation, is not recommended. Measurement of an external signal’s duty cycle requires that the trigger edge is changed after each capture. Changing the edge sensing must be done as early as possible after the ICR1 Register has been read. After a change of the edge, the Input Capture Flag (ICF1) must be cleared by software (writing a logical one to the I/O bit location). For measuring frequency only, the clearing of the ICF1 Flag is not required (if an interrupt handler is used). 11.6 Modes of Operation The mode of operation, i.e., the behavior of the Timer/Counter and the Output Compare pins, is defined by the Waveform Generation mode (WGM1) For detailed timing information refer to “Timer/Counter Timing Diagrams” on page 94. 11.6.1 Normal Mode The simplest mode of operation is the Normal mode (WGM13:0 = 0). In this mode the counting direction is always up (incrementing), and no counter clear is performed. The counter simply overruns when it passes its maximum 16-bit value (MAX = 0xFFFF) and then restarts from the BOTTOM (0x0000). In normal operation the Timer/Counter Overflow Flag (TOV1) will be set in the same timer clock cycle as the TCNT1 becomes zero. The TOV1 Flag in this case behaves like a 17th bit, except that it is only set, 93 7734P–AVR–08/10 not cleared. However, combined with the timer overflow interrupt that automatically clears the TOV1 Flag, the timer resolution can be increased by software. There are no special cases to consider in the Normal mode, a new counter value can be written anytime. The Input Capture unit is easy to use in Normal mode. However, observe that the maximum interval between the external events must not exceed the resolution of the counter. If the interval between events are too long, the timer overflow interrupt must be used to extend the resolution for the capture unit. 11.6.2 Clear Timer on Compare Match (CTC) Mode In Clear Timer on Compare or CTC mode (WGM13 = 1, previous mode 12), the ICR1 Register are used to manipulate the counter resolution. In CTC mode the counter is cleared to zero when the counter value (TCNT1) matches the ICR1 . The ICR1 define the top value for the counter, hence also its resolution. This mode allows greater control of the compare match output frequency. It also simplifies the operation of counting external events. The timing diagram for the CTC mode is shown in Figure 11-5. The counter value (TCNT1) increases until a compare match occurs with ICR1, and then counter (TCNT1) is cleared. Figure 11-5. CTC Mode, Timing Diagram ICFn Interrupt Flag Set (Interrupt on TOP) TCNTn An interrupt can be generated at each time the counter value reaches the TOP value by using the ICF1 Flag . If the interrupt is enabled, the interrupt handler routine can be used for updating the TOP value. However, changing the TOP to a value close to BOTTOM when the counter is running with none or a low prescaler value must be done with care since the CTC mode does not have the double buffering feature. If the new value written to ICR1 is lower than the current value of TCNT1, the counter will miss the compare match. The counter will then have to count to its maximum value (0xFFFF) and wrap around starting at 0x0000 before the compare match can occur. In many cases this feature is not desirable. As for the Normal mode of operation, the TOV1 Flag is set in the same timer clock cycle that the counter counts from MAX to 0x0000. 11.7 Timer/Counter Timing Diagrams The Timer/Counter is a synchronous design and the timer clock (clkT1) is therefore shown as a clock enable signal in the following figures. The figures include information on when Interrupt Flags are set. Figure 11-6 shows the count sequence close to TOP in various modes. 94 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 11-6. Timer/Counter Timing Diagram, no Prescaling clkI/O clkTn (clk I/O/1) TCNTn TOP - 1 TOP BOTTOM BOTTOM + 1 ICFn Figure 11-7 shows the count sequence close to MAX in various modes.. Figure 11-7. Timer/Counter Timing Diagram, no Prescaling clkI/O clkTn (clk I/O/1) TCNTn MAX-1 MAX BOTTOM BOTTOM + 1 TOVn 95 7734P–AVR–08/10 11.8 16-bit Timer/Counter Register Description 11.8.1 Timer/Counter1 Control Register B – TCCR1B Bit 7 6 5 4 3 2 1 0 ICNC1 ICES1 - WGM13 - CS12 CS11 CS10 Read/Write R/W R/W R R/W R R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 TCCR1B • Bit 7 – ICNC1: Input Capture Noise Canceler Setting this bit (to one) activates the Input Capture Noise Canceler. When the noise canceler is activated, the input from the Input Capture pin (ICP1) is filtered. The filter function requires four successive equal valued samples of the ICP1 pin for changing its output. The Input Capture is therefore delayed by four Oscillator cycles when the noise canceler is enabled. • Bit 6 – ICES1: Input Capture Edge Select This bit selects which edge on the Input Capture pin (ICP1) that is used to trigger a capture event. When the ICES1 bit is written to zero, a falling (negative) edge is used as trigger, and when the ICES1 bit is written to one, a rising (positive) edge will trigger the capture. When a capture is triggered according to the ICES1 setting, the counter value is copied into the Input Capture Register (ICR1). The event will also set the Input Capture Flag (ICF1), and this can be used to cause an Input Capture Interrupt, if this interrupt is enabled. When the ICR1 is used as TOP value (see description of the WGM13:0 bits located in the TCCR1A and the TCCR1B Register), the ICP1 is disconnected and consequently the Input Capture function is disabled. • Bit 5 – Reserved • Bit 4 – WGM13: Waveform Generation Mode See the table below for the modes definition Table 11-1. Waveform Generation Mode Bit Description Timer/Counter Mode of Operation TOP TOV1 Flag Set on 0 Normal 0xFFFF MAX 1 CTC ICR1 MAX Mode WGM13 0 12 • Bit 3 – Reserved • Bit 2:0 – CS12:0: Clock Select The three Clock Select bits select the clock source to be used by the Timer/Counter, see Table 11-2. Table 11-2. 96 Clock Select Bit Description CS12 CS11 CS10 Description 0 0 0 No clock source (Timer/Counter stopped). 0 0 1 clkI/O/1 (No prescaling) 0 1 0 Reserved 0 1 1 Reserved AT90PWM81 7734P–AVR–08/10 AT90PWM81 Table 11-2. Clock Select Bit Description CS12 CS11 CS10 Description 1 0 0 Reserved 1 0 1 Reserved 1 1 0 External clock source on T1 pin. Clock on falling edge. 1 1 1 External clock source on T1 pin. Clock on rising edge. If external pin modes are used for the Timer/Counter1, transitions on the T1 pin will clock the counter even if the pin is configured as an output. This feature allows software control of the counting. 11.8.2 Timer/Counter1 – TCNT1H and TCNT1L Bit 7 6 5 4 3 2 1 0 TCNT1[15:8] TCNT1H TCNT1[7:0] TCNT1L Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 The two Timer/Counter I/O locations (TCNT1H and TCNT1L, combined TCNT1) give direct access, both for read and for write operations, to the Timer/Counter unit 16-bit counter. To ensure that both the high and low bytes are read and written simultaneously when the CPU accesses these registers, the access is performed using an 8-bit temporary High Byte Register (TEMP). This temporary register is shared by all the other 16-bit registers. See “Accessing 16-bit Registers” on page 86. Modifying the counter (TCNT1) while the counter is running introduces a risk of missing a compare match between TCNT1 and one of the OCR1x Registers. Writing to the TCNT1 Register blocks (removes) the compare match on the following timer clock for all compare units. 11.8.3 Input Capture Register 1 – ICR1H and ICR1L Bit 7 6 5 4 3 2 1 0 ICR1[15:8] ICR1H ICR1[7:0] ICR1L Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 The Input Capture is updated with the counter (TCNT1) value each time an event occurs on the ICP1 pin (or optionally on the Analog Comparator output for Timer/Counter1). The Input Capture can be used for defining the counter TOP value. The Input Capture Register is 16-bit in size. To ensure that both the high and low bytes are read simultaneously when the CPU accesses these registers, the access is performed using an 8-bit temporary High Byte Register (TEMP). This temporary register is shared by all the other 16-bit registers. See “Accessing 16-bit Registers” on page 86. 11.8.4 Timer/Counter1 Interrupt Mask Register – TIMSK1 Bit 7 6 5 4 3 2 1 0 – – ICIE1 – – – – TOIE1 Read/Write R R R/W R R R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 TIMSK1 97 7734P–AVR–08/10 • Bit 7, 6 – Res: Reserved Bits These bits are unused bits in the AT90PWM81, and will always read as zero. • Bit 5 – ICIE1: Timer/Counter1, Input Capture Interrupt Enable When this bit is written to one, and the I-flag in the Status Register is set (interrupts globally enabled), the Timer/Counter1 Input Capture interrupt is enabled. The corresponding Interrupt Vector (see XXXX) is executed when the ICF1 Flag, located in TIFR1, is set. • Bit 4, 3, 2,1 – Res: Reserved Bits These bits are unused bits in the AT90PWM81, and will always read as zero. • Bit 0 – TOIE1: Timer/Counter1, Overflow Interrupt Enable When this bit is written to one, and the I-flag in the Status Register is set (interrupts globally enabled), the Timer/Counter1 Overflow interrupt is enabled. The corresponding Interrupt Vector (see Table 8-1 on page 61) is executed when the TOV1 Flag, located in TIFR1, is set. 11.8.5 Timer/Counter1 Interrupt Flag Register – TIFR1 Bit 7 6 5 4 3 2 1 – – ICF1 – – – – 0 TOV1 Read/Write R R R/W R R R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 TIFR1 • Bit 7, 6 – Res: Reserved Bits These bits are unused bits in the AT90PWM81, and will always read as zero. • Bit 5 – ICF1: Timer/Counter1, Input Capture Flag This flag is set when a capture event occurs on the ICP1 pin. When the Input Capture Register (ICR1) is set by the WGM13:0 to be used as the TOP value, the ICF1 Flag is set when the counter reaches the TOP value. ICF1 is automatically cleared when the Input Capture Interrupt Vector is executed. Alternatively, ICF1 can be cleared by writing a logic one to its bit location. • Bit 4, 3, 2,1 – Res: Reserved Bits • Bit 0 – TOV1: Timer/Counter1, Overflow Flag The setting of this flag is dependent of the WG. TOV1 is automatically cleared when the Timer/Counter1 Overflow Interrupt Vector is executed. Alternatively, TOV1 can be cleared by writing a logic one to its bit location. 98 AT90PWM81 7734P–AVR–08/10 AT90PWM81 12. Power Stage Controller – (PSCn) The Power Stage Controller is a high performance waveform controller. The AT90PWM81 includes one PSC2 block. 12.1 Features • • • • • • • • • • • PWM waveform generation function (2 complementary programmable outputs) Dead time control Standard mode up to 12 bit resolution Frequency and pulse width Resolution Enhancement Mode (12 + 4 bits) Frequency up to 64 Mhz Conditional Waveform on External Events (Zero Crossing, Current Sensing ...) All on chip PSC synchronization ADC synchronization with digital delay register Input Blanking Overload protection function Abnormality protection function, emergency input to force all outputs to high impedance or in inactive state (fuse configurable) • Center aligned and edge aligned modes synchronization • Fast emergency stop by hardware 12.2 Overview Many register and bit references in this section are written in general form. • A lower case “n” replaces the PSC number, in this case 2. However, when using the register or bit defines in a program, the precise form must be used, i.e., PSOC2 for accessing PSC 2 Synchro and Output Configuration register and so on. • A lower case “x” replaces the PSC part , in this case A or B. However, when using the register or bit defines in a program, the precise form must be used, i.e., PFRC2A for accessing PSC n Fault/Retrigger 2 A Control register and so on. The purpose of a Power Stage Controller (PSC) is to control power modules on a board. It has two outputs on PSCn and four outputs on PSC2. These outputs can be used in various ways: • “Two Outputs” to drive a half bridge (lighting, DC motor ...) • “One Output” to drive single power transistor (DC/DC converter, PFC, DC motor ...) • “Four Outputs” in the case of PSC2 to drive a full bridge (lighting, DC motor ...) Each PSC has two inputs the purpose of which is to provide means to act directly on the generated waveforms: • Current sensing regulation • Zero crossing retriggering • Demagnetization retriggering • Fault input The PSC can be chained and synchronized to provide a configuration to drive three half bridges. Thanks to this feature it is possible to generate a three phase waveforms for applications such as Asynchronous or BLDC motor drive. 99 7734P–AVR–08/10 12.3 PSC Description Figure 12-1. Power Stage Controller 0 or 1 Block Diagram PSC Counter = Waveform Generator B PSCOUTn1 PSC Input Module B PSCn Input B OCRnRB DATABUS = OCRnSB Part B = PSC Input Module A PSCn Input A Waveform Generator A PSCOUTn0 OCRnRA = OCRnSA Part A PICRn PCNFEn PCNFn PCTLn Note: PASDLYn PFRCnB PFRCnA PSOCn n = 0, 1 The principle of the PSC is based on the use of a counter (PSC counter). This counter is able to count up and count down from and to values stored in registers according to the selected running mode. The PSC is seen as two symmetrical entities. One part named part A which generates the output PSCOUTn0 and the second one named part B which generates the PSCOUTn1 output. Each part A or B has its own PSC Input Module to manage selected input. 100 AT90PWM81 7734P–AVR–08/10 AT90PWM81 12.3.1 PSC2 Distinctive Feature Figure 12-2. PSC2 versus PSC1&PSC0 Block Diagram PSC Counter PSCOUTn3 = POS23 Waveform Generator B PSCOUTn1 OCRnRB DATABUS = PSC Input Module B OCRnSB Part A = PSCn Input B Output Matrix PSC Input Module A PSCn Input A OCRnRA = PSCOUTn2 POS22 Waveform Generator A PSCOUTn0 OCRnSA Part B PICRn PCNFEn PCNFn PCTLn Note: PASDLYn PFRCnB PFRCnA POM2(PSC2 only) PSOCn n=2 PSC2 has two supplementary outputs PSCOUT22 and PSCOUT23. Thanks to a first selector PSCOUT22 can duplicate PSCOUT20 or PSCOUT21. Thanks to a second selector PSCOUT23 can duplicate PSCOUT20 or PSCOUT21. The Output Matrix is a kind of 2*2 look up table which gives the possibility to program the output values according to a PSC sequence (See “Output Matrix” on page 129.) 12.3.2 Output Polarity The polarity “active high” or “active low” of the PSC outputs is programmable. All the timing diagrams in the following examples are given in the “active high” polarity. 101 7734P–AVR–08/10 12.4 Signal Description Figure 12-3. PSC External Block View CLK PLL CLK I/O SYnIn StopOut OCRnR B[11:0] OCRnSB[11:0] OCRnR A[11:0] OCRnSA[11:0] OCRnR B[15:12] (FlankWidth Modulation) 12 PSCOUT n0 12 PSCOUT n1 12 PSCOUT n2 12 PSCOUT n3 (1) 4 PICRn[11:0] 2 12 2 IRQ PSC n StopIn SYnOut Note: (1) PSCINn Analog Comparator n Output PSCnASY 1. available only for PSC2 2. n = 0, 1 or 2 12.4.1 Input Description Table 12-1. Name 102 Internal Inputs Description Type Width OCRnRB[11 :0] Compare Value which Reset Signal on Part B (PSCOUTn1) Register 12 bits OCRnSB[11 :0] Compare Value which Set Signal on Part B (PSCOUTn1) Register 12 bits OCRnRA[1 1:0] Compare Value which Reset Signal on Part A (PSCOUTn0) Register 12 bits OCRnSA[11 :0] Compare Value which Set Signal on Part A (PSCOUTn0) Register 12 bits AT90PWM81 7734P–AVR–08/10 AT90PWM81 Name OCRnRB[1 5:12] Frequency Resolution Enhancement value (Flank Width Modulation) Register 4 bits CLK I/O Clock Input from I/O clock Signal CLK PLL Clock Input from PLL Signal (1) SYnIn Synchronization In (from adjacent PSC) Signal StopIn Stop Input (for synchronized mode) Signal Note: 1. See Figure 12-41 on page 131 Table 12-2. Name 12.4.2 Type Width Description Block Inputs Type Width Description PSCINn Input 0 used for Retrigger or Fault functions Signal from 1st A C Input 1 used for Retrigger or Fault functions Signal PSCINnA Input 2 used for Retrigger or Fault functions Signal from 2nd A C Input 3 used for Retrigger or Fault functions Signal Output Description Table 12-3. Name Block Outputs Type Width Description PSCOUTn0 PSC n Output 0 (from part A of PSC) Signal PSCOUTn1 PSC n Output 1 (from part B of PSC) Signal PSCOUTn2 (PSC2 only) PSC n Output 2 (from part A or part B of PSC) Signal PSCOUTn3(P SC2 only) PSC n Output 3 (from part A or part B of PSC) Signal Table 12-4. Name Internal Outputs Type Width Description SYnOut Synchronization Output(1) Signal PICRn [11:0] PSC n Input Capture Register Counter value at retriggering event Register 12 bits IRQPSCn PSC Interrupt Request : three sources, overflow, fault, and input capture (2) PSCnASY ADC Synchronization (+ Amplifier Syncho. ) StopOut Stop Output (for synchronized mode) Signal Signal 103 7734P–AVR–08/10 Note: 1. See Figure 12-41 on page 131 2. See “Analog Synchronization” on page 130. 12.5 12.5.1 Functional Description Waveform Cycles The waveform generated by PSC can be described as a sequence of two waveforms. The first waveform is relative to PSCOUTn0 output and part A of PSC. The part of this waveform is subcycle A in the following figure. The second waveform is relative to PSCOUTn1 output and part B of PSC. The part of this waveform is sub-cycle B in the following figure. The complete waveform is ended with the end of sub-cycle B. It means at the end of waveform B. Figure 12-4. Cycle Presentation in 1, 2 & 4 Ramp Mode PSC Cycle Sub-Cycle A Sub-Cycle B 4 Ramp Mode Ramp A0 Ramp A1 Ramp B0 Ramp B1 2 Ramp Mode Ramp A Ramp B 1 Ramp Mode UPDATE Figure 12-5. Cycle Presentation in Centered Mode PSC Cycle Centered Mode UPDATE Ramps illustrate the output of the PSC counter included in the waveform generators. Centered Mode is like a one ramp mode which count down up and down. Notice that the update of a new set of values is done regardless of ramp Mode at the top of the last ramp. 104 AT90PWM81 7734P–AVR–08/10 AT90PWM81 12.5.2 Running Mode Description Waveforms and length of output signals are determined by Time Parameters (DT0, OT0, DT1, OT1) and by the running mode. Four modes are possible : – Four Ramp mode – Two Ramp mode – One Ramp mode – Center Aligned mode 12.5.2.1 Four Ramp Mode In Four Ramp mode, each time in a cycle has its own definition Figure 12-6. PSCn0 & PSCn1 Basic Waveforms in Four Ramp mode OCRnRA PSC Counter OCRnSA OCRnRB OCRnSB 0 0 On-Time 0 On-Time 1 PSCOUTn0 PSCOUTn1 Dead-Time 1 Dead-Time 0 PSC Cycle The input clock of PSC is given by CLKPSC. PSCOUTn0 and PSCOUTn1 signals are defined by On-Time 0, Dead-Time 0, On-Time 1 and Dead-Time 1 values with : On-Time 0 = OCRnRAH/L * 1/Fclkpsc On-Time 1 = OCRnRBH/L * 1/Fclkpsc Dead-Time 0 = (OCRnSAH/L + 2) * 1/Fclkpsc Dead-Time 1 = (OCRnSBH/L + 2) * 1/Fclkpsc Note: 12.5.2.2 Minimal value for Dead-Time 0 and Dead-Time 1 = 2 * 1/Fclkpsc Two Ramp Mode In Two Ramp mode, the whole cycle is divided in two moments One moment for PSCn0 description with OT0 which gives the time of the whole moment One moment for PSCn1 description with OT1 which gives the time of the whole moment 105 7734P–AVR–08/10 Figure 12-7. PSCn0 & PSCn1 Basic Waveforms in Two Ramp mode OCRnRA OCRnRB PSC Counter OCRnSA OCRnSB 0 0 On-Time 0 On-Time 1 PSCOUTn0 PSCOUTn1 Dead-Time 1 Dead-Time 0 PSC Cycle PSCOUTn0 and PSCOUTn1 signals are defined by On-Time 0, Dead-Time 0, On-Time 1 and Dead-Time 1 values with : On-Time 0 = (OCRnRAH/L - OCRnSAH/L) * 1/Fclkpsc On-Time 1 = (OCRnRBH/L - OCRnSBH/L) * 1/Fclkpsc Dead-Time 0 = (OCRnSAH/L + 1) * 1/Fclkpsc Dead-Time 1 = (OCRnSBH/L + 1) * 1/Fclkpsc Note: 12.5.2.3 106 Minimal value for Dead-Time 0 and Dead-Time 1 = 1/Fclkpsc One Ramp Mode In One Ramp mode, PSCOUTn0 and PSCOUTn1 outputs can overlap each other. AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 12-8. PSCn0 & PSCn1 Basic Waveforms in One Ramp mode OCRnRB OCRnSB OCRnRA PSC Counter OCRnSA 0 On-Time 0 On-Time 1 PSCOUTn0 PSCOUTn1 Dead-Time 1 Dead-Time 0 PSC Cycle On-Time 0 = (OCRnRAH/L - OCRnSAH/L) * 1/Fclkpsc On-Time 1 = (OCRnRBH/L - OCRnSBH/L) * 1/Fclkpsc Dead-Time 0 = (OCRnSAH/L + 1) * 1/Fclkpsc Dead-Time 1 = (OCRnSBH/L - OCRnRAH/L) * 1/Fclkpsc Note: 12.5.2.4 Minimal value for Dead-Time 0 = 1/Fclkpsc Center Aligned Mode In center aligned mode, the center of PSCn00 and PSCn01 signals are centered. 107 7734P–AVR–08/10 Figure 12-9. PSCn0 & PSCn1 Basic Waveforms in Center Aligned Mode OCRnRB PSC Counter OCRnSB OCRnSA 0 On-Time 0 On-Time 1 On-Time 1 PSCOUTn0 PSCOUTn1 Dead-Time Dead-Time PSC Cycle On-Time 0 = 2 * OCRnSAH/L * 1/Fclkpsc On-Time 1 = 2 * (OCRnRBH/L - OCRnSBH/L + 1) * 1/Fclkpsc Dead-Time = (OCRnSBH/L - OCRnSAH/L) * 1/Fclkpsc PSC Cycle = 2 * (OCRnRBH/L + 1) * 1/Fclkpsc Note: Minimal value for PSC Cycle = 2 * 1/Fclkpsc OCRnRAH/L is not used to control PSC Output waveform timing. Nevertheless, it can be useful to adjust ADC synchronization (See “Analog Synchronization” on page 130.). Figure 12-10. Run and Stop Mechanism in Centered Mode OCRnRB OCRnSB OCRnSA PSC Counter 0 Run PSCOUTn0 PSCOUTn1 Note: 108 See “PSC 2 Control Register – PCTL2” on page 139.(or PCTL1 or PCTL2) AT90PWM81 7734P–AVR–08/10 AT90PWM81 12.5.3 12.6 Fifty Percent Waveform Configuration When PSCOUTn0 and PSCOUTn1 have the same characteristics, it’s possible to configure the PSC in a Fifty Percent mode. When the PSC is in this configuration, it duplicates the OCRnSBH/L and OCRnRBH/L registers in OCRnSAH/L and OCRnRAH/L registers. So it is not necessary to program OCRnSAH/L and OCRnRAH/L registers. Update of Values The update of PSC waveform registers are done in the following way: • Immediately when the PSC is stopped • At the PSC end of cycle when the PSC is running • At the PSC end of cycle following the required condition when LOCK or AUTOLOCK modes are used. To avoid asynchronous and incoherent values in a cycle, if an update of one of several values is necessary, all values can be updated at the same time at the end of the cycle by the PSC. The new set of values is calculated by software and the update is initiated by software. Figure 12-11. Update at the end of complete PSC cycle. Regulation Loop Calculation Writting in PSC Registers Software Cycle With Set i Cycle With Set i Cycle With Set i Request for an Update Cycle With Set i PSC Cycle With Set j End of Cycle The software can stop the cycle before the end to update the values and restart a new PSC cycle. 12.6.1 Value Update Synchronization New timing values or PSC output configuration can be written during the PSC cycle. Thanks to LOCK and AUTOLOCK configuration bits, the new whole set of values can be taken into account with the following conditions: • When AUTOLOCK configuration is selected, the update of the PSC internal registers will be done at the end of the PSC cycle following a write in the Output Compare Register RB. The AUTOLOCK configuration bit is taken into account at the end of the first PSC cycle. • When LOCK configuration bit is set, there is no update. The update of the PSC internal registers will be done at the end of the PSC cycle if the LOCK bit is released to zero. The registers which update is synchronized thanks to LOCK and AUTOLOCK are PSOCn, POM2, OCRnSAH/L, OCRnRAH/L, OCRnSBH/L and OCRnRBH/L. See these register’s description starting on page 134. When set, AUTOLOCK configuration bit prevails over LOCK configuration bit. See “PSC 2 Configuration Register – PCNF2” on page 135. 109 7734P–AVR–08/10 12.7 Enhanced Resolution Lamp Ballast applications need an enhanced resolution down to 50Hz. The method to improve the normal resolution is based on Flank Width Modulation (also called Fractional Divider). Cycles are grouped into frames of 16 cycles. Cycles are modulated by a sequence given by the fractional divider number. The resulting output frequency is the average of the frequencies in the frame. The fractional divider (d) is given by OCRnRB[15:12]. The PSC output period is directly equal to the PSCOUTn0 On Time + Dead Time (OT0+DT0) and PSCOUTn1 On Time + Dead Time (OT1+DT1) values. These values are 12 bits numbers. The frequency adjustment can only be done in steps like the dedicated counters. The step width is defined as the frequency difference between two neighboring PSC frequencies. It is possible to apply the Flank Width Modulation (FWM) on RB, RB+RA, SB, SB+SA. The selection is done bit the bits PBFMn0 and PBFMn. According to the ramp mode and the enhanced resolution mode (defined by PBFMn1:0), the frequency difference Δf can take three different values: Δf = 0 f PSC f PSC 1 – ------------ = f PSC × ------------------Δf1 = f1 – f2 = ---------k( k + 1 ) k k+1 f PSC f PSC 2 – ------------ = f PSC × ------------------Δf2 = f1 – f2 = ---------k( k + 2 ) k k+2 with k is the number of CLKPSC period in a PSC cycle and is given by the following formula: f PSC k = ---------f OP with fOP is the output operating frequency. Example, in normal mode, with maximum operating frequency 160 kHz and fPLL = 64 Mhz, k equals 400. The resulting resolution is Delta F equals 64MHz / 400 / 401 = 400 Hz. In enhanced mode, the output frequency is the average of the frame formed by the 16 consecutive cycles. fb1 and fb2 are two neighboring base frequencies. d 16 – d f AVERAGE = --------------- × f b1 + ------ × f b2 16 16 Then the frequency resolution is divided by 16. In the example above, the resolution equals 25 Hz. 16 – d f PLL d f PLL f AVERAGE = --------------- × ---------- + ------ × -----------k 16 k + 1 16 110 AT90PWM81 7734P–AVR–08/10 AT90PWM81 According to the ramp mode and the enhanced resolution mode (defined by PBFMn1:0), the average frequency deviation Δf can take three different values: Δf ( average ) = 0 d Δf1 ( average ) = f PSC × -------------------------16k ( k + 1 ) d Δf2 ( average ) = f PSC × ----------------------8k ( k + 2 ) These values are applied according to the running mode and the enhanced resolution mode as per Table 12-5 on page 111; It must be noted that, in one and two ramps modes, it is possible to apply the FWM only on pulse width while keeping a constant frequency. Table 12-5. Frequency deviation with Flank Width Modulation PBFMn1:0 00 01 10 11 RB RB+RA SB SB+SA Four Ramps Δf1 Δf2 Δf1 Δf2 Two Ramps Δf1 Δf2 0 (1) 0 One Ramp Δf1 Δf1 0 0 Center aligned Δf2 Δf2 Δf2 Δf2 Running Mode 1. 12.7.1 Note: The modulation is on the pulse width. Frequency distribution The frequency modulation is done by switching two frequencies in a 16 consecutive cycle frame. These two frequencies are fb1 and fb2 where fb1 is the nearest base frequency above the wanted frequency and fb2 is the nearest base frequency below the wanted frequency. The number of fb1 in the frame is (d-16) and the number of fb2 is d. The fb1 and fb2 frequencies are evenly distributed in the frame according to a predefined pattern. This pattern can be as given in the following table or by any other implementation which give an equivalent evenly distribution. At the end of the 15th cycle (numbered 14 on Table 12-6 ) an interrupt can be generated. This is the case if the bit PEOEPEn (PSC n End Of Enhanced Cycle Interrupt Enable) is set. This allows: • To modify the modulation only on a new enhanced cycle start. • To extend the enhanced modulation accuracy by software. 111 7734P–AVR–08/10 Table 12-6. Distribution of fb2 in the modulated frame Distribution of fb2 in the modulated frame PWM - cycle Fraction al Divider (d) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 X 2 X 3 X X X 4 X X X X 5 X X X X X 6 X X X X X X 7 X X X X X X X 8 X X X X X X X X 9 X X X X X X X X X 10 X X X X X X X X X X 11 X X X X X X X X X X X 12 X X X X X X X X X X X X 13 X X X X X X X X X X X X X 14 X X X X X X X X X X X X X X 15 X X X X X X X X X X X X X X X X While ‘X’ in the table, fb2 prime to fb1 in cycle corresponding cycle. So for each row, a number of fb2 take place of fb1. Figure 12-12. Resulting Frequency versus d. fb1 fb2 fOP d: 12.7.2 12.7.2.1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Modes of Operation Normal Mode The simplest mode of operation is the normal mode. See Figure 12-6. The active time of PSCOUTn0 is given by the OT0 value. The active time of PSCOUTn1 is given by the OT1 value. Both of them are 12 bit values. Thanks to DT0 & DT1 to adjust the dead time between PSCOUTn0 and PSCOUTn1 active signals. 112 AT90PWM81 7734P–AVR–08/10 AT90PWM81 The waveform frequency is defined by the following equation: f CLK_PSCn 1 f PSCn = ------------------------------ = -------------------------------------------------------------------PSCnCycle ( OT0 + OT1 + DT0 + DT1 ) 12.7.2.2 Enhanced Mode The Enhanced Mode uses the previously described method to generate a high resolution frequency. Figure 12-13 gives an example of FWM with PBFMn1:0 = 00. Figure 12-13. Enhanced Mode, Timing Diagram DT0 OT0 DT1 DT0 OT1 DT1 OT0 OT1+1 DT0 PSCOUTn0 PSCOUTn1 Period T2 T1 The supplementary step in counting to generate fb2 is added on the PSCn0 signal while needed in the frame according to the fractional divider. SeeTable 12-6, “Distribution of fb2 in the modulated frame,” on page 112. The waveform frequency is defined by the following equations: f CLK_PSCn 1 f1 PSCn = ----= -------------------------------------------------------------------T1 ( OT0 + OT1 + DT0 + DT1 ) f CLK_PSCn 1 f2 PSCn = ----= -----------------------------------------------------------------------------T2 ( OT0 + OT1 + DT0 + DT1 + 1 ) 16 – d d f AVERAGE = ------ × f1 PSCn + --------------- × f2 PSCn 16 16 d is the fractional divider factor. The FWM can be applied on different locations within the PSC output waveforms as defined per Table 12-15 on page 137 12.8 PSC Inputs Part A or B of PSC has its own system to take into account one PSC n internal input. Each part A or B is configured by the PSC n Input A/B Control Register (PFRCnA/B page 140) and the PSC n Extended Configuration Register ((see Section “PSC 2 Configuration Register – PCNF2”, page 135) The PSC input module A is shown on Table 12-14 113 7734P–AVR–08/10 According to PSC n Input A Control Register (see Section “PSC n Input A Control Register – PFRCnA”, page 140), PSC n input A can act as a Retrigger or Fault input. Each part A or B can be triggered by up to four signals as defined per Table 12-18 on page 138 and Table 12-19 on page 139 Part A of PSC has also a blanking module allowing to cancel unwanted transitions which may appear on the PSC n input A during a certain period of time. The blanking start is defined by the bits PASDLKn(2:0) as per Table 12-14 on page 136. The blanking duration is defined by the register PASDLYn. If the blanking is selected by the corresponding PASDLKn(2:0) bit, all transitions which may appears from the blanking start until a time period are ignored. Blanking is level sensitive, i.e. a pulse started in the blanking window and still at active level after the window will generate a valid retriggering event. Figure 12-14. PSC Input Module A PAOCnA 0 0 AC2O: Analog Comparator Output 0 1 PSCINnA 1 0 AC3O: Analog Comparator Output 1 1 PSCINn Input Blanking 0 PSC n Input A Digital Filter 1 PFLTEnA CLK PSC PISELnA1PISELnA0 PASDLY OCR SB 3 OSR SA PSC start ycle c 2 Blanking Start 1 PCAEnA PASDLKn(2:0) =0, 4..7 No Blanking PRFMnA3:0 4 Input Processing (retriggering ...) PELE VnA / PSC C ore (Counter, Waveform Generator, ...) CLK PSC Output Control PSCOUT n0 (PSCOUT n1) (PSCOUT2 (PSCOUT2 PSC input module B is shown on Table 12-15 According to PSC n Input B Control Register (see Section “PSC n Input B Control Register – PFRCnB”, page 140), PSC n input B can act as a Retrigger or Fault input. 114 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 12-15. PSC Input Module B PAOCnB PSCINn 0 0 0 AC2O: Analog Comparator Output 0 1 PSCINnA 1 0 AC3O:Analog Comparator Output PSC n Input B Digital Filter CLK PSC 1 1 PFLTEnB 1 PCAEnB PISELnB1 PISELnB0 PELE VnB PRFMnB3:0 4 Input Processing (retriggering ...) CLK PSC PSC C ore (Counter, Waveform Generator, ...) Output Control CLK PSC 12.8.1 PSCOUT n0 (PSCOUT n1) (PSCOUT2 (PSCOUT2 PSC Retrigger Behavior versus PSC running modes In centered mode, Retrigger Inputs have no effect. In two ramp or four ramp mode, Retrigger Inputs A or B cause the end of the corresponding cycle A or B and the beginning of the following cycle B or A. In one ramp mode, Retrigger Inputs A or B reset the current PSC counting to zero. 12.8.2 Retrigger PSCOUTn0 On External Event PSCOUTn0 output can be reset before end of On-Time 0 on the change on PSCn Input A. PSCn Input A can be configured to do not act or to act on level or edge modes. The polarity of PSCn Input A is configurable thanks to a sense control block. PSCn Input A can be the Output of the analog comparator or the PSCINn input. As the period of the cycle decreases, the instantaneous frequency of the two outputs increases. 115 7734P–AVR–08/10 Figure 12-16. PSCOUTn0 retrograde by PSCn Input A (Edge Retriggering) On-Time 0 On-Time 1 PSCOUTn0 PSCOUTn1 PSCn Input A (falling edge) PSCn Input A (rising edge) Dead-Time 0 Note: Dead-Time 1 This example is given in “Input Mode 8” in “2 or 4 ramp mode” See Figure 12-33. for details. Figure 12-17. PSCOUTn0 retriggered by PSCn Input A (Level Acting) On-Time 0 On-Time 1 PSCOUTn0 PSCOUTn1 PSCn Input A (high level) PSCn Input A (low level) Dead-Time 0 Note: 12.8.3 Dead-Time 1 This example is given in “Input Mode 1” in “2 or 4 ramp mode” See Figure 12-22. for details. Retrigger PSCOUTn1 On External Event PSCOUTn1 output can be reset before end of On-Time 1 on the change on PSCn Input B. The polarity of PSCn Input B is configurable thanks to a sense control block. PSCn Input B can be configured to do not act or to act on level or edge modes. PSCn Input B can be the Output of the analog comparator or the PSCINn input. As the period of the cycle decreases, the instantaneous frequency of the two outputs increases. 116 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 12-18. PSCOUTn1 retriggered by PSCn Input B (Edge Retriggering) On-Time 0 On-Time 1 PSCOUTn0 PSCOUTn1 PSCn Input B (falling edge) PSCn Input B (rising edge) Dead-Time 0 Note: Dead-Time 1 Dead-Time 0 This example is given in “Input Mode 8” in “2 or 4 ramp mode” See Figure 12-33. for details. Figure 12-19. PSCOUTn1 retriggered by PSCn Input B (Level Acting) On-Time 0 On-Time 1 PSCOUTn0 PSCOUTn1 PSCn Input B (high level) PSCn Input B (low level) Dead-Time 0 Note: 12.8.3.1 Dead-Time 1 Dead-Time 0 This example is given in “Input Mode 1” in “2 or 4 ramp mode” See Figure 12-22. for details. Burst Generation Note: On level mode, it’s possible to use PSC to generate burst by using Input Mode 3 or Mode 4 (See Figure 12-26. and Figure 12-27. for details.) 117 7734P–AVR–08/10 Figure 12-20. Burst Generation OFF BURST PSCOUTn0 PSCOUTn1 PSCn Input A (high level) PSCn Input A (low level) 12.8.4 12.8.4.1 PSC Input Configuration The PSC Input Configuration is done by programming bits in configuration registers. Filter Enable If the “Filter Enable” bit is set, a digital filter of 4 cycles is inserted before evaluation of the signal. The disable of this function is mainly needed for prescaled PSC clock sources, where the noise cancellation gives too high latency. Important: If the digital filter is active, the level sensitivity is true also with a disturbed PSC clock to deactivate the outputs (emergency protection of external component). Likewise when used as fault input, PSCn Input A or Input B have to go through PSC to act on PSCOUTn0/1/2/3 output. This way needs that CLKPSC is running. So thanks to PSC Asynchronous Output Control bit (PAOCnA/B), PSCnIN0/1 input can deactivate directly the PSC output. Notice that in this case, input is still taken into account as usually by Input Module System as soon as CLKPSC is running. Figure 12-21. PSC Input Flittering CLKPSC Digital Filter 4 x CLK PSC PSC Input Module X 12.8.4.2 118 PSCn Input A or B Ouput Stage PSCOUTnX PIN Signal Polarity One can select the active edge (edge modes) or the active level (level modes) See PELEVnx bit description in Section “PSC n Input A Control Register – PFRCnA”, page 14012.25.10. AT90PWM81 7734P–AVR–08/10 AT90PWM81 If PELEVnx bit set, the significant edge of PSCn Input A or B is rising (edge modes) or the active level is high (level modes) and vice versa for unset/falling/low - In 2- or 4-ramp mode, PSCn Input A is taken into account only during Dead-Time0 and On-Time0 period (respectively Dead-Time1 and On-Time1 for PSCn Input B). - In 1-ramp-mode PSC Input A or PSC Input B act on the whole ramp. 12.8.4.3 Input Mode Operation Thanks to 4 configuration bits (PRFM3:0), it’s possible to define the mode of the PSC input. All Table 12-7. PSC Input Mode Operation PRFM3:0 Description 0 0000b PSCn Input has no action on PSC output 1 0001b 2 0010b 3 0011b 4 0100b 5 0101b 6 0110b 7 0111b See “PSC Input Mode 6: Stop signal, Jump to Opposite Dead-Time and Wait.” on page 124. See “PSC Input Mode 7: Halt PSC and Wait for Software Action” on page 124. 8 1000b See “PSC Input Mode 8: Edge Retrigger PSC” on page 125. 9 1001b See “PSC Input Mode 9: Fixed Frequency Edge Retrigger PSC” on page 126. 10 1010b Reserved : Do not use 11 1011b 12 1100b 13 1101b 14 1110b 15 1111b 12.9See “PSC Input Mode 1: Stop signal, Jump to Opposite Dead-Time and Wait” on page 120. See “PSC Input Mode 2: Stop signal, Execute Opposite Pulse and Wait” on page 121. See “PSC Input Mode 3: Stop signal, Execute Opposite Pulse while Fault active” on page 122. See “PSC Input Mode 4: Deactivate outputs without changing timing.” on page 123. See “PSC Input Mode 5: Stop signal and Insert Dead-Time” on page 123. See “PSC Input Mode 14: Fixed Frequency Edge Retrigger PSC and Deactivate Output” on page 127. Reserved : Do not use Notice: All following examples are given with rising edge or high level active inputs. 119 7734P–AVR–08/10 12.9 PSC Input Mode 1: Stop signal, Jump to Opposite Dead-Time and Wait Figure 12-22. PSCn behavior versus PSCn Input A in Fault Mode 1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSC Input A PSC Input B PSC Input A is taken into account during DT0 and OT0 only. It has no effect during DT1 and OT1. When PSC Input A event occurs, PSC releases PSCOUTn0, waits for PSC Input A inactive state and then jumps and executes DT1 plus OT1. Figure 12-23. PSCn behavior versus PSCn Input B in Fault Mode 1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSC Input A PSC Input B PSC Input B is take into account during DT1 and OT1 only. It has no effect during DT0 and OT0. When PSC Input B event occurs, PSC releases PSCOUTn1, waits for PSC Input B inactive state and then jumps and executes DT0 plus OT0. 120 AT90PWM81 7734P–AVR–08/10 AT90PWM81 12.10 PSC Input Mode 2: Stop signal, Execute Opposite Pulse and Wait Figure 12-24. PSCn behavior versus PSCn Input A in Fault Mode 2 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSC Input A PSC Input B PSC Input A is take into account during DT0 and OT0 only. It has no effect during DT1 and OT1. When PSCn Input A event occurs, PSC releases PSCOUTn0, jumps and executes DT1 plus OT1 and then waits for PSC Input A inactive state. Even if PSC Input A is released during DT1 or OT1, DT1 plus OT1 sub-cycle is always completely executed. Figure 12-25. PSCn behavior versus PSCn Input B in Fault Mode 2 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSC Input A PSC Input B PSC Input B is take into account during DT1 and OT1 only. It has no effect during DT0 and OT0. When PSC Input B event occurs, PSC releases PSCOUTn1, jumps and executes DT0 plus OT0 and then waits for PSC Input B inactive state. Even if PSC Input B is released during DT0 or OT0, DT0 plus OT0 sub-cycle is always completely executed. 121 7734P–AVR–08/10 12.11 PSC Input Mode 3: Stop signal, Execute Opposite Pulse while Fault active Figure 12-26. PSCn behavior versus PSCn Input A in Mode 3 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT1 OT1 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSC Input A PSC Input B PSC Input A is taken into account during DT0 and OT0 only. It has no effect during DT1 and OT1. When PSC Input A event occurs, PSC releases PSCOUTn0, jumps and executes DT1 plus OT1 plus DT0 while PSC Input A is in active state. Even if PSC Input A is released during DT1 or OT1, DT1 plus OT1 sub-cycle is always completely executed. Figure 12-27. PSCn behavior versus PSCn Input B in Mode 3 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT0 OT0 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSC Input A PSC Input B PSC Input B is taken into account during DT1 and OT1 only. It has no effect during DT0 and OT0. When PSC Input B event occurs, PSC releases PSCnOUT1, jumps and executes DT0 plus OT0 plus DT1 while PSC Input B is in active state. Even if PSC Input B is released during DT0 or OT0, DT0 plus OT0 sub-cycle is always completely executed. 122 AT90PWM81 7734P–AVR–08/10 AT90PWM81 12.12 PSC Input Mode 4: Deactivate outputs without changing timing. Figure 12-28. PSC behavior versus PSCn Input A or Input B in Mode 4 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input A or PSCn Input B Figure 12-29. PSC behavior versus PSCn Input A or Input B in Fault Mode 4 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input A or PSCn Input B PSCn Input A or PSCn Input B act indifferently on On-Time0/Dead-Time0 or on On-Time1/Dead-Time1. 12.13 PSC Input Mode 5: Stop signal and Insert Dead-Time PSCOUTn0 DT0 OT0 DT0 DT1 OT1 DT1 DT0 DT1 OT0 DT1 DT0 DT0 Figure 12-30. PSC behavior versus PSCn Input A in Fault Mode 5 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn1 PSCn Input A or PSCn Input B 123 7734P–AVR–08/10 Used in Fault mode 5, PSCn Input A or PSCn Input B act indifferently on On-Time0/Dead-Time0 or on On-Time1/Dead-Time1. 12.14 PSC Input Mode 6: Stop signal, Jump to Opposite Dead-Time and Wait. Figure 12-31. PSC behavior versus PSCn Input A in Fault Mode 6 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input A or PSCn Input B Used in Fault mode 6, PSCn Input A or PSCn Input B act indifferently on On-Time0/Dead-Time0 or on On-Time1/Dead-Time1. 12.15 PSC Input Mode 7: Halt PSC and Wait for Software Action Figure 12-32. PSC behavior versus PSCn Input A in Fault Mode 7 DT0 OT0 DT1 OT1 DT0 OT0 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input A or PSCn Input B Software Action (1) Note: 1. Software action is the setting of the PRUNn bit in PCTLn register. Used in Fault mode 7, PSCn Input A or PSCn Input B act indifferently on On-Time0/Dead-Time0 or on On-Time1/Dead-Time1. 124 AT90PWM81 7734P–AVR–08/10 AT90PWM81 12.16 PSC Input Mode 8: Edge Retrigger PSC Figure 12-33. PSC behavior versus PSCn Input A in Mode 8 DT0 OT0 DT1 DT0 OT0 OT1 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input A The output frequency is modulated by the occurrence of significative edge of retriggering input. Figure 12-34. PSC behavior versus PSCn Input B in Mode 8 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input B or PSCn Input B The output frequency is modulated by the occurrence of significative edge of retriggering input. The retrigger event is taken into account only if it occurs during the corresponding On-Time. Note: In one ramp mode, the retrigger event on input A resets the whole ramp. So the PSC doesn’t jump to the opposite dead-time. 125 7734P–AVR–08/10 12.17 PSC Input Mode 9: Fixed Frequency Edge Retrigger PSC Figure 12-35. PSC behavior versus PSCn Input A in Mode 9 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input A The output frequency is not modified by the occurrence of significative edge of retriggering input. Only the output is deactivated when significative edge on retriggering input occurs. Note: In this mode the output of the PSC becomes active during the next ramp even if the Retrigger/Fault input is active. Only the significative edge of Retrigger/Fault input is taken into account. Figure 12-36. PSC behavior versus PSCn Input B in Mode 9 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input B The retrigger event is taken into account only if it occurs during the corresponding On-Time. 126 AT90PWM81 7734P–AVR–08/10 AT90PWM81 12.18 PSC Input Mode 14: Fixed Frequency Edge Retrigger PSC and Deactivate Output Figure 12-37. PSC behavior versus PSCn Input A in Mode 14 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input A The output frequency is not modified by the occurrence of significative edge of retriggering input. Figure 12-38. PSC behavior versus PSCn Input B in Mode 14 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input B The output is deactivated while retriggering input is active. The output of the PSC is set to an inactive state and the corresponding ramp is not aborted. The output stays in an inactive state while the Retrigger/Fault input is active. The PSC runs at constant frequency. 127 7734P–AVR–08/10 12.18.1 Available Input Mode according to Running Mode Some Input Modes are not consistent with some Running Modes. So the table below gives the input modes which are valid according to running modes. Table 12-8. Available Input Modes according to Running Modes Input Mode Number : 1 Ramp Mode 2 Ramp Mode 4 Ramp Mode Centered Mode 1 Valid Valid Valid Do not use 2 Do not use Valid Valid Do not use 3 Do not use Valid Valid Do not use 4 Valid Valid Valid Valid 5 Do not use Valid Valid Do not use 6 Do not use Valid Valid Do not use 7 Valid Valid Valid Valid 8 Valid Valid Valid Do not use 9 Valid Valid Valid Do not use Valid Valid Do not use 10 11 Do not use 12 13 12.18.2 14 Valid 15 Do not use Event Capture The PSC can capture the value of time (PSC counter) when a retrigger event or fault event occurs on PSC inputs. This value can be read by software in PICRnH/L register. 12.18.3 Using the Input Capture Unit The main challenge when using the Input Capture unit is to assign enough processor capacity for handling the incoming events. The time between two events is critical. If the processor has not read the captured value in the PICR1 Register before the next event occurs, the PICR1 will be overwritten with a new value. In this case the result of the capture will be incorrect. When using the Input Capture interrupt, the PICR1 Register should be read as early in the interrupt handler routine as possible. Even though the Input Capture interrupt has relatively high priority, the maximum interrupt response time is dependent on the maximum number of clock cycles it takes to handle any of the other interrupt requests. 128 AT90PWM81 7734P–AVR–08/10 AT90PWM81 12.19 PSC2 Outputs 12.19.1 Output Matrix PSC2 has an output matrix which allow in 4 ramp mode to program a value of PSCOUT20 and PSCOUT21 binary value for each ramp. Table 12-9. Output Matrix versus ramp number Ramp 0 Ramp 1 Ramp 2 Ramp 3 PSCOUT20 POMV2A0 POMV2A1 POMV2A2 POMV2A3 PSCOUT21 POMV2B0 POMV2B1 POMV2B2 POMV2B3 PSCOUT2m takes the value given in Table 12-9. during all corresponding ramp. Thanks to the Output Matrix it is possible to generate all kind of PSCOUT20/PSCOUT21 combination. When Output Matrix is used, the PSC n Output Polarity POPn has no action on the outputs. 12.19.2 PSCOUT22 & PSCOUT23 Selectors PSC 2 has two supplementary outputs PSCOUT22 and PSCOUT23. According to POS22 and POS23 bits in PSOC2 register, PSCOUT22 and PSCOUT23 duplicate PSCOUT20 and PSCOU21. If POS22 bit in PSOC2 register is clear, PSCOUT22 duplicates PSCOUT20. If POS22 bit in PSOC2 register is set, PSCOUT22 duplicates PSCOUT21. If POS23 bit in PSOC2 register is clear, PSCOUT23 duplicates PSCOUT21. If POS23 bit in PSOC2 register is set, PSCOUT23 duplicates PSCOUT20. Figure 12-39. PSCOUT22 and PSCOUT23 Outputs PSCOUT20 Waveform Generator A 0 PSCOUT22 1 POS22 POS23 Output Matrix 1 PSCOUT23 0 Waveform Generator B PSCOUT21 129 7734P–AVR–08/10 12.20 Analog Synchronization PSC generates a signal to synchronize the sample and hold or the ADC start; synchronization is mandatory for measurements. This signal can be selected between all falling or rising edge of PSCn0 or PSCn1 outputs as defined per Table 12-11 on page 133 and Table 12-12 on page 134. The signal can be shifted by a digital delay defined by the register PASDLY. The shifting clock can be either Clkpsc or Clkpsc/4, as described per Bit 7, 6, 5– PASDLKn(2:0): Analog Synchronization Output Delay or Input Blanking select . Figure 12-40. Analog synchronization OCRnRA match A Trig/Fault 11 01 00 10 OCRnSB match OCRnSA match CLKPSCn/8 CLKPSCn/4 CLKPSCn/2 CLKPSCn OCRnRB match B Trig/Fault PSYNCn(1:0) 7 6 5 4 Digital Delay PASDLYn 0 PSCnASY 1 PASDLKn(2:0) PASDLKn(2) 12.21 Interrupt Handling As each PSC can be dedicated for one function, each PSC has its own interrupt system (vector ...) List of interrupt sources: • Counter reload (end of On Time 1) • End of Enhanced Cycle • PSC Input event (active edge or at the beginning of level configured event) • PSC Mutual Synchronization Error 130 AT90PWM81 7734P–AVR–08/10 AT90PWM81 12.22 PSC Synchronization Note : In AT90PWM81, this feature is not relevant and PRUN2, PARUN2 are stuck at zero. 2 or 3 PSC can be synchronized together. In this case, two waveform alignments are possible: • The waveforms are center aligned in the Center Aligned mode if master and slaves are all with the same PSC period (which is the natural use). • The waveforms are edge aligned in the 1, 2 or 4 ramp mode Figure 12-41. PSC Run Synchronization SY0In PRUN0 Run PSC0 PARUN0 SY0Out PSC0 SY1In PRUN1 Run PSC1 PARUN1 SY1Out PSC1 SY2In PRUN2 Run PSC2 PARUN2 SY2Out PSC2 If the PSCm has its PARUNn bit set, then it can start at the same time than PSCn-1. PRUNn and PARUNn bits are located in PCTLn register. See “PSC 2 Control Register – PCTL2” on page 139. Note : Do not set the PARUNn bits on the three PSC at the same time. Thanks to this feature, we can for example configure two PSC in slave mode (PARUNn = 1 / PRUNn = 0) and one PSC in master mode (PARUNm = 0 / PRUNm = 0). This PSC master can start all PSC at the same moment ( PRUNm = 1). 12.22.1 Fault events in Autorun mode To complete this master/slave mechanism, fault event (input mode 7) is propagated from PSCn-1 to PSCn and from PSCn to PSCn-1. A PSC which propagate a Run signal to the following PSC stops this PSC when the Run signal is deactivate. 131 7734P–AVR–08/10 According to the architecture of the PSC synchronization which build a “daisy-chain on the PSC run signal” between the three PSC, only the fault event (mode 7) which is able to “stop” the PSC through the PRUN bits is transmitted along this daisy-chain. A PSC which receive its Run signal from the previous PSC transmits its fault signal (if enabled) to this previous PSC. So a slave PSC propagates its fault events when they are configured and enabled. 12.23 PSC Clock Sources PSC must be able to generate high frequency with enhanced resolution. Each PSC has two clock inputs: • CLK PLL from the PLL • CLK I/O Figure 12-42. Clock selection CLK 1 PLL CK CK CK/4 CK/32 CK/256 01 10 11 0 I/O 00 CLK PRESCALER PCLKSELn PPREn1/0 CLK PSCn PCLKSELn bit in PSC n Configuration register (PCNFn) is used to select the clock source. PPREn1/0 bits in PSC n Control Register (PCTLn) are used to select the divide factor of the clock. Table 12-10. Output Clock versus Selection and Prescaler PCLKSELn PPREn1 PPREn0 CLKPSCn output 0 0 0 CLK I/O 0 0 1 CLK I/O / 4 0 1 0 CLK I/O / 32 0 1 1 CLK I/O / 256 1 0 0 CLK PLL 1 0 1 CLK PLL / 4 1 1 0 CLK PLL / 32 1 1 1 CLK PLL / 256 12.24 Interrupts This section describes the specifics of the interrupt handling as performed in AT90PWM81. 132 AT90PWM81 7734P–AVR–08/10 AT90PWM81 12.24.1 List of Interrupt Vector Each PSC provides 3 interrupt vectors • PSCn EC (End of Cycle): When enabled and when a match with OCRnRB occurs • PSCn EEC (End of Enhanced Cycle): When enabled and when a match with OCRnRB occurs at the 15th enhanced cycle • PSCn CAPT (Capture Event): When enabled and one of the two following events occurs : retrigger, capture of the PSC counter or Synchro Error. See “PSC2 Interrupt Mask Register – PIM2” on page 143. . 12.25 PSC Register Definition Registers are explained for PSC0. They are identical for PSC1. For PSC2 only different registers are described. 12.25.1 PSC 2 Synchro and Output Configuration – PSOC2 Bit 7 6 5 4 3 2 1 0 POS23 POS22 PSYNC21 PSYNC20 POEN2D POEN2B POEN2C POEN2A Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 PSOC2 • Bit 7 – POS23 : PSCOUT23 Selection (PSC2 only) When this bit is clear, PSCOUT23 outputs the waveform generated by Waveform Generator B. When this bit is set, PSCOUT23 outputs the waveform generated by Waveform Generator A. • Bit 6 – POS22 : PSCOUT22 Selection (PSC2 only) When this bit is clear, PSCOUT22 outputs the waveform generated by Waveform Generator A. When this bit is set, PSCOUT22 outputs the waveform generated by Waveform Generator B. • Bit 5:4 – PSYNCn1:0: Synchronization Out for ADC Selection Select the polarity and signal source for generating a signal which will be sent to the ADC for synchronization. Table 12-11. Synchronization Source Description in One/Two/Four Ramp Modes PSYNCn1 PSYNCn0 Description 0 0 Send signal on leading edge of PSCOUTn0 (match with OCRnSA) 0 1 Send signal on trailing edge of PSCOUTn0 (match with OCRnRA or fault/retrigger on part A) 1 0 Send signal on leading edge of PSCOUTn1 (match with OCRnSB) 1 1 Send signal on trailing edge of PSCOUTn1 (match with OCRnRB or fault/retrigger on part B) 133 7734P–AVR–08/10 Table 12-12. Synchronization Source Description in Centered Mode PSYNCn1 PSYNCn0 Description 0 0 Send signal on match with OCRnRA (during counting down of PSC). The min value of OCRnRA must be 1. 0 1 Send signal on match with OCRnRA (during counting up of PSC). The min value of OCRnRA must be 1. 1 0 no synchronization signal 1 1 no synchronization signal • Bit 3 – POEN2D : PSCOUT23 Output Enable (PSC2 only) When this bit is clear, second I/O pin affected to PSCOUT23 acts as a standard port. When this bit is set, second I/O pin affected to PSCOUT23 is connected to the PSC waveform generator B output and is set and clear according to the PSC operation. • Bit 2 – POENnB: PSC n OUT Part B Output Enable When this bit is clear, I/O pin affected to PSCOUTn1 acts as a standard port. When this bit is set, I/O pin affected to PSCOUTn1 is connected to the PSC waveform generator B output and is set and clear according to the PSC operation. • Bit 1 – POEN2C : PSCOUT22 Output Enable (PSC2 only) When this bit is clear, second I/O pin affected to PSCOUT22 acts as a standard port. When this bit is set, second I/O pin affected to PSCOUT22 is connected to the PSC waveform generator A output and is set and clear according to the PSC operation. • Bit 0 – POENnA: PSC n OUT Part A Output Enable When this bit is clear, I/O pin affected to PSCOUTn0 acts as a standard port. When this bit is set, I/O pin affected to PSCOUTn0 is connected to the PSC waveform generator A output and is set and clear according to the PSC operation. 12.25.2 Output Compare SA Register – OCRnSAH and OCRnSAL Bit 7 6 5 4 3 – – – – OCRnSA[11:8] 2 1 0 OCRnSAH OCRnSA[7:0] 12.25.3 OCRnSAL Read/Write W W W W W W W W Initial Value 0 0 0 0 0 0 0 0 2 1 0 Output Compare RA Register – OCRnRAH and OCRnRAL Bit 7 6 5 4 3 – – – – OCRnRA[11:8] OCRnRAH OCRnRA[7:0] 134 OCRnRAL Read/Write W W W W W W W W Initial Value 0 0 0 0 0 0 0 0 AT90PWM81 7734P–AVR–08/10 AT90PWM81 12.25.4 Output Compare SB Register – OCRnSBH and OCRnSBL Bit 7 6 5 4 3 – – – – OCRnSB[11:8] 2 1 0 OCRnSBH OCRnSB[7:0] 12.25.5 OCRnSBL Read/Write W W W W W W W W Initial Value 0 0 0 0 0 0 0 0 3 2 1 0 Output Compare RB Register – OCRnRBH and OCRnRBL Bit 7 6 5 4 OCRnRB[15:12] OCRnRB[11:8] OCRnRBH OCRnRB[7:0] OCRnRBL Read/Write W W W W W W W W Initial Value 0 0 0 0 0 0 0 0 Note : n = 0 to 2 according to PSC number. The Output Compare Registers RA, RB, SA and SB contain a 12-bit value that is continuously compared with the PSC counter value. A match can be used to generate an Output Compare interrupt, or to generate a waveform output on the associated pin. The Output Compare Registers RB contains also a 4-bit value that is used for the flank width modulation. The Output Compare Registers are 16bit and 12-bit in size. To ensure that both the high and low bytes are written simultaneously when the CPU writes to these registers, the access is performed using an 8-bit temporary high byte register (TEMP). This temporary register is shared by all the other 16-bit registers. 12.25.6 PSC 2 Configuration Register – PCNF2 Bit 7 6 PFIFTY2 PALOCK2 PLOCK2 5 4 PMODE21 PMODE20 POP2 3 2 PCLKSEL2 POME2 1 0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 PCNF2 The PSC n Configuration Register is used to configure the running mode of the PSC. • Bit 7 - PFIFTYn: PSC n Fifty Writing this bit to one, set the PSC in a fifty percent mode where only OCRnRBH/L and OCRnSBH/L are used. They are duplicated in OCRnRAH/L and OCRnSAH/L during the update of OCRnRBH/L. This feature is useful to perform fifty percent waveforms. • Bit 6 - PALOCKn: PSC n Autolock When this bit is set, the Output Compare Registers RA, SA, SB, the Output Matrix POM2 and the PSC Output Configuration PSOCn can be written without disturbing the PSC cycles. The update of the PSC internal registers will be done at the end of the PSC cycle if the Output Compare Register RB has been the last written. When set, this bit prevails over LOCK (bit 5) • Bit 5 – PLOCKn: PSC n Lock When this bit is set, the Output Compare Registers RA, RB, SA, SB, the Output Matrix POM2 and the PSC Output Configuration PSOCn can be written without disturbing the PSC cycles. The update of the PSC internal registers will be done if the LOCK bit is released to zero. 135 7734P–AVR–08/10 • Bit 4:3 – PMODEn1: 0: PSC n Mode Select the mode of PSC. Table 12-13. PSC n Mode Selection PMODEn1 PMODEn0 Description 0 0 One Ramp Mode 0 1 Two Ramp Mode 1 0 Four Ramp Mode 1 1 Center Aligned Mode • Bit 2 – POPn: PSC n Output Polarity If this bit is cleared, the PSC outputs are active Low. If this bit is set, the PSC outputs are active High. • Bit 1 – PCLKSELn: PSC n Input Clock Select This bit is used to select between CLKPF or CLKPS clocks. Set this bit to select the fast clock input (CLKPF). Clear this bit to select the slow clock input (CLKPS). • Bit 0 – POME2: PSC 2 Output Matrix Enable (PSC2 only) Set this bit to enable the Output Matrix feature on PSC2 outputs. See “PSC2 Outputs” on page 129. When Output Matrix is used, the PSC n Output Polarity POPn has no action on the outputs. 12.25.7 PSC 2 Extended Configuration Register – PCNFE2 Bit 7 6 5 4 PASDLKn2 PASDLKn1 PASDLKn0 PBFMn1 3 2 1 0 PELEVnA1 PELEVnB1 PISELnA1 PISELnB1 PCNFE2 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 The PSC n Extended Configuration Register is used to configure the running mode of the PSC • Bit 7, 6, 5– PASDLKn(2:0): Analog Synchronization Output Delay or Input Blanking select Defines the modes for Analog signal synchronization delay or Input Blanking. Table 12-14. Analog signal synchronization or Input Blanking Mode Selection PASDLKn2 PASDLKn1 PASDLKn0 Description 0 0 0 No Analog signal synchronization delay, no Input Blanking 0 0 1 No Analog signal synchronization delay , Input Blanking using PSC clock, started on PSC end of cycle 0 1 0 No Analog signal synchronization delay , Input Blanking using PSC clock, started on OCR SA event 0 1 1 No Analog signal synchronization delay , Input Blanking using PSC clock, started on OCR SB event 136 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Table 12-14. Analog signal synchronization or Input Blanking Mode Selection PASDLKn2 PASDLKn1 PASDLKn0 Description 1 0 0 Analog signal synchronization delay with PSC clock, no Input Blanking 1 0 1 Analog signal synchronization delay with PSC clock /2 , no Input Blanking 1 1 0 Analog signal synchronization delay with PSC clock /4 , no Input Blanking 1 1 1 Analog signal synchronization delay with PSC clock /8, no Input Blanking • Bit 4- PBFMn1: Balance Flank Width Modulation, bit 1 Defines the Flank Width Modulation, together with PBFMn0 bit in PCTLn register. Table 12-15. Flank Width Mode Selection PBFMn1 PBFMn0 Description 0 0 Flank Width Modulation operates on RB (On-Time 1 only). 0 1 Flank Width Modulation operates on RB + RA (On-Time 0 and On-Time 1). 1 0 Flank Width Modulation operates on SB (Dead-Time 1 only) (1). 1 1 Flank Width Modulation operates on SB +SA (Dead-Time 0 and DeadTime 1). 1. Note: In one ramp mode, changing SA or SA+SB also affect On-Time ; see PSCn0 & PSCn1 Basic Waveforms in One Ramp mode 137 7734P–AVR–08/10 • Bit 3– PELEVnA1: PSC n Input Select for part A Together with PELEVnA0, defines active edge or level on PSC part A. Table 12-16. PSC edge & level input Selection PELEVnA1 PELEVnA0 Description 0 0 The falling edge or low level of selected input generates the significative event for retrigger or fault function 0 1 The rising edge or high level of selected input generates the significative event for retrigger or fault function 1 0 The toggle of selected input generates the significative event for retrigger or fault function 1 1 Reserved • Bit 2– PELEVnB1: PSC n Input Select for part B Together with PELEVnB0, defines active edge or level on PSC part B. Table 12-17. PSC edge & level input Selection PELEVnB1 PELEVnB0 Description 0 0 The falling edge or low level of selected input generates the significative event for retrigger or fault function 0 1 The rising edge or high level of selected input generates the significative event for retrigger or fault function 1 0 The toggle of selected input generates the significative event for retrigger or fault function 1 1 Reserved • Bit 1– PISELnA1: PSC n Input Select for part A Together with PISELnA0, defines active signal on PSC part A. Table 12-18. 138 PSC trigger & fault input Selection PISELnA1 PISELnA0 Description 0 0 PSCINn 0 1 First analog comparator output 1 0 PSCINnA 1 1 Second analog comparator output AT90PWM81 7734P–AVR–08/10 AT90PWM81 • Bit 0– PISELnB1: PSC n Input Select for part B Together with PISELnB0, defines active signal on PSC part B. Table 12-19. 12.25.8 PSC trigger & fault input Selection PISELnB1 PISELnB0 Description 0 0 PSCINn 0 1 First analog comparator output 1 0 PSCINnA 1 1 Second analog comparator output Analog Synchronization Delay Register – PASDLYn Bit 7 6 5 4 3 2 1 0 PASDLYn[7:0] PASDLYn Read/Write W W W W W W W W Initial Value 0 0 0 0 0 0 0 0 The Analog Synchronization Delay Register store an 8 bit delay used: • For the input signal blanking. See Section “PSC Inputs”, page 113 • For shifting the PSCOUTnx edges and the PSCnASY signal. See Section “Analog Synchronization”, page 130 See also the bit definition Section “Bit 7, 6, 5– PASDLKn(2:0): Analog Synchronization Output Delay or Input Blanking select”, page 136 and Section “Bit 5:4 – PSYNCn1:0: Synchronization Out for ADC Selection”, page 133 12.25.9 PSC 2 Control Register – PCTL2 Bit 7 6 5 4 3 2 1 0 PPRE21 PPRE20 PBFM20 PAOC2B PAOC2A PARUN2 PCCYC2 PRUN2 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 PCTL2 • Bit 7:6 – PPREn1:0 : PSC n Prescaler Select This two bits select the PSC input clock division factor.All generated waveform will be modified by this factor. Table 12-20. PSC n Prescaler Selection PPREn1 PPREn0 Description 0 0 No divider on PSC input clock 139 7734P–AVR–08/10 Table 12-20. PSC n Prescaler Selection PPREn1 PPREn0 Description 0 1 Divide the PSC input clock by 4 1 0 Divide the PSC input clock by 16 1 1 Divide the PSC clock by 64 • Bit 5 – PBFMn0 : Balance Flank Width Modulation bit 0 Defines the Flank Width Modulation, together with PBFMn1 bit in PCNFEn register. See Table 12-15 on page 137 • Bit 4 – PAOCnB : PSC n Asynchronous Output Control B When this bit is set, Fault input selected to block B can act directly to PSCOUTn1 and PSCOUT23 outputs. See Section “PSC Clock Sources”, page 132. • Bit 3 – PAOCnA : PSC n Asynchronous Output Control A When this bit is set, Fault input selected to block A can act directly to PSCOUTn0 and PSCOUT22 outputs. See Section “PSC Clock Sources”, page 132. • Bit 2 – PARUNn : PSC n Autorun When this bit is set, the PSC n starts with PSCn-1. That means that PSC n starts : • when PRUNn bit in PCTLn register is set, • or when PARUNn bit in PCTLn is set and PRUNn-1 bit in PCTLn-1 register is set (or PARUN0 bit and PRUN0). • Bit 1 – PCCYCn : PSC n Complete Cycle When this bit is set, the PSC n completes the entire waveform cycle before halt operation requested by clearing PRUNn. This bit is not relevant in slave mode (PARUNn = 1). • Bit 0 – PRUNn : PSC n Run Writing this bit to one starts the PSC n. When set, this bit prevails over PARUNn bit. 12.25.10 PSC n Input A Control Register – PFRCnA Bit 12.25.11 6 PISELnA0 PELEVnA0 PFLTEnA 5 4 3 2 1 0 PRFMnA3 PRFMnA2 PRFMnA1 PRFMnA0 PFRCnA Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 5 4 3 2 1 0 PSC n Input B Control Register – PFRCnB Bit 140 7 PCAEnA 7 6 PCAEnB PISELnB0 PELEVnB0 PFLTEnB PRFMnB3 PRFMnB2 PRFMnB1 PRFMnB0 PFRCnB Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 AT90PWM81 7734P–AVR–08/10 AT90PWM81 The Input Control Registers are used to configure the 2 PSC’s Retrigger/Fault block A & B. The 2 blocks are identical, so they are configured on the same way. • Bit 7 – PCAEnx : PSC n Capture Enable Input Part x Writing this bit to one enables the capture function when external event occurs on input selected as input for Part x (see PISELnx1:0 bit in the same register). • Bit 6 – PISELnx0 : PSC n Input Select for Part x Together with PISELnx1 in PCNFEn register, defines active signal on PSC module A. See Table 12-18 on page 138 and Table 12-19 on page 139 • Bit 5 –PELEVnx0 : PSC n Edge Level Selector of Input Part x Together with PELEVnx1 n PCNFEn register, defines active edge & level on PSC part x ; See Table 1216 on page 138 and Table 12-17 on page 138 • Bit 4 – PFLTEnx : PSC n Filter Enable on Input Part x Setting this bit (to one) activates the Input Capture Noise Canceler. When the noise canceler is activated, the input from the retrigger pin is filtered. The filter function requires four successive equal valued samples of the retrigger pin for changing its output. The Input Capture is therefore delayed by four oscillator cycles when the noise canceler is enabled. • Bit 3:0 – PRFMnx3:0: PSC n Fault Mode These four bits define the mode of operation of the Fault or Retrigger functions. (see PSC Functional Specification for more explanations) Table 12-21. Level Sensitivity and Fault Mode Operation PRFMnx3:0 Description 0000b No action, PSC Input is ignored 0001b PSC Input Mode 1: Stop signal, Jump to Opposite Dead-Time and Wait 0010b PSC Input Mode 2: Stop signal, Execute Opposite Pulse and Wait 0011b PSC Input Mode 3: Stop signal, Execute Opposite Pulse while Fault active 0100b PSC Input Mode 4: Deactivate outputs without changing timing. 0101b PSC Input Mode 5: Stop signal and Insert Dead-Time 0110b PSC Input Mode 6: Stop signal, Jump to Opposite Dead-Time and Wait. 0111b PSC Input Mode 7: Halt PSC and Wait for Software Action 1000b PSC Input Mode 8: Edge Retrigger PSC 1001b PSC Input Mode 9: Fixed Frequency Edge Retrigger PSC 141 7734P–AVR–08/10 Table 12-21. Level Sensitivity and Fault Mode Operation PRFMnx3:0 Description 1010b Reserved (do not use) 1011b 1100b 1101b 12.25.12 1110b PSC Input Mode 14: Fixed Frequency Edge Retrigger PSC and Deactivate Output 1111b Reserved (do not use) PSC 2 Input Capture Register – PICR2H and PICR2L Bit 7 6 5 4 3 PCST2 – – – PICR2[11:8] 2 1 0 PICR2H PICR2[7:0] PICR2L Read/Write R R R R R R R R Initial Value 0 0 0 0 0 0 0 0 • Bit 7 – PCSTn : PSC Capture Software Trig bit Set this bit to trigger off a capture of the PSC counter. When reading, if this bit is set it means that the capture operation was triggered by PCSTn setting otherwise it means that the capture operation was triggered by a PSC input. The Input Capture is updated with the PSC counter value each time an event occurs on the enabled PSC input pin (or optionally on the Analog Comparator output) if the capture function is enabled (bit PCAEnx in PFRCnx register is set). The Input Capture Register is 12-bit in size. To ensure that both the high and low bytes are read simultaneously when the CPU accesses these registers, the access is performed using an 8-bit temporary high byte register (TEMP). This temporary register is shared by all the other 16-bit or 12-bit registers. 12.26 PSC2 Specific Register 12.26.1 PSC 2 Output Matrix – POM2 Bit 7 6 POMV2B3 POMV2B2 POMV2B1 POMV2B0 POMV2A3 POMV2A2 POMV2A1 POMV2A0 POM2 5 4 3 2 1 0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 • Bit 7 – POMV2B3: Output Matrix Output B Ramp 3 This bit gives the state of the PSCOUT21 (and/or PSCOUT23) during ramp 3 • Bit 6 – POMV2B2: Output Matrix Output B Ramp 2 This bit gives the state of the PSCOUT21 (and/or PSCOUT23) during ramp 2 • Bit 5 – POMV2B1: Output Matrix Output B Ramp 1 This bit gives the state of the PSCOUT21 (and/or PSCOUT23) during ramp 1 142 AT90PWM81 7734P–AVR–08/10 AT90PWM81 • Bit 4 – POMV2B0: Output Matrix Output B Ramp 0 This bit gives the state of the PSCOUT21 (and/or PSCOUT23) during ramp 0 • Bit 3 – POMV2A3: Output Matrix Output A Ramp 3 This bit gives the state of the PSCOUT20 (and/or PSCOUT22) during ramp 3 • Bit 2 – POMV2A2: Output Matrix Output A Ramp 2 This bit gives the state of the PSCOUT20 (and/or PSCOUT22) during ramp 2 • Bit 1 – POMV2A1: Output Matrix Output A Ramp 1 This bit gives the state of the PSCOUT20 (and/or PSCOUT22) during ramp 1 • Bit 0 – POMV2A0: Output Matrix Output A Ramp 0 This bit gives the state of the PSCOUT20 (and/or PSCOUT22) during ramp 0 12.26.2 PSC2 Interrupt Mask Register – PIM2 Bit 7 6 5 4 3 2 1 0 - - PSEIE2 PEVE2B PEVE2A - PEOEPE2 PEOPE2 Read/Write R R R/W R/W R/W R R/W R/W Initial Value 0 0 0 0 0 0 0 0 PIM2 • Bit 5 – PSEIEn : PSC n Synchro Error Interrupt Enable When this bit is set, the PSEIn bit (if set) generate an interrupt. • Bit 4 – PEVEnB : PSC n External Event B Interrupt Enable When this bit is set, an external event which can generates a capture from Retrigger/Fault block B generates also an interrupt. • Bit 3 – PEVEnA : PSC n External Event A Interrupt Enable When this bit is set, an external event which can generates a capture from Retrigger/Fault block A generates also an interrupt. • Bit 1– PEOEPEn : PSC n End Of Enhanced Cycle Interrupt Enable When this bit is set, an interrupt is generated when PSC reaches the end of the 15th PSC cycle. This allows to update the PSC values in the interrupt routine and to start a new enhanced cycle with the new values at the next PSC cycle end. • Bit 0 – PEOPEn : PSC n End Of Cycle Interrupt Enable When this bit is set, an interrupt is generated when PSC reaches the end of the whole cycle. 143 7734P–AVR–08/10 12.26.3 PSC2 Interrupt Flag Register – PIFR2 Bit 7 6 5 4 3 2 1 0 POAC2B POAC2A PSEI2 PEV2B PEV2A PRN21 PRN20 PEOP2 Read/Write R R R/W R/W R/W R R R/W Initial Value 0 0 0 0 0 0 0 0 PIFR2 • Bit 7 – POACnB : PSC n Output B Activity This bit is set by hardware each time the output PSCOUTn1 changes from 0 to 1 or from 1 to 0. Must be cleared by software by writing a one to its location. This feature is useful to detect that a PSC output doesn’t change due to a frozen external input signal. • Bit 6 – POACnA : PSC n Output A Activity This bit is set by hardware each time the output PSCOUTn0 changes from 0 to 1 or from 1 to 0. Must be cleared by software by writing a one to its location. This feature is useful to detect that a PSC output doesn’t change due to a frozen external input signal. • Bit 5 – PSEIn : PSC n Synchro Error Interrupt This bit is set by hardware when the update (or end of PSC cycle) of the PSCn configured in auto run (PARUNn = 1) does not occur at the same time than the PSCn-1 which has generated the input run signal. (For PSC0, PSCn-1 is PSC2). Must be cleared by software by writing a one to its location. This feature is useful to detect that a PSC doesn’t run at the same speed or with the same phase than the PSC master. • Bit 4 – PEVnB : PSC n External Event B Interrupt This bit is set by hardware when an external event which can generates a capture or a retrigger from Retrigger/Fault block B occurs. Must be cleared by software by writing a one to its location. This bit can be read even if the corresponding interrupt is not enabled (PEVEnB bit = 0). • Bit 3 – PEVnA : PSC n External Event A Interrupt This bit is set by hardware when an external event which can generates a capture or a retrigger from Retrigger/Fault block A occurs. Must be cleared by software by writing a one to its location. This bit can be read even if the corresponding interrupt is not enabled (PEVEnA bit = 0). • Bit 2:1 – PRNn1:0 : PSC n Ramp Number Memorization of the ramp number when the last PEVnA or PEVnB occurred . 144 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Table 12-22. PSC n Ramp Number Description PRNn1 PRNn0 Description 0 0 The last event which has generated an interrupt occurred during ramp 1 0 1 The last event which has generated an interrupt occurred during ramp 2 1 0 The last event which has generated an interrupt occurred during ramp 3 1 1 The last event which has generated an interrupt occurred during ramp 4 • Bit 0 – PEOPn: End Of PSC n Interrupt This bit is set by hardware when PSC n achieves its whole cycle. Must be cleared by software by writing a one to its location. 12.26.4 PSC Output Behavior During Reset For external component safety reason, the state of PSC outputs during Reset can be programmed by fuses PSCRV, PSCRRB & PSC2RB. These fuses are located in the Extended Fuse Byte : Table 12-23. Extended Low Fuse Byte Extended Fuse Byte Bit No Description Default Value PSC2RB 7 PSC2 Reset Behavior 1 PSC2RBA 6 PSC2 Reset Behavior for OUT22 & 23 1 PSCRRB 5 PSC Reduced Reset Behavior 1 PSCRV 4 PSCOUT & PSCOUTR Reset Value 1 PSCINRB 3 PSC & PSCR Inputs Reset Behavior 1 BODLEVEL2(1) 2 Brown-out Detector trigger level 1 (unprogrammed) BODLEVEL1(1) 1 Brown-out Detector trigger level 0 (programmed) (1) 0 Brown-out Detector trigger level 1 (unprogrammed) BODLEVEL0 Notes: 1. See Table 7-2 on page 52 for BODLEVEL Fuse decoding PSCRV gives the state low or high which will be forced on PSC outputs selected by PSC0RB & PSC2RB fuses. If PSCRV fuse equals 0 (programmed), the selected PSC outputs will be forced to low state. If PSCRV fuse equals 1 (unprogrammed), the selected PSC outputs will be forced to high state. If PSCRRB fuse equals 1 (unprogrammed), PSCOUTR0 & PSCOUTR1 keep a standard port behavior. If PSC0RB fuse equals 0 (programmed), PSCOUTR0 & PSCOUTR1 are forced at reset to low level or high level according to PSCRV fuse bit. In this second case, PSCOUTR0 & PSCOUTR1 keep the forced state until PSOC0 register is written. If PSC2RB fuse equals 1 (unprogrammed), PSCOUT20 & PSCOUT21 keep a standard port behavior. If PSC2RB fuse equals 0 (programmed), PSCOUT20 & PSCOUT21 are forced at reset to low level or high 145 7734P–AVR–08/10 level according to PSCRV fuse bit. In this second case, PSCOUT20 & PSCOUT21 keep the forced state until PSOC2 register is written. If PSC2RBA fuse equals 1 (unprogrammed), PSCOUT22 & PSCOUT23 keep a standard port behavior. If PSC2RBA fuse equals 0 (programmed), PSCOUT22 & PSCOUT23 are forced at reset to low level or high level according to PSCRV fuse bit. In this second case, PSCOUT22 & PSCOUT23 keep the forced state until PSOC2 register is written. 12.26.5 PSC Input Behavior During Reset For power consumption under reset reason, the state of PSC & PSCR inputs during Reset can be programmed by fuse PSCINRB. If PSCINRB fuse equals 1 (unprogrammed), PSC & PSCR input keep a standard port behavior. If PSCINRB fuse equals 0 (programmed), PSC & PSCR input pull-up are forced while the reset is active. Affected pins are PSCIN2, PSCINr, PSCIN2A, PSCINrA. To prevent any conflict on PD1, this fuse has no effect on PSCINrB. 146 AT90PWM81 7734P–AVR–08/10 AT90PWM81 13. Reduced Power Stage Controller – (PSCR) The Reduced Power Stage Controller is a high performance waveform controller. 13.1 Features • • • • • • • • • PWM waveform generation function (2 complementary programmable outputs) Dead time control Standard mode up to 12 bit resolution Enhanced resolution up to 16 bits Frequency up to 64 Mhz Conditional Waveform on External Events (Zero Crossing, Current Sensing ...) ADC synchronization Overload protection function Abnormality protection function, emergency input to force all outputs to high impedance or in inactive state (fuse configurable) • Fast emergency stop by hardware 13.2 Overview Many register and bit references in this section are written in general form. • A lower case “r” (or “n” replaces the PSC number, in this case 0. However, when using the register or bit defines in a program, the precise form must be used, i.e., PSOC0 for accessing PSCR 0 Synchro and Output Configuration register and so on. • A lower case “x” replaces the PSCR part , in this case A or B. However, when using the register or bit defines in a program, the precise form must be used, i.e., PFRC0A for accessing PSCR 0 Fault/Retrigger A Control register and so on. The purpose of a Power Stage Controller (PSC) is to control power modules on a board. It has two outputs . These outputs can be used in various ways: • “Two Outputs” to drive a half bridge (lighting, ...) • “One Output” to drive single power transistor (DC/DC converter, PFC, ...) The PSCR has two inputs the purpose of which is to provide means to act directly on the generated waveforms: • Current sensing regulation • Zero crossing retriggering • Demagnetization retriggering • Fault input 147 7734P–AVR–08/10 13.3 PSCR Description Figure 13-1. Power Stage Controller Block Diagram PSCR Counter = Waveform Gererator B PSCOUTr1 PSC Input Module B PSCr Input B OCRrRB DATABUS = OCRrSB Part B = PSC Input Module A PSCr Input A Waveform Gererator A PSCOUTr0 OCRrRA = OCRrSA Part A PICRr PCNFr PCTLr PFRCrB PFRCrA PSOCr The principle of the PSCR is based on the use of a counter (PSCR counter). This counter is able to count up and count down from and to values stored in registers according to the selected running mode. The PSCR is seen as two symmetrical entities. One part named part A which generates the output PSCOUTr0 and the second one named part B which generates the PSCOUTr1 output. Each part A or B has its own PSCR Input Module to manage selected input. 148 AT90PWM81 7734P–AVR–08/10 AT90PWM81 13.3.1 Output Polarity The polarity “active high” or “active low” of the PSCR outputs is programmable. All the timing diagrams in the following examples are given in the “active high” polarity. 13.4 Signal Description Figure 13-2. PSCR External Block View CLK PLL CLK I/O OCRrR B[11:0] OCRrSB[11:0] OCRrR A[11:0] OCRrSA[11:0] 12 PSCOUT r0 12 PSCOUT r1 12 12 PICRr[11:0] 12 3 IRQ PSC r PSCINr Aralog Comparator Output PSCrASY 13.4.1 Input Description Table 13-1. Name Internal Inputs Description Type Width OCRrRB[11 :0] Compare Value which Reset Signal on Part B (PSCOUTr1) Register 12 bits OCRrSB[11: 0] Compare Value which Set Signal on Part B (PSCOUTr1) Register 12 bits OCRrRA[11 :0] Compare Value which Reset Signal on Part A (PSCOUTr0) Register 12 bits 149 7734P–AVR–08/10 Name Type Width OCRrSA[11 :0] Compare Value which Set Signal on Part A (PSCOUTr0) Register 12 bits CLK I/O Clock Input from I/O clock Signal CLK PLL Clock Input from PLL Signal Table 13-2. Name 13.4.2 Description Block Inputs Description Type Width PSCINr Input 0 used for Retrigger or Fault functions Signal from Analog Comparator Input 1 used for Retrigger or Fault functions Signal PSCINrA Input 2 used for Retrigger or Fault functions Signal PSCINrB Input 3 used for Retrigger or Fault functions Signal Output Description Table 13-3. Name Block Outputs Description Type Width PSCOUTr0 PSCR Output 0 (from part A of PSC) Signal PSCOUTr1 PSCR Output 1 (from part B of PSC) Signal Table 13-4. Name Internal Outputs Description Type Width PICRr [11:0] PSCR Input Capture Register Counter value at retriggering event Register 12 bits IRQPSCr PSCR Interrupt Request : three sources, overflow, fault, and input capture Signal PSCrASY ADC Synchronization (+ Amplifier Syncho. )(2) Signal 2. See “Analog Synchronization” on page 169. 150 AT90PWM81 7734P–AVR–08/10 AT90PWM81 13.5 13.5.1 Functional Description Waveform Cycles The waveform generated by PSCR can be described as a sequence of two waveforms. The first waveform is relative to PSCOUTr0 output and part A of PSC. The part of this waveform is subcycle A in the following figure. The second waveform is relative to PSCOUTr1 output and part B of PSC. The part of this waveform is sub-cycle B in the following figure. The complete waveform is ended with the end of sub-cycle B. It means at the end of waveform B. Figure 13-3. Cycle Presentation in 1, 2 & 4 Ramp Mode PSC Cycle Sub-Cycle A Sub-Cycle B 4 Ramp Mode Ramp A0 Ramp A1 Ramp B0 Ramp B1 2 Ramp Mode Ramp A Ramp B 1 Ramp Mode UPDATE Ramps illustrate the output of the PSCR counter included in the waveform generators. Centered Mode is like a one ramp mode which count down up and down. Notice that the update of a new set of values is done regardless of ramp Mode at the top of the last ramp. 13.5.2 Running Mode Description Waveforms and length of output signals are determined by Time Parameters (DT0, OT0, DT1, OT1) and by the running mode. Three modes are possible : – Four Ramp mode – Two Ramp mode – One Ramp mode The active time of PSCOUTn0 is given by the OT0 value. The active time of PSCOUTn1 is given by the OT1 value. Both of them are 12 bit values. Thanks to DT0 & DT1 to adjust the dead time between PSCOUTn0 and PSCOUTn1 active signals. 151 7734P–AVR–08/10 The waveform frequency is defined by the following equation: f CLK_PSCn 1 f PSCn = ------------------------------ = -------------------------------------------------------------------PSCnCycle ( OT0 + OT1 + DT0 + DT1 ) 13.5.2.1 Four Ramp Mode In Four Ramp mode, each time in a cycle has its own definition Figure 13-4. PSCr0 & PSCr1 Basic Waveforms in Four Ramp mode OCRnRA PSC Counter OCRnSA OCRnRB OCRnSB 0 0 On-Time 0 On-Time 1 PSCOUTn0 PSCOUTn1 Dead-Time 1 Dead-Time 0 PSC Cycle The input clock of PSCR is given by CLKPSC. PSCOUTr0 and PSCOUTr1 signals are defined by On-Time 0, Dead-Time 0, On-Time 1 and Dead-Time 1 values with : On-Time 0 = OCRrRAH/L * 1/Fclkpsc On-Time 1 = OCRrRBH/L * 1/Fclkpsc Dead-Time 0 = (OCRrSAH/L + 2) * 1/Fclkpsc Dead-Time 1 = (OCRrSBH/L + 2) * 1/Fclkpsc Note: 152 Minimal value for Dead-Time 0 and Dead-Time 1 = 2 * 1/Fclkpsc AT90PWM81 7734P–AVR–08/10 AT90PWM81 13.5.2.2 Two Ramp Mode In Two Ramp mode, the whole cycle is divided in two moments One moment for PSCr0 description with OT0 which gives the time of the whole moment One moment for PSCr1 description with OT1 which gives the time of the whole moment Figure 13-5. PSCr0 & PSCr1 Basic Waveforms in Two Ramp mode OCRnRA OCRnRB PSC Counter OCRnSA OCRnSB 0 0 On-Time 0 On-Time 1 PSCOUTn0 PSCOUTn1 Dead-Time 1 Dead-Time 0 PSC Cycle PSCOUTr0 and PSCOUTr1 signals are defined by On-Time 0, Dead-Time 0, On-Time 1 and Dead-Time 1 values with : On-Time 0 = (OCRrRAH/L - OCRrSAH/L) * 1/Fclkpsc On-Time 1 = (OCRrRBH/L - OCRrSBH/L) * 1/Fclkpsc Dead-Time 0 = (OCRrSAH/L + 1) * 1/Fclkpsc Dead-Time 1 = (OCRrSBH/L + 1) * 1/Fclkpsc Note: 13.5.2.3 Minimal value for Dead-Time 0 and Dead-Time 1 = 1/Fclkpsc One Ramp Mode In One Ramp mode, PSCOUTr0 and PSCOUTr1 outputs can overlap each other. 153 7734P–AVR–08/10 Figure 13-6. PSCr0 & PSCr1 Basic Waveforms in One Ramp mode OCRnRB OCRnSB OCRnRA PSC Counter OCRnSA 0 On-Time 0 On-Time 1 PSCOUTn0 PSCOUTn1 Dead-Time 1 Dead-Time 0 PSC Cycle On-Time 0 = (OCRrRAH/L - OCRrSAH/L) * 1/Fclkpsc On-Time 1 = (OCRrRBH/L - OCRrSBH/L) * 1/Fclkpsc Dead-Time 0 = (OCRrSAH/L + 1) * 1/Fclkpsc Dead-Time 1 = (OCRrSBH/L - OCRrRAH/L) * 1/Fclkpsc Note: 13.5.3 13.6 Minimal value for Dead-Time 0 = 1/Fclkpsc Fifty Percent Waveform Configuration When PSCOUTr0 and PSCOUTr1 have the same characteristics, it’s possible to configure the PSCR in a Fifty Percent mode. When the PSCR is in this configuration, it duplicates the OCRrSBH/L and OCRrRBH/L registers in OCRrSAH/L and OCRrRAH/L registers. So it is not necessary to program OCRrSAH/L and OCRrRAH/L registers. Update of Values The update of PSCR waveform registers are done in the following way: • • • Immediately when the PSC is stopped At the PSC end of cycle when the PSC is running At the PSC end of cycle following the required condition when LOCK or AUTOLOCK modes are used. To avoid asynchronous and incoherent values in a cycle, if an update of one of several values is necessary, all values are updated at the same time at the end of the cycle by the PSC. The new set of values is calculated by software and the update is initiated by software. 154 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 13-7. Update at the end of complete PSCR cycle. Regulation Loop Calculation Writting in PSC Registers Software Cycle With Set i Cycle With Set i Cycle With Set i Request for an Update Cycle With Set i PSC Cycle With Set j End of Cycle The software can stop the cycle before the end to update the values and restart a new PSCR cycle. 13.6.1 Value Update Synchronization New timing values or PSCR output configuration can be written during the PSCR cycle. Thanks to LOCK and AUTOLOCK configuration bits, the new whole set of values can be taken into account with the following conditions: • When AUTOLOCK configuration is selected, the update of the PSCR internal registers will be done at the end of the PSCR cycle following a write in the Output Compare Register RB. The AUTOLOCK configuration bit is taken into account at the end of the first PSCR cycle. • When LOCK configuration bit is set, there is no update. The update of the PSCR internal registers will be done at the end of the PSCR cycle if the LOCK bit is released to zero. The registers which update is synchronized thanks to LOCK and AUTOLOCK are OCRrSAH/L, OCRrRAH/L, OCRrSBH/L, OCRrRBH/L and PSOCr. PISELrA1 and PISELrB1 bits of PSOCr are immediatly updated in order to behave as PISELrA0 and PISELrB0. See these register’s description starting on page 172. When set, AUTOLOCK configuration bit prevails over LOCK configuration bit. See “PSCR Configuration Register – PCNF0” on page 173. 13.7 Enhanced resolution The PSCR includes the same resolution enhancement as in PSC. Please see Section “Enhanced Resolution”, page 110 for the description of this feature. 13.8 PSCR Inputs Each part A or B of PSCR has its own system to take into account one PSCR input. According to PSCR Input A/B Control Register (see description 13.23.8page 175), PSCrIN0/1 input can act has a Retrigger or Fault input. This system A or B is also configured by this PSCR Input A/B Control Register (PFRCrA/B). 155 7734P–AVR–08/10 Figure 13-8. PSCR Input Module PAOCrA (PAOCrB) PSCINr 0 0 0 AC1O: Analog Comparator Output 0 1 PSCINrA 1 0 PSCR Input A (PSCR Input B) Digital Filter CLK PSC PSCINrB 1 1 PFLTErA (PFLTErB) 1 PELEVrA / (PELE VrB) PISELrA1 PISELrA0 (PISELrB1)(PISELrB0) PCAErA (PCAErB) PRFMrA3:0 (PRFMrB3:0) 2 4 Input Processing (retriggering ...) CLK PSC PSC C ore (Counter, Waveform Generator, ...) Output Control PSCOUT r0 (PSCOUT r1) CLK PSC 13.8.1 PSCR Retrigger Behavior versus PSCR running modes In two ramp or four ramp mode, Retrigger Inputs A or B cause the end of the corresponding cycle A or B and the beginning of the following cycle B or A. In one ramp mode, Retrigger Inputs A or B reset the current PSCR counting to zero. 13.8.2 Retrigger PSCOUTr0 On External Event PSCOUTr0 output can be reset before end of On-Time 0 on the change on PSCr Input A. PSCr Input A can be configured to do not act or to act on level or edge modes. The polarity of PSCr Input A is configurable thanks to a sense control block. PSCr Input A can be the Output of the analog comparator or the PSCINr input. As the period of the cycle decreases, the instantaneous frequency of the two outputs increases. 156 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 13-9. PSCOUTr0 retriggered by PSCr Input A (Edge Retriggering) On-Time 0 On-Time 1 PSCOUTn0 PSCOUTn1 PSCn Input A (falling edge) PSCn Input A (rising edge) Dead-Time 0 Note: Dead-Time 1 This example is given in “Input Mode 8” in “2 or 4 ramp mode” See Figure 13-25. for details. Figure 13-10. PSCOUTr0 retriggered by PSCr Input A (Level Acting) On-Time 0 On-Time 1 PSCOUTn0 PSCOUTn1 PSCn Input A (high level) PSCn Input A (low level) Dead-Time 0 Note: 13.8.3 Dead-Time 1 This example is given in “Input Mode 1” in “2 or 4 ramp mode” See Figure 13-14. for details. Retrigger PSCOUTr1 On External Event PSCOUTr1 output can be reset before end of On-Time 1 on the change on PSCr Input B. The polarity of PSCr Input B is configurable thanks to a sense control block. PSCr Input B can be configured to do not act or to act on level or edge modes. PSCr Input B can be the Output of the analog comparator or the PSCINr input. As the period of the cycle decreases, the instantaneous frequency of the two outputs increases. 157 7734P–AVR–08/10 Figure 13-11. PSCOUTr1 retriggered by PSCr Input B (Edge Retriggering) On-Time 0 On-Time 1 PSCOUTn0 PSCOUTn1 PSCn Input B (falling edge) PSCn Input B (rising edge) Dead-Time 0 Note: Dead-Time 1 Dead-Time 0 This example is given in “Input Mode 8” in “2 or 4 ramp mode” See Figure 13-25. for details. Figure 13-12. PSCOUTr1 retriggered by PSCr Input B (Level Acting) On-Time 0 On-Time 1 PSCOUTn0 PSCOUTn1 PSCn Input B (high level) PSCn Input B (low level) Dead-Time 0 Note: 13.8.3.1 Dead-Time 1 Dead-Time 0 This example is given in “Input Mode 1” in “2 or 4 ramp mode” See Figure 13-14. for details. Burst Generation Note: On level mode, it’s possible to use PSCR to generate burst by using Input Mode 3 or Mode 4 (See Figure 13-18. and Figure 13-19. for details.) 158 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 13-13. Burst Generation OFF BURST PSCOUTn0 PSCOUTn1 PSCn Input A (high level) PSCn Input A (low level) 13.8.4 13.8.4.1 PSCR Input Configuration The PSCR Input Configuration is done by programming bits in configuration registers. Filter Enable If the “Filter Enable” bit is set, a digital filter of 4 cycles is inserted before evaluation of the signal. The disable of this function is mainly needed for prescaled PSCR clock sources, where the noise cancellation gives too high latency. Important: If the digital filter is active, the level sensitivity is true also with a disturbed PSCR clock to deactivate the outputs (emergency protection of external component). Likewise when used as fault input, PSCr Input A or Input B have to go through PSCR to act on PSCOUTr0/1/2/3 output. This way needs that CLKPSCR is running. So thanks to PSCR Asynchronous Output Control bit (PAOCrA/B), PSCrIN0/1 input can deactivate directly the PSCR output. Notice that in this case, input is still taken into account as usually by Input Module System as soon as CLKPSCR is running. PSCR Input Flittering CLKPSC Digital Filter 4 x CLK PSC PSC Input Module X 13.8.4.2 PSCn Input A or B Ouput Stage PSCOUTnX PIN Signal Polarity One can select the active edge (edge modes) or the active level (level modes) See PELEV0x bit description in Section “PSCR Input A Control Register – PFRC0A”, page 17513.23.8. 159 7734P–AVR–08/10 If PELEV0x bit set, the significant edge of PSCr Input A or B is rising (edge modes) or the active level is high (level modes) and vice versa for unset/falling/low - In 2- or 4-ramp mode, PSCr Input A is taken into account only during Dead-Time0 and On-Time0 period (respectively Dead-Time1 and On-Time1 for PSCr Input B). - In 1-ramp-mode PSCR Input A or PSCR Input B act on the whole ramp. 13.8.4.3 Input Mode Operation Thanks to 4 configuration bits (PRFM3:0), it’s possible to define the mode of the PSCR input. All Table 13-5. PSCR Input Mode Operation PRFM3:0 Description 0 0000b PSCr Input has no action on PSCR output 1 0001b 2 0010b 3 0011b 4 0100b 5 0101b 6 0110b 7 0111b 8 1000b See “PSCR Input Mode 6: Stop signal, Jump to Opposite Dead-Time and Wait.” on page 165. See “PSCR Input Mode 7: Halt PSCR and Wait for Software Action” on page 165. See “PSCR Input Mode 8: Edge Retrigger PSC” on page 166. 9 1001b See “PSCR Input Mode 9: Fixed Frequency Edge Retrigger PSC” on page 167. 10 1010b Reserved : Do not use 11 1011b 12 1100b 13 1101b 14 1110b 15 1111b 13.9See “PSCR Input Mode 1: Stop signal, Jump to Opposite Dead-Time and Wait” on page 161. See “PSCR Input Mode 2: Stop signal, Execute Opposite Dead-Time and Wait” on page 162. See “PSCR Input Mode 3: Stop signal, Execute Opposite while Fault active” on page 163. See “PSCR Input Mode 4: Deactivate outputs without changing timing.” on page 164. See “PSCR Input Mode 5: Stop signal and Insert Dead-Time” on page 164. See “PSCR Input Mode 14: Fixed Frequency Edge Retrigger PSCR and Deactivate Output” on page 168. Reserved : Do not use Notice: All following examples are given with rising edge or high level active inputs. 160 AT90PWM81 7734P–AVR–08/10 AT90PWM81 13.9 PSCR Input Mode 1: Stop signal, Jump to Opposite Dead-Time and Wait Figure 13-14. PSCr behavior versus PSCr Input A in Fault Mode 1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSC Input A PSC Input B PSCR Input A is taken into account during DT0 and OT0 only. It has no effect during DT1 and OT1. When PSCR Input A event occurs, PSCR releases PSCOUTr0, waits for PSCR Input A inactive state and then jumps and executes DT1 plus OT1. Figure 13-15. PSCr behavior versus PSCr Input B in Fault Mode 1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSC Input A PSC Input B PSCR Input B is take into account during DT1 and OT1 only. It has no effect during DT0 and OT0. When PSCR Input B event occurs, PSCR releases PSCOUTr1, waits for PSCR Input B inactive state and then jumps and executes DT0 plus OT0. 161 7734P–AVR–08/10 13.10 PSCR Input Mode 2: Stop signal, Execute Opposite Dead-Time and Wait Figure 13-16. PSCr behavior versus PSCr Input A in Fault Mode 2 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSC Input A PSC Input B PSCR Input A is take into account during DT0 and OT0 only. It has no effect during DT1 and OT1. When PSCr Input A event occurs, PSCR releases PSCOUTr0, jumps and executes DT1 plus OT1 and then waits for PSCR Input A inactive state. Even if PSCR Input A is released during DT1 or OT1, DT1 plus OT1 sub-cycle is always completely executed. Figure 13-17. PSCr behavior versus PSCr Input B in Fault Mode 2 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSC Input A PSC Input B PSCR Input B is take into account during DT1 and OT1 only. It has no effect during DT0 and OT0. When PSCR Input B event occurs, PSCR releases PSCOUTr1, jumps and executes DT0 plus OT0 and then waits for PSCR Input B inactive state. Even if PSCR Input B is released during DT0 or OT0, DT0 plus OT0 sub-cycle is always completely executed. 162 AT90PWM81 7734P–AVR–08/10 AT90PWM81 13.11 PSCR Input Mode 3: Stop signal, Execute Opposite while Fault active Figure 13-18. PSCr behavior versus PSCr Input A in Mode 3 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT1 OT1 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSC Input A PSC Input B PSCR Input A is taken into account during DT0 and OT0 only. It has no effect during DT1 and OT1. When PSCR Input A event occurs, PSCR releases PSCOUTr0, jumps and executes DT1 plus OT1 plus DT0 while PSCR Input A is in active state. Even if PSCR Input A is released during DT1 or OT1, DT1 plus OT1 sub-cycle is always completely executed. Figure 13-19. PSCr behavior versus PSCr Input B in Mode 3 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT0 OT0 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSC Input A PSC Input B PSCR Input B is taken into account during DT1 and OT1 only. It has no effect during DT0 and OT0. When PSCR Input B event occurs, PSCR releases PSCOUTR1, jumps and executes DT0 plus OT0 plus DT1 while PSCR Input B is in active state. Even if PSCR Input B is released during DT0 or OT0, DT0 plus OT0 sub-cycle is always completely executed. 163 7734P–AVR–08/10 13.12 PSCR Input Mode 4: Deactivate outputs without changing timing. Figure 13-20. PSCR behavior versus PSCr Input A or Input B in Mode 4 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input A or PSCn Input B Figure 13-21. PSCR behavior versus PSCr Input A or Input B in Fault Mode 4 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input A or PSCn Input B PSCr Input A or PSCr Input B act indifferently on On-Time0/Dead-Time0 or on On-Time1/Dead-Time1. 13.13 PSCR Input Mode 5: Stop signal and Insert Dead-Time PSCOUTn0 DT0 OT0 DT0 DT1 OT1 DT1 DT0 DT1 OT0 DT1 DT0 DT0 Figure 13-22. PSCR behavior versus PSCr Input A in Fault Mode 5 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn1 PSCn Input A or PSCn Input B 164 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Used in Fault mode 5, PSCr Input A or PSCr Input B act indifferently on On-Time0/Dead-Time0 or on On-Time1/Dead-Time1. 13.14 PSCR Input Mode 6: Stop signal, Jump to Opposite Dead-Time and Wait. Figure 13-23. PSCR behavior versus PSCr Input A in Fault Mode 6 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input A or PSCn Input B Used in Fault mode 6, PSCr Input A or PSCr Input B act indifferently on On-Time0/Dead-Time0 or on On-Time1/Dead-Time1. 13.15 PSCR Input Mode 7: Halt PSCR and Wait for Software Action Figure 13-24. PSCR behavior versus PSCr Input A in Fault Mode 7 DT0 OT0 DT1 OT1 DT0 OT0 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input A or PSCn Input B Software Action (1) Note: 1. Software action is the setting of the PRUNn bit in PCTLr register. Used in Fault mode 7, PSCr Input A or PSCr Input B act indifferently on On-Time0/Dead-Time0 or on On-Time1/Dead-Time1. 165 7734P–AVR–08/10 13.16 PSCR Input Mode 8: Edge Retrigger PSC Figure 13-25. PSCR behavior versus PSCr Input A in Mode 8 DT0 OT0 DT1 DT0 OT0 OT1 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input A The output frequency is modulated by the occurrence of significative edge of retriggering input. Figure 13-26. PSCR behavior versus PSCr Input B in Mode 8 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input B or PSCn Input B The output frequency is modulated by the occurrence of significative edge of retriggering input. The retrigger event is taken into account only if it occurs during the corresponding On-Time. Note: In one ramp mode, the retrigger event on input A resets the whole ramp. So the PSCR doesn’t jump to the opposite dead-time. 166 AT90PWM81 7734P–AVR–08/10 AT90PWM81 13.17 PSCR Input Mode 9: Fixed Frequency Edge Retrigger PSC Figure 13-27. PSCR behavior versus PSCr Input A in Mode 9 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input A The output frequency is not modified by the occurrence of significative edge of retriggering input. Only the output is deactivated when significative edge on retriggering input occurs. Note: In this mode the output of the PSCR becomes active during the next ramp even if the Retrigger/Fault input is active. Only the significative edge of Retrigger/Fault input is taken into account. Figure 13-28. PSCR behavior versus PSCr Input B in Mode 9 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input B The retrigger event is taken into account only if it occurs during the corresponding On-Time. 167 7734P–AVR–08/10 13.18 PSCR Input Mode 14: Fixed Frequency Edge Retrigger PSCR and Deactivate Output Figure 13-29. PSCR behavior versus PSCr Input A in Mode 14 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input A The output frequency is not modified by the occurrence of significative edge of retriggering input. Figure 13-30. PSCR behavior versus PSCr Input B in Mode 14 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 DT0 OT0 DT1 OT1 PSCOUTn0 PSCOUTn1 PSCn Input B The output is deactivated while retriggering input is active. The output of the PSCR is set to an inactive state and the corresponding ramp is not aborted. The output stays in an inactive state while the Retrigger/Fault input is active. The PSCR runs at constant frequency. 168 AT90PWM81 7734P–AVR–08/10 AT90PWM81 13.18.1 Available Input Mode according to Running Mode Some Input Modes are not consistent with some Running Modes. So the table below gives the input modes which are valid according to running modes. Table 13-6. Available Input Modes according to Running Modes Input Mode Number : 1 Ramp Mode 2 Ramp Mode 4 Ramp Mode 1 Valid Valid Valid 2 Do not use Valid Valid 3 Do not use Valid Valid 4 Valid Valid Valid 5 Do not use Valid Valid 6 Do not use Valid Valid 7 Valid Valid Valid 8 Valid Valid Valid 9 Valid Valid Valid Valid Valid 10 11 Do not use 12 13 13.18.2 14 Valid 15 Do not use Event Capture The PSCR can capture the value of time (PSCR counter) when a retrigger event or fault event occurs on PSCR inputs. This value can be read by software in PICRrH/L register. 13.18.3 Using the Input Capture Unit The main challenge when using the Input Capture unit is to assign enough processor capacity for handling the incoming events. The time between two events is critical. If the processor has not read the captured value in the PICR1 Register before the next event occurs, the PICR1 will be overwritten with a new value. In this case the result of the capture will be incorrect. When using the Input Capture interrupt, the PICR1 Register should be read as early in the interrupt handler routine as possible. Even though the Input Capture interrupt has relatively high priority, the maximum interrupt response time is dependent on the maximum number of clock cycles it takes to handle any of the other interrupt requests. 13.19 Analog Synchronization PSCR generates a signal to synchronize the sample and hold; synchronization is mandatory for measurements. 169 7734P–AVR–08/10 This signal can be selected between all falling or rising edge of PSCr0 or PSCr1 outputs. 13.20 Interrupt Handling List of interrupt sources: • Counter reload (end of On Time 1) • PSCR Input event (active edge or at the beginning of level configured event) 13.21 PSC Clock Sources PSCR must be able to generate high frequency with enhanced resolution. The PSCR has two clock inputs: • CLK PLL from the PLL • CLK I/O Figure 13-31. Clock selection CLK 1 PLL CK CK CK/4 CK/32 CK/256 01 10 11 0 I/O 00 CLK PRESCALER PCLKSELr PPREr1/0 CLK PSCr PCLKSELr bit in PSCR Configuration register (PCNFr) is used to select the clock source. PPREr1/0 bits in PSCR Control Register (PCTLr) are used to select the divide factor of the clock. Table 13-7. 170 Output Clock versus Selection and Prescaler PCLKSELr PPREr1 PPREr0 CLKPSCr output 0 0 0 CLK I/O 0 0 1 CLK I/O / 4 0 1 0 CLK I/O / 32 0 1 1 CLK I/O / 256 1 0 0 CLK PLL 1 0 1 CLK PLL / 4 1 1 0 CLK PLL / 32 1 1 1 CLK PLL / 256 AT90PWM81 7734P–AVR–08/10 AT90PWM81 13.22 Interrupts This section describes the specifics of the interrupt handling as performed in AT90PWM81. 13.22.1 List of Interrupt Vector The PSCR provides 3 interrupt vectors • PSC0EC (End of Cycle): When enabled and when a match with OCRrRB occurs • PSC0EEC (End of Enhanced Cycle): When enabled and when a match with OCRrRB occurs at the 15th enhanced cycle • PSC0CAPT (Capture Event): When enabled and one of the two following events occurs : retrigger, capture of the PSCR counter or Synchro Error. • See PSC0 Interrupt Mask Register page 177 and PSC0 Interrupt Flag Register page 178. 13.23 PSCR Register Definition 13.23.1 PSCR Synchro and Output Configuration – PSOC0 Bit 7 6 4 3 2 1 PISEL0A1 PISEL0B1 PSYNC01 5 PSYNC00 - POEN0B - 0 POEN0A Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 PSOC0 • Bit 7– PISEL0A1: PSC Input Select for part A Together with PISEL0A0, defines active signal on PSCR part A. Table 13-8. PSC trigger & fault input Selection PISEL0A1 PISEL0A0 Description 0 0 PSCIN0 0 1 Analog comparator output 1 0 PSCIN0A 1 1 PSCIN0B • Bit 6– PISEL0B1: PSCR Input Select for part B Together with PISEL0B0, defines active signal on PSCR part B. Table 13-9. PSC trigger & fault input Selection PISEL0B1 PISEL0B0 Description 0 0 PSCIN0 0 1 Analog comparator output 1 0 PSCIN0A 1 1 PSCIN0B 171 7734P–AVR–08/10 • Bit 5:4 – PSYNC01:0: Synchronization Out for ADC Selection) Select the polarity and signal source for generating a signal which will be sent to the ADC for synchronization. Table 13-10. Synchronization Source Description in One/Two/Four Ramp Modes PSYNC01 PSYNC00 Description 0 0 Send signal on leading edge of PSCOUT00 (match with OCR0SA) 0 1 Send signal on trailing edge of PSCOUT00 (match with OCR0RA or fault/retrigger on part A) 1 0 Send signal on leading edge of PSCOUT01 (match with OCR0SB) 1 1 Send signal on trailing edge of PSCOUT01 (match with OCR0RB or fault/retrigger on part B) • Bit 3 – Reserved. • Bit 2 – POEN0B: PSCR OUT Part B Output Enable When this bit is clear, I/O pin affected to PSCOUT01 acts as a standard port. When this bit is set, I/O pin affected to PSCOUT01 is connected to the PSCR waveform generator B output and is set and clear according to the PSCR operation. • Bit 1 – Reserved • Bit 0 – POEN0A: PSCR OUT Part A Output Enable When this bit is clear, I/O pin affected to PSCOUT00 acts as a standard port. When this bit is set, I/O pin affected to PSCOUT00 is connected to the PSCR waveform generator A output and is set and clear according to the PSCR operation. 13.23.2 Output Compare SA Register – OCR0SAH and OCR0SAL Bit 7 6 5 4 3 – – – – OCR0SA[11:8] 2 1 0 OCR0SAH OCR0SA[7:0] 13.23.3 OCR0SAL Read/Write W W W W W W W W Initial Value 0 0 0 0 0 0 0 0 2 1 0 Output Compare RA Register – OCR0RAH and OCR0RAL Bit 7 6 5 4 3 – – – – OCR0RA[11:8] OCR0RAH OCR0RA[7:0] 13.23.4 OCR0RAL Read/Write W W W W W W W W Initial Value 0 0 0 0 0 0 0 0 2 1 0 Output Compare SB Register – OCR0SBH and OCR0SBL Bit 7 6 5 4 3 – – – – OCR0SB[11:8] OCR0SBH OCR0SB[7:0] 172 OCR0SBL Read/Write W W W W W W W W Initial Value 0 0 0 0 0 0 0 0 AT90PWM81 7734P–AVR–08/10 AT90PWM81 13.23.5 Output Compare RB Register – OCR0RBH and OCR0RBL Bit 7 6 5 4 OCR0RB[15:12] 3 2 1 0 OCR0RB[11:8] OCR0RBH OCR0RB[7:0] OCR0RBL Read/Write W W W W W W W W Initial Value 0 0 0 0 0 0 0 0 The Output Compare Registers RA, RB, SA and SB contain a 12-bit value that is continuously compared with the PSCR counter value. A match can be used to generate an Output Compare interrupt, or to generate a waveform output on the associated pin. The Output Compare Registers RB contains also a 4-bit value that is used for the flank width modulation. The Output Compare Registers are 12-bit in size. To ensure that both the high and low bytes are written simultaneously when the CPU writes to these registers, the access is performed using an 8-bit temporary high byte register (TEMP). This temporary register is shared by all the other 16-bit registers. 13.23.6 PSCR Configuration Register – PCNF0 Bit 7 6 PFIFTY0 PALOCK0 PLOCK0 5 4 PMODE01 PMODE00 POP0 3 2 PCLKSEL0 - 1 0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 PCNF0 • Bit 7 - PFIFTY0: PSCR Fifty Writing this bit to one, set the PSCR in a fifty percent mode where only OCR0RBH/L and OCR0SBH/L are used. They are duplicated in OCR0RAH/L and OCR0SAH/L during the update of OCR0RBH/L. This feature is useful to perform fifty percent waveforms. • Bit 6 - PALOCK0: PSCR Autolock When this bit is set, the Output Compare Registers RA, SA, SB, the Output Matrix POM2 and the PSCR Output Configuration PSOC0 can be written without disturbing the PSCR cycles. The update of the PSCR internal registers will be done at the end of the PSCR cycle if the Output Compare Register RB has been the last written. When set, this bit prevails over LOCK (bit 5) • Bit 5 – PLOCK0: PSCR Lock When this bit is set, the Output Compare Registers RA, RB, SA, SB, the Output Matrix POM2 and the PSCR Output Configuration PSOC0 can be written without disturbing the PSCR cycles. The update of the PSCR internal registers will be done if the LOCK bit is released to zero. • Bit 4:3 – PMODE01: 0: PSCR Mode Select the mode of PSC. 173 7734P–AVR–08/10 Table 13-11. PSCR Mode Selection PMODE01 PMODE00 Description 0 0 One Ramp Mode 0 1 Two Ramp Mode 1 0 Four Ramp Mode 1 1 Reserved • Bit 2 – POP0: PSCR Output Polarity If this bit is cleared, the PSCR outputs are active Low. If this bit is set, the PSCR outputs are active High. • Bit 1 – PCLKSEL0: PSCR Input Clock Select This bit is used to select between CLKPF or CLKPS clocks. Set this bit to select the fast clock input (CLKPF). Clear this bit to select the slow clock input (CLKPS). • Bit 0 – Reserved 13.23.7 PSCR Control Register – PCTL0 Bit 7 6 5 4 3 2 1 0 PPRE01 PPRE00 PBFM01 PAOC0B PAOC0A PBFM00 PCCYC0 PRUN0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 PCTL0 • Bit 7:6 – PPRE01:0 : PSCR Prescaler Select This two bits select the PSCR input clock division factor. All generated waveform will be modified by this factor. Table 13-12. 174 PSCR Prescaler Selection PPRE01 PPRE00 Description 0 0 No divider on PSCR input clock 0 1 Divide the PSCR input clock by 4 1 0 Divide the PSCR input clock by 32 1 1 Divide the PSCR clock by 256 AT90PWM81 7734P–AVR–08/10 AT90PWM81 • Bit 5- PBFM01: Balance Flank Width Modulation, bit 1 Defines the Flank Width Modulation, together with PBFM00 bit. Table 13-13. Flank Width Mode Selection PBFM01 PBFM00 Description 0 0 Flank Width Modulation operates on RB (On-Time 1 only). 0 1 Flank Width Modulation operates on RB + RA (On-Time 0 and On-Time 1). 1 0 Flank Width Modulation operates on SB (Dead-Time 1 only) (1). 1 1 Flank Width Modulation operates on SB +SA (Dead-Time 0 and DeadTime 1). 1. Note: In one ramp mode, changing SA or SA+SB also affect On-Time ; see PSCr0 & PSCr1 Basic Waveforms in One Ramp mode • Bit 4 – PAOC0B : PSCR Asynchronous Output Control B When this bit is set, Fault input selected to block B can act directly to PSCOUT01 output. See Section “PSCR Input Configuration”, page 159. • Bit 3 – PAOC0A : PSCR Asynchronous Output Control A When this bit is set, Fault input selected to block A can act directly to PSCOUT00 output. See Section “PSCR Input Configuration”, page 159. • Bit 2- PBFM00: Balance Flank Width Modulation, bit 0 Defines the Flank Width Modulation, together with PBFM01 bit • Bit 1 – PCCYC0 : PSCR Complete Cycle When this bit is set, the PSCR completes the entire waveform cycle before halt operation requested by clearing PRUN0. This bit is not relevant in slave mode (PARUN0 = 1). • Bit 0 – PRUN0 : PSCR Run Writing this bit to one starts the PSCR. When set, this bit prevails over PARUN0 bit. 13.23.8 PSCR Input A Control Register – PFRC0A Bit 13.23.9 7 6 4 3 2 1 0 PCAE0A PISEL0A0 PELEV0A 5 PFLTE0A PRFM0A3 PRFM0A2 PRFM0A1 PRFM0A0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 PFRC0A PSCR Input B Control Register – PFRC0B Bit 7 6 4 3 2 1 0 PCAE0B PISEL0B0 PELEV0B 5 PFLTE0B PRFM0B3 PRFM0B2 PRFM0B1 PRFM0B0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 PFRC0B 175 7734P–AVR–08/10 The Input Control Registers are used to configure the 2 PSC’s Retrigger/Fault block A & B. The 2 blocks are identical, so they are configured on the same way. • Bit 7 – PCAE0x : PSCR Capture Enable Input Part x Writing this bit to one enables the capture function when external event occurs on input selected as input for Part x (see PISEL0x0 bit in the same register). • Bit 6 – PISEL0x0 : PSCR Input Select for Part x Together with PISEL0x1 in PSOC0 register, defines active signal on PSC module A. See Table 13-8 on page 171 and Table 13-9 on page 171 • Bit 5 –PELEV0x : PSCR Edge Level Selector of Input Part x When this bit is clear, the falling edge or low level of selected input generates the significative event for retrigger or fault function . When this bit is set, the rising edge or high level of selected input generates the significative event for retrigger or fault function. • Bit 4 – PFLTE0x : PSCR Filter Enable on Input Part x Setting this bit (to one) activates the Input Capture Noise Canceler. When the noise canceler is activated, the input from the retrigger pin is filtered. The filter function requires four successive equal valued samples of the retrigger pin for changing its output. The Input Capture is therefore delayed by four oscillator cycles when the noise canceler is enabled. • Bit 3:0 – PRFM0x3:0: PSCR Fault Mode These four bits define the mode of operation of the Fault or Retrigger functions. (see PSCR Functional Specification for more explanations) Table 13-14. 176 Level Sensitivity and Fault Mode Operation PRFM0x3:0 Description 0000b No action, PSCR Input is ignored 0001b PSCR Input Mode 1: Stop signal, Jump to Opposite Dead-Time and Wait 0010b PSCR Input Mode 2: Stop signal, Execute Opposite Dead-Time and Wait 0011b PSCR Input Mode 3: Stop signal, Execute Opposite while Fault active 0100b PSCR Input Mode 4: Deactivate outputs without changing timing. 0101b PSCR Input Mode 5: Stop signal and Insert Dead-Time 0110b PSCR Input Mode 6: Stop signal, Jump to Opposite Dead-Time and Wait. 0111b PSCR Input Mode 7: Halt PSCR and Wait for Software Action 1000b PSCR Input Mode 8: Edge Retrigger PSC 1001b PSCR Input Mode 9: Fixed Frequency Edge Retrigger PSC AT90PWM81 7734P–AVR–08/10 AT90PWM81 Table 13-14. Level Sensitivity and Fault Mode Operation PRFM0x3:0 Description 1010b Reserved (do not use) 1011b 1100b 1101b PSCR Input Mode 14: Fixed Frequency Edge Retrigger PSCR and Deactivate Output Reserved (do not use) 1110b 1111b 13.23.10 PSCR Input Capture Register – PICR0H and PICR0L Bit 7 6 5 4 3 PCST0 – – – PICR0[11:8] 2 1 0 PICR0H PICR0[7:0] PICR0L Read/Write R R R R R R R R Initial Value 0 0 0 0 0 0 0 0 • Bit 7 – PCST0 : PSCR Capture Software Trig bit Set this bit to trigger off a capture of the PSCR counter. When reading, if this bit is set it means that the capture operation was triggered by PCST0 setting otherwise it means that the capture operation was triggered by a PSCR input. The Input Capture is updated with the PSCR counter value each time an event occurs on the enabled PSCR input pin (or optionally on the Analog Comparator output) if the capture function is enabled (bit PCAE0x in PFRC0x register is set). The Input Capture Register is 12-bit in size. To ensure that both the high and low bytes are read simultaneously when the CPU accesses these registers, the access is performed using an 8-bit temporary high byte register (TEMP). This temporary register is shared by all the other 16-bit or 12-bit registers. 13.23.11 PSCR Interrupt Mask Register – PIM0 Bit 7 6 5 4 3 2 1 0 - - - PEVE0B PEVE0A - PEOEPE0 PEOPE0 Read/Write R R R R/W R/W R R R/W Initial Value 0 0 0 0 0 0 0 0 PIM0 • Bit 7- 5 – Reserved • Bit 4 – PEVE0B : PSCR External Event B Interrupt Enable When this bit is set, an external event which can generates a capture from Retrigger/Fault block B generates also an interrupt. • Bit 3 – PEVE0A : PSCR External Event A Interrupt Enable When this bit is set, an external event which can generates a capture from Retrigger/Fault block A generates also an interrupt. 177 7734P–AVR–08/10 • Bit 2 – Reserved • Bit 1– PEOEPE0 : PSCR End Of Enhanced Cycle Interrupt Enable When this bit is set, an interrupt is generated when PSC reduced reaches the end of the 15th PSC cycle. This allows to update the PSCR values in the interrupt routine and to start a new enhanced cycle with the new values at the next PSCR cycle end. • Bit 0 – PEOPE0 : PSCR End Of Cycle Interrupt Enable When this bit is set, an interrupt is generated when PSCR reaches the end of the whole cycle. 13.23.12 PSCR Interrupt Flag Register – PIFR0 Bit 7 6 5 4 3 2 1 0 POAC0B POAC0A - PEV0B PEV0A PRN01 PRN00 PEOP0 Read/Write R R R R/W R/W R R R/W Initial Value 0 0 0 0 0 0 0 0 PIFR0 • Bit 7 – POAC0B : PSCR Output B Activity This bit is set by hardware each time the output PSCOUT01 changes from 0 to 1 or from 1 to 0. Must be cleared by software by writing a one to its location. This feature is useful to detect that a PSCR output doesn’t change due to a frozen external input signal. • Bit 6 – POAC0A : PSCR Output A Activity This bit is set by hardware each time the output PSCOUT00 changes from 0 to 1 or from 1 to 0. Must be cleared by software by writing a one to its location. This feature is useful to detect that a PSCR output doesn’t change due to a freezen external input signal. • Bit 5 – Reserved • Bit 4 – PEV0B : PSCR External Event B Interrupt This bit is set by hardware when an external event which can generates a capture or a retrigger from Retrigger/Fault block B occurs. Must be cleared by software by writing a one to its location. This bit can be read even if the corresponding interrupt is not enabled (PEVE0B bit = 0). • Bit 3 – PEV0A : PSCR External Event A Interrupt This bit is set by hardware when an external event which can generates a capture or a retrigger from Retrigger/Fault block A occurs. Must be cleared by software by writing a one to its location. This bit can be read even if the corresponding interrupt is not enabled (PEVE0A bit = 0). • Bit 2:1 – PRN01:0 : PSCR Ramp Number Memorization of the ramp number when the last PEV0A or PEV0B occurred. 178 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Table 13-15. PSCR Ramp Number Description PRN01 PRN00 Description 0 0 The last event which has generated an interrupt occurred during ramp 1 0 1 The last event which has generated an interrupt occurred during ramp 2 1 0 The last event which has generated an interrupt occurred during ramp 3 1 1 The last event which has generated an interrupt occurred during ramp 4 • Bit 0 – PEOP0: End Of PSCR Interrupt This bit is set by hardware when PSCR achieves its whole cycle. Must be cleared by software by writing a one to its location. 179 7734P–AVR–08/10 14. Serial Peripheral Interface – SPI: 14.1 Features • • • • • • • • 14.2 Full-duplex, Three-wire Synchronous Data Transfer Master or Slave Operation LSB First or MSB First Data Transfer Seven Programmable Bit Rates End of Transmission Interrupt Flag Write Collision Flag Protection Wake-up from Idle Mode Double Speed (CK/2) Master SPI Mode Overview The Serial Peripheral Interface (SPI) allows high-speed synchronous data transfer between the AT90PWM81 and peripheral devices or between several AVR devices. The AT90PWM81 SPI includes the following features SPI Block Diagram(1) Figure 14-1. MISO clk IO MOSI DIVIDER /2/4/8/16/32/64/128 SPI2X SCK SPI2X SS Note: 180 1. Refer to Figure 2-1 on page 3, and Table 9-3 on page 73 for SPI pin placement. AT90PWM81 7734P–AVR–08/10 AT90PWM81 The interconnection between Master and Slave CPUs with SPI is shown in Figure 14-2. The system consists of two shift Registers, and a Master clock generator. The SPI Master initiates the communication cycle when pulling low the Slave Select SS pin of the desired Slave. Master and Slave prepare the data to be sent in their respective shift Registers, and the Master generates the required clock pulses on the SCK line to interchange data. Data is always shifted from Master to Slave on the Master Out – Slave In, MOSI, line, and from Slave to Master on the Master In – Slave Out, MISO, line. After each data packet, the Master will synchronize the Slave by pulling high the Slave Select, SS, line. When configured as a Master, the SPI interface has no automatic control of the SS line. This must be handled by user software before communication can start. When this is done, writing a byte to the SPI Data Register starts the SPI clock generator, and the hardware shifts the eight bits into the Slave. After shifting one byte, the SPI clock generator stops, setting the end of transmission flag (SPIF). If the SPI Interrupt Enable bit (SPIE) in the SPCR Register is set, an interrupt is requested. The Master may continue to shift the next byte by writing it into SPDR, or signal the end of packet by pulling high the Slave Select, SS line. The last incoming byte will be kept in the Buffer Register for later use. When configured as a Slave, the SPI interface will remain sleeping with MISO tri-stated as long as the SS pin is driven high. In this state, software may update the contents of the SPI Data Register, SPDR, but the data will not be shifted out by incoming clock pulses on the SCK pin until the SS pin is driven low. As one byte has been completely shifted, the end of transmission flag, SPIF is set. If the SPI Interrupt Enable bit, SPIE, in the SPCR Register is set, an interrupt is requested. The Slave may continue to place new data to be sent into SPDR before reading the incoming data. The last incoming byte will be kept in the Buffer Register for later use. Figure 14-2. SPI Master-slave Interconnection SHIFT ENABLE The system is single buffered in the transmit direction and double buffered in the receive direction. This means that bytes to be transmitted cannot be written to the SPI Data Register before the entire shift cycle is completed. When receiving data, however, a received character must be read from the SPI Data Register before the next character has been completely shifted in. Otherwise, the first byte is lost. In SPI Slave mode, the control logic will sample the incoming signal of the SCK pin. To ensure correct sampling of the clock signal, the frequency of the SPI clock should never exceed fclkio/4. 181 7734P–AVR–08/10 When the SPI is enabled, the data direction of the MOSI, MISO, SCK, and SS pins is overridden according to Table 14-1. For more details on automatic port overrides, refer to “Alternate Port Functions” on page 71. Table 14-1. Pin SPI Pin Overrides(1) Direction, Master SPI Direction, Slave SPI MOSI User Defined Input MISO Input User Defined SCK User Defined Input SS User Defined Input Note: 1. See “Alternate Functions of Port B” on page 73 for a detailed description of how to define the direction of the user defined SPI pins. The following code examples show how to initialize the SPI as a Master and how to perform a simple transmission. DDR_SPI in the examples must be replaced by the actual Data Direction Register controlling the SPI pins. DD_MOSI, DD_MISO and DD_SCK must be replaced by the actual data direction bits for these pins. E.g. if MOSI is placed on pin PB2, replace DD_MOSI with DDB2 and DDR_SPI with DDRB. 182 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Assembly Code Example(1) SPI_MasterInit: ; Set MOSI and SCK output, all others input ldi r17,(1<<DD_MOSI)|(1<<DD_SCK) out DDR_SPI,r17 ; Enable SPI, Master, set clock rate fck/16 ldi r17,(1<<SPE)|(1<<MSTR)|(1<<SPR0) out SPCR,r17 ret SPI_MasterTransmit: ; Start transmission of data (r16) out SPDR,r16 Wait_Transmit: ; Wait for transmission complete sbis SPSR,SPIF rjmp Wait_Transmit ret C Code Example(1) void SPI_MasterInit(void) { /* Set MOSI and SCK output, all others input */ DDR_SPI = (1<<DD_MOSI)|(1<<DD_SCK); /* Enable SPI, Master, set clock rate fck/16 */ SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR0); } void SPI_MasterTransmit(char cData) { /* Start transmission */ SPDR = cData; /* Wait for transmission complete */ while(!(SPSR & (1<<SPIF))) ; } Note: 1. The example code assumes that the part specific header file is included. The following code examples show how to initialize the SPI as a Slave and how to perform a simple reception. 183 7734P–AVR–08/10 Assembly Code Example(1) SPI_SlaveInit: ; Set MISO output, all others input ldi r17,(1<<DD_MISO) out DDR_SPI,r17 ; Enable SPI ldi r17,(1<<SPE) out SPCR,r17 ret SPI_SlaveReceive: ; Wait for reception complete sbis SPSR,SPIF rjmp SPI_SlaveReceive ; Read received data and return in r16,SPDR ret C Code Example(1) void SPI_SlaveInit(void) { /* Set MISO output, all others input */ DDR_SPI = (1<<DD_MISO); /* Enable SPI */ SPCR = (1<<SPE); } char SPI_SlaveReceive(void) { /* Wait for reception complete */ while(!(SPSR & (1<<SPIF))) ; /* Return data register */ return SPDR; } Note: 14.3 14.3.1 1. The example code assumes that the part specific header file is included. SS Pin Functionality Slave Mode When the SPI is configured as a Slave, the Slave Select (SS) pin is always input. When SS is held low, the SPI is activated, and MISO becomes an output if configured so by the user. All other pins are inputs. When SS is driven high, all pins are inputs, and the SPI is passive, which means that it will not receive incoming data. Note that the SPI logic will be reset once the SS pin is driven high. 184 AT90PWM81 7734P–AVR–08/10 AT90PWM81 The SS pin is useful for packet/byte synchronization to keep the slave bit counter synchronous with the master clock generator. When the SS pin is driven high, the SPI slave will immediately reset the send and receive logic, and drop any partially received data in the Shift Register. 14.3.2 Master Mode When the SPI is configured as a Master (MSTR in SPCR is set), the user can determine the direction of the SS pin. If SS is configured as an output, the pin is a general output pin which does not affect the SPI system. Typically, the pin will be driving the SS pin of the SPI Slave. If SS is configured as an input, it must be held high to ensure Master SPI operation. If the SS pin is driven low by peripheral circuitry when the SPI is configured as a Master with the SS pin defined as an input, the SPI system interprets this as another master selecting the SPI as a slave and starting to send data to it. To avoid bus contention, the SPI system takes the following actions: 1. The MSTR bit in SPCR is cleared and the SPI system becomes a Slave. As a result of the SPI becoming a Slave, the MOSI and SCK pins become inputs. 2. The SPIF flag in SPSR is set, and if the SPI interrupt is enabled, and the I-bit in SREG is set, the interrupt routine will be executed. Thus, when interrupt-driven SPI transmission is used in Master mode, and there exists a possibility that SS is driven low, the interrupt should always check that the MSTR bit is still set. If the MSTR bit has been cleared by a slave select, it must be set by the user to re-enable SPI Master mode. 14.4 Data Modes There are four combinations of SCK phase and polarity with respect to serial data, which are determined by control bits CPHA and CPOL. The SPI data transfer formats are shown in Figure 14-3 and Figure 14-4. Data bits are shifted out and latched in on opposite edges of the SCK signal, ensuring sufficient time for data signals to stabilize. This is clearly seen by summarizing Table 14-3 and Table 14-4, as done below: Table 14-2. CPOL Functionality Leading Edge Trailing eDge SPI Mode CPOL=0, CPHA=0 Sample (Rising) Setup (Falling) 0 CPOL=0, CPHA=1 Setup (Rising) Sample (Falling) 1 CPOL=1, CPHA=0 Sample (Falling) Setup (Rising) 2 CPOL=1, CPHA=1 Setup (Falling) Sample (Rising) 3 185 7734P–AVR–08/10 Figure 14-3. SPI Transfer Format with CPHA = 0 SCK (CPOL = 0) mode 0 SCK (CPOL = 1) mode 2 SAMPLE I MOSI/MISO CHANGE 0 MOSI PIN CHANGE 0 MISO PIN SS MSB first (DORD = 0) MSB LSB first (DORD = 1) LSB Figure 14-4. Bit 6 Bit 1 Bit 5 Bit 2 Bit 4 Bit 3 Bit 3 Bit 4 Bit 2 Bit 5 Bit 1 Bit 6 LSB MSB SPI Transfer Format with CPHA = 1 SCK (CPOL = 0) mode 1 SCK (CPOL = 1) mode 3 SAMPLE I MOSI/MISO CHANGE 0 MOSI PIN CHANGE 0 MISO PIN SS MSB first (DORD = 0) LSB first (DORD = 1) 14.5 14.5.1 MSB LSB Bit 6 Bit 1 Bit 5 Bit 2 Bit 4 Bit 3 Bit 3 Bit 4 Bit 2 Bit 5 Bit 1 Bit 6 LSB MSB SPI registers SPI Control Register – SPCR Bit 7 6 5 4 3 2 1 0 SPIE SPE DORD MSTR CPOL CPHA SPR1 SPR0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 SPCR • Bit 7 – SPIE: SPI Interrupt Enable This bit causes the SPI interrupt to be executed if SPIF bit in the SPSR Register is set and the if the Global Interrupt Enable bit in SREG is set. • Bit 6 – SPE: SPI Enable When the SPE bit is written to one, the SPI is enabled. This bit must be set to enable any SPI operations. 186 AT90PWM81 7734P–AVR–08/10 AT90PWM81 • Bit 5 – DORD: Data Order When the DORD bit is written to one, the LSB of the data word is transmitted first. When the DORD bit is written to zero, the MSB of the data word is transmitted first. • Bit 4 – MSTR: Master/Slave Select This bit selects Master SPI mode when written to one, and Slave SPI mode when written logic zero. If SS is configured as an input and is driven low while MSTR is set, MSTR will be cleared, and SPIF in SPSR will become set. The user will then have to set MSTR to re-enable SPI Master mode. • Bit 3 – CPOL: Clock Polarity When this bit is written to one, SCK is high when idle. When CPOL is written to zero, SCK is low when idle. Refer to Figure 14-3 and Figure 14-4 for an example. The CPOL functionality is summarized below: Table 14-3. CPOL Functionality CPOL Leading Edge Trailing Edge 0 Rising Falling 1 Falling Rising • Bit 2 – CPHA: Clock Phase The settings of the Clock Phase bit (CPHA) determine if data is sampled on the leading (first) or trailing (last) edge of SCK. Refer to Figure 14-3 and Figure 14-4 for an example. The CPOL functionality is summarized below: Table 14-4. CPHA Functionality CPHA Leading Edge Trailing Edge 0 Sample Setup 1 Setup Sample • Bits 1, 0 – SPR1, SPR0: SPI Clock Rate Select 1 and 0 These two bits control the SCK rate of the device configured as a Master. SPR1 and SPR0 have no effect on the Slave. The relationship between SCK and the clkIO frequency fclkio is shown in the following table: Table 14-5. Relationship Between SCK and the Oscillator Frequency SPI2X SPR1 SPR0 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 SCK Frequency fclkio/4 fclkio/16 fclkio/64 fclkio/128 fclkio/2 fclkio/8 fclkio/32 fclkio/64 187 7734P–AVR–08/10 14.5.2 SPI Status Register – SPSR Bit 7 6 5 4 3 2 1 SPIF WCOL – – – – – 0 SPI2X Read/Write R R R R R R R R/W Initial Value 0 0 0 0 0 0 0 0 SPSR • Bit 7 – SPIF: SPI Interrupt Flag When a serial transfer is complete, the SPIF flag is set. An interrupt is generated if SPIE in SPCR is set and global interrupts are enabled. If SS is an input and is driven low when the SPI is in Master mode, this will also set the SPIF flag. SPIF is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, the SPIF bit is cleared by first reading the SPI Status Register with SPIF set, then accessing the SPI Data Register (SPDR). • Bit 6 – WCOL: Write COLlision Flag The WCOL bit is set if the SPI Data Register (SPDR) is written during a data transfer. The WCOL bit (and the SPIF bit) are cleared by first reading the SPI Status Register with WCOL set, and then accessing the SPI Data Register. • Bit 5..1 – Res: Reserved Bits These bits are reserved bits in the AT90PWM81 and will always read as zero. • Bit 0 – SPI2X: Double SPI Speed Bit When this bit is written logic one the SPI speed (SCK Frequency) will be doubled when the SPI is in Master mode (see Table 14-5). This means that the minimum SCK period will be two CPU clock periods. When the SPI is configured as Slave, the SPI is only guaranteed to work at fclkio/4 or lower. The SPI interface on the AT90PWM81 is also used for program memory and EEPROM downloading or uploading. See Serial Programming Algorithm261 for serial programming and verification. 14.5.3 SPI Data Register – SPDR Bit 7 6 5 4 3 2 1 0 SPD7 SPD6 SPD5 SPD4 SPD3 SPD2 SPD1 SPD0 Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value X X X X X X X X SPDR Undefined • Bits 7:0 - SPD7:0: SPI Data The SPI Data Register is a read/write register used for data transfer between the Register File and the SPI Shift Register. Writing to the register initiates data transmission. Reading the register causes the Shift Register Receive buffer to be read. 188 AT90PWM81 7734P–AVR–08/10 AT90PWM81 15. Voltage Reference and Temperature Sensor 15.1 Features • Accurate Voltage Reference of 2.56V • Internal Temperature Sensor • Possibility for Runtime Compensation of Temperature Drift in Both Voltage Reference and On Chip Oscillators • Low Power Consumption 15.2 On Chip voltage Reference and Temperature sensor overview A low power band-gap reference provides AT90PWM81 with an accurate On-chip Bandgap voltage of 1.100 V (Vbg). Then when SW1 is off and SW2/SW3 is on, the bandgap voltage is multiplied and generates the internal reference VREF of 2.56V. This reference voltage is used as reference for the ADC, the DAC and can use a buffer with external decoupling capacitor (when SW0 is on) to enable excellent noise performance with minimum power consumption as shown on Figure 15-1. The selection of the Voltage Reference for all the analog components (ADC, DAC, Comparators) is done using the REFS1:0 bits in ADMUX register; see “ADC Multiplexer Register – ADMUX” on page 216. For conditions using the Bandgap and the internal voltage reference, see “Bandgap and Internal Voltage Reference Enable Signals and Start-up Time” on page 54 189 7734P–AVR–08/10 Figure 15-1. Reference Circuitry Aref SW0 REFS0,REFS1 are used to control SW0..3 AVcc SW1 VPTAT Vref Voltage Reference SW2 Vbg /1.60 /2.13 BG Ref erence BG Calibr ation Fuses /3.20 ADC BG Calibr ation Registers BGCC R, BGCRR /6.40 Comp SW3 AT90PWM81 has an On-chip temperature sensor for monitoring the die temperature. A voltage Proportional-To-Absolute-Temperature, VPTAT, is generated in the voltage reference circuit and after buffering, is connected to the ADC multiplexer. This temperature sensor can be used for runtime compensation of temperature drift in both the voltage reference and the On-chip Oscillator. To get the absolute temperature in degrees Kelvin, the measured Vtemp voltage must be scaled with the Vtemp factory calibration value stored in the signature row. See Section “Temperature Measurement”, page 192 for details. Vbg and Vtemp can be measured with the integrated ADC by selecting the proper ADC channel with ADMUX (see See “ADC Multiplexer Register – ADMUX” on page 216.). 190 AT90PWM81 7734P–AVR–08/10 AT90PWM81 15.3 15.3.1 Register Description BGCCR – Bandgap Calibration Current Register Bit 7 6 5 4 3 2 1 - - - - BGCC3 BGCC2 BGCC1 0 BGCC0 Read/Write - - - - R/W R/W R/W R/W Initial Value 0 0 0 0 1 0 0 0 BGCCR • Bit 7:4 – Res: Reserved Bit This bit is reserved for future use. • Bit 3:0 – BGCC3:0: BG Calibration of PTAT Current These bits are used for trimming of the nominal value of the bandgap reference voltage. These bits are binary coded, so the lowest value for Vbg is reached when BGCC3:0 is 0000 and the maximum value when BGCC3:0 is 1111. The step size is approximately 5 mV. Updating the BGCC bits will affect the BOD detection level. The BOD will react quickly to the new detection level. 15.3.2 BGCRR – Bandgap Calibration Resistor Register Bit 7 6 5 4 3 2 1 - - - - BGCR3 BGCR2 BGCR1 0 BGCR0 Read/Write - - - - R/W R/W R/W R/W Initial Value 0 0 0 0 1 0 0 0 BGCRR • Bit 7:4 – Res: Reserved Bit This bit is reserved for future use. • Bit 3:0 – BGCR3:0: BG Calibration of Resistor ladder These bits are used for temperature gradient adjustment of the bandgap reference. Figure 15-2 illustrates Vbg as a function of temperature. Vbg has a positive temperature coefficient at low temperatures and negative temperature coefficient at high temperatures. Depending on the process variations, the top of the Vbg curve may be located at higher or lower temperatures. To minimize the temperature drift in the temperature range of interest, BGCRR is used to adjust the top of the curve towards the centre of the temperature range of interest. The BGCRR bits are thermometer coded, resulting in 5 possible settings: 0000, 0001, 0011, 0111, 1111. The value 0000 shifts the top of the Vbg curve to the highest possible temperature, and the value 1111 shifts the top of the Vbg curve to the lowest possible temperature. 191 7734P–AVR–08/10 Figure 15-2. Illustration of Vbg as a function of temperature. 1.5 BGCRR is used to move the top of the Vbg curve to the center of the temperature range of interest 1.0 Temperature range of interest 0.5 -40 -20 -0 20 40 60 80 100 Temperature (°C) 15.4 Temperature Measurement The temperature measurement is based on an on-chip temperature sensor that is coupled to a single ended ADC12 channel, as shown on Figure 15-3. Figure 15-3. Temperature sensor Circuitry Enable when ADEN=1 VPTAT Current-voltage Convertor Enable when ADC Mux=1100 + - Vtemp ADC Mux=1100 BG Ref erence Selecting the ADC12 channel by writing the MUX3..0 bits in ADMUX register to “1100” enables the temperature sensor (see See “ADC Multiplexer Register – ADMUX” on page 216.). The recommended ADC voltage reference source is the internal 2.56V voltage reference for temperature sensor measurement. When the temperature sensor is enabled, the ADC converter can be used in single conversion mode to measure the voltage over the temperature sensor. The amplifier allows to charge the ADC sample capacitor at full CKadc clock speed. The measured voltage has a linear relationship to temperature as 192 AT90PWM81 7734P–AVR–08/10 AT90PWM81 described in Table 15-1. When the voltage reference equals 2.56V, the conversion result has approximately a 1 LSB/°C (or 2.5 mV/°C) correlation to temperature and the typical accuracy of the temperature measurement is +/- 10°C after offset calibration. Table 15-1. Temperature vs. Sensor Output Voltage (Typical Case) Temperature -40°C 25°C 105°C 125°C Voltage (mV) 600 762 1012 ADC 240 305 405 The values described in Table 15-1 are typical values. However, due to the process variation the temperature sensor output voltage varies from one chip to another. To be capable of achieving more accurate results the temperature measurement can be calibrated in the application software. When using temperature sensor, the temperature (in Kelvin) is calculated as follows: T = A * Tptat + B, where A Gain correction multiplier (constant '1', or unsigned fixed point number) B Offset correction term (2. complement signed byte) Tptat ADC result when measuring temperature sensor voltage, Vref with 2.56V internal reference T Temperature in Kelvin ('K = 'C + 273) Example: If A=0x80 (=1.00) and B=8, and ADC result is 0x15E (=350), this gives a measured temperature of: T = 1.00 * 350 + 8 = 358 K (+85°C) 15.4.1 Manufacturing Calibration One can also use the calibration values available in the signature row See “Reading the Signature Row from Software” on page 243. The calibration values are determined from values measured during test at room temperature which is approximatively +25°C. Calibration measures are done at Vcc = 3V and with ADC in internal Vref (1.1V) mode. The temperature in Celsius degrees can be calculated utilizing the formula: T = ((([ (ADCH << 8) | ADCL ] -(273 + 25-TSOFFSET)) * TSGAIN)/128) + 25 Where: a. ADCH & ADCL are the ADC data registers, b. TSGAIN is the temperature sensor gain (unsigned fixed point 8-bit temperature sensor gain factor in 1/128th units stored as previously in the signature row at address 0x0007) See “Reading the Signature Row from Software” on page 243. c. TSOFFSET is the temperature sensor offset correction term (signed twos complement 7-bit temperature sensor offset reading stored as previously in the signature row at address 0x0005) 193 7734P–AVR–08/10 16. Analog Comparator The Analog Comparator compares the input values on the positive pin ACMPx and negative pin ACMPM or ACMPMx. 16.1 Features • • • • • 16.2 3 Analog Comparators High Speed analog Comparators +/-25mV or +/-10mV or 0 Hysteresis 4 reference levels Generation of Configurable Interrupts Overview The AT90PWM81 features 3 fast analog comparators. Each comparator has a dedicated input on the positive input, and the negative input of each comparator can be configured as: • a steady value among the 4 internal reference levels defined by the Vref selected thanks to the REFS1:0 bits in ADMUX register. • a value generated from the internal DAC • an external analog input ACMPMx. When the voltage on the positive ACMPn pin is higher than the voltage selected by the ACnM multiplexer on the negative input, the Analog Comparator output, ACnO, is set. Each comparator can trigger a separate interrupt, exclusive to the Analog Comparator. In addition, the user can select Interrupt triggering on comparator output rise, fall or toggle. The interrupt flags can also be used to synchronize ADC or DAC conversions. Moreover, the comparator’s output of the comparator 1 can be set to trigger the Timer/Counter1 Input Capture function. A block diagram of the comparators and their surrounding logic is shown in Figure 16-1. 194 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 16-1. Analog Comparator Block Diagram AC1OE AC1OI ACMP1_OUT AC1O (to PSCR) AC1H 2 1 0 AC1IF ACMP1 + Interrupt Sensitivity Control Band Gap Analog Comparator 1 Interrupt AC1IE AC1EN AC1IS1 AC1IS0 T1 Capture Trigger ACMPM1 AC1ICE AC2OE AC2OI AC1M 2 1 0 ACMP2_OUT AC2O (to PSC2) AC2IF ACMP2 AC2H 2 1 0 Band Gap Interrupt Sensitivity Control Analog Comparator 2 Interrupt AC2IE + AC2IS1 AC2IS0 - ACMPM2 AC3OEA AC2EN ACMP3_OUT_A AC3OI AC3OE AC2M 2 1 0 ACMP3_OUT AC3O (to PSC2) AC3IF ACMP3 AC3H 2 1 0 Band Gap Interrupt Sensitivity Control + ACMPM3 AC3IE AC3IS1 - Analog Comparator 3 Interrupt AC3IS0 ACMPM Vref DAC10 AC3EN DAC Result AC3M 2 1 0 DACEN Aref REFS0 AVcc Vref Internal 2.56V Reference REFS1 Notes: REFS0 +REFS1 /1.60 /2.13 /3.20 /6.40 1. .Refer to Figure 2-1 on page 3 and for Analog Comparator pin placement 2. The voltage on Vref is defined in 17-3 ”ADC Voltage Reference Selection” on page 217 195 7734P–AVR–08/10 Figure 16-2. Comparator PSC links ACMP1 + ACMPM1 - AC1EN PSCINr PSCINrA PSCINrB PSCR PSCIN 2 ACMP2 + ACMPM2 AC2EN PSCIN2A PSC2 ACMP3 + ACMPM3 - AC3EN 16.3 Shared pins between Analog Comparator and ADC Several Analog comparators input pins can also be used as ADC inputs, so it is possible to measure the comparison voltages. However, when a comparator input is selected as the ADC input, a spike occurs during the sampling phase of the ADC. This may lead to an unwanted transition on the comparator output. So it is a safe software practice to devalidate the comparator output before measuring the voltage on one of the inputs. 16.4 Analog Comparator Register Description Each analog comparator has its own control register. A dedicated register has been designed to consign the outputs and the flags of the 3 analog comparators. 196 AT90PWM81 7734P–AVR–08/10 AT90PWM81 16.4.1 Analog Comparator 1Control Register – AC1CON Bit 7 6 5 4 3 2 1 AC1EN AC1IE AC1IS1 AC1IS0 - AC1M2 AC1M1 0 AC1M0 Read/Write R/W R/W R/W R R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 AC1CON • Bit 7– AC1EN: Analog Comparator 1 Enable Bit Set this bit to enable the analog comparator 1. Clear this bit to disable the analog comparator 1. • Bit 6– AC1IE: Analog Comparator 1 Interrupt Enable bit Set this bit to enable the analog comparator 1 interrupt. Clear this bit to disable the analog comparator 1 interrupt. • Bit 5, 4– AC1IS1, AC1IS0: Analog Comparator 1 Interrupt Select bit These 2 bits determine the sensitivity of the interrupt trigger. The different setting are shown in Table 16-1. Table 16-1. Interrupt sensitivity selection AC1IS1 AC1IS0 Description 0 0 Comparator Interrupt on output toggle 0 1 Reserved 1 0 Comparator interrupt on output falling edge 1 1 Comparator interrupt on output rising edge • Bit 3– Reserved • Bit 2, 1, 0– AC1M2, AC1M1, AC1M0: Analog Comparator 1 Multiplexer register These 3 bits determine the input of the negative input of the analog comparator. The different setting are shown in Table 16-2. Table 16-2. Analog Comparator 1 negative input selection AC1M2 AC1M1 AC1M0 Description 0 0 0 “Vref”/6.40 0 0 1 “Vref”/3.20 0 1 0 “Vref”/2.13 0 1 1 “Vref”/1.60 1 0 0 Band Gap voltage 1 0 1 DAC result 1 1 0 Analog Comparator Negative Input (ACMPM1 pin) 1 1 1 Analog Comparator Negative Input (ACMPM pin) 197 7734P–AVR–08/10 16.4.2 Analog Comparator 2 Control Register – AC2CON Bit 7 6 5 4 3 2 1 AC2EN AC2IE AC2IS1 AC2IS0 - AC2M2 AC2M1 0 AC2M0 Read/Write R/W R/W R/W R/W -R R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 AC2CON • Bit 7– AC2EN: Analog Comparator 2 Enable Bit Set this bit to enable the analog comparator 2. Clear this bit to disable the analog comparator 2. • Bit 6– AC2IE: Analog Comparator 2 Interrupt Enable bit Set this bit to enable the analog comparator 2 interrupt. Clear this bit to disable the analog comparator 2 interrupt. • Bit 5, 4– AC2IS1, AC2IS0: Analog Comparator 2 Interrupt Select bit These 2 bits determine the sensitivity of the interrupt trigger. The different setting are shown in Table 16-3. Table 16-3. Interrupt sensitivity selection AC2IS1 AC2IS0 Description 0 0 Comparator Interrupt on output toggle 0 1 Reserved 1 0 Comparator interrupt on output falling edge 1 1 Comparator interrupt on output rising edge • Bit 3– Reserved • Bit 2, 1, 0– AC2M2, AC2M1, AC2M0: Analog Comparator 2 Multiplexer register These 3 bits determine the input of the negative input of the analog comparator. The different setting are shown in Table 16-4. Table 16-4. 198 Analog Comparator 2 negative input selection AC2M2 AC2M1 AC2M0 Description 0 0 0 “Vref”/6.40 0 0 1 “Vref”/3.20 0 1 0 “Vref”/2.13 0 1 1 “Vref”/1.60 1 0 0 Band Gap voltage 1 0 1 DAC result 1 1 0 Analog Comparator Negative Input (ACMPM2 pin) 1 1 1 Analog Comparator Negative Input (ACMPM pin) AT90PWM81 7734P–AVR–08/10 AT90PWM81 16.4.3 Analog Comparator 3 Control Register – AC3CON Bit 7 6 5 4 3 2 1 AC3EN AC3IE AC3IS1 AC3IS0 AC3OEA AC3M2 AC3M1 0 AC3M0 Read/Write R/W R/W R/W R/W - R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 AC3CON • Bit 7– AC3EN: Analog Comparator 3 Enable Bit Set this bit to enable the analog comparator 3. Clear this bit to disable the analog comparator 3. • Bit 6– AC3IE: Analog Comparator 3 Interrupt Enable bit Set this bit to enable the analog comparator 3 interrupt. Clear this bit to disable the analog comparator 3 interrupt. • Bit 5, 4– AC3IS1, AC3IS0: Analog Comparator 3 Interrupt Select bit These 2 bits determine the sensitivity of the interrupt trigger. The different setting are shown in Table 16-5. Table 16-5. Interrupt sensitivity selection AC3IS1 AC3IS0 Description 0 0 Comparator Interrupt on output toggle 0 1 Reserved 1 0 Comparator interrupt on output falling edge 1 1 Comparator interrupt on output rising edge • Bit 3– AC3OEA: Analog Comparator 3 Alternate Output Enable Set this bit to enable the analog comparator 3 alternate output pin. Clear this bit to disable the analog comparator 3 alternate output pin. • Bit 2, 1, 0– AC3M2, AC3M1, AC3M0: Analog Comparator 3 Multiplexer register These 3 bits determine the input of the negative input of the analog comparator. The different setting are shown in Table 16-4. Table 16-6. Analog Comparator 2 negative input selection AC3M2 AC3M1 AC3M0 Description 0 0 0 “Vref”/6.40 0 0 1 “Vref”/3.20 0 1 0 “Vref”/2.13 0 1 1 “Vref”/1.60 1 0 0 Band Gap voltage 1 0 1 DAC result 1 1 0 Analog Comparator Negative Input (ACMPM3 pin) 1 1 1 Analog Comparator Negative Input (ACMPM pin) 199 7734P–AVR–08/10 16.4.4 Analog Comparator n Extended Control Register – ACnECON Bit 7 6 Read/Write Initial Value 0 0 5 4 3 2 1 ACnOI ACnOE AC1ICE ACnH2 ACnH1 0 ACnH0 R/W R/W R/W R/W R/W R/W 0 0 0 0 0 0 ACnECON • Bit 7..6– Reserved • Bit 5– AC1OI: Analog Comparator n Output Invert Set this bit to invert the analog comparator n output . Clear this bit to keep the analog comparator n output . • Bit 4– AC1OE: Analog Comparator n Output Enable Set this bit to enable the analog comparator n output pin. Clear this bit to disable the analog comparator n output pin. • Bit 3 – AC1ICE: Analog Comparator 1 Interrupt Capture Enable bit Set this bit to enable the input capture of the Timer/Counter1 on the analog comparator event. The comparator output is in this case directly connected to the input capture front-end logic, making the comparator utilize the noise canceler and edge select features of the Timer/Counter1 Input Capture interrupt. To make the comparator trigger the Timer/Counter1 Input Capture interrupt, the ICIE1 bit in the Timer Interrupt Mask Register (TIMSK1) must be set. In case ICES1 bit (“Timer/Counter1 Control Register B – TCCR1B” on page 96) is set high, the rising edge of AC3O is the capture/trigger event of the Timer/Counter1, in case ICES1 is set to zero, it is the falling edge which is taken into account. Clear this bit to disable this function. In this case, no connection between the Analog Comparator and the input capture function exists • Bit 2, 1, 0– ACnH2, ACnH1, ACnH0: Analog Comparator n Hysteresis select These 3 bits determine the hysteresis value of the analog comparator The different setting are shown in Table 16-7. Table 16-7. 200 Analog Comparator n Hysteresis selection AC1M2 AC1M1 AC1M0 Description 0 0 0 No Hysteresis 0 0 1 Hysteresis + 10 mV 0 1 0 Hysteresis - 10 mV 0 1 1 Hysteresis +- 10 mV 1 0 0 Reserved 1 0 1 Hysteresis + 25 mV 1 1 0 Hysteresis - 25 mV 1 1 1 Hysteresis +- 25 mV AT90PWM81 7734P–AVR–08/10 AT90PWM81 16.4.5 Analog Comparator Status Register – ACSR Bit 7 6 5 4 3 2 1 0 AC3IF AC2IF AC1IF - AC3O AC2O AC1O - Read/Write R/W R/W R/W R/W - R R R Initial Value 0 0 0 0 0 0 0 0 ACSR • Bit 7– AC3IF: Analog Comparator 3 Interrupt Flag Bit This bit is set by hardware when comparator 3 output event triggers off the interrupt mode defined by AC3IS1 and AC3IS0 bits in AC3CON register. This bit is cleared by hardware when the corresponding interrupt vector is executed in case the AC3IE in AC3CON register is set. Anyway, this bit is cleared by writing a logical one on it. This bit can also be used to synchronize ADC or DAC conversions.. • Bit 6– AC2IF: Analog Comparator 2 Interrupt Flag Bit This bit is set by hardware when comparator 2 output event triggers off the interrupt mode defined by AC2IS1 and AC2IS0 bits in AC2CON register. This bit is cleared by hardware when the corresponding interrupt vector is executed in case the AC2IE in AC2CON register is set. Anyway, this bit is cleared by writing a logical one on it. This bit can also be used to synchronize ADC or DAC conversions. • Bit 5– AC1IF: Analog Comparator 1 Interrupt Flag Bit This bit is set by hardware when comparator 1 output event triggers off the interrupt mode defined by AC1IS1 and AC1IS0 bits in AC1CON register. This bit is cleared by hardware when the corresponding interrupt vector is executed in case the AC1IE in AC1CON register is set. Anyway, this bit is cleared by writing a logical one on it. This bit can also be used to synchronize ADC or DAC conversions. • Bit 4– Reserved • Bit 3– AC3O: Analog Comparator 3 Output Bit AC2O bit is directly the output of the Analog comparator 2. Set when the output of the comparator is high. Cleared when the output comparator is low. • Bit 2– AC2O: Analog Comparator 2 Output Bit AC2O bit is directly the output of the Analog comparator 2. Set when the output of the comparator is high. Cleared when the output comparator is low. • Bit 1– AC1O: Analog Comparator 1 Output Bit AC1O bit is directly the output of the Analog comparator 1. Set when the output of the comparator is high. Cleared when the output comparator is low. Bit 0– Reserved 201 7734P–AVR–08/10 16.4.6 Digital Input Disable Register 0 – DIDR0 Bit 7 6 5 4 ADC8D AMP3D ADC7D AMP0-D ADC5D ACMP2D ADC4D ADC3D ACMP3MD ACMPMD 3 2 1 ADC2D ADC1D ACMP2MD 0 ADC0D ACMP1D Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 DIDR0 • Bit 7:0 – ACMPMxD and ACMPxD: ACMPxMD, ACMPxD & APM0+Digital Input Disable When this bit is written logic one, the digital input buffer on the corresponding Analog pin is disabled. The corresponding PIN Register bit will always read as zero when this bit is set. When an analog signal is applied to one of these pins and the digital input from this pin is not needed, this bit should be written logic one to reduce power consumption in the digital input buffer. 16.4.7 Digital Input Disable Register 1– DIDR1 Bit 7 6 5 4 3 1 0 - - - - ACMP1MD AMP0+D 2 ADC10D ADC9D Read/Write - - R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 DIDR1 • Bit 3, 0: ACMPxMD, ACMPxD & APM0+ Digital Input Disable When this bit is written logic one, the digital input buffer on the corresponding analog pin is disabled. The corresponding PIN Register bit will always read as zero when this bit is set. When an analog signal is applied to one of these pins and the digital input from this pin is not needed, this bit should be written logic one to reduce power consumption in the digital input buffer. 202 AT90PWM81 7734P–AVR–08/10 AT90PWM81 17. Analog to Digital Converter - ADC 17.1 Features • • • • • • • • • • • • • • • 10-bit Resolution 0.5 LSB Integral Non-linearity ± 2 LSB Absolute Accuracy 8- 250 µs Conversion Time Up to 120 kSPS at Maximum Resolution 11 Multiplexed Single Ended Input Channels One Differential input channels with accurate (5%) programmable gain 5, 10, 20 and 40 Optional Left Adjustment for ADC Result Readout 0 - VCC ADC Input Voltage Range Selectable 2.56 V ADC Reference Voltage Free Running or Single Conversion Mode ADC Start Conversion by Auto Triggering on Interrupt Sources Interrupt on ADC Conversion Complete Sleep Mode Noise Canceler Temperature sensor The AT90PWM81 features a 10-bit successive approximation ADC. The ADC is connected to an 15channel Analog Multiplexer which allows eleven single-ended input. The single-ended voltage inputs refer to 0V (GND). The device also supports 2 differential voltage input combinations which are equipped with a programmable gain stage, providing amplification steps of 14dB (5x), 20 dB (10x), 26 dB (20x), or 32dB (40x) on the differential input voltage before the A/D conversion. On the amplified channels, 8-bit resolution can be expected. The ADC contains a Sample and Hold circuit which ensures that the input voltage to the ADC is held at a constant level during conversion. A block diagram of the ADC is shown in Figure 17-1. The ADC has a separate analog supply voltage pin, AVCC. AVCC must not differ more than ± 0.3V from VCC. See the paragraph “ADC Noise Canceler” on page 209 on how to connect this pin. Internal reference voltages of nominally 2.56V or AVCC are provided On-chip. The voltage reference may be externally decoupled at the AREF pin by a capacitor for better noise performance. 203 7734P–AVR–08/10 Figure 17-1. Analog to Digital Converter Block Schematic AREF/ADC6 AVCC Internal 2.56V Reference Vref Logic ADC0 ADC1 ADC2 ADC3 ADC4 ADC5 REFS0,REFS1 Coarse/Fine DAC 10 + - ADC8 ADC9 ADC10 AMP0GS AMP0-/ADC7 AMP0+ Temp Sensor VCC/4 GND Bandgap CONTROL CK ADLAR MUX3 MUX2 MUX1 MUX0 ADEN ADCL Edge Detector ADSC ADATE ADIF ADIE PRESCALER ADPS2 ADPS1 ADPS0 ADCSRA ADMUX Sources 10 ADC CONVERSION COMPLETE IRQ AMP0CSR REFS0 ADCH CKADC CKADC + REFS1 10 SAR ADATE 3 ADHSM ADNCDIS - ADSSEN ADTS3 ADTS2 ADTS1 ADTS0 ADCSRB 204 AT90PWM81 7734P–AVR–08/10 AT90PWM81 17.2 Operation The ADC converts an analog input voltage to a 10-bit digital value through successive approximation. The minimum value represents GND and the maximum value represents the voltage on the AREF pin minus 1 LSB. Optionally, AVCC or an internal 2.56V reference voltage may be connected to the AREF pin by writing to the REFSn bits in the ADMUX Register. The internal voltage reference may thus be decoupled by an external capacitor at the AREF pin to improve noise immunity. The analog input channel are selected by writing to the MUX bits in ADMUX. Any of the ADC input pins, as well as GND and a fixed bandgap voltage reference, can be selected as single ended inputs to the ADC. The ADC is enabled by setting the ADC Enable bit, ADEN in ADCSRA. Voltage reference is set by the REFS1 and REFS0 bits in ADMUX register, whatever the ADC is enabled or not. The ADC does not consume power when ADEN is cleared, so it is recommended to switch off the ADC before entering power saving sleep modes. The ADC generates a 10-bit result which is presented in the ADC Data Registers, ADCH and ADCL. By default, the result is presented right adjusted, but can optionally be presented left adjusted by setting the ADLAR bit in ADMUX. If the result is left adjusted and no more than 8-bit precision is required, it is sufficient to read ADCH. Otherwise, ADCL must be read first, then ADCH, to ensure that the content of the Data Registers belongs to the same conversion. Once ADCL is read, ADC access to Data Registers is blocked. This means that if ADCL has been read, and a conversion completed before ADCH is read, neither register is updated and the result from the conversion is lost. When ADCH is read, ADC access to the ADCH and ADCL Registers is re-enabled. The ADC has its own interrupt which can be triggered when a conversion completes. The ADC access to the Data Registers is prohibited between reading of ADCH and ADCL, the interrupt will trigger even if the result is lost. 17.3 Starting a Conversion A single conversion is started by writing a logical one to the ADC Start Conversion bit, ADSC. This bit stays high as long as the conversion is in progress and will be cleared by hardware when the conversion is completed. If a different data channel is selected while a conversion is in progress, the ADC will finish the current conversion before performing the channel change. Alternatively, a conversion can be triggered automatically by various sources. Auto Triggering is enabled by setting the ADC Auto Trigger Enable bit, ADATE in ADCSRA. The trigger source is selected by setting the ADC Trigger Select bits, ADTS in ADCSRB (See description of the ADTS bits for a list of the trigger sources). When a positive edge occurs on the selected trigger signal, the ADC prescaler is reset and a conversion is started. This provides a method of starting conversions at fixed intervals. If the trigger signal is still set when the conversion completes, a new conversion will not be started. If another positive edge occurs on the trigger signal during conversion, the edge will be ignored. Note that an interrupt flag will be set even if the specific interrupt is disabled or the Global Interrupt Enable bit in SREG is cleared. A conversion can thus be triggered without causing an interrupt. However, the interrupt flag must be cleared in order to trigger a new conversion at the next interrupt event. Triggering from the PSC’s synchronization signal is different as there is no flag. In this case, a new conversion is started at each triggering signal. However, a single shot mode can be activated by setting the bit ADSSEN in ADCSRB register. In this case the synchronization signal is blocked until the ADCH registed is read. 205 7734P–AVR–08/10 Figure 17-2. ADC Auto Trigger Logic ADTS[2:0] PRESCALER START CLKADC ADATE ADIF SOURCE 1 . . . . CONVERSION LOGIC EDGE DETECTOR SOURCE n ADSC Using the ADC Interrupt Flag as a trigger source makes the ADC start a new conversion as soon as the ongoing conversion has finished. The ADC then operates in Free Running mode, constantly sampling and updating the ADC Data Register. The first conversion must be started by writing a logical one to the ADSC bit in ADCSRA. In this mode the ADC will perform successive conversions independently of whether the ADC Interrupt Flag, ADIF is cleared or not. The free running mode is not allowed on the amplified channels. If Auto Triggering is enabled, single conversions can be started by writing ADSC in ADCSRA to one. ADSC can also be used to determine if a conversion is in progress. The ADSC bit will be read as one during a conversion, independently of how the conversion was started. 17.4 Prescaling and Conversion Timing Figure 17-3. ADC Prescaler ADEN START Reset 7-BIT ADC PRESCALER CK/64 CK/128 CK/32 CK/8 CK/16 CK/4 CK/2 CK ADPS0 ADPS1 ADPS2 ADC CLOCK SOURCE By default, the successive approximation circuitry requires an input clock frequency between 50 kHz and 2 MHz to get maximum resolution. If a lower resolution than 10 bits is needed, the input clock frequency to the ADC can be higher than 2 MHz to get a higher sample rate. The ADC module contains a prescaler, which generates an acceptable ADC clock frequency from any CPU frequency above 100 kHz. The prescaling is set by the ADPS bits in ADCSRA. The prescaler starts counting from the moment the ADC is switched on by setting the ADEN bit in ADCSRA. The prescaler keeps running for as long as the ADEN bit is set, and is continuously reset when ADEN is low. 206 AT90PWM81 7734P–AVR–08/10 AT90PWM81 When initiating a single ended conversion by setting the ADSC bit in ADCSRA, the conversion starts at the following rising edge of the ADC clock cycle. See “Changing Channel or Reference Selection” on page 208 for details on differential conversion timing. A normal conversion takes 13 ADC clock cycles. The first conversion after the ADC is switched on (ADEN in ADCSRA is set) takes 25 ADC clock cycles in order to initialize the analog circuitry. The actual sample-and-hold takes place 3.5 ADC clock cycles after the start of a normal conversion and 13.5 ADC clock cycles after the start of an first conversion. When a conversion is complete, the result is written to the ADC Data Registers, and ADIF is set. In Single Conversion mode, ADSC is cleared simultaneously. The software may then set ADSC again, and a new conversion will be initiated on the first rising ADC clock edge. When Auto Triggering is used, the prescaler is reset when the trigger event occurs. This assures a fixed delay from the trigger event to the start of conversion. In this mode, the sample-and-hold takes place (four XXX to be confirmed) two ADC clock cycles after the rising edge on the trigger source signal. Three additional CPU clock cycles are used for synchronization logic. In Free Running mode, a new conversion will be started immediately after the conversion completes, while ADSC remains high. For a summary of conversion times, see Table 17-1. Figure 17-4. ADC Timing Diagram, First Conversion (Single Conversion Mode) Next Conversion First Conversion Cycle Number 1 2 12 13 14 16 15 17 18 19 20 21 22 24 23 25 1 2 3 ADC Clock ADEN ADSC ADIF Sign and MSB of Result ADCH LSB of Result ADCL MUX and REFS Update Figure 17-5. ADC Timing Diagram, Single Conversion One Conversion Cycle Number MUX and REFS Update Conversion Complete Sample & Hold 1 2 3 4 5 6 7 8 9 10 11 12 Next Conversion 13 14 15 16 1 2 3 ADC Clock ADSC ADIF ADCH Sign and MSB of Result ADCL LSB of Result Sample & Hold MUX and REFS Update Conversion Complete MUX and REFS Update 207 7734P–AVR–08/10 Figure 17-6. ADC Timing Diagram, Auto Triggered Conversion One Conversion Cycle Number 1 2 3 4 5 6 7 Next Conversion 8 13 14 15 16 1 2 ADC Clock Trigger Source ADATE ADIF ADCH Sign and MSB of Result ADCL LSB of Result Prescaler Reset Figure 17-7. Sample & Hold Prescaler Reset Conversion Complete MUX and REFS Update ADC Timing Diagram, Free Running Conversion One Conversion Cycle Number 14 15 Next Conversion 16 1 2 3 4 ADC Clock ADSC ADIF ADCH Sign and MSB of Result ADCL LSB of Result Sample & Hold Conversion Complete Table 17-1. ADC Conversion Time Condition Sample & Hold (Cycles from Start of Conversion) Conversion Time (Cycles) 17.5 MUX and REFS Update First Conversion Normal Conversion, Single Ended Auto Triggered Conversion 13.5 3.5 4 25 15.5 16 Changing Channel or Reference Selection The MUXn and REFS1:0 bits in the ADMUX Register are single buffered through a temporary register to which the CPU has random access. This ensures that the channels and reference selection only takes place at a safe point during the conversion. The channel and reference selection is continuously updated until a conversion is started. Once the conversion starts, the channel and reference selection is locked to ensure a sufficient sampling time for the ADC. Continuous updating resumes in the last ADC clock cycle before the conversion completes (ADIF in ADCSRA is set). Note that the conversion starts on the following rising ADC clock edge after ADSC is written. The user is thus advised not to write new channel or reference selection values to ADMUX until one ADC clock cycle after ADSC is written. 208 AT90PWM81 7734P–AVR–08/10 AT90PWM81 If Auto Triggering is used, the exact time of the triggering event can be indeterministic. Special care must be taken when updating the ADMUX Register, in order to control which conversion will be affected by the new settings. If both ADATE and ADEN is written to one, an interrupt event can occur at any time. If the ADMUX Register is changed in this period, the user cannot tell if the next conversion is based on the old or the new settings. ADMUX can be safely updated in the following ways: a. When ADATE or ADEN is cleared. b. During conversion, minimum one ADC clock cycle after the trigger event. c. After a conversion, before the interrupt flag used as trigger source is cleared. When updating ADMUX in one of these conditions, the new settings will affect the next ADC conversion. 17.5.1 ADC Input Channels When changing channel selections, the user should observe the following guidelines to ensure that the correct channel is selected: • In Single Conversion mode, always select the channel before starting the conversion. The channel selection may be changed one ADC clock cycle after writing one to ADSC. However, the simplest method is to wait for the conversion to complete before changing the channel selection. • In Free Running mode, always select the channel before starting the first conversion. The channel selection may be changed one ADC clock cycle after writing one to ADSC. However, the simplest method is to wait for the first conversion to complete, and then change the channel selection. Since the next conversion has already started automatically, the next result will reflect the previous channel selection. Subsequent conversions will reflect the new channel selection. • In Free Running mode, because the amplifier clear the ADSC bit at the end of an amplified conversion, it is not possible to use the free running mode, unless ADSC bit is set again by soft at the end of each conversion. 17.5.2 ADC Voltage Reference The reference voltage for the ADC (VREF) indicates the conversion range for the ADC. Single ended channels that exceed VREF will result in codes close to 0x3FF. VREF can be selected as either AVCC, internal 2.56V reference, or external AREF pin. AVCC is connected to the ADC through a passive switch. The internal 2.56V reference is generated from the internal bandgap reference (VBG) through an internal amplifier. If the external AREF pin is connected to the ADC, the reference voltage can be made more immune to noise by connecting a capacitor between the AREF pin and ground. VREF can also be measured at the AREF pin with a high impedant voltmeter. Note that VREF is a high impedant source, and only a capacitive load should be connected in a system. The user may switch between AVCC, AREF pin and 2.56V as reference selection. The first ADC conversion result after switching reference voltage source may be inaccurate, and the user is advised to discard this result. If differential channels are used, the selected reference should not be closer to AVCC than indicated in Table 24-5 on page 281. 17.6 ADC Noise Canceler The ADC features a noise canceler that enables conversion during sleep mode to reduce noise induced from the CPU core and other I/O peripherals. The noise canceler can be used with ADC Noise Reduction and Idle mode. To make use of this feature, the following procedure should be used: 209 7734P–AVR–08/10 a. Make sure the ADNCDIS bit is reset b. Make sure the ADATE bit is reset c. Make sure that the ADC is enabled and is not busy converting (ADSC reset). Single Conversion mode must be selected and the ADC conversion complete interrupt must be enabled. d. Enter ADC Noise Reduction mode (or Idle mode). The ADC will start a conversion once the CPU has been halted. e. If no other interrupts occur before the ADC conversion completes, the ADC interrupt will wake up the CPU and execute the ADC Conversion Complete interrupt routine. If another interrupt wakes up the CPU before the ADC conversion is complete, that interrupt will be executed, and an ADC Conversion Complete interrupt request will be generated when the ADC conversion completes. The CPU will remain in active mode until a new sleep command is executed. Another possible procedure is possible for Auto trigger conversions: a. Make sure the ADNCDIS bit is set b. Make sure the ADATE bit is set c. Enter ADC Noise Reduction mode (or Idle mode). The ADC will start a conversion on the next triggering event. d. If no other interrupts occur before the ADC conversion completes, the ADC interrupt will wake up the CPU and execute the ADC Conversion Complete interrupt routine. If another interrupt wakes up the CPU before the ADC conversion is complete, that interrupt will be executed, and an ADC Conversion Complete interrupt request will be generated when the ADC conversion completes. The CPU will remain in active mode until a new sleep command is executed. Note that the ADC will not be automatically turned off when entering other sleep modes than Idle mode and ADC Noise Reduction mode. The user is advised to write zero to ADEN before entering such sleep modes to avoid excessive power consumption. If the ADC is enabled in such sleep modes and the user wants to perform differential conversions, the user is advised to switch the ADC off and on after waking up from sleep to prompt an extended conversion to get a valid result. 17.6.1 Analog Input Circuitry The analog input circuitry for single ended channels is illustrated in Figure 17-8 An analog source applied to ADCn is subjected to the pin capacitance and input leakage of that pin, regardless of whether that channel is selected as input for the ADC. When the channel is selected, the source must drive the S/H capacitor through the series resistance (combined resistance in the input path). The ADC is optimized for analog signals with an output impedance of approximately 5 kΩ or less. If such a source is used, the sampling time will be negligible. If a source with higher impedance is used, the sampling time will depend on how long time the source needs to charge the S/H capacitor, witch can vary widely. The user is recommended to only use low impedant sources with slowly varying signals, since this minimizes the required charge transfer to the S/H capacitor. If differential gain channels are used, the input circuitry looks somewhat different, although source impedances of a few hundred kΩ or less is recommended. Signal components higher than the Nyquist frequency (fADC/2) should not be present for either kind of channels, to avoid distortion from unpredictable signal convolution. The user is advised to remove high frequency components with a low-pass filter before applying the signals as inputs to the ADC. 210 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 17-8. Analog Input Circuitry IIH ADCn 1..100 kΩ CS/H= 14 pF IIL VCC/2 17.6.2 Analog Noise Canceling Techniques Digital circuitry inside and outside the device generates EMI which might affect the accuracy of analog measurements. If conversion accuracy is critical, the noise level can be reduced by applying the following techniques: a. Keep analog signal paths as short as possible. Make sure analog tracks run over the analog ground plane, and keep them well away from high-speed switching digital tracks. b. The AVCC pin on the device should be connected to the digital VCC supply voltage via an LC network as shown in Figure 17-9. c. Use the ADC noise canceler function to reduce induced noise from the CPU. d. If any ADC port pins are used as digital outputs, it is essential that these do not switch while a conversion is in progress. Figure 17-9. ADC Power Connections 10 µH VCC GND AREF AGND AVCC 100nF Analog Ground Plane 17.6.3 Offset Compensation Schemes The gain stage has a built-in offset cancellation circuitry that nulls the offset of differential measurements as much as possible. The remaining offset in the analog path can be measured directly by shortening both 211 7734P–AVR–08/10 differential inputs using the AMPxIS bit with both inputs unconnected. (See “Amplifier 0 Control and Status register – AMP0CSR” on page 224.). This offset residue can be then subtracted in software from the measurement results. Using this kind of software based offset correction, offset on any channel can be reduced below one LSB. 17.6.4 ADC Accuracy Definitions An n-bit single-ended ADC converts a voltage linearly between GND and VREF in 2n steps (LSBs). The lowest code is read as 0, and the highest code is read as 2n-1. Several parameters describe the deviation from the ideal behavior: • Offset: The deviation of the first transition (0x000 to 0x001) compared to the ideal transition (at 0.5 LSB). Ideal value: 0 LSB. Figure 17-10. Offset Error Output Code Ideal ADC Actual ADC Offset Error VREF Input Voltage • Gain Error: After adjusting for offset, the Gain Error is found as the deviation of the last transition (0x3FE to 0x3FF) compared to the ideal transition (at 1.5 LSB below maximum). Ideal value: 0 LSB 212 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 17-11. Gain Error Gain Error Output Code Ideal ADC Actual ADC VREF Input Voltage • Integral Non-linearity (INL): After adjusting for offset and gain error, the INL is the maximum deviation of an actual transition compared to an ideal transition for any code. Ideal value: 0 LSB. Figure 17-12. Integral Non-linearity (INL) Output Code INL Ideal ADC Actual ADC VREF Input Voltage • Differential Non-linearity (DNL): The maximum deviation of the actual code width (the interval between two adjacent transitions) from the ideal code width (1 LSB). Ideal value: 0 LSB. 213 7734P–AVR–08/10 Figure 17-13. Differential Non-linearity (DNL) Output Code 0x3FF 1 LSB DNL 0x000 0 VREF Input Voltage • Quantization Error: Due to the quantization of the input voltage into a finite number of codes, a range of input voltages (1 LSB wide) will code to the same value. Always ± 0.5 LSB. • Absolute Accuracy: The maximum deviation of an actual (unadjusted) transition compared to an ideal transition for any code. This is the compound effect of offset, gain error, differential error, nonlinearity, and quantization error. Ideal value: ± 0.5 LSB. 17.7 ADC Conversion Result After the conversion is complete (ADIF is high), the conversion result can be found in the ADC Result Registers (ADCL, ADCH). For single ended conversion, the result is: V IN ⋅ 1023 ADC = -----------------------V REF where VIN is the voltage on the selected input pin and VREF the selected voltage reference (see Table 17-3 on page 217 and Table 17-4 on page 217). 0x000 represents analog ground, and 0x3FF represents the selected reference voltage. If differential channels are used, the result is: ( V POS – V NEG ) ⋅ GAIN ⋅ 512 ADC = ---------------------------------------------------------------------V REF where VPOS is the voltage on the positive input pin, VNEG the voltage on the negative input pin, GAIN the selected gain factor and VREF the selected voltage reference. The result is presented in two’s complement form, from 0x200 (-512d) through 0x1FF (+511d). Note that if the user wants to perform a quick polarity check of the result, it is sufficient to read the MSB of the result (ADC9 in ADCH). If the bit is one, the 214 AT90PWM81 7734P–AVR–08/10 AT90PWM81 result is negative, and if this bit is zero, the result is positive. Figure 17-14 shows the decoding of the differential input range. Table 82 shows the resulting output codes if the differential input channel pair (ADCn - ADCm) is selected with a reference voltage of VREF. Figure 17-14. Differential Measurement Range Output Code 0x1FF 0x000 - VREF /Gain 0x3FF 0 VREF/Gain Differential Input Voltage (Volts) 0x200 215 7734P–AVR–08/10 Table 17-2. Correlation Between Input Voltage and Output Codes VADCn Read code Corresponding decimal value VADCm + VREF /GAIN 0x1FF 511 VADCm + 0.999 VREF /GAIN 0x1FF 511 VADCm + 0.998 VREF /GAIN 0x1FE 510 ... ... ... VADCm + 0.001 VREF /GAIN 0x001 1 VADCm 0x000 0 VADCm - 0.001 VREF /GAIN 0x3FF -1 ... ... ... VADCm - 0.999 VREF /GAIN 0x201 -511 VADCm - VREF /GAIN 0x200 -512 Example 1: – ADMUX = 0xED (ADC3 - ADC2, 10x gain, 2.56V reference, left adjusted result) – Voltage on ADC3 is 300 mV, voltage on ADC2 is 500 mV. – ADCR = 512 * 10 * (300 - 500) / 2560 = -400 = 0x270 – ADCL will thus read 0x00, and ADCH will read 0x9C. Writing zero to ADLAR right adjusts the result: ADCL = 0x70, ADCH = 0x02. Example 2: – ADMUX = 0xFB (ADC3 - ADC2, 1x gain, 2.56V reference, left adjusted result) – Voltage on ADC3 is 300 mV, voltage on ADC2 is 500 mV. – ADCR = 512 * 1 * (300 - 500) / 2560 = -41 = 0x029. – ADCL will thus read 0x40, and ADCH will read 0x0A. Writing zero to ADLAR right adjusts the result: ADCL = 0x00, ADCH = 0x29. 17.8 ADC Register Description The ADC of the AT90PWM81 is controlled through 3 different registers. The ADCSRA and The ADCSRB registers which are the ADC Control and Status registers, and the ADMUX which allows to select the Vref source and the channel to be converted. The conversion result is stored on ADCH and ADCL register which contain respectively the most significant bits and the less significant bits. 17.8.1 ADC Multiplexer Register – ADMUX Bit 216 7 6 5 4 3 2 1 0 REFS1 REFS0 ADLAR - MUX3 MUX2 MUX1 MUX0 Read/Write R/W R/W R/W -R R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 ADMUX AT90PWM81 7734P–AVR–08/10 AT90PWM81 • Bit 7, 6 – REFS1, 0: ADC Vref Selection Bits These 2 bits determine the voltage reference for the ADC and for the other analog devices. The different setting are shown in Table 17-3. Table 17-3. REFS1 ADC Voltage Reference Selection REFS0 Description Voltage Reference PE3/AREF pin External Voltage reference 0 0 External Vref 0 1 AVcc 1 0 Internal 2.56V Reference voltage External capacitor for decoupling of the Internal Reference voltage 1 1 Internal 2.56V Reference voltage PE3 pin free as port If these bits are changed during a conversion, the change will not take effect until this conversion is complete (it means while the ADIF bit in ADCSRA register is set). In case the internal Vref is selected, it is turned ON as soon as an analog feature needed it is set. • Bit 5 – ADLAR: ADC Left Adjust Result Set this bit to left adjust the ADC result. Clear it to right adjust the ADC result. The ADLAR bit affects the configuration of the ADC result data registers. Changing this bit affects the ADC data registers immediately regardless of any on going conversion. For a complete description of this bit, see Section “ADC Result Data Registers – ADCH and ADCL”, page 220. • Bit 3, 2, 1, 0 – MUX3, MUX2, MUX1, MUX0: ADC Channel Selection Bits These 4 bits determine which analog inputs are connected to the ADC input. The different setting are shown in Table 17-4. Table 17-4. ADC Input Channel Selection MUX3 MUX2 MUX1 MUX0 Description 0 0 0 0 ADC0 0 0 0 1 ADC1 0 0 1 0 ADC2 0 0 1 1 ADC3 0 1 0 0 ADC4 0 1 0 1 ADC5 0 1 1 0 ADC6 0 1 1 1 ADC7 1 0 0 0 ADC8 1 0 0 1 ADC9 1 0 1 0 ADC10 1 0 1 1 AMP0 1 1 0 0 Temp sensor (Vtemp) 217 7734P–AVR–08/10 Table 17-4. ADC Input Channel Selection MUX3 MUX2 MUX1 MUX0 Description 1 1 0 1 VCC/4 1 1 1 0 Bandgap (Vbg) 1 1 1 1 GND If these bits are changed during a conversion, the change will not take effect until this conversion is complete (it means while the ADIF bit in ADCSRA register is set). 17.8.2 ADC Control and Status Register A – ADCSRA Bit 7 6 5 4 3 2 1 0 ADEN ADSC ADATE ADIF ADIE ADPS2 ADPS1 ADPS0 Read/Write R/W R/W R/W R R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 ADCSRA • Bit 7 – ADEN: ADC Enable Bit Set this bit to enable the ADC. Clear this bit to disable the ADC. Clearing this bit while a conversion is running will take effect at the end of the conversion. • Bit 6– ADSC: ADC Start Conversion Bit Set this bit to start a conversion in single conversion mode or to start the first conversion in free running mode. Cleared by hardware when the conversion is complete. Writing this bit to zero has no effect. The first conversion performs the initialization of the ADC. • Bit 5 – ADATE: ADC Auto trigger Enable Bit Set this bit to enable the auto triggering mode of the ADC. Clear it to return in single conversion mode. In auto trigger mode the trigger source is selected by the ADTS bits in the ADCSRB register. See Table 17-6 on page 220. • Bit 4– ADIF: ADC Interrupt Flag Set by hardware as soon as a conversion is complete and the Data register are updated with the conversion result. Cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, ADIF can be cleared by writing it to logical one. • Bit 3– ADIE: ADC Interrupt Enable Bit Set this bit to activate the ADC end of conversion interrupt. Clear it to disable the ADC end of conversion interrupt. • Bit 2, 1, 0– ADPS2, ADPS1, ADPS0: ADC Prescaler Selection Bits These 3 bits determine the division factor between the system clock frequency and input clock of the ADC. The different setting are shown in Table 17-5 on page 219. 218 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Table 17-5. 17.8.3 ADC Prescaler Selection ADPS2 ADPS1 ADPS0 Division Factor 0 0 0 2 0 0 1 2 0 1 0 4 0 1 1 8 1 0 0 16 1 0 1 32 1 1 0 64 1 1 1 128 ADC Control and Status Register B– ADCSRB Bit 7 6 5 4 3 2 1 ADHSM ADNCDIS - ADSSEN ADTS3 ADTS2 ADTS1 0 ADTS0 Read/Write R/W R/W - R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 ADCSRB • Bit 7 – ADHSM: ADC High Speed Mode Writing this bit to one enables the ADC High Speed mode. Set this bit if you wish to convert with an ADC clock frequency higher than 200KHz. • Bit 6 – ADNCDIS: ADC Noise Canceller Disable Set this bit to disable automatic ADC start when entering Idle or ADC Noise reduction Modes. Clear it to enable automatic ADC start when entering Idle or ADC reduction Modes.. The ADNCDIS must be set before entering Idle or ADC Noise reduction Modes if the ADC is running or Auto triggered to prevent false ADC restart. • Bit 5 – Reserved • Bit 4 – ADSSEN: ADC Single Shot Enable on PSC’s synchronization signals Set this bit to enable single shot mode when auto trigger on PSCRASY & PSC2ASY. In this case a single conversion will be performed and PSCRASY & PSC2ASY will be blocked until ADCH reading. Clear it to enable continuous conversion on PSCRASY & PSC2ASY auto triggering. • Bit 3, 2, 1, 0– ADTS3:ADTS0: ADC Auto Trigger Source Selection Bits These bits are only necessary in case the ADC works in auto trigger mode. It means if ADATE bit in ADCSRA register is set. In accordance with the Table 17-6, these 3 bits select the interrupt event which will generate the trigger of the start of conversion. The start of conversion will be generated by the rising edge of the selected interrupt flag whether the interrupt is enabled or not. 219 7734P–AVR–08/10 In case of trig on PSCnASY event, there is no flag. So, if ADSSEN is reset, a conversion will start each time the trig event appears and the previous conversion is completed .. Table 17-6. 17.8.4 ADC Auto Trigger Source Selection ADTS3 ADTS2 ADTS1 ADTS0 Description 0 0 0 0 Free Running Mode 0 0 0 1 Analog Comparator 1 0 0 1 0 External Interrupt Request 0 0 0 1 1 Timer/Counter1 Overflow 0 1 0 0 Timer/Counter1 Capture Event 0 1 0 1 PSCRASY Event 0 1 1 0 PSC2ASY Event 0 1 1 1 Analog comparator 2 1 0 0 0 Analog comparator 3 1 0 0 1 Reserved 1 0 1 0 Reserved 1 0 1 1 Reserved 1 1 0 0 Reserved 1 1 0 1 Reserved 1 1 1 0 Reserved 1 1 1 1 Reserved ADC Result Data Registers – ADCH and ADCL When an ADC conversion is complete, the conversion results are stored in these two result data registers. When the ADCL register is read, the two ADC result data registers can’t be updated until the ADCH register has also been read. Consequently, in 10-bit configuration, the ADCL register must be read first before the ADCH. Nevertheless, to work easily with only 8-bit precision, there is the possibility to left adjust the result thanks to the ADLAR bit in the ADCSRA register. Like this, it is sufficient to only read ADCH to have the conversion result. 17.8.4.1 ADLAR = 0 Bit Read/Write Initial Value 220 7 6 5 4 3 2 1 - - - - - - ADC9 0 ADC8 ADCH ADC7 ADC6 ADC5 ADC4 ADC3 ADC2 ADC1 ADC0 ADCL R R R R R R R R R R R R R R R R 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 AT90PWM81 7734P–AVR–08/10 AT90PWM81 17.8.4.2 ADLAR = 1 Bit 17.8.5 7 6 5 4 3 2 1 0 ADC9 ADC8 ADC7 ADC6 ADC5 ADC4 ADC3 ADC2 ADCH ADC1 ADC0 - - - - - - ADCL Read/Write R R R R R R R R R R R R R R R R Initial Value 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Digital Input Disable Register 0 – DIDR0 Bit 7 6 5 4 ADC8D AMP3D ADC7D AMP0-D ADC5D ACMP2D ADC4D ADC3D ACMP3MD ACMPMD 3 2 1 ADC2D ADC1D ACMP2MD 0 ADC0D ACMP1D Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 DIDR0 • Bit 7:0 – ADC7D..ADC0D: AMP0-D and ADC7:0 Digital Input Disable When this bit is written logic one, the digital input buffer on the corresponding ADC pin is disabled. The corresponding PIN Register bit will always read as zero when this bit is set. When an analog signal is applied to the ADC7..0 pin and the digital input from this pin is not needed, this bit should be written logic one to reduce power consumption in the digital input buffer. 17.8.6 Digital Input Disable Register 1– DIDR1 Bit 7 6 5 4 - - - - 3 2 1 0 ADC10D ADC9D DIDR1 ACMP1MD AMP0+D Read/Write - - R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 • Bit 2:0 – AMP0+D and ADC10:8 Digital Input Disable When this bit is written logic one, the digital input buffer on the corresponding ADC pin is disabled. The corresponding PIN Register bit will always read as zero when this bit is set. When an analog signal is applied to an analog pin and the digital input from this pin is not needed, this bit should be written logic one to reduce power consumption in the digital input buffer. 17.9 Amplifier The AT90PWM81 features one differential amplified channel with programmable 5, 10, 20, and 40 gain stage. Despite the result is given by the 10 bit ADC, the amplifier has been sized to give a 8bits resolution. The negative input on the amplifier can be internally switched to the analog ground. However, amplifier characteristics are specified with differential inputs. Because the amplifier is a switching capacitor amplifier, it needs to be clocked by a synchronization signal called in this document the amplifier synchronization clock. The amplifier samples the input value at the falling edge of the synchronization signal. This allow to measure analog signals with same period as the synchronization. The maximum clock for the amplifier is 250kHz. 221 7734P–AVR–08/10 To ensure an accurate result in case of large voltage change, the amplifier input needs to have a quite stable sampled input value during at least 4 Amplifier synchronization clock periods. Amplified conversions can be synchronized to PSC events (See “Synchronization Source Description in One/Two/Four Ramp Modes” on page 133 and “Synchronization Source Description in Centered Mode” on page 134) or to the internal clock CKADC equal to eighth the ADC clock frequency. In case the synchronization is done by the ADC clock divided by 8, this synchronization is done automatically by the ADC interface in such a way that the sample-and-hold occurs at a specific phase of CKADC2. A conversion initiated by the user (i.e., all single conversions, and the first free running conversion) when CKADC2 is low will take the same amount of time as a single ended conversion (13 ADC clock cycles from the next prescaled clock cycle). A conversion initiated by the user when CKADC2 is high will take 14 ADC clock cycles due to the synchronization mechanism. The normal way to use the amplifier is to select a synchronization clock via the AMPxTS1:0 bits in the AMPxCSR register. Then the amplifier can be switched on, and the amplification is done on each synchronization event. The amplification is done independently of the ADC. In order to start an amplified Analog to Digital Conversion on the amplified channel, the ADMUX must be configured as specified on Table 17-4 on page 217. The ADC starting is done by setting the ADSC (ADC Start conversion) bit in the ADCSRB register. Until the conversion is not achieved, it is not possible to start a conversion on another channel. On AT90PWM81, conversion takes advantage of the amplifier characteristics to ensure minimum conversion time. As soon as a conversion is requested thanks to the ADSC bit, the Analog to Digital Conversion is started. In order to have a better understanding of the functioning of the amplifier synchronization, a timing diagram example is shown Figure 17-15. In case the amplifier output is modified during the sample phase of the ADC, the on-going conversion is aborted and restarted as soon as the output of the amplifier is stable as shown Figure 17-16. The only precaution to take is to be sure that the trig signal (PSC) frequency is lower than ADCclk/4. It is also possible to auto trigger conversion on the amplified channel. In this case, the conversion is started at the next amplifier clock event following the last auto trigger event selected thanks to the ADTS bits in the ADCSRB register. In auto trigger conversion, the free running mode is not possible unless the ADSC bit in ADCSRA is set by soft after each conversion. Figure 17-15. Amplifier synchronization timing diagram with change on analog input signal. Figure 17-16. Amplifier synchronization timing diagram: behavior when ADSC is set when theamplifier output is changing. The block diagram of the two amplifiers is shown on Figure 17-17. 222 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Delta V 4th stable sample Signal to be measured PSC Block PSCn_ASY AMPLI_clk (Sync Clock) CK ADC Ampli er Block Ampli er Sample Enable Ampli er Hold Value Valid sample ADSC ADC ADC Activity ADC Conv ADC Sampling ADC Conv ADC Sampling ADC Result Ready ADC Resu Ready Signal to be measured PSC Block PSCn_ASY AMPLI_clk (Sync Clock) CK ADC Ampli er Block Ampli er Sample Enable Ampli er Hold Value Valid sample ADSC ADC ADC Activity ADC Conv ADC Sampling ADC Sampling Aborted ADC Conv ADC Sampling ADC Result Ready ADC Result Ready 223 7734P–AVR–08/10 Figure 17-17. Amplifiers block diagram + SAMPLING AMP0+ AMP0- Toward ADC MUX (AMP0) - ADCK/8 PSCRASY 00 01 10 11 Sampling Clock PSC2ASY no short AMP0+ GND AMP0EN AMP0IS AMP0G1 AMP0G0 AMP0GS - AMP0TS1 AMP0TS0 AMP0CSR If APMP0GS bit is set, the AMP0- input is open and PD5/AMP0- pin is free for another use. At the same time the negative input of the Amplifier is internally grounded. 17.10 Amplifier Control Registers The configuration of the amplifier is controlled via the register AMP0CSR. Then the start of conversion is done via the ADC control and status registers. The conversion result is stored on ADCH and ADCL register which contain respectively the most significant bits and the least significant bits. 17.10.1 Amplifier 0 Control and Status register – AMP0CSR Bit 7 6 5 4 3 2 1 AMP0EN AMP0IS AMP0G1 AMP0G0 AMP0GS - AMP0TS1 0 AMP0TS0 Read/Write R/W R/W R/W R/W - - R/W R/W Initial Value 0 0 0 0 0 0 0 0 AMP0CSR • Bit 7 – AMP0EN: Amplifier 0 Enable Bit Set this bit to enable the Amplifier 0. Clear this bit to disable the Amplifier 0. Clearing this bit while a conversion is running will take effect at the end of the conversion. • Bit 6– AMP0IS: Amplifier 0 Input Shunt Set this bit to short-circuit the Amplifier 0 input. If AMP0GS is set, the ground switch is released during shunt of inputs. Clear this bit to normally use the Amplifier 0. 224 AT90PWM81 7734P–AVR–08/10 AT90PWM81 • Bit 5, 4– AMP0G1, 0: Amplifier 0 Gain Selection Bits These 2 bits determine the gain of the amplifier 0. The different setting are shown in Table 17-7. Table 17-7. Amplifier 0 Gain Selection AMP0G1 AMP0G0 Description 0 0 Gain 5 0 1 Gain 10 1 0 Gain 20 1 1 Gain 40 To ensure an accurate result, after the gain value has been changed, the amplifier input needs to have a quite stable input value during at least 4 Amplifier synchronization clock periods. • Bit 3– AMP0GS: Amplifier 0 Ground Select of AMP0 This bit select negative input of the amplifier: Set this bit to ground the Amplifier 0 negative input. Clear this bit to normally use the Amplifier 0 differential input. • Bit 1, 0– AMP0TS1, AMP0TS0: Amplifier 0 Trigger Source Selection Bits In accordance with the Table 17-8, these 2 bits select the event which will generate the trigger for the amplifier 0. This trigger source is necessary to start the conversion on the amplified channel. Table 17-8. AMP0 Auto Trigger Source Selection AMP0TS1 AMP0TS0 Description 0 0 Auto synchronization on ADC Clock/8 0 1 Trig on PSCRASY 1 0 1 1 Trig on PSC2ASY 225 7734P–AVR–08/10 18. Digital to Analog Converter - DAC 18.1 Features • • • • • 10 bits resolution 8 bits linearity +/- 0.5 LSB accuracy between 100mV and AVcc-100mV Vout = DAC*Vref/1023 The DAC could be connected to the negative inputs of the analog comparators and/or to a dedicated output driver. • Output impedance around 1KOhm. The AT90PWM81 features a 10-bit Digital to Analog Converter. This DAC can be used for the analog comparators The DAC has a separate analog supply voltage pin, AVCC. AVCC must not differ more than ± 0.3V from VCC. See the paragraph “ADC Noise Canceler” on page 209 on how to connect this pin. The reference voltage is the same as the one used for the ADC, See “ADC Multiplexer Register – ADMUX” on page 216.. These nominally 2.56V Vref or AVCC are provided On-chip. The voltage reference may be externally decoupled at the AREF pin by a capacitor for better noise performance. 226 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 18-1. Digital to Analog Converter Block Schematic VRef DAC Result DAC 10 1 0 10 10 DAC High bits DAC Low bits Sources DACH Update DAC Trigger Edge Detector DAATE DACL DATS2 DATS1 DATS0 - DALA DAEN DACON 18.2 Operation The Digital to Analog Converter generates an analog signal proportional to the value of the DAC registers value. In order to have an accurate sampling frequency control, there is the possibility to update the DAC input values through different trigger events. 18.3 Starting a Conversion The DAC is configured thanks to the DACON register. As soon as the DAEN bit in DACON register is set, the DAC converts the value present on the DACH and DACL registers in accordance with the register DACON setting. Alternatively, a conversion can be triggered automatically by various sources. Auto Triggering is enabled by setting the DAC Auto Trigger Enable bit, DAATE in DACON. The trigger source is selected by setting the DAC Trigger Select bits, DATS in DACON (See description of the DATS bits for a list of the trigger sources). When a positive edge occurs on the selected trigger signal, the DAC converts the value present on the DACH and DACL registers in accordance with the register DACON setting. This provides a method of starting conversions at fixed intervals. If the trigger signal is still set when the conversion completes, a new conversion will not be started. If another positive edge occurs on the trigger signal during conversion, the edge will be ignored. Note that an interrupt flag will be set even if the specific interrupt is 227 7734P–AVR–08/10 disabled or the Global Interrupt Enable bit in SREG is cleared. A conversion can thus be triggered without causing an interrupt. However, the interrupt flag must be cleared in order to trigger a new conversion at the next interrupt event. 18.3.1 DAC Voltage Reference The reference voltage for the ADC (VREF) indicates the conversion range for the DAC. VREF can be selected as either AVCC, internal 2.56V reference, or external AREF pin. AVCC is connected to the DAC through a passive switch. The internal 2.56V reference is generated from the internal bandgap reference (VBG) through an internal amplifier. When the external AREF pin is connected to the DAC, the reference voltage can be made more immune to noise by connecting a capacitor between the AREF pin and ground. VREF can also be measured at the AREF pin with a high impedance voltmeter. Note that VREF is a high impedance source, and only a capacitive load should be connected in a system. The user may switch between AVCC, AVCC and 2.56V as reference selection. The first DAC conversion result after switching reference voltage source may be inaccurate, and the user is advised to discard this result. 18.4 DAC Register Description The DAC is controlled via three dedicated registers: • The DACON register which is used for DAC configuration • DACH and DACL which are used to set the value to be converted. 18.4.1 Digital to Analog Conversion Control Register – DACON Bit 7 6 5 4 3 2 1 DAATE DATS2 DATS1 DATS0 - DALA - 0 DAEN Read/Write R/W R/W R/W R/W - R/W - R/W Initial Value 0 0 0 0 0 0 0 0 DACON • Bit 7 – DAATE: DAC Auto Trigger Enable bit (not useful, may be left for compatibility) Set this bit to update the DAC input value on the positive edge of the trigger signal selected with the DACTS2-0 bit in DACON register. Clear it to automatically update the DAC input when a value is written on DACH register. • Bit 6:4 – DATS2, DATS1, DATS0: DAC Trigger Selection bits (not useful, may be left for compatibility) These bits are only necessary in case the DAC works in auto trigger mode. It means if DAATE bit is set. In accordance with the Table 18-1, these 3 bits select the interrupt event which will generate the update of the DAC input values. The update will be generated by the rising edge of the selected interrupt flag whether the interrupt is enabled or not. Table 18-1. 228 DAC Auto Trigger source selection DATS2 DATS1 DATS0 Description 0 0 0 Analog comparator 0 0 0 1 Analog comparator 1 0 1 0 External Interrupt Request 0 0 1 1 Reserved AT90PWM81 7734P–AVR–08/10 AT90PWM81 Table 18-1. DAC Auto Trigger source selection (Continued) DATS2 DATS1 DATS0 Description 1 0 0 Reserved 1 0 1 Reserved 1 1 0 Timer/Counter1 Overflow 1 1 1 Timer/Counter1 Capture Event • Bit 2 – DALA: Digital to Analog Left Adjust Set this bit to left adjust the DAC input data. Clear it to right adjust the DAC input data. The DALA bit affects the configuration of the DAC data registers. Changing this bit affects the DAC output on the next DACH writing. • Bit 1 – Reserved . • Bit 0 – DAEN: Digital to Analog Enable bit Set this bit to enable the DAC, Clear it to disable the DAC. 18.4.2 Digital to Analog Converter input Register – DACH and DACL DACH and DACL registers contain the value to be converted into analog voltage. Writing the DACL register forbid the update of the input value until DACH has not been written too. So the normal way to write a 10-bit value in the DAC register is firstly to write DACL the DACH. In order to work easily with only 8 bits, there is the possibility to left adjust the input value. Like this it is sufficient to write DACH to update the DAC value. 18.4.2.1 DALA = 0 Bit Read/Write Initial Value 18.4.2.2 7 6 5 4 3 2 1 - - - - - - DAC9 0 DAC8 DACH DAC7 DAC6 DAC5 DAC4 DAC3 DAC2 DAC1 DAC0 DACL R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 DALA = 1 Bit 7 6 5 4 3 2 1 0 DAC9 DAC8 DAC7 DAC6 DAC5 DAC4 DAC3 DAC2 DACH DAC1 DAC0 - - - - - - DACL Read/Write R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 229 7734P–AVR–08/10 To work with the 10-bit DAC, two registers have to be updated. In order to avoid intermediate value, the DAC input values which are really converted into analog signal are buffering into unreachable registers. In normal mode, the update of the shadow register is done when the register DACH is written. In case DAATE bit is set, the DAC input values will be updated on the trigger event selected through DATS bits. In order to avoid wrong DAC input values, the update can only be done after having written respectively DACL and DACH registers. It is possible to work on 8-bit configuration by only writing the DACH value. In this case, update is done each trigger event. In case DAATE bit is cleared, the DAC is in an automatic update mode. Writing the DACH register automatically update the DAC input values with the DACH and DACL register values. It means that whatever is the configuration of the DAATE bit, changing the DACL register has no effect on the DAC output until the DACH register has also been updated. So, to work with 10 bits, DACL must be written first before DACH. To work with 8-bit configuration, writing DACH allows the update of the DAC. 230 AT90PWM81 7734P–AVR–08/10 AT90PWM81 19. debugWIRE On-chip Debug System 19.1 Features • • • • • • • • • • 19.2 Complete Program Flow Control Emulates All On-chip Functions, Both Digital and Analog, except RESET Pin Real-time Operation Symbolic Debugging Support (Both at C and Assembler Source Level, or for Other HLLs) Unlimited Number of Program Break Points (Using Software Break Points) Non-intrusive Operation Electrical Characteristics Identical to Real Device Automatic Configuration System High-Speed Operation Programming of Non-volatile Memories Overview The debugWIRE On-chip debug system uses a One-wire, bi-directional interface to control the program flow, execute AVR instructions in the CPU and to program the different non-volatile memories. 19.3 Physical Interface When the debugWIRE Enable (DWEN) Fuse is programmed and Lock bits are unprogrammed, the debugWIRE system within the target device is activated. The RESET port pin is configured as a wireAND (open-drain) bi-directional I/O pin with pull-up enabled and becomes the communication gateway between target and emulator. Figure 19-1. The debugWIRE Setup 1.8 - 5.5V VCC dW dW(RESET) GND Figure 19-1 shows the schematic of a target MCU, with debugWIRE enabled, and the emulator connector. The system clock is not affected by debugWIRE and will always be the clock source selected by the CKSEL Fuses. When designing a system where debugWIRE will be used, the following observations must be made for correct operation: 231 7734P–AVR–08/10 • Pull-up resistors on the dW/(RESET) line must not be smaller than 10kΩ. The pull-up resistor is not required for debugWIRE functionality. • Connecting the RESET pin directly to VCC will not work. • Capacitors connected to the RESET pin must be disconnected when using debugWire. • All external reset sources must be disconnected. 19.4 Software Break Points debugWIRE supports Program memory Break Points by the AVR Break instruction. Setting a Break Point in AVR Studio® will insert a BREAK instruction in the Program memory. The instruction replaced by the BREAK instruction will be stored. When program execution is continued, the stored instruction will be executed before continuing from the Program memory. A break can be inserted manually by putting the BREAK instruction in the program. The Flash must be re-programmed each time a Break Point is changed. This is automatically handled by AVR Studio through the debugWIRE interface. The use of Break Points will therefore reduce the Flash Data retention. Devices used for debugging purposes should not be shipped to end customers. 19.5 Limitations of debugWIRE The debugWIRE communication pin (dW) is physically located on the same pin as External Reset (RESET). An External Reset source is therefore not supported when the debugWIRE is enabled. The debugWIRE system accurately emulates all I/O functions when running at full speed, i.e., when the program in the CPU is running. When the CPU is stopped, care must be taken while accessing some of the I/O Registers via the debugger (AVR Studio). A programmed DWEN Fuse enables some parts of the clock system to be running in all sleep modes. This will increase the power consumption while in sleep. Thus, the DWEN Fuse should be disabled when debugWire is not used. 19.6 debugWIRE Related Register in I/O Memory The following section describes the registers used with the debugWire. 19.6.1 debugWire Data Register – DWDR Bit 7 6 5 4 3 2 1 0 DWDR[7:0] DWDR Read/Write R/W R/W R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 The DWDR Register provides a communication channel from the running program in the MCU to the debugger. This register is only accessible by the debugWIRE and can therefore not be used as a general purpose register in the normal operations. 20. Boot Loader Support – Read-While-Write Self-Programming In AT90PWM81, the Boot Loader Support provides a real Read-While-Write Self-Programming mechanism for downloading and uploading program code by the MCU itself. This feature allows flexible application software updates controlled by the MCU using a Flash-resident Boot Loader program. The Boot Loader program can use any available data interface and associated protocol to read code and write (program) that code into the Flash memory, or read the code from the program memory. The program 232 AT90PWM81 7734P–AVR–08/10 AT90PWM81 code within the Boot Loader section has the capability to write into the entire Flash, including the Boot Loader memory. The Boot Loader can thus even modify itself, and it can also erase itself from the code if the feature is not needed anymore. The size of the Boot Loader memory is configured with fuses and the Boot Loader has two separate sets of Boot Lock bits which can be set independently. This gives the user a unique flexibility to select different levels of protection. 20.1 Boot Loader Features • • • • • • • Read-While-Write Self-Programming Flexible Boot Memory Size High Security (Separate Boot Lock Bits for a Flexible Protection) Separate Fuse to Select Reset Vector Optimized Page(1) Size Code Efficient Algorithm Efficient Read-Modify-Write Support Note: 20.2 1. A page is a section in the Flash consisting of several bytes (see Table 21-11 on page 254) used during programming. The page organization does not affect normal operation. Application and Boot Loader Flash Sections The Flash memory is organized in two main sections, the Application section and the Boot Loader section (see Figure 20-2). The size of the different sections is configured by the BOOTSZ Fuses as shown in Table 20-7 on page 246 and Figure 20-2. These two sections can have different level of protection since they have different sets of Lock bits. 20.2.1 Application Section The Application section is the section of the Flash that is used for storing the application code. The protection level for the Application section can be selected by the application Boot Lock bits (Boot Lock bits 0), see Table 20-2 on page 237. The Application section can never store any Boot Loader code since the SPM instruction is disabled when executed from the Application section. 20.2.2 BLS – Boot Loader Section While the Application section is used for storing the application code, the The Boot Loader software must be located in the BLS since the SPM instruction can initiate a programming when executing from the BLS only. The SPM instruction can access the entire Flash, including the BLS itself. The protection level for the Boot Loader section can be selected by the Boot Loader Lock bits (Boot Lock bits 1), see Table 20-3 on page 237. 20.3 Read-While-Write and No Read-While-Write Flash Sections Whether the CPU supports Read-While-Write or if the CPU is halted during a Boot Loader software update is dependent on which address that is being programmed. In addition to the two sections that are configured by the BOOTSZ Fuses as described above, the Flash is also divided into two fixed sections, the Read-While-Write (RWW) section and the No Read-While-Write (NRWW) section. The limit between the RWW- and NRWW sections is given in Table 20-8 on page 246 and Figure 20-2 on page 236. The main difference between the two sections is: • When erasing or writing a page located inside the RWW section, the NRWW section can be read during the operation. • When erasing or writing a page located inside the NRWW section, the CPU is halted during the entire operation. 233 7734P–AVR–08/10 Note that the user software can never read any code that is located inside the RWW section during a Boot Loader software operation. The syntax “Read-While-Write section” refers to which section that is being programmed (erased or written), not which section that actually is being read during a Boot Loader software update. 20.3.1 RWW – Read-While-Write Section If a Boot Loader software update is programming a page inside the RWW section, it is possible to read code from the Flash, but only code that is located in the NRWW section. During an on-going programming, the software must ensure that the RWW section never is being read. If the user software is trying to read code that is located inside the RWW section (i.e., by a call/jmp/lpm or an interrupt) during programming, the software might end up in an unknown state. To avoid this, the interrupts should either be disabled or moved to the Boot Loader section. The Boot Loader section is always located in the NRWW section. The RWW Section Busy bit (RWWSB) in the Store Program Memory Control and Status Register (SPMCSR) will be read as logical one as long as the RWW section is blocked for reading. After a programming is completed, the RWWSB must be cleared by software before reading code located in the RWW section. See “Store Program Memory Control and Status Register – SPMCSR” on page 238. for details on how to clear RWWSB. 20.3.2 NRWW – No Read-While-Write Section The code located in the NRWW section can be read when the Boot Loader software is updating a page in the RWW section. When the Boot Loader code updates the NRWW section, the CPU is halted during the entire Page Erase or Page Write operation. Table 20-1. 234 Read-While-Write Features Which Section does the Z-pointer Address During the Programming? Which Section Can be Read During Programming? Is the CPU Halted? Read-While-Write Supported? RWW Section NRWW Section No Yes NRWW Section None Yes No AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 20-1. Read-While-Write vs. No Read-While-Write Read-While-Write (RWW) Section Z-pointer Addresses RWW Section Z-pointer Addresses NRWW Section No Read-While-Write (NRWW) Section CPU is Halted During the Operation Code Located in NRWW Section Can be Read During the Operation 235 7734P–AVR–08/10 Figure 20-2. Memory Sections Program Memory BOOTSZ = '10' Program Memory BOOTSZ = '11' 0x0000 Read-While-Write Section Application Flash Section End RWW Start NRWW Application Flash Section Boot Loader Flash Section End Application Start Boot Loader Flashend No Read-While-Write Section No Read-While-Write Section Read-While-Write Section 0x0000 Program Memory BOOTSZ = '01' Application Flash Section End RWW Start NRWW Application Flash Section End Application Start Boot Loader Boot Loader Flash Section Flashend Program Memory BOOTSZ = '00' Note: 20.4 Read-While-Write Section 0x0000 Application Flash Section End RWW Start NRWW Application Flash Section End Application Start Boot Loader Boot Loader Flash Section Flashend No Read-While-Write Section No Read-While-Write Section Read-While-Write Section 0x0000 Application Flash Section End RWW, End Application Start NRWW, Start Boot Loader Boot Loader Flash Section Flashend 1. The parameters in the figure above are given in Table 20-7 on page 246. Boot Loader Lock Bits If no Boot Loader capability is needed, the entire Flash is available for application code. The Boot Loader has two separate sets of Boot Lock bits which can be set independently. This gives the user a unique flexibility to select different levels of protection. The user can select: • To protect the entire Flash from a software update by the MCU. • To protect only the Boot Loader Flash section from a software update by the MCU. • To protect only the Application Flash section from a software update by the MCU. • Allow software update in the entire Flash. See Table 20-2 and Table 20-3 for further details. The Boot Lock bits can be set in software and in Serial or Parallel Programming mode, but they can be cleared by a Chip Erase command only. The general Write Lock (Lock Bit mode 2) does not control the programming of the Flash memory by SPM instruction. Sim- 236 AT90PWM81 7734P–AVR–08/10 AT90PWM81 ilarly, the general Read/Write Lock (Lock Bit mode 1) does not control reading nor writing by LPM/SPM, if it is attempted. Table 20-2. BLB0 Mode BLB02 BLB01 1 1 1 No restrictions for SPM or LPM accessing the Application section. 2 1 0 SPM is not allowed to write to the Application section. 0 SPM is not allowed to write to the Application section, and LPM executing from the Boot Loader section is not allowed to read from the Application section. If Interrupt Vectors are placed in the Boot Loader section, interrupts are disabled while executing from the Application section. 1 LPM executing from the Boot Loader section is not allowed to read from the Application section. If Interrupt Vectors are placed in the Boot Loader section, interrupts are disabled while executing from the Application section. 3 4 Note: 0 0 Protection 1. “1” means unprogrammed, “0” means programmed Table 20-3. Boot Lock Bit1 Protection Modes (Boot Loader Section)(1) BLB1 Mode BLB12 BLB11 1 1 1 No restrictions for SPM or LPM accessing the Boot Loader section. 2 1 0 SPM is not allowed to write to the Boot Loader section. 0 SPM is not allowed to write to the Boot Loader section, and LPM executing from the Application section is not allowed to read from the Boot Loader section. If Interrupt Vectors are placed in the Application section, interrupts are disabled while executing from the Boot Loader section. 1 LPM executing from the Application section is not allowed to read from the Boot Loader section. If Interrupt Vectors are placed in the Application section, interrupts are disabled while executing from the Boot Loader section. 3 4 Note: 20.5 Boot Lock Bit0 Protection Modes (Application Section)(1) 0 0 Protection 1. “1” means unprogrammed, “0” means programmed Entering the Boot Loader Program Entering the Boot Loader takes place by a jump or call from the application program. This may be initiated by a trigger such as a command received via SPI interface. Alternatively, the Boot Reset Fuse can be programmed so that the Reset Vector is pointing to the Boot Flash start address after a reset. In this case, the Boot Loader is started after a reset. After the application code is loaded, the program can start executing the application code. Note that the fuses cannot be changed by the MCU itself. This means that once the Boot Reset Fuse is programmed, the Reset Vector will always point to the Boot Loader Reset and the fuse can only be changed through the serial or parallel programming interface. Table 20-4. BOOTRST Note: Boot Reset Fuse(1) Reset Address 1 Reset Vector = Application Reset (address 0x0000) 0 Reset Vector = Boot Loader Reset (see Table 20-7 on page 246) 1. “1” means unprogrammed, “0” means programmed 237 7734P–AVR–08/10 20.5.1 Store Program Memory Control and Status Register – SPMCSR The Store Program Memory Control and Status Register contains the control bits needed to control the Boot Loader operations. Bit 7 6 5 4 3 2 1 0 SPMIE RWWSB SIGRD RWWSRE BLBSET PGWRT PGERS SPMEN Read/Write R/W R R/W R/W R/W R/W R/W R/W Initial Value 0 0 0 0 0 0 0 0 SPMCSR • Bit 7 – SPMIE: SPM Interrupt Enable When the SPMIE bit is written to one, and the I-bit in the Status Register is set (one), the SPM ready interrupt will be enabled. The SPM ready Interrupt will be executed as long as the SPMEN bit in the SPMCSR Register is cleared. • Bit 6 – RWWSB: Read-While-Write Section Busy When a Self-Programming (Page Erase or Page Write) operation to the RWW section is initiated, the RWWSB will be set (one) by hardware. When the RWWSB bit is set, the RWW section cannot be accessed. The RWWSB bit will be cleared if the RWWSRE bit is written to one after a Self-Programming operation is completed. Alternatively the RWWSB bit will automatically be cleared if a page load operation is initiated. • Bit 5 – SIGRD: Signature Row Read If this bit is written to one at the same time as SPMEN, the next LPM instruction within three clock cycles will read a byte from the signature row into the destination register. see Reading the Signature Row from Software243“ for details. An SPM instruction within four cycles after SIGRD and SPMEN are set will have no effect. This operation is reserved for future use and should not be used. • Bit 4 – RWWSRE: Read-While-Write Section Read Enable When programming (Page Erase or Page Write) to the RWW section, the RWW section is blocked for reading (the RWWSB will be set by hardware). To re-enable the RWW section, the user software must wait until the programming is completed (SPMEN will be cleared). Then, if the RWWSRE bit is written to one at the same time as SPMEN, the next SPM instruction within four clock cycles re-enables the RWW section. The RWW section cannot be re-enabled while the Flash is busy with a Page Erase or a Page Write (SPMEN is set). If the RWWSRE bit is written while the Flash is being loaded, the Flash load operation will abort and the data loaded will be lost. • Bit 3 – BLBSET: Boot Lock Bit Set If this bit is written to one at the same time as SPMEN, the next SPM instruction within four clock cycles sets Boot Lock bits and Memory Lock bits, according to the data in R0. The data in R1 and the address in the Z-pointer are ignored. The BLBSET bit will automatically be cleared upon completion of the Lock bit set, or if no SPM instruction is executed within four clock cycles. An LPM instruction within three cycles after BLBSET and SPMEN are set in the SPMCSR Register, will read either the Lock bits or the Fuse bits (depending on Z0 in the Z-pointer) into the destination register. See “Reading the Fuse and Lock Bits from Software” on page 242 for details. • Bit 2 – PGWRT: Page Write 238 AT90PWM81 7734P–AVR–08/10 AT90PWM81 If this bit is written to one at the same time as SPMEN, the next SPM instruction within four clock cycles executes Page Write, with the data stored in the temporary buffer. The page address is taken from the high part of the Z-pointer. The data in R1 and R0 are ignored. The PGWRT bit will auto-clear upon completion of a Page Write, or if no SPM instruction is executed within four clock cycles. The CPU is halted during the entire Page Write operation if the NRWW section is addressed. • Bit 1 – PGERS: Page Erase If this bit is written to one at the same time as SPMEN, the next SPM instruction within four clock cycles executes Page Erase. The page address is taken from the high part of the Z-pointer. The data in R1 and R0 are ignored. The PGERS bit will auto-clear upon completion of a Page Erase, or if no SPM instruction is executed within four clock cycles. The CPU is halted during the entire Page Write operation if the NRWW section is addressed. • Bit 0 – SPMEN: Self Programming Enable This bit enables the SPM instruction for the next four clock cycles. If written to one together with either RWWSRE, BLBSET, PGWRT or PGERS, the following SPM instruction will have a special meaning, see description above. If only SPMEN is written, the following SPM instruction will store the value in R1:R0 in the temporary page buffer addressed by the Z-pointer. The LSB of the Z-pointer is ignored. The SPMEN bit will auto-clear upon completion of an SPM instruction, or if no SPM instruction is executed within four clock cycles. During Page Erase and Page Write, the SPMEN bit remains high until the operation is completed. Writing any other combination than “10001”, “01001”, “00101”, “00011” or “00001” in the lower five bits will have no effect. 20.6 Addressing the Flash During Self-Programming The Z-pointer is used to address the SPM commands. Bit 15 14 13 12 11 10 9 ZH (R31) Z15 Z14 Z13 Z12 Z11 Z10 Z9 8 Z8 ZL (R30) Z7 Z6 Z5 Z4 Z3 Z2 Z1 Z0 7 6 5 4 3 2 1 0 Since the Flash is organized in pages (see Table 21-11 on page 254), the Program Counter can be treated as having two different sections. One section, consisting of the least significant bits, is addressing the words within a page, while the most significant bits are addressing the pages. This is1 shown in Figure 203. Note that the Page Erase and Page Write operations are addressed independently. Therefore it is of major importance that the Boot Loader software addresses the same page in both the Page Erase and Page Write operation. Once a programming operation is initiated, the address is latched and the Z-pointer can be used for other operations. The only SPM operation that does not use the Z-pointer is Setting the Boot Loader Lock bits. The content of the Z-pointer is ignored and will have no effect on the operation. The LPM instruction does also use the Z-pointer to store the address. Since this instruction addresses the Flash byte-by-byte, also the LSB (bit Z0) of the Z-pointer is used. 239 7734P–AVR–08/10 Addressing the Flash During SPM(1) Figure 20-3. BIT 15 ZPCMSB ZPAGEMSB Z - REGISTER 1 0 0 PCMSB PROGRAM COUNTER PAGEMSB PCPAGE PAGE ADDRESS WITHIN THE FLASH PROGRAM MEMORY PAGE PCWORD WORD ADDRESS WITHIN A PAGE PAGE INSTRUCTION WORD PCWORD[PAGEMSB:0]: 00 01 02 PAGEEND Note: 20.7 1. The different variables used in Figure 20-3 are listed in Table 20-9 on page 247. Self-Programming the Flash The program memory is updated in a page by page fashion. Before programming a page with the data stored in the temporary page buffer, the page must be erased. The temporary page buffer is filled one word at a time using SPM and the buffer can be filled either before the Page Erase command or between a Page Erase and a Page Write operation: Alternative 1, fill the buffer before a Page Erase • Fill temporary page buffer • Perform a Page Erase • Perform a Page Write Alternative 2, fill the buffer after Page Erase • Perform a Page Erase • Fill temporary page buffer • Perform a Page Write If only a part of the page needs to be changed, the rest of the page must be stored (for example in the temporary page buffer) before the erase, and then be rewritten. When using alternative 1, the Boot Loader provides an effective Read-Modify-Write feature which allows the user software to first read the page, do the necessary changes, and then write back the modified data. If alternative 2 is used, it is not possible to read the old data while loading since the page is already erased. The temporary page buffer can be accessed in a random sequence. It is essential that the page address used in both the Page Erase and Page Write operation is addressing the same page. See “Simple Assembly Code Example for a Boot Loader” on page 244 for an assembly code example. 240 AT90PWM81 7734P–AVR–08/10 AT90PWM81 20.7.1 Performing Page Erase by SPM To execute Page Erase, set up the address in the Z-pointer, write “X0000011” to SPMCSR and execute SPM within four clock cycles after writing SPMCSR. The data in R1 and R0 is ignored. The page address must be written to PCPAGE in the Z-register. Other bits in the Z-pointer will be ignored during this operation. • Page Erase to the RWW section: The NRWW section can be read during the Page Erase. • Page Erase to the NRWW section: The CPU is halted during the operation. 20.7.2 Filling the Temporary Buffer (Page Loading) To write an instruction word, set up the address in the Z-pointer and data in R1:R0, write “00000001” to SPMCSR and execute SPM within four clock cycles after writing SPMCSR. The content of PCWORD in the Z-register is used to address the data in the temporary buffer. The temporary buffer will auto-erase after a Page Write operation or by writing the RWWSRE bit in SPMCSR. It is also erased after a system reset. Note that it is not possible to write more than one time to each address without erasing the temporary buffer. If the EEPROM is written in the middle of an SPM Page Load operation, all data loaded will be lost. 20.7.3 Performing a Page Write To execute Page Write, set up the address in the Z-pointer, write “X0000101” to SPMCSR and execute SPM within four clock cycles after writing SPMCSR. The data in R1 and R0 is ignored. The page address must be written to PCPAGE. Other bits in the Z-pointer must be written to zero during this operation. • Page Write to the RWW section: The NRWW section can be read during the Page Write. • Page Write to the NRWW section: The CPU is halted during the operation. 20.7.4 Using the SPM Interrupt If the SPM interrupt is enabled, the SPM interrupt will generate a constant interrupt when the SPMEN bit in SPMCSR is cleared. This means that the interrupt can be used instead of polling the SPMCSR Register in software. When using the SPM interrupt, the Interrupt Vectors should be moved to the BLS section to avoid that an interrupt is accessing the RWW section when it is blocked for reading. How to move the interrupts is described in Section “Moving Interrupts Between Application and Boot Space”, page 64. 20.7.5 Consideration While Updating BLS Special care must be taken if the user allows the Boot Loader section to be updated by leaving Boot Lock bit11 unprogrammed. An accidental write to the Boot Loader itself can corrupt the entire Boot Loader, and further software updates might be impossible. If it is not necessary to change the Boot Loader software itself, it is recommended to program the Boot Lock bit11 to protect the Boot Loader software from any internal software changes. 20.7.6 Prevent Reading the RWW Section During Self-Programming During Self-Programming (either Page Erase or Page Write), the RWW section is always blocked for reading. The user software itself must prevent that this section is addressed during the self programming operation. The RWWSB in the SPMCSR will be set as long as the RWW section is busy. During Self-Programming the Interrupt Vector table should be moved to the BLS as described in Section “Moving Interrupts Between Application and Boot Space”, page 64, or the interrupts must be disabled. Before addressing the RWW section after the programming is completed, the user software must clear the RWWSB by writing the RWWSRE. See “Simple Assembly Code Example for a Boot Loader” on page 244 for an example. 241 7734P–AVR–08/10 20.7.7 Setting the Boot Loader Lock Bits by SPM To set the Boot Loader Lock bits, write the desired data to R0, write “X0001001” to SPMCSR and execute SPM within four clock cycles after writing SPMCSR. The only accessible Lock bits are the Boot Lock bits that may prevent the Application and Boot Loader section from any software update by the MCU. Bit 7 6 5 4 3 2 1 0 R0 1 1 BLB12 BLB11 BLB02 BLB01 1 1 See Table 20-2 and Table 20-3 for how the different settings of the Boot Loader bits affect the Flash access. If bits 5..2 in R0 are cleared (zero), the corresponding Boot Lock bit will be programmed if an SPM instruction is executed within four cycles after BLBSET and SPMEN are set in SPMCSR. The Z-pointer is don’t care during this operation, but for future compatibility it is recommended to load the Z-pointer with 0x0001 (same as used for reading the lOck bits). For future compatibility it is also recommended to set bits 7, 6, 1, and 0 in R0 to “1” when writing the Lock bits. When programming the Lock bits the entire Flash can be read during the operation. 20.7.8 EEPROM Write Prevents Writing to SPMCSR Note that an EEPROM write operation will block all software programming to Flash. Reading the Fuses and Lock bits from software will also be prevented during the EEPROM write operation. It is recommended that the user checks the status bit (EEPE) in the EECR Register and verifies that the bit is cleared before writing to the SPMCSR Register. 20.7.9 Reading the Fuse and Lock Bits from Software It is possible to read both the Fuse and Lock bits from software. To read the Lock bits, load the Z-pointer with 0x0001 and set the BLBSET and SPMEN bits in SPMCSR. When an LPM instruction is executed within three CPU cycles after the BLBSET and SPMEN bits are set in SPMCSR, the value of the Lock bits will be loaded in the destination register. The BLBSET and SPMEN bits will auto-clear upon completion of reading the Lock bits or if no LPM instruction is executed within three CPU cycles or no SPM instruction is executed within four CPU cycles. When BLBSET and SPMEN are cleared, LPM will work as described in the Instruction set Manual. Bit 7 6 5 4 3 2 1 0 Rd – – BLB12 BLB11 BLB02 BLB01 LB2 LB1 The algorithm for reading the Fuse Low byte is similar to the one described above for reading the Lock bits. To read the Fuse Low byte, load the Z-pointer with 0x0000 and set the BLBSET and SPMEN bits in SPMCSR. When an LPM instruction is executed within three cycles after the BLBSET and SPMEN bits are set in the SPMCSR, the value of the Fuse Low byte (FLB) will be loaded in the destination register as shown below. Refer to Table 21-4 on page 249 for a detailed description and mapping of the Fuse Low byte. Bit 7 6 5 4 3 2 1 0 Rd FLB7 FLB6 FLB5 FLB4 FLB3 FLB2 FLB1 FLB0 Similarly, when reading the Fuse High byte, load 0x0003 in the Z-pointer. When an LPM instruction is executed within three cycles after the BLBSET and SPMEN bits are set in the SPMCSR, the value of the Fuse High byte (FHB) will be loaded in the destination register as shown below. Refer to Table 21-5 on page 251 for detailed description and mapping of the Fuse High byte. 242 Bit 7 6 5 4 3 2 1 0 Rd FHB7 FHB6 FHB5 FHB4 FHB3 FHB2 FHB1 FHB0 AT90PWM81 7734P–AVR–08/10 AT90PWM81 When reading the Extended Fuse byte, load 0x0002 in the Z-pointer. When an LPM instruction is executed within three cycles after the BLBSET and SPMEN bits are set in the SPMCSR, the value of the Extended Fuse byte (EFB) will be loaded in the destination register as shown below. Refer to Table 21-4 on page 249 for detailed description and mapping of the Extended Fuse byte. Bit 7 6 5 4 3 2 1 0 Rd – – – – EFB3 EFB2 EFB1 EFB0 Fuse and Lock bits that are programmed, will be read as zero. Fuse and Lock bits that are unprogrammed, will be read as one. 20.7.10 Reading the Signature Row from Software To read the Signature Row from software, load the Z-pointer with the signature byte address given in Table 20-5 and set the SIGRD and SPMEN bits in SPMCSR. When an LPM instruction is executed within three CPU cycles after the SIGRD and SPMEN bits are set in SPMCSR, the signature byte value will be loaded in the destination register. The SIGRD and SPMEN bits will auto-clear upon completion of reading the Signature Row Lock bits or if no LPM instruction is executed within three CPU cycles. When SIGRD and SPMEN are cleared, LPM will work as described in the ”AVR Instruction Set” description. Table 20-5. Signature Row Addressing Signature Byte Address Data Device ID 0, Manufacturer ID 0x00 1EH OSCAL 8M, RC-OSC calibration 0x01 XXH Device ID 1, Flash size 0x02 93H Reserved 0x03 XXH Device ID 2, Device 0x04 88H Temperature Sensor Offset : TSOFFSET 0x05 XXH Reserved 0x06 XXH 0x07 XXH Lot number at sort, byte 2, ASCII 0x0E XXH Lot number at sort, Byte 1, ASCII (most left lot#) 0x0F XXH Lot number at sort, byte 2, ASCII 0x10 XXH Lot number at sort, Byte 1, ASCII 0x11 XXH Lot number at sort, byte 2, ASCII 0x12 XXH 0x13 XXH 0x3C XXH 0x3D XXH Final Test Hot VRef : LOW BYTE ( only a Read) (4) 0x3E XXH Final Test Hot VRef : HIGH BYTE( only a Read) (5) 0x3F XXH (1) Temperature Sensor Gain : TSGAIN Lot number at sort, Byte 1, ASCII Final test Amb VRef : LOW BYTE (2) Final Test Amb VRef : HIGH BYTE (3) 1.TSGAIN typical value is 0x80=128 243 7734P–AVR–08/10 2.See Note 3 3.Final Test Amb VRef HIGH BYTE and LOW BYTE : Typical values arefor Vref. = 2.56V: HIGH BYTE = 0x0A LOW BYTE = 0x00 This means : Final Test Amb VRef= 0x0A00 = 2560 = Vref. * 1000. 4.See Note 3 which details the value format. 5.See Note 3 which details the value format. 20.7.11 Preventing Flash Corruption During periods of low VCC, the Flash program can be corrupted because the supply voltage is too low for the CPU and the Flash to operate properly. These issues are the same as for board level systems using the Flash, and the same design solutions should be applied. A Flash program corruption can be caused by two situations when the voltage is too low. First, a regular write sequence to the Flash requires a minimum voltage to operate correctly. Secondly, the CPU itself can execute instructions incorrectly, if the supply voltage for executing instructions is too low. Flash corruption can easily be avoided by following these design recommendations (one is sufficient): 20.7.12 1. If there is no need for a Boot Loader update in the system, program the Boot Loader Lock bits to prevent any Boot Loader software updates. 2. Keep the AVR RESET active (low) during periods of insufficient power supply voltage. This can be done by enabling the internal Brown-out Detector (BOD) if the operating voltage matches the detection level. If not, an external low VCC reset protection circuit can be used. If a reset occurs while a write operation is in progress, the write operation will be completed provided that the power supply voltage is sufficient. 3. Keep the AVR core in Power-down sleep mode during periods of low VCC. This will prevent the CPU from attempting to decode and execute instructions, effectively protecting the SPMCSR Register and thus the Flash from unintentional writes. Programming Time for Flash when Using SPM The calibrated RC Oscillator is used to time Flash accesses. Table 20-6 shows the typical programming time for Flash accesses from the CPU. Table 20-6. SPM Programming Time Symbol Flash write (Page Erase, Page Write, and write Lock bits by SPM) 20.7.13 Min Programming Time Max Programming Time 3.7 ms 4.5 ms Simple Assembly Code Example for a Boot Loader ;-the routine writes one page of data from RAM to Flash ; the first data location in RAM is pointed to by the Y pointer ; the first data location in Flash is pointed to by the Z-pointer ;-error handling is not included ;-the routine must be placed inside the Boot space ; (at least the Do_spm sub routine). Only code inside NRWW section can ; be read during Self-Programming (Page Erase and Page Write). ;-registers used: r0, r1, temp1 (r16), temp2 (r17), looplo (r24), ; loophi (r25), spmcrval (r20) 244 AT90PWM81 7734P–AVR–08/10 AT90PWM81 ; storing and restoring of registers is not included in the routine ; register usage can be optimized at the expense of code size ;-It is assumed that either the interrupt table is moved to the Boot ; loader section or that the interrupts are disabled. .equ PAGESIZEB = PAGESIZE*2 ;PAGESIZEB is page size in BYTES, not words .org SMALLBOOTSTART Write_page: ; Page Erase ldi spmcrval, (1<<PGERS) | (1<<SPMEN) call Do_spm ; re-enable the RWW section ldi spmcrval, (1<<RWWSRE) | (1<<SPMEN) call Do_spm ; transfer data from RAM to Flash page buffer ldi looplo, low(PAGESIZEB) ;init loop variable ldi loophi, high(PAGESIZEB) ;not required for PAGESIZEB<=256 Wrloop: ld r0, Y+ ld r1, Y+ ldi spmcrval, (1<<SPMEN) call Do_spm adiw ZH:ZL, 2 sbiw loophi:looplo, 2 ;use subi for PAGESIZEB<=256 brne Wrloop ; execute Page Write subi ZL, low(PAGESIZEB) ;restore pointer sbci ZH, high(PAGESIZEB) ;not required for PAGESIZEB<=256 ldi spmcrval, (1<<PGWRT) | (1<<SPMEN) call Do_spm ; re-enable the RWW section ldi spmcrval, (1<<RWWSRE) | (1<<SPMEN) call Do_spm ; read back and check, optional ldi looplo, low(PAGESIZEB) ;init loop variable ldi loophi, high(PAGESIZEB) ;not required for PAGESIZEB<=256 subi YL, low(PAGESIZEB) ;restore pointer sbci YH, high(PAGESIZEB) Rdloop: lpm r0, Z+ ld r1, Y+ cpse r0, r1 jmp Error sbiw loophi:looplo, 1 ;use subi for PAGESIZEB<=256 brne Rdloop ; return to RWW section ; verify that RWW section is safe to read Return: in temp1, SPMCSR sbrs temp1, RWWSB ; If RWWSB is set, the RWW section is not ready yet ret ; re-enable the RWW section ldi spmcrval, (1<<RWWSRE) | (1<<SPMEN) call Do_spm 245 7734P–AVR–08/10 rjmp Return Do_spm: ; check for previous SPM complete Wait_spm: in temp1, SPMCSR sbrc temp1, SPMEN rjmp Wait_spm ; input: spmcrval determines SPM action ; disable interrupts if enabled, store status in temp2, SREG cli ; check that no EEPROM write access is present Wait_ee: sbic EECR, EEPE rjmp Wait_ee ; SPM timed sequence out SPMCSR, spmcrval spm ; restore SREG (to enable interrupts if originally enabled) out SREG, temp2 ret 20.7.14 Boot Loader Parameters In Table 20-7 through Table 20-9, the parameters used in the description of the self programming are given. Table 20-7. BOOTSZ1 Boot Size Configuration BOOTSZ0 Boot Size Boot Loader Flash Section End Application Section Boot Reset Address (Start Boot Loader Section) 1 1 128 words 4 0x000 - 0xF7F 0xF80 0xFFF 0xF7F 0xF80 1 0 256 words 8 0x000 - 0xEFF 0xF00 0xFFF 0xEFF 0xF00 0 1 512 words 16 0x000 - 0xDFF 0xE00 0xFFF 0xDFF 0xE00 0 0 1024 words 32 0x000 - 0xBFF 0xC00 0xFFF 0xBFF 0xC00 Note: The different BOOTSZ Fuse configurations are shown in Figure 20-2. Table 20-8. Read-While-Write Limit Section 246 Pages Application Flash Section Pages Address Read-While-Write section (RWW) 96 0x000 - 0xBFF No Read-While-Write section (NRWW) 32 0xC00 - 0xFFF AT90PWM81 7734P–AVR–08/10 AT90PWM81 For details about these two section, see “NRWW – No Read-While-Write Section” on page 234 and “RWW – Read-While-Write Section” on page 234 Table 20-9. Explanation of Different Variables used in Figure 20-3 and the Mapping to the Z-pointer Corresponding Z-value(1) Variable Description PCMSB 11 Most significant bit in the Program Counter. (The Program Counter is 12 bits PC[11:0]) PAGEMSB 4 Most significant bit which is used to address the words within one page (32 words in a page requires 5 bits PC [4:0]). ZPCMSB Z12 Bit in Z-register that is mapped to PCMSB. Because Z0 is not used, the ZPCMSB equals PCMSB + 1. ZPAGEMSB Z5 Bit in Z-register that is mapped to PAGEMSB. Because Z0 is not used, the ZPAGEMSB equals PAGEMSB + 1. PCPAGE PC[11:5] Z12:Z6 Program counter page address: Page select, for page erase and page write PCWORD PC[4:0] Z5:Z1 Program counter word address: Word select, for filling temporary buffer (must be zero during page write operation) Note: 1. Z15:Z13: always ignored Z0: should be zero for all SPM commands, byte select for the LPM instruction. See “Addressing the Flash During Self-Programming” on page 239 for details about the use of Zpointer during Self-Programming. 21. Memory Programming 21.1 Program And Data Memory Lock Bits The AT90PWM81 provides six Lock bits which can be left unprogrammed (“1”) or can be programmed (“0”) to obtain the additional features listed in Table 21-2. The Lock bits can only be erased to “1” with the Chip Erase command. Table 21-1. Lock Bit Byte(1) Lock Bit Byte Bit No Description Default Value 7 – 1 (unprogrammed) 6 – 1 (unprogrammed) BLB12 5 Boot Lock bit 1 (unprogrammed) BLB11 4 Boot Lock bit 1 (unprogrammed) BLB02 3 Boot Lock bit 1 (unprogrammed) BLB01 2 Boot Lock bit 1 (unprogrammed) LB2 1 Lock bit 1 (unprogrammed) LB1 0 Lock bit 1 (unprogrammed) 247 7734P–AVR–08/10 Notes: 1. “1” means unprogrammed, “0” means programmed. Table 21-2. Lock Bit Protection Modes(1)(2) Memory Lock Bits Protection Type LB Mode LB2 LB1 1 1 1 No memory lock features enabled. 2 1 0 Further programming of the Flash and EEPROM is disabled in Parallel and Serial Programming mode. The Fuse bits are locked in both Serial and Parallel Programming mode.(1) 0 Further programming and verification of the Flash and EEPROM is disabled in Parallel and Serial Programming mode. The Boot Lock bits and Fuse bits are locked in both Serial and Parallel Programming mode.(1) 3 Notes: 0 1. Program the Fuse bits and Boot Lock bits before programming the LB1 and LB2. 2. “1” means unprogrammed, “0” means programmed 248 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Table 21-3. Lock Bit Protection Modes(1)(2). Only ATmega88/168. BLB0 Mode BLB02 BLB01 1 1 1 No restrictions for SPM or LPM accessing the Application section. 2 1 0 SPM is not allowed to write to the Application section. 0 SPM is not allowed to write to the Application section, and LPM executing from the Boot Loader section is not allowed to read from the Application section. If Interrupt Vectors are placed in the Boot Loader section, interrupts are disabled while executing from the Application section. LPM executing from the Boot Loader section is not allowed to read from the Application section. If Interrupt Vectors are placed in the Boot Loader section, interrupts are disabled while executing from the Application section. 3 0 4 0 1 BLB1 Mode BLB12 BLB11 1 1 1 No restrictions for SPM or LPM accessing the Boot Loader section. 2 1 0 SPM is not allowed to write to the Boot Loader section. 0 SPM is not allowed to write to the Boot Loader section, and LPM executing from the Application section is not allowed to read from the Boot Loader section. If Interrupt Vectors are placed in the Application section, interrupts are disabled while executing from the Boot Loader section. 1 LPM executing from the Application section is not allowed to read from the Boot Loader section. If Interrupt Vectors are placed in the Application section, interrupts are disabled while executing from the Boot Loader section. 3 0 4 Notes: 0 1. Program the Fuse bits and Boot Lock bits before programming the LB1 and LB2. 2. “1” means unprogrammed, “0” means programmed 21.2 Fuse Bits The AT90PWM81 has three Fuse bytes. Table 21-4 - Table 21-6 describe briefly the functionality of all the fuses and how they are mapped into the Fuse bytes. Note that the fuses are read as logical zero, “0”, if they are programmed. Table 21-4. Extended Low Fuse Byte Extended Fuse Byte Bit No Description Default Value PSC2RB 7 PSC2 Reset Behavior 1 PSC2RBA 6 PSC2 Reset Behavior for OUT22 & 23 1 PSCRRB 5 PSC Reduced Reset Behavior 1 PSCRV 4 PSCOUT & PSCOUTR Reset Value 1 PSCINRB 3 PSC & PSCR Inputs Reset Behavior 1 249 7734P–AVR–08/10 Table 21-4. Extended Low Fuse Byte Extended Fuse Byte BODLEVEL2 (1) BODLEVEL1 (1) BODLEVEL0 (1) Notes: 21.2.1 Bit No Description Default Value 2 Brown-out Detector trigger level 1 (unprogrammed) 1 Brown-out Detector trigger level 0 (programmed) 0 Brown-out Detector trigger level 1 (unprogrammed) 1. See Table 7-2 on page 52 for BODLEVEL Fuse decoding PSC Output Behavior During Reset For external component safety reason, the state of PSC outputs during Reset can be programmed by fuses PSCRV, PSCRRB & PSC2RB. These fuses are located in the Extended Fuse Byte ( see Table 21-4) PSCRV gives the state low or high which will be forced on PSC outputs selected by PSC0RB & PSC2RB fuses. If PSCRV fuse equals 0 (programmed), the selected PSC outputs will be forced to low state. If PSCRV fuse equals 1 (unprogrammed), the selected PSC outputs will be forced to high state. If PSCRRB fuse equals 1 (unprogrammed), PSCOUTR0 & PSCOUTR1 keep a standard port behavior. If PSC0RB fuse equals 0 (programmed), PSCOUTR0 & PSCOUTR1 are forced at reset to low level or high level according to PSCRV fuse bit. In this second case, PSCOUTR0 & PSCOUTR1 keep the forced state until PSOC0 register is written. If PSC2RB fuse equals 1 (unprogrammed), PSCOUT20 & PSCOUT21 keep a standard port behavior. If PSC2RB fuse equals 0 (programmed), PSCOUT20 & PSCOUT21 are forced at reset to low level or high level according to PSCRV fuse bit. In this second case, PSCOUT20 & PSCOUT21 keep the forced state until PSOC2 register is written. If PSC2RBA fuse equals 1 (unprogrammed), PSCOUT22 & PSCOUT23 keep a standard port behavior. If PSC2RBA fuse equals 0 (programmed), PSCOUT22 & PSCOUT23 are forced at reset to low level or high level according to PSCRV fuse bit. In this second case, PSCOUT22 & PSCOUT23 keep the forced state until PSOC2 register is written. 21.2.2 PSC Input Behavior During Reset For power consumption under reset reason, the state of PSC & PSCR inputs during Reset can be programmed by fuse PSCINRB. If PSCINRB fuse equals 1 (unprogrammed), PSC & PSCR input keep a standard port behavior. If PSCINRB fuse equals 0 (programmed), PSC & PSCR input pull-up are forced while the reset is active. Affected pins are PSCIN2, PSCINr, PSCIN2A, PSCINrA. To prevent any conflict on PD1, this fuse has no effect on PSCINrB. 250 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Table 21-5. Fuse High Byte High Fuse Byte Description Default Value 7 External Reset Disable 1 (unprogrammed) DWEN 6 debugWIRE Enable 1 (unprogrammed) SPIEN(2) 5 Enable Serial Program and Data Downloading 0 (programmed, SPI programming enabled) WDTON(3) 4 Watchdog Timer Always On 1 (unprogrammed) EESAVE 3 EEPROM memory is preserved through the Chip Erase 1 (unprogrammed), EEPROM not reserved BOOTSZ1 2 Select Boot Size (see Table 113 for details) 0 (programmed)(4) BOOTSZ0 1 Select Boot Size (see Table 113 for details) 0 (programmed)(4) BOOTRST 0 Select Reset Vector 1 (unprogrammed) RSTDISBL Notes: Bit No (1) 1. See “Alternate Functions of Port E” on page 78 for description of RSTDISBL Fuse. 2. The SPIEN Fuse is not accessible in serial programming mode. 3. See “Watchdog Timer Configuration” on page 59 for details. 4. The default value of BOOTSZ1..0 results in maximum Boot Size. See Table 21-7 on page 253 for details. Table 21-6. Low Fuse Byte Fuse Low Byte Description Default Value 7 Divide clock by 8 0 (programmed) CKOUT(3) 6 Clock output 1 (unprogrammed) SUT1 5 Select start-up time 1 (unprogrammed)(1) SUT0 4 Select start-up time 0 (programmed)(1) CKSEL3 3 Select Clock source 0 (programmed)(2) CKSEL2 2 Select Clock source 0 (programmed)(2) CKSEL1 1 Select Clock source 1 (unprogrammed)(2) CKSEL0 0 Select Clock source 0 (programmed)(2) CKDIV8 Note: (4) Bit No 1. The default value of SUT1..0 results in maximum start-up time for the default clock source. See Table 5-4 on page 30 for details. 2. The default setting of CKSEL3..0 results in internal RC Oscillator @ 8 MHz. See Table 5-1 on page 28 for details. 3. The CKOUT Fuse allows the system clock to be output on PORTD0. See “Clock Output Buffer” on page 34 for details. 4. See “System Clock Prescaler” on page 38 for details. The status of the Fuse bits is not affected by Chip Erase. Note that the Fuse bits are locked if Lock bit1 (LB1) is programmed. Program the Fuse bits before programming the Lock bits. 251 7734P–AVR–08/10 21.2.3 21.3 Latching of Fuses The fuse values are latched when the device enters programming mode and changes of the fuse values will have no effect until the part leaves Programming mode. This does not apply to the EESAVE Fuse which will take effect once it is programmed. The fuses are also latched on Power-up in Normal mode. Signature Bytes All Atmel microcontrollers have a three-byte signature code which identifies the device. This code can be read in both serial and parallel mode, also when the device is locked. The three bytes reside in a separate address space, the signature row. 21.3.1 Signature Bytes For the AT90PWM81 the signature bytes are: 21.4 1. 0x000: 0x1E (indicates manufactured by Atmel). 2. 0x002: 0x93 (indicates 8KB Flash memory). 3. 0x004: 0x88 (indicates AT90PWM81 device when 0x002 is 0x93). Calibration Byte The AT90PWM81 has a byte calibration value for the internal RC Oscillator. This byte resides in the byte of address 0x003 in the signature address space. During reset, this byte is automatically written into the OSCCAL Register to ensure correct frequency of the calibrated RC Oscillator. 21.5 Parallel Programming Parameters, Pin Mapping, and Commands This section describes how to parallel program and verify Flash Program memory, EEPROM Data memory, Memory Lock bits, and Fuse bits in the AT90PWM81. Pulses are assumed to be at least 250 ns unless otherwise noted. 21.5.1 Signal Names In this section, some pins of the AT90PWM81 are referenced by signal names describing their functionality during parallel programming, see Figure 21-1 and Table 21-7. Pins not described in the following table are referenced by pin names. The XA1/XA0 pins determine the action executed when the XTAL1 pin is given a positive pulse. The bit coding is shown in Table 21-9. When pulsing WR or OE, the command loaded determines the action executed. The different Commands are shown in Table 21-10. 252 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 21-1. Parallel Programming + 5V RDY/BSY AREF OE PD2 WR PD1 VCC + 5V AVCC XA0 XA1/BS2 PAGEL/BS1 + 12 V PD5 PB[7:0] PD6 DATA PE 2 RESET/PE0 XTAL1/PE1 GND Table 21-7. Pin Name Mapping Signal Name in Programming Mode Pin Name I/O RDY/BSY AREF O 0: Device is busy programming, 1: Device is ready for new command OE PD2 I Output Enable (Active low) WR PD1 I Write Pulse (Active low) XA0 PD5 I XTAL Action Bit 0 XA1/BS2 PD6 I XTAL Action Bit 1 Byte Select 2 (“0” selects Low byte, “1” selects 2’nd High byte) PAGEL/BS1 PE2 I Program memory and EEPROM Data Page Load Byte Select 1 (“0” selects Low byte, “1” selects High byte) DATA PB[7:0] I/O Bi-directional Data bus (Output when OE is low) Table 21-8. Function Pin Values Used to Enter Programming Mode Pin Symbol Value XA1/BS2 Prog_enable[3] 0 XA0 Prog_enable[2] 0 OE Prog_enable[1] 0 WR Prog_enable[0] 0 253 7734P–AVR–08/10 Table 21-9. XA1 and XA0 Coding XA1 XA0 0 0 Load Flash or EEPROM Address (High or low address byte determined by BS1). 0 1 Load Data (High or Low data byte for Flash determined by BS1). 1 0 Load Command 1 1 No Action, Idle Table 21-10. Action when XTAL1 is Pulsed Command Byte Bit Coding Command Byte 1000 0000 Chip Erase 0100 0000 Write Fuse bits 0010 0000 Write Lock bits 0001 0000 Write Flash 0001 0001 Write EEPROM 0000 1000 Read Signature Bytes and Calibration byte 0000 0100 Read Fuse and Lock bits 0000 0010 Read Flash 0000 0011 Read EEPROM Table 21-11. No. of Words in a Page and No. of Pages in the Flash Device Flash Size Page Size PCWORD No. of Pages PCPAGE PCMSB AT90PWM81 4K words (8K bytes) 32 words PC[4:0] 128 PC[11:5] 11 Table 21-12. 21.6 No. of Words in a Page and No. of Pages in the EEPROM Device EEPROM Size Page Size PCWORD No. of Pages PCPAGE EEAMSB AT90PWM81 512 bytes 4 bytes EEA[1:0] 128 EEA[8:2] 8 Serial Programming Pin Mapping Table 21-13. Pin Mapping Serial Programming Symbol 254 Command Executed Pins I/O Description MOSI I Serial Data in MISO O Serial Data out SCK I Serial Clock AT90PWM81 7734P–AVR–08/10 AT90PWM81 21.7 21.7.1 Parallel Programming Enter Programming Mode The following algorithm puts the device in Parallel (High-voltage) > Programming mode: 1. Set Prog_enable pins listed in Table 21-8. to “0000”, RESET pin to “0” and Vcc to 0V. 2. Apply 4.5 - 5.5V between VCC and GND. Ensure that Vcc reaches at least 1.8V within the next 20µs. 3. Wait 20 - 60µs, and apply 11.5 - 12.5V to RESET. 4. Keep the Prog_enable pins unchanged for at least 10µs after the High-voltage has been applied to ensure the Prog_enable Signature has been latched. 5. Wait at least 300µs before giving any parallel programming commands. 6. Exit Programming mode by power the device down or by bringing RESET pin to 0V. If the rise time of the Vcc is unable to fulfill the requirements listed above, the following alternative algorithm can be used. 21.7.2 1. Set Prog_enable pins listed in Table 21-8. to “0000”, RESET pin to “0” and Vcc to 0V. 2. Apply 4.5 - 5.5V between VCC and GND. 3. Monitor Vcc, and as soon as Vcc reaches 0.9 - 1.1V, apply 11.5 - 12.5V to RESET. 4. Keep the Prog_enable pins unchanged for at least 10µs after the High-voltage has been applied to ensure the Prog_enable Signature has been latched. 5. Wait until Vcc actually reaches 4.5 -5.5V before giving any parallel programming commands. 6. Exit Programming mode by power the device down or by bringing RESET pin to 0V. Considerations for Efficient Programming The loaded command and address are retained in the device during programming. For efficient programming, the following should be considered. • The command needs only be loaded once when writing or reading multiple memory locations. • Skip writing the data value 0xFF, that is the contents of the entire EEPROM (unless the EESAVE Fuse is programmed) and Flash after a Chip Erase. • Address high byte needs only be loaded before programming or reading a new 256 word window in Flash or 256 byte EEPROM. This consideration also applies to Signature bytes reading. 21.7.3 Chip Erase The Chip Erase will erase the Flash and EEPROM(1) memories plus Lock bits. The Lock bits are not reset until the program memory has been completely erased. The Fuse bits are not changed. A Chip Erase must be performed before the Flash and/or EEPROM are reprogrammed. Note: 1. The EEPRPOM memory is preserved during Chip Erase if the EESAVE Fuse is programmed. Load Command “Chip Erase” 1. Set XA1, XA0 to “10”. This enables command loading. 2. Set BS1 to “0”. 3. Set DATA to “1000 0000”. This is the command for Chip Erase. 4. Give XTAL1 a positive pulse. This loads the command. 5. Give WR a negative pulse. This starts the Chip Erase. RDY/BSY goes low. 6. Wait until RDY/BSY goes high before loading a new command. 255 7734P–AVR–08/10 21.7.4 Programming the Flash The Flash is organized in pages, see Table 21-11 on page 254. When programming the Flash, the program data is latched into a page buffer. This allows one page of program data to be programmed simultaneously. The following procedure describes how to program the entire Flash memory: A. Load Command “Write Flash” 1. Set XA1, XA0 to “10”. This enables command loading. 2. Set BS1 to “0”. 3. Set DATA to “0001 0000”. This is the command for Write Flash. 4. Give XTAL1 a positive pulse. This loads the command. B. Load Address Low byte 1. Set XA1, XA0 to “00”. This enables address loading. 2. Set BS1 to “0”. This selects low address. 3. Set DATA = Address low byte (0x00 - 0xFF). 4. Give XTAL1 a positive pulse. This loads the address low byte. C. Load Data Low Byte 1. Set XA1, XA0 to “01”. This enables data loading. 2. Set DATA = Data low byte (0x00 - 0xFF). 3. Give XTAL1 a positive pulse. This loads the data byte. D. Load Data High Byte 1. Set BS1 to “1”. This selects high data byte. 2. Set XA1, XA0 to “01”. This enables data loading. 3. Set DATA = Data high byte (0x00 - 0xFF). 4. Give XTAL1 a positive pulse. This loads the data byte. E. Latch Data 1. Set BS1 to “1”. This selects high data byte. 2. Give PAGEL a positive pulse. This latches the data bytes. (See Figure 21-3 for signal waveforms) F. Repeat B through E until the entire buffer is filled or until all data within the page is loaded. While the lower bits in the address are mapped to words within the page, the higher bits address the pages within the FLASH. This is illustrated in Figure 21-2 on page 257. Note that if less than eight bits are required to address words in the page (pagesize < 256), the most significant bit(s) in the address low byte are used to address the page when performing a Page Write. G. Load Address High byte 1. Set XA1, XA0 to “00”. This enables address loading. 2. Set BS1 to “1”. This selects high address. 3. Set DATA = Address high byte (0x00 - 0xFF). 4. Give XTAL1 a positive pulse. This loads the address high byte. H. Program Page 1. Give WR a negative pulse. This starts programming of the entire page of data. RDY/BSY goes low. 2. Wait until RDY/BSY goes high (See Figure 21-3 for signal waveforms). I. Repeat B through H until the entire Flash is programmed or until all data has been programmed. 256 AT90PWM81 7734P–AVR–08/10 AT90PWM81 J. End Page Programming 1. 1. Set XA1, XA0 to “10”. This enables command loading. 2. Set DATA to “0000 0000”. This is the command for No Operation. 3. Give XTAL1 a positive pulse. This loads the command, and the internal write signals are reset. Figure 21-2. Addressing the Flash Which is Organized in Pages(1) PCMSB PROGRAM COUNTER PAGEMSB PCPAGE PCWORD PAGE ADDRESS WITHIN THE FLASH WORD ADDRESS WITHIN A PAGE PROGRAM MEMORY PAGE PAGE PCWORD[PAGEMSB:0]: 00 INSTRUCTION WORD 01 02 PAGEEND Note: 1. PCPAGE and PCWORD are listed in Table 21-11 on page 254. Figure 21-3. Programming the Flash Waveforms(1) F DATA A B 0x10 ADDR. LOW C DATA LOW D DATA HIGH E XX B ADDR. LOW C D DATA LOW DATA HIGH E XX G ADDR. HIGH H XX XA1/BS2 XA0 PAGEL/BS1 XTAL1 WR RDY/BSY RESET +12V OE Note: 21.7.5 1. “XX” is don’t care. The letters refer to the programming description above. Programming the EEPROM The EEPROM is organized in pages, see Table 21-12 on page 254. When programming the EEPROM, the program data is latched into a page buffer. This allows one page of data to be programmed simultaneously. The programming algorithm for the EEPROM data memory is as follows (refer to “Programming the Flash” on page 256 for details on Command, Address and Data loading): 257 7734P–AVR–08/10 1. A: Load Command “0001 0001”. 2. G: Load Address High Byte (0x00 - 0xFF). 3. B: Load Address Low Byte (0x00 - 0xFF). 4. C: Load Data (0x00 - 0xFF). 5. E: Latch data (give PAGEL a positive pulse). K: Repeat 3 through 5 until the entire buffer is filled. L: Program EEPROM page 1. Set BS1 to “0”. 2. Give WR a negative pulse. This starts programming of the EEPROM page. RDY/BSY goes low. 3. Wait until to RDY/BSY goes high before programming the next page (See Figure 21-4 for signal waveforms). Figure 21-4. Programming the EEPROM Waveforms K DATA A G 0x11 ADDR. HIGH B ADDR. LOW C DATA E XX B ADDR. LOW C DATA E L XX XA1/BS2 XA0 PAGEL/BS1 XTAL1 WR RDY/BSY RESET +12V OE 21.7.6 21.7.7 Reading the Flash The algorithm for reading the Flash memory is as follows (refer to “Programming the Flash” on page 256 for details on Command and Address loading): 1. A: Load Command “0000 0010”. 2. G: Load Address High Byte (0x00 - 0xFF). 3. B: Load Address Low Byte (0x00 - 0xFF). 4. Set OE to “0”, and BS1 to “0”. The Flash word low byte can now be read at DATA. 5. Set BS1 to “1”. The Flash word high byte can now be read at DATA. 6. Set OE to “1”. Reading the EEPROM The algorithm for reading the EEPROM memory is as follows (refer to “Programming the Flash” on page 256 for details on Command and Address loading): 1. 258 A: Load Command “0000 0011”. 2. G: Load Address High Byte (0x00 - 0xFF). 3. B: Load Address Low Byte (0x00 - 0xFF). AT90PWM81 7734P–AVR–08/10 AT90PWM81 21.7.8 21.7.9 21.7.10 4. Set OE to “0”, and BS1 to “0”. The EEPROM Data byte can now be read at DATA. 5. Set OE to “1”. Programming the Fuse Low Bits The algorithm for programming the Fuse Low bits is as follows (refer to “Programming the Flash” on page 256 for details on Command and Data loading): 1. A: Load Command “0100 0000”. 2. C: Load Data Low Byte. Bit n = “0” programs and bit n = “1” erases the Fuse bit. 3. Give WR a negative pulse and wait for RDY/BSY to go high. Programming the Fuse High Bits The algorithm for programming the Fuse High bits is as follows (refer to “Programming the Flash” on page 256 for details on Command and Data loading): 1. A: Load Command “0100 0000”. 2. C: Load Data Low Byte. Bit n = “0” programs and bit n = “1” erases the Fuse bit. 3. Set BS1 to “1” and BS2 to “0”. This selects high data byte. 4. Give WR a negative pulse and wait for RDY/BSY to go high. 5. Set BS1 to “0”. This selects low data byte. Programming the Extended Fuse Bits The algorithm for programming the Extended Fuse bits is as follows (refer to “Programming the Flash” on page 256 for details on Command and Data loading): 1. 1. A: Load Command “0100 0000”. 2. 2. C: Load Data Low Byte. Bit n = “0” programs and bit n = “1” erases the Fuse bit. 3. 3. Set BS1 to “0” and BS2 to “1”. This selects extended data byte. 4. 4. Give WR a negative pulse and wait for RDY/BSY to go high. 5. 5. Set BS2 to “0”. This selects low data byte. Figure 21-5. Programming the FUSES Waveforms Write Fuse Low byte DATA A C 0x40 DATA XX Write Fuse high byte A C 0x40 DATA XX Write Extended Fuse byte A C 0x40 DATA XX XA1/BS2 XA0 PAGEL/BS1 XTAL1 WR RDY/BSY RESET +12V OE 259 7734P–AVR–08/10 21.7.11 Programming the Lock Bits The algorithm for programming the Lock bits is as follows (refer to “Programming the Flash” on page 256 for details on Command and Data loading): 1. A: Load Command “0010 0000”. 2. C: Load Data Low Byte. Bit n = “0” programs the Lock bit. If LB mode 3 is programmed (LB1 and LB2 is programmed), it is not possible to program the Boot Lock bits by any External Programming mode. 3. Give WR a negative pulse and wait for RDY/BSY to go high. The Lock bits can only be cleared by executing Chip Erase. 21.7.12 Reading the Fuse and Lock Bits The algorithm for reading the Fuse and Lock bits is as follows (refer to “Programming the Flash” on page 256 for details on Command loading): 1. A: Load Command “0000 0100”. 2. Set OE to “0”, BS2 to “0” and BS1 to “0”. The status of the Fuse Low bits can now be read at DATA (“0” means programmed). 3. Set OE to “0”, BS2 to “1” and BS1 to “1”. The status of the Fuse High bits can now be read at DATA (“0” means programmed). 4. Set OE to “0”, BS2 to “1”, and BS1 to “0”. The status of the Extended Fuse bits can now be read at DATA (“0” means programmed). 5. Set OE to “0”, BS2 to “0” and BS1 to “1”. The status of the Lock bits can now be read at DATA (“0” means programmed). 6. Set OE to “1”. Figure 21-6. Mapping Between BS1, BS2 and the Fuse and Lock Bits During Read 0 Fuse Low Byte 0 Extended Fuse Byte 1 DATA BS2 0 Lock Bits 1 Fuse High Byte 1 BS1 BS2 21.7.13 260 Reading the Signature Bytes The algorithm for reading the Signature bytes is as follows (refer to “Programming the Flash” on page 256 for details on Command and Address loading): 1. A: Load Command “0000 1000”. 2. B: Load Address Low Byte (0x00 - 0x02). 3. Set OE to “0”, and BS1 to “0”. The selected Signature byte can now be read at DATA. 4. Set OE to “1”. AT90PWM81 7734P–AVR–08/10 AT90PWM81 21.7.14 Reading the Calibration Byte The algorithm for reading the Calibration byte is as follows (refer to “Programming the Flash” on page 256 for details on Command and Address loading): 1. A: Load Command “0000 1000”. 2. B: Load Address Low Byte, 0x00. 3. Set OE to “0”, and BS1 to “1”. The Calibration byte can now be read at DATA. 4. Set OE to “1”. 2. 21.8 Serial Downloading Both the Flash and EEPROM memory arrays can be programmed using the serial SPI bus while RESET is pulled to GND. The serial interface consists of pins SCK, MOSI (input) and MISO (output). After RESET is set low, the Programming Enable instruction needs to be executed first before program/erase operations can be executed. NOTE, in Table 21-13 on page 254, the pin mapping for SPI programming is listed. Not all parts use the SPI pins dedicated for the internal SPI interface. Figure 21-7. Serial Programming and Verify(1) +1.8 - 5.5V VCC +1.8 - 5.5V(2) MOSI_A AVCC MISO_A SCK_A XTAL1 RESET GND Notes: 1. If the device is clocked by the internal Oscillator, it is no need to connect a clock source to the XTAL1 pin. 2. VCC - 0.3V < AVCC < VCC + 0.3V, however, AVCC should always be within 1.8 - 5.5V When programming the EEPROM, an auto-erase cycle is built into the self-timed programming operation (in the Serial mode ONLY) and there is no need to first execute the Chip Erase instruction. The Chip Erase operation turns the content of every memory location in both the Program and EEPROM arrays into 0xFF. Depending on CKSEL Fuses, a valid clock must be present. The minimum low and high periods for the serial clock (SCK) input are defined as follows: Low: > 2 CPU clock cycles for fck < 12 MHz, 3 CPU clock cycles for fck >= 12 MHz High: > 2 CPU clock cycles for fck < 12 MHz, 3 CPU clock cycles for fck >= 12 MHz 21.8.1 Serial Programming Algorithm When writing serial data to the AT90PWM81, data is clocked on the rising edge of SCK. 261 7734P–AVR–08/10 When reading data from the AT90PWM81, data is clocked on the falling edge of SCK. See Figure 21-8 for timing details. To program and verify the AT90PWM81 in the serial programming mode, the following sequence is recommended (See four byte instruction formats in Table 21-15): 1. Power-up sequence: Apply power between VCC and GND while RESET and SCK are set to “0”. In some systems, the programmer can not guarantee that SCK is held low during power-up. In this case, RESET must be given a positive pulse of at least two CPU clock cycles duration after SCK has been set to “0”. 2. Wait for at least 20 ms and enable serial programming by sending the Programming Enable serial instruction to pin MOSI. 3. The serial programming instructions will not work if the communication is out of synchronization. When in sync. the second byte (0x53), will echo back when issuing the third byte of the Programming Enable instruction. Whether the echo is correct or not, all four bytes of the instruction must be transmitted. If the 0x53 did not echo back, give RESET a positive pulse and issue a new Programming Enable command. 4. The Flash is programmed one page at a time. The memory page is loaded one byte at a time by supplying the 6 LSB of the address and data together with the Load Program Memory Page instruction. To ensure correct loading of the page, the data low byte must be loaded before data high byte is applied for a given address. The Program Memory Page is stored by loading the Write Program Memory Page instruction with the 8 MSB of the address. If polling is not used, the user must wait at least tWD_FLASH before issuing the next page. (See Table 21-14.) Accessing the serial programming interface before the Flash write operation completes can result in incorrect programming. 5. The EEPROM array is programmed one byte at a time by supplying the address and data together with the appropriate Write instruction. An EEPROM memory location is first automatically erased before new data is written. If polling is not used, the user must wait at least tWD_EEPROM before issuing the next byte. (See Table 21-14.) In a chip erased device, no 0xFFs in the data file(s) need to be programmed. 6. Any memory location can be verified by using the Read instruction which returns the content at the selected address at serial output MISO. 7. At the end of the programming session, RESET can be set high to commence normal operation. 8. Power-off sequence (if needed): Set RESET to “1”. Turn VCC power off. 21.8.2 Data Polling Flash When a page is being programmed into the Flash, reading an address location within the page being programmed will give the value 0xFF. At the time the device is ready for a new page, the programmed value will read correctly. This is used to determine when the next page can be written. Note that the entire page is written simultaneously and any address within the page can be used for polling. Data polling of the Flash will not work for the value 0xFF, so when programming this value, the user will have to wait for at least tWD_FLASH before programming the next page. As a chip-erased device contains 0xFF in all locations, programming of addresses that are meant to contain 0xFF, can be skipped. See Table 21-14 for tWD_FLASH value. 21.8.3 Data Polling EEPROM When a new byte has been written and is being programmed into EEPROM, reading the address location being programmed will give the value 0xFF. At the time the device is ready for a new byte, the pro- 262 AT90PWM81 7734P–AVR–08/10 AT90PWM81 grammed value will read correctly. This is used to determine when the next byte can be written. This will not work for the value 0xFF, but the user should have the following in mind: As a chip-erased device contains 0xFF in all locations, programming of addresses that are meant to contain 0xFF, can be skipped. This does not apply if the EEPROM is re-programmed without chip erasing the device. In this case, data polling cannot be used for the value 0xFF, and the user will have to wait at least t WD_EEPROM before programming the next byte. See Table 21-14 for tWD_EEPROM value. Table 21-14. Minimum Wait Delay Before Writing the Next Flash or EEPROM Location Symbol Minimum Wait Delay tWD_FLASH 4.5 ms tWD_EEPROM 3.6 ms tWD_ERASE 9.0 ms Figure 21-8. Serial Programming Waveforms SERIAL DATA INPUT (MOSI) MSB LSB SERIAL DATA OUTPUT (MISO) MSB LSB SERIAL CLOCK INPUT (SCK) SAMPLE Table 21-15. Serial Programming Instruction Set Instruction Format Instruction Programming Enable Chip Erase Read Program Memory Byte 1 Byte 2 Byte 3 Byte4 1010 1100 0101 0011 xxxx xxxx xxxx xxxx Enable Serial Programming after RESET goes low. 1010 1100 100x xxxx xxxx xxxx xxxx xxxx Chip Erase EEPROM and Flash. 0010 H000 000a aaaa bbbb bbbb oooo oooo Read H (high or low) data o from Program memory at word address a:b. 0100 H000 000x xxxx xxbb bbbb iiii iiii Write H (high or low) data i to Program Memory page at word address b. Data low byte must be loaded before Data high byte is applied within the same address. 0100 1100 000a aaaa bbxx xxxx xxxx xxxx Write Program Memory Page at address a:b. 1010 0000 000x xxaa bbbb bbbb oooo oooo Read data o from EEPROM memory at address a:b. 1100 0000 000x xxaa bbbb bbbb iiii iiii 1100 0001 0000 0000 0000 00bb iiii iiii Load Program Memory Page Write Program Memory Page Read EEPROM Memory Write EEPROM Memory Load EEPROM Memory Page (page access) Operation Write data i to EEPROM memory at address a:b. Load data i to EEPROM memory page buffer. After data is loaded, program EEPROM page. 263 7734P–AVR–08/10 Table 21-15. Serial Programming Instruction Set (Continued) Instruction Format Instruction Write EEPROM Memory Page (page access) Byte 1 Byte 2 Byte 3 Byte4 1100 0010 00xx xxaa bbbb bb00 xxxx xxxx 0101 1000 0000 0000 xxxx xxxx xxoo oooo Read Lock bits. “0” = programmed, “1” = unprogrammed. See Table 21-1 on page 247 for details. 1010 1100 111x xxxx xxxx xxxx 11ii iiii Write Lock bits. Set bits = “0” to program Lock bits. See Table 21-1 on page 247 for details. 0011 0000 000x xxxx xxxx xxbb oooo oooo 1010 1100 1010 0000 xxxx xxxx iiii iiii Set bits = “0” to program, “1” to unprogram. See Table XXX on page XXX for details. 1010 1100 1010 1000 xxxx xxxx iiii iiii Set bits = “0” to program, “1” to unprogram. See Table 21-5 on page 251 for details. 1010 1100 1010 0100 xxxx xxxx xxxx xxii Set bits = “0” to program, “1” to unprogram. See Table 21-4 on page 249 for details. 0101 0000 0000 0000 xxxx xxxx oooo oooo Read Fuse bits. “0” = programmed, “1” = unprogrammed. See Table XXX on page XXX for details. 0101 1000 0000 1000 xxxx xxxx oooo oooo Read Fuse High bits. “0” = pro-grammed, “1” = unprogrammed. See Table 21-5 on page 251 for details. 0101 0000 0000 1000 xxxx xxxx oooo oooo Read Extended Fuse bits. “0” = programmed, “1” = unprogrammed. See Table 21-4 on page 249 for details. 0011 1000 000x xxxx 0000 0000 oooo oooo Read Calibration Byte 1111 0000 0000 0000 xxxx xxxx xxxx xxxo If o = “1”, a programming operation is still busy. Wait until this bit returns to “0” before applying another command. Read Lock bits Write Lock bits Read Signature Byte Write Fuse bits Write Fuse High bits Write Extended Fuse Bits Read Fuse bits Read Fuse High bits Read Extended Fuse Bits Read Calibration Byte Poll RDY/BSY Note: 21.8.4 264 Operation Write EEPROM page at address a:b. Read Signature Byte o at address b. a = address high bits, b = address low bits, H = 0 - Low byte, 1 - High Byte, o = data out, i = data in, x = don’t care SPI Serial Programming Characteristics For characteristics of the SPI module see “SPI Serial Programming Characteristics” on page 264. AT90PWM81 7734P–AVR–08/10 AT90PWM81 22. Electrical Characteristics(1) 22.1 Absolute Maximum Ratings* Operating Temperature............................................ -40°C to +105°C Or Operating Temperature ...................................... -40°C to +125°C Storage Temperature ............................................... -65°C to +150°C Voltage on any Pin except RESET with respect to Ground .........................................-1.0V to VCC+0.5V Voltage on RESET with respect to Ground.............. -1.0V to +13.0V *NOTICE: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Maximum Operating Voltage ......................................................6.0V DC Current per I/O Pin .........................................................40.0 mA DC Current VCC and GND Pins .........................................200.0 mA Note: 1. Electrical Characteristics for this product have not yet been finalized. Please consider all values listed herein as preliminary and non-contractual. 265 7734P–AVR–08/10 22.2 DC Characteristics TA = -40°C to +105°C, VCC = 2.7V to 5.5V (unless otherwise noted) Symbol Parameter Condition Min. VIL Input Low Voltage Port B & D and XTAL1, XTAL2 pins as I/O VIH Input High Voltage Port B D and XTAL1, XTAL2 pins as I/O VIL1 Input Low Voltage VIH1 VIL2 VIH2 Max. Units -0.5 0.2VCC(1) V 0.6VCC(2) VCC+0.5 V XTAL1 pin , External Clock Selected -0.5 0.1VCC(1) V Input High Voltage XTAL1 pin , External Clock Selected 0.7VCC(2) VCC+0.5 V Input Low Voltage RESET pin -0.5 0.2VCC(1) V RESET pin 0.9VCC(2) VCC+0.5 V V Input High Voltage Typ. VIL3 Input Low Voltage RESET pin as I/O -0.5 0.2VCC(1) VIH3 Input High Voltage RESET pin as I/O 0.8VCC(2) VCC+0.5 V VOL Output Low Voltage(3) (Port B & D and XTAL1, XTAL2 pins as I/O) IOL = 10 mA, VCC = 5V IOL = 5 mA, VCC = 3V 0.6 0.5 V V VOH Output High Voltage(4) (Port B & D and XTAL1, XTAL2 pins as I/O) IOH = -10 mA, VCC = 5V IOH = -5 mA, VCC = 3V VOL3 Output Low Voltage(3) (RESET pin as I/O) IOL = 2.1 mA, VCC = 5V IOL = 0.8 mA, VCC = 3V VOH3 Output High Voltage(4) (RESET pin as I/O) IOH = -0.6 mA, VCC = 5V IOH = -0.4 mA, VCC = 3V IIL Input Leakage Current I/O Pin VCC = 5.5V, pin low (absolute value) 1 µA IIH Input Leakage Current I/O Pin VCC = 5.5V, pin high (absolute value) 1 µA RRST Reset Pull-up Resistor 30 200 kΩ Rpu I/O Pin Pull-up Resistor 20 50 kΩ 266 4.3 2.5 V V 0.7 0.5 3.8 2.2 V V V V AT90PWM81 7734P–AVR–08/10 AT90PWM81 TA = -40°C to +105°C, VCC = 2.7V to 5.5V (unless otherwise noted) (Continued) Symbol Parameter Condition Power Supply Current Min. Typ. Max. Units Active 8 MHz, VCC = 3V, RC osc, , @25°C, PRR = 0xFF 3.5 5 mA Active 16 MHz, VCC = 5V, Ext Clock, , @25°C, PRR = 0xFF 10.5 15 mA Idle 8 MHz, VCC = 3V, RC Osc, @25°C 1.5 2 mA Idle 16 MHz, VCC = 5V, Ext Clock, @25°C 4.5 7 mA WDT enabled, VCC = 3V 25°C 7 WDT enabled, VCC = 3V 105°C ICC 30 WDT enabled, VCC = 5V 25°C (5) µA 10 WDT enabled, VCC = 5V 105°C µA 50 Power-down mode WDT disabled, VCC = 3V 25°C 0.5 WDT disabled, VCC = 3V 105°C 25 WDT disabled, VCC = 5V 25°C 1 WDT disabled, VCC = 5V 105°C VREF Internal voltage reference(7) @25°C Analog Comparator input common mode range VACIO Analog Comparator Input Offset Voltage µA 2.46 2.56 0.1 40 µA 2.66 V Vcc - 0.1 V Input offset voltage 0.1<Vin<Vcc-0.1V ± 1.5 ± 10 mV With ± 10mV Hysteresis 0.1<Vin<Vcc-0.1V ± 10 ± 20 mV With ± 25mV Hysteresis 0.1<Vin<Vcc-0.1V ± 25 ± 60 mV 50 nA IACLK Analog Comparator Input Leakage Current VCC = 5V Vin = VCC/2 tACID Analog Comparator Propagation Delay VCC = 2.7V VCC = 5.0V -50 50 (6) ns 267 7734P–AVR–08/10 TA = -40°C to +125°C, VCC = 2.7V to 5.5V (unless otherwise noted) (Continued) Symbol Parameter Condition Min. VIL Input Low Voltage Port B & D and XTAL1, XTAL2 pins as I/O VIH Input High Voltage Port B D and XTAL1, XTAL2 pins as I/O VIL1 Input Low Voltage VIH1 Max. Units -0.5 0.2VCC(1) V 0.6VCC(2) VCC+0.5 V XTAL1 pin , External Clock Selected -0.5 0.1VCC(1) V Input High Voltage XTAL1 pin , External Clock Selected 0.7VCC(2) VCC+0.5 V VIL2 Input Low Voltage RESET pin -0.5 0.2VCC(1) V VIH2 Input High Voltage RESET pin 0.9VCC(2) VCC+0.5 V RESET pin as I/O -0.5 0.2VCC(1) V RESET pin as I/O 0.8VCC(2) VCC+0.5 V 0.6 0.5 V V VIL3 VIH3 Input Low Voltage Input High Voltage Typ. (3) VOL Output Low Voltage (Port B & D and XTAL1, XTAL2 pins as I/O) IOL = 10 mA, VCC = 5V IOL = 5 mA, VCC = 3V VOH Output High Voltage(4) (Port B & D and XTAL1, XTAL2 pins as I/O) IOH = -10 mA, VCC = 5V IOH = -5 mA, VCC = 3V VOL3 Output Low Voltage(3) (RESET pin as I/O) IOL = 2.1 mA, VCC = 5V IOL = 0.8 mA, VCC = 3V VOH3 Output High Voltage(4) (RESET pin as I/O) IOH = -0.6 mA, VCC = 5V IOH = -0.4 mA, VCC = 3V IIL Input Leakage Current I/O Pin VCC = 5.5V, pin low (absolute value) 1 µA IIH Input Leakage Current I/O Pin VCC = 5.5V, pin high (absolute value) 1 µA RRST Reset Pull-up Resistor 30 200 kΩ Rpu I/O Pin Pull-up Resistor 20 50 kΩ 268 4.3 2.5 V V 0.7 0.5 3.8 2.2 V V V V AT90PWM81 7734P–AVR–08/10 AT90PWM81 Symbol Parameter Condition Min. Typ. Max. Units Active 8 MHz, VCC = 3V, RC osc, PRR = 0xFF 3.5 5 mA Active 16 MHz, VCC = 5V, Ext Clock, PRR = 0xFF 10.5 15 mA Idle 8 MHz, VCC = 3V, RC Osc, @25°C 1.5 2 mA Idle 16 MHz, VCC = 5V, Ext Clock, @25°C 4.5 7 mA Power Supply Current WDT enabled, VCC = 3V 25°C 7 WDT enabled, VCC = 3V 105°C 30 µA WDT enabled, VCC = 3V 125°C 70 µA WDT enabled, VCC = 5V 25°C ICC (5) µA 10 µA WDT enabled, VCC = 5V 105°C 50 µA WDT enabled, VCC = 5V 125°C 110 µA Power-down mode WDT disabled, VCC = 3V 25°C 0.5 WDT disabled, VCC = 3V 105°C 25 µA WDT disabled, VCC = 3V 125°C 35 µA WDT disabled, VCC = 5V 25°C VREF Internal voltage reference(7) Analog Comparator Input Offset Voltage 1 µA WDT disabled, VCC = 5V 105°C 40 µA WDT disabled, VCC = 5V 125°C 55 µA 2.66 V Vcc - 0.1 V @25°C Analog Comparator input common mode range VACIO µA 2.46 2.56 0.1 Input offset voltage 0.1<Vin<Vcc-0.1V ± 1.5 ± 10 mV With ± 10mV Hysteresis 0.1<Vin<Vcc-0.1V ± 10 ± 20 mV With ± 25mV Hysteresis 0.1<Vin<Vcc-0.1V ± 25 ± 60 mV 269 7734P–AVR–08/10 Symbol Parameter Condition IACLK Analog Comparator Input Leakage Current VCC = 5V Vin = VCC/2 tACID Analog Comparator Propagation Delay VCC = 2.7V VCC = 5.0V Note: Min. Typ. -50 Max. Units 50 nA 50 (6) ns 1. “Max” means the highest value where the pin is guaranteed to be read as low 2. “Min” means the lowest value where the pin is guaranteed to be read as high 3. Although each I/O port can sink more than the test conditions (20 mA at VCC = 5V, 10 mA at VCC = 3V) under steady state conditions (non-transient), the following must be observed: SO20 and TQFN Package: 1] The sum of all IOL, for all ports, should not exceed 400 mA. 2] The sum of all IOL, for ports B6 - B7, D0 - D3, E0 should not exceed 100 mA. 3] The sum of all IOL, for ports B0 - B1, D4, E1 - E2 should not exceed 100 mA. If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater than the listed test condition. 4. Although each I/O port can source more than the test conditions (20 mA at Vcc = 5V, 10 mA at Vcc = 3V) under steady state conditions (non-transient), the following must be observed: SO20 and TQFN Package: 1] The sum of all IOH, for all ports, should not exceed 400 mA. 2] The sum of all IOH, for ports B6 - B7, D0 - D3, E0 should not exceed 150 mA. 3] The sum of all IOH, for ports B0 - B1, D4, E1 - E2 should not exceed 150 mA. If IOH exceeds the test condition, VOH may exceed the related specification. Pins are not guaranteed to source current greater than the listed test condition. 5. Minimum VCC for Power-down is 2.5V. 6. Propagation delay of the internal comparator with 100mV overdrive condition. 7. accuracy : ±8% from -40°C to +125°C 22.3 22.3.1 Clock Drive Characteristics Calibrated Internal RC Oscillator Accuracy Table 22-1. Calibration Accuracy of Internal RC Oscillator Frequency VCC Temperature Calibration Accuracy Factory Calibration 8.0 MHz 3V 25°C ±1% Factory Calibration 8.0 MHz 2.7V - 5.5V -40°C +105 or 125°C ±6% User Calibration 7.6 - 8.4 MHz 2.7V - 5.5V -40°C +105 or 125°C ±5% 270 AT90PWM81 7734P–AVR–08/10 AT90PWM81 22.3.2 Watchdog Oscillator Accuracy Table 22-2. 22.3.3 Accuracy of Watchdog Oscillator Frequency Calibration Accuracy 128 kHz ±40% External Clock Drive Waveforms Figure 22-1. External Clock Drive Waveforms V IH1 V IL1 22.3.4 External Clock Drive Table 22-3. External Clock Drive VCC=2.7-5.5V 22.4 VCC=4.5-5.5V Min. Max. Min. Max. Units Oscillator Frequency 0 12 0 16 MHz tCLCL Clock Period 83 62 ns tCHCX High Time 30 20 ns tCLCX Low Time 30 20 ns tCLCH Rise Time 1.6 0.5 μs tCHCL Fall Time 1.6 0.5 μs ΔtCLCL Change in period from one clock cycle to the next 2 2 % Symbol Parameter 1/tCLCL Maximum Speed vs. VCC Maximum frequency is depending on VCC. As shown in Figure 22-2 , the Maximum Frequency equals 12MHz when VCC is contained between 2.7V and 4.5V and equals 16Mhz when VCC is contained between 4.5V and 5.5V. 271 7734P–AVR–08/10 Figure 22-2. Maximum Frequency vs. VCC, AT90PWM81 16Mhz 12Mhz 8Mhz Safe Operating Area 2.7V 22.5 4.5V 5.5V PLL Characteristics . Table 22-4. Symbol PLLIF 272 PLL Characteristics - VCC = 2.7V to 5.5V (unless otherwise noted) Parameter Input Frequency PLLF PLL Factor PLLLT Lock-in Time Min. (1) Typ. Max. 8 4 Units MHz 8 (2) 64 µS 1. While connected to external clock or external oscillator, PLL Input Frequency must be selected to provide outputs with frequency in accordance with driven parts of the circuit (CPU core, PSC... 2. When Vcc is below 4.5V, Max. PLLF is 6. AT90PWM81 7734P–AVR–08/10 AT90PWM81 22.6 SPI Timing Characteristics See Figure 22-3 and Figure 22-4 for details. Table 22-5. SPI Timing Parameters Description Mode 1 SCK period Master See Table 14-5 2 SCK high/low Master 50% duty cycle 3 Rise/Fall time Master 3.6 4 Setup Master 10 5 Hold Master 10 6 Out to SCK Master 0.5 • tsck 7 SCK to out Master 10 8 SCK to out high Master 10 9 SS low to out Slave 15 10 SCK period Slave 4 • tck 11 SCK high/low (1) Slave 2 • tck 12 Rise/Fall time Slave 13 Setup Slave 10 14 Hold Slave tck 15 SCK to out Slave 16 SCK to SS high Slave 17 SS high to tri-state Slave 18 SS low to SCK Slave Note: Min. Typ. Max. ns 1.6 15 20 10 2 • tck In SPI Programming mode the minimum SCK high/low period is: - 2 tCLCL for fCK < 12 MHz - 3 tCLCL for fCK >12 MHz Figure 22-3. SPI Interface Timing Requirements (Master Mode) SS 6 1 SCK (CPOL = 0) 2 2 SCK (CPOL = 1) 4 MISO (Data Input) 5 3 MSB ... LSB 7 MOSI (Data Output) MSB 8 ... LSB 273 7734P–AVR–08/10 Figure 22-4. SPI Interface Timing Requirements (Slave Mode) SS 10 9 16 SCK (CPOL = 0) 11 11 SCK (CPOL = 1) 13 MOSI (Data Input) 14 12 MSB ... LSB 15 MISO (Data Output) 274 MSB 17 ... LSB X AT90PWM81 7734P–AVR–08/10 AT90PWM81 22.7 ADC Characteristics Table 22-6. Symbol ADC Characteristics - TA = -45°C to +105°C, VCC = 2.7V to 5.5V (unless otherwise noted) Parameter Resolution Absolute accuracy Integral Non-linearity Condition Min Typ Max Single Ended Conversion 10 Differential conversion, Gain=5X or 10x 8 Differential conversion, Gain=20X or 40x 8 Single Ended Conversion Vcc=4V,VREF = 4V ADC clock = 1 MHz 2 4 Single Ended Conversion Vcc=2.7V,VREF =2.56V ADC clock = 2 MHz 2.2 4 Differential conversion, Gain=5X or 10x Vcc=5V,VREF = 4V ADC clock = 1 MHz 1.2 2.0 Differential conversion, Gain=20X or 40x Vcc=5V,VREF = 4V ADC clock = 2MHz 1.5 3.0 Single Ended Conversion Vcc=4V,VREF = 4V ADC clock = 1 MHz 0.6 1 Single Ended Conversion Vcc=4V,VREF = 4V ADC clock = 2 MHz 0.8 1.5 Single Ended Conversion Vcc=2.7V,VREF =2.56V ADC clock = 2 MHz 1.0 2.5 Differential conversion, Gain=5X or 10x Vcc=5V,VREF = 4V ADC clock = 1 MHz 0.5 1.0 Differential conversion, Gain=20X or 40x Vcc=5V,VREF = 4V ADC clock = 2MHz 0.8 2.0 Units Bits LSB LSB 275 7734P–AVR–08/10 Table 22-6. Symbol ADC Characteristics - TA = -45°C to +105°C, VCC = 2.7V to 5.5V (unless otherwise noted) (Continued) Parameter Differential Non-linearity Gain Error Offset Error Conversion Time Condition Typ Max Single Ended Conversion Vcc=4V,VREF = 4V ADC clock = 1 MHz 0.2 0.5 Single Ended Conversion Vcc=4V,VREF = 4V ADC clock = 2 MHz 0.6 1 Single Ended Conversion Vcc=2.7V,VREF =2.56V ADC clock = 2 MHz 1.0 2.5 Differential conversion, Gain=5X or 10x Vcc=5V,VREF = 4V ADC clock = 1 MHz 0.3 0.8 Differential conversion, Gain=20X or 40x Vcc=5V,VREF = 4V ADC clock = 2MHz 0.5 1.0 Analog Supply Voltage VREF Reference Voltage VIN Units LSB Single Ended Conversion Vcc=4V,VREF = 4V ADC clock = 1 MHz 0.0 -6.0 Single Ended Conversion Vcc=2.7V,VREF =2.56V ADC clock = 2 MHz 0.0 -6.0 Differential conversion, Vcc=5V,VREF = 4V ADC clock = 1 MHz -2.0 +2.0 Single Ended Conversion Vcc=4V,VREF = 4V ADC clock = 1 MHz -1.0 2.0 Single Ended Conversion Vcc=2.7V,VREF =2.56V ADC clock = 2 MHz 1.0 4.0 Differential conversion, Vcc=5V,VREF = 4V ADC clock = 1 MHz -1.0 +1.0 8 260 µs 50 2000 kHz VCC - 0.3 VCC + 0.3 V 2.56 AVCC - 0.6 V GND VREF -VREF/Gain +VREF/Gain Single Conversion Clock Frequency AVCC Min Single Ended Conversion Input voltage Differential Conversion Single Ended Conversion LSB LSB 38.5 kHz 4 kHz Input bandwidth Differential Conversion 276 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Table 22-6. Symbol ADC Characteristics - TA = -45°C to +105°C, VCC = 2.7V to 5.5V (unless otherwise noted) (Continued) Parameter Condition Min Typ Max Units RREF Reference Input Resistance 30 kΩ RAIN Analog Input Resistance 23 KΩ CAIN Analog Input Capacitor 10 pF IHSM Increased Current Consumption 22.8 Symbol 22.9 380 µA Max Units DAC Characteristics Table 22-7. VREF High Speed Mode Single Ended Conversion DAC Characteristics - TA = -45°C to +105°C, VCC = 2.7V to 5.5V (unless otherwise noted) Parameter Condition Min Resolution DAC 10 Absolute accuracy Vcc=4V,VREF = 4V 2.5 5 LSB Integral Non-linearity Vcc=4V,VREF = 4V 0.8 1.5 LSB Differential Non-linearity Vcc=4V,VREF = 4V 0.2 0.5 LSB Gain Error Vcc=4V,VREF = 4V -5.0 0.0 LSB Offset Error Vcc=4V,VREF = 4V 0.0 2.0 LSB 2.56 AVCC V Reference Voltage Typ Parallel Programming Characteristics Figure 22-5. Parallel Programming Timing, Including some General Timing Requirements tXLWL tXHXL XTAL1 tDVXH tXLDX tBVPH tPLBX t BVWL Data & Contol (DATA, XA0, XA1/BS2, PAGEL/BS1) tWLBX tWLWH WR tPLWL WLRL RDY/BSY tWLRH 277 7734P–AVR–08/10 Figure 22-6. LOAD ADDRESS (LOW BYTE) Parallel Programming Timing, Loading Sequence with Timing Requirements(1) LOAD DATA (LOW BYTE) LOAD DATA (HIGH BYTE) LOAD ADDRESS (LOW BYTE) t XLXH XTAL1 PAGEL/BS1 DATA ADDR0 (Low Byte) DATA (Low Byte) DATA (High Byte) ADDR1 (Low Byte) XA0 XA1/BS2 Note: 1. The timing requirements shown in Figure 22-5 (i.e., tDVXH, tXHXL, and tXLDX) also apply to loading operation. Figure 22-7. LOAD ADDRESS (LOW BYTE) Parallel Programming Timing, Reading Sequence (within the Same Page) with Timing Requirements(1) READ DATA (LOW BYTE) READ DATA (HIGH BYTE) LOAD ADDRESS (LOW BYTE) tXLOL XTAL1 tBVDV PAGEL/BS1 tOLDV OE DATA tOHDZ ADDR0 (Low Byte) DATA (Low Byte) DATA (High Byte) ADDR1 (Low Byte) XA0 XA1/BS2 Note: 278 1. The timing requirements shown in Figure 22-5 (i.e., tDVXH, tXHXL, and tXLDX) also apply to reading operation. AT90PWM81 7734P–AVR–08/10 AT90PWM81 Table 22-8. Parallel Programming Characteristics, VCC = 5V ± 10% Symbol Parameter Min. VPP Programming Enable Voltage 11.5 IPP Programming Enable Current tDVXH Data and Control Valid before XTAL1 High 67 ns tXLXH XTAL1 Low to XTAL1 High 200 ns tXHXL XTAL1 Pulse Width High 150 ns tXLDX Data and Control Hold after XTAL1 Low 67 ns tXLWL XTAL1 Low to WR Low 0 ns tXLPH XTAL1 Low to PAGEL high 0 ns tPLXH PAGEL low to XTAL1 high 150 ns tBVPH BS1 Valid before PAGEL High 67 ns tPHPL PAGEL Pulse Width High 150 ns tPLBX BS1 Hold after PAGEL Low 67 ns tWLBX BS2/1 Hold after WR Low 67 ns tPLWL PAGEL Low to WR Low 67 ns tBVWL BS1 Valid to WR Low 67 ns tWLWH WR Pulse Width Low 150 ns tWLRL WR Low to RDY/BSY Low tWLRH WR Low to RDY/BSY High(1) (2) Max. Units 12.5 V 250 μA 0 1 μs 3.7 5 ms 7.5 10 ms tWLRH_CE WR Low to RDY/BSY High for Chip Erase tXLOL XTAL1 Low to OE Low 0 tBVDV BS1 Valid to DATA valid 0 tOLDV tOHDZ Notes: Typ. ns 250 ns OE Low to DATA Valid 250 ns OE High to DATA Tri-stated 250 ns 1. tWLRH is valid for the Write Flash, Write EEPROM, Write Fuse bits and Write Lock bits commands. 2. tWLRH_CE is valid for the Chip Erase command. 279 7734P–AVR–08/10 23. AT90PWM81 Typical Characteristics The following charts show typical behavior. These figures are not tested during manufacturing. All current consumption measurements are performed with all I/O pins configured as inputs and with internal pull-ups enabled. A sine wave generator with rail-to-rail output is used as clock source. All Active- and Idle current consumption measurements are done with all bits in the PRR register set and thus, the corresponding I/O modules are turned off. Also the Analog Comparator is disabled during these measurements. The power consumption in Power-down mode is independent of clock selection. The current consumption is a function of several factors such as: operating voltage, operating frequency, loading of I/O pins, switching rate of I/O pins, code executed and ambient temperature. The dominating factors are operating voltage and frequency. The current drawn from capacitive loaded pins may be estimated (for one pin) as CL*VCC*f where CL = load capacitance, VCC = operating voltage and f = average switching frequency of I/O pin. The parts are characterized at frequencies higher than test limits. Parts are not guaranteed to function properly at frequencies higher than the ordering code indicates. The difference between current consumption in Power-down mode with Watchdog Timer enabled and Power-down mode with Watchdog Timer disabled represents the differential current drawn by the Watchdog Timer. 280 AT90PWM81 7734P–AVR–08/10 AT90PWM81 23.1 Active Supply Current Figure 23-1. Active Supply Current vs. Frequency (0.1 - 1.0 MHz) ACTIVE SUPPLY CURRENT vs. LOW FREQUENCY 1.2 5.5V 1 5V 4.5V ICC [mA] 0.8 4V 0.6 3.6V 3.3V 0.4 2.7V 0.2 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Frequency [MHz] 281 7734P–AVR–08/10 Figure 23-2. Active Supply Current vs. Frequency (1 - 16 MHz) ACTIVE SUPPLY CURRENT vs. FREQUENCY 14 12 5.5V 10 5V 4.5V ICC [mA] 8 6 4V 3.6V 4 2.7V 3.3V 2 0 1 3 5 7 9 11 13 15 Frequency [MHz] Figure 23-3. Active Supply Current vs. VCC (Internal RC Oscillator, 8 MHz) ACTIVE SUPPLY CURRENT vs. VCC INTERNAL RC OSCILLATOR, 8 MHz E AT 10 9 8 7 T ICC [mA] 6 PL TE M C TE RA A CH E OB ZE RI D 125°C 105°C 25°C -40°C 5 4 3 2 1 0 2.7 3.2 3.7 4.2 4.7 5.2 V CC [V] 282 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 23-4. Active Supply Current vs. VCC (External clock, 16 MHz) ACTIVE SUPPLY CURRENT vs. VCC EXTERNAL CLOCK 16 MHz - ATD ON 16 14 125°C 105°C 25°C -40°C 12 ICC [mA] 10 8 6 4 2 0 2.7 3.2 3.7 4.2 4.7 5.2 V CC [V] 23.2 Idle Supply Current Figure 23-5. Idle Supply Current vs. Frequency (0.1 - 1.0 MHz) IDLE SUPPLY CURRENT vs. LOW FREQUENCY 0.35 5.5V 0.3 5V ICC [mA] 0.25 4.5V 4V 0.2 3.6V 3.3V 0.15 2.7V 0.1 0.05 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Frequency [MHz] 283 7734P–AVR–08/10 Figure 23-6. Idle Supply Current vs. Frequency (1 - 16 MHz) IDLE SUPPLY CURRENT vs. FREQUENCY 5 5.5V 4.5 5V 4 4.5V 3.5 4V ICC [mA] 3 3.6V 2.5 3.3V 2 2.7V 1.5 1 0.5 0 1 Figure 23-7. 3 5 7 9 Frequency [MHz] 11 13 15 Idle Supply Current vs. VCC (Internal RC Oscillator, 8 MHz) IDLE SUPPLY CURRENT vs. VCC INTERNAL RC OSCILLATOR, 8 MHz 4 3.5 125°C 105°C 2.5 25°C -40°C ICC [mA] 3 2 1.5 1 0.5 0 2.7 3.2 3.7 4.2 4.7 5.2 V CC [V] 284 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 23-8. Idle Supply Current vs. VCC (External clock, 16 MHz) IDLE SUPPLY CURRENT vs. VCC EXTERNAL CLOCK 16 MHz 6 -40°C 125°C 105°C 25°C 5 ICC [mA] 4 3 2 1 0 2.7 23.3 3.2 3.7 4.2 V CC [V] 4.7 5.2 Power-Down Supply Current Figure 23-9. Power-Down Supply Current vs. VCC (Watchdog Timer Disabled) POWER-DOWN SUPPLY CURRENT vs. VCC WATCHDOG TIMER DISABLED 12 10 125°C ICC [uA] 8 6 4 105°C 2 25°C 0 2.7 3.2 3.7 4.2 4.7 5.2 -40°C V CC [V] 285 7734P–AVR–08/10 Figure 23-10. Power-Down Supply Current vs. VCC (Watchdog Timer Enabled) POWER-DOWN SUPPLY CURRENT vs. VCC WATCHDOG TIMER ENABLED 25 20 125°C ICC [uA] 15 105°C 10 -40°C 25°C 5 0 2.7 3.2 3.7 4.2 4.7 5.2 V CC [V] 23.4 Pin Pull-up Figure 23-11. I/O Pin Pull-Up Resistor Current vs. Input Voltage (VCC = 5V) I/O PIN PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE Vcc = 5V 160 TE ZE I A R PL TE M C TE RA A CH E B TO 25°C 105°C 140 -40°C 120 125°C IOP [uA] 100 80 D 60 40 20 0 0 286 0.5 1 1.5 2 2.5 V OP [V] 3 3.5 4 4.5 5 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 23-12. I/O Pin Pull-Up Resistor Current vs. Input Voltage (VCC = 2.7V) I/O PIN PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE Vcc = 2.7V 80 25°C -40°C 70 105°C 125°C 60 IOP [uA] 50 40 30 20 10 0 0 0.5 1 1.5 2 2.5 V OP [V] 3 3.5 4 4.5 5 Figure 23-13. I/O Pin Pull-Up Resistor Current vs. Input Voltage, PE1 & PE2 pins (VCC = 5V) I/O PIN PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE PE1 & PE2 PINS Vcc = 5V 160 105°C 25°C 140 -40°C 120 125°C IOP [uA] 100 80 60 40 20 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 V OP [V] 287 7734P–AVR–08/10 Figure 23-14. I/O Pin Pull-Up Resistor Current vs. Input Voltage, PE1 & PE2 pins (VCC = 2.7V) I/O PIN PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE PE1 & PE2 PINS Vcc = 2.7V 90 80 -40°C 105°C 25°C 70 125°C IOP [uA] 60 50 40 30 20 10 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 V OP [V] Figure 23-15. Reset Pull-Up Resistor Current vs. Reset Pin Voltage (VCC = 5V) RESET PULL-UP RESISTOR CURRENT vs. RESET PIN VOLTAGE Vcc = 5V 120 -40°C 105°C 25°C 100 125°C IRESET [uA] 80 60 40 20 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 V RESET [V] 288 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 23-16. Reset Pull-Up Resistor Current vs. Reset Pin Voltage (VCC = 2.7V) RESET PULL-UP RESISTOR CURRENT vs. RESET PIN VOLTAGE Vcc = 2.7V 60 -40°C 105°C 25°C 50 125°C IRESET [uA] 40 30 20 10 0 0 23.5 0.5 1 1.5 2 2.5 V RESET [V] 3 3.5 4 4.5 5 Pin output high voltage Figure 23-17. I/O Pin Output Voltage vs. Source current (Vcc = 5V)) I/O PIN OUTPUT VOLTAGE vs. SOURCE CURRENT Vcc = 5.0 V 6 -40°C 5 125°C 25°C 105°C V OH [V] 4 3 2 1 0 0 1 2 3 4 5 6 7 8 9 10 IOH [mA] 289 7734P–AVR–08/10 Figure 23-18. I/O Pin Output Voltage vs. Source current (Vcc = 3V)) I/O PIN OUTPUT VOLTAGE vs. SOURCE CURRENT Vcc = 3.0 V 3.5 3 -40°C 25°C 105°C 125°C 2.5 V OH [V] 2 1.5 1 0.5 0 0 1 2 3 4 5 6 7 8 9 10 IOH [mA] 23.6 Pin output low voltage Figure 23-19. I/O Pin Output Voltage vs. Sink current (Vcc = 5V)) I/O PIN OUTPUT VOLTAGE vs. SINK CURRENT Vcc = 5.0 V 0.6 0.5 125°C 105°C V OL [V] 0.4 25°C 0.3 -40°C 0.2 0.1 0 0 1 2 3 4 5 6 7 8 9 10 IOL [mA] 290 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 23-20. I/O Pin Output Voltage vs. Sink current (Vcc = 3V)) I/O PIN OUTPUT VOLTAGE vs. SINK CURRENT Vcc = 3.0 V 0.8 125°C 105°C 0.7 V OL [V] 0.6 0.5 25°C 0.4 -40°C 0.3 0.2 0.1 0 0 23.7 1 2 3 4 5 IOL [mA] 6 7 8 9 10 Pin Thresholds Figure 23-21. I/O Pin Input Threshold Voltage vs. VCC (VIL, I/O Pin Read As '0') I/O PIN INPUT THRESHOLD VOLTAGE vs. VCC VIL, IO PIN READ AS '0' 3 125°C 2.5 -40°C 105°C 25°C Threshold [V] 2 1.5 1 0.5 0 2.7 3.2 3.7 4.2 V CC [V] 4.7 5.2 291 7734P–AVR–08/10 Figure 23-22. I/O Pin Input Threshold Voltage vs. VCC (VIH, I/O Pin Read As '1') I/O PIN INPUT THRESHOLD VOLTAGE vs. VCC VIH, IO PIN READ AS '1' 4 3.5 125°C 105°C Threshold [V] 3 -40°C 2.5 25°C 2 1.5 1 0.5 0 2.7 23.8 3.2 3.7 4.2 V CC [V] 4.7 5.2 BOD Thresholds Figure 23-23. BOD Thresholds vs. Temperature (BODLEVEL is 4.3V) BOD THRESHOLDS vs. TEMPERATURE BODLEVEL is 4.3V 4.6 Rising Vcc 4.5 4.4 Threshold [V] Falling Vcc 4.3 4.2 4.1 4 3.9 3.8 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 Temperature [C] 292 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 23-24. BOD Thresholds vs. Temperature (BODLEVEL is 2.7V) BOD THRESHOLDS vs. TEMPERATURE BODLEVEL is 2.7V 2.9 Rising Vcc Threshold [V] 2.8 Falling Vcc 2.7 2.6 2.5 2.4 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 Temperature [C] 23.9 Analog Reference Figure 23-25. VREF Voltage vs. VCC IINTERNAL VREF vs Vcc 2.65 125°C 105°C 2.6 25°C VRef (V) 2.55 2.5 2.45 -40°C 2.4 2.35 2.3 2.7 3.2 3.7 4.2 4.7 5.2 Vcc (V) 293 7734P–AVR–08/10 Figure 23-26. VREF Voltage vs. Temperature INTERNAL VREF vs TEMPERATURE 2.65 5.5V 2.6 2.7V Aref (V) 2.55 2.5 2.45 2.4 2.35 -40 -30 -20 -10 0 10 20 30 40 50 60 Temperature (°C) 70 80 90 100 110 120 23.10 Internal Oscillator Speed Figure 23-27. Watchdog Oscillator Frequency vs. VCC WATCHDOG OSCILLATOR FREQUENCY vs. OPERATING VOLTAGE 0.14 0.135 0.13 -40°C FRC [MHz] 0.125 25°C 0.12 125°C 0.115 105°C 0.11 0.105 0.1 2.7 3.2 3.7 4.2 4.7 5.2 V CC [V] 294 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 23-28. Calibrated 8 MHz RC Oscillator Frequency vs. Temperature CALIBRATED 8 MHz RC OSCILLATOR FREQUENCY vs. TEMPERATURE RC OSC CALIBRATED @ ROOM TEMP 8.3 5.6V 5.4V 5.2V 5V4V 2.6V 2.8V 8.2 FRC [MHz] 8.1 V 8 7.9 7.8 7.7 -40 -25 -10 5 20 35 50 Temperature 65 80 95 110 125 Figure 23-29. Calibrated 8 MHz RC Oscillator Frequency vs. VCC CALIBRATED 8 MHz RC OSCILLATOR FREQUENCY vs. OPERATING VOLTAGE RC OSC CALIBRATED @ ROOM TEMP 8.3 125°C 105°C 8.2 FRC [MHz] 8.1 25°C 8 7.9 -40°C 7.8 7.7 7.6 2.4 2.9 3.4 3.9 4.4 4.9 5.4 V CC [V] 295 7734P–AVR–08/10 Figure 23-30. Calibrated 8 MHz RC Oscillator Frequency vs. Osccal Value INT RC OSCILLATOR Frequency vs. OSCCAL 10000 Cycles sampled w ith 250nS - VCC 3 V 105°C 25°C 1600000 -40°C 1400000 FRC 1200000 1000000 800000 600000 400000 0 16 32 48 64 80 96 112 128 144 160 176 192 208 224 240 OSCCAL 23.11 Current Consumption in Reset Figure 23-31. Reset Supply Current vs. VCC (0.1 - 1.0 MHz, Excluding Current through the Reset Pullup) RESET SUPPLY CURRENT vs Vcc EXCLUDING CURRENT THROUGH THE RESET PULLUP 1 0.9 5.5V 0.8 ICC (mA) 0.7 0.6 0.5 0.4 0.3 2.7V 0.2 0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Frequency MHz All temperatures 296 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Figure 23-32. Reset Supply Current vs. VCC (1 - 16 MHz, Excluding Current through the Reset Pull-up) RESET SUPPLY CURRENT vs VCC EXCLUDING CURRENT THROUGH THE RESET PULLUP 4 3.5 3 5.5V ICC (mA) 2.5 2 1.5 1 2.7V 0.5 0 1 3 5 7 9 Frequency MHz All temperatures 11 13 15 297 7734P–AVR–08/10 24. Register Summary Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 (0xFF) Reserved – – – – – – – – 298 (0xFE) Reserved – – – – – – – – (0xFD) Reserved – – – – – – – – (0xFC) Reserved – – – – – – – – (0xFB) Reserved – – – – – – – – (0xFA) Reserved – – – – – – – – (0xF9) Reserved – – – – – – – – (0xF8) Reserved – – – – – – – – (0xF7) Reserved – – – – – – – – (0xF6) Reserved – – – – – – – – (0xF5) Reserved – – – – – – – – (0xF4) Reserved – – – – – – – – (0xF3) Reserved – – – – – – – – (0xF2) Reserved – – – – – – – – (0xF1) Reserved – – – – – – – – (0xF0) Reserved – – – – – – – – (0xEF) Reserved – – – – – – – – (0xEE) Reserved – – – – – – – – (0xED) Reserved – – – – – – – – (0xEC) Reserved – – – – – – – – (0xEB) Reserved – – – – – – – – (0xEA) Reserved – – – – – – – – (0xE9) Reserved – – – – – – – – (0xE8) Reserved – – – – – – – – (0xE7) Reserved – – – – – – – – (0xE6) Reserved – – – – – – – – (0xE5) Reserved – – – – – – – – (0xE4) Reserved – – – – – – – – (0xE3) Reserved – – – – – – – – (0xE2) Reserved – – – – – – – – (0xE1) Reserved – – – – – – – – (0xE0) Reserved – – – – – – – – (0xDF) Reserved – – – – – – – – (0xDE) Reserved – – – – – – – – (0xDD) Reserved – – – – – – – – (0xDC) Reserved – – – – – – – – (0xDB) Reserved – – – – – – – – (0xDA) Reserved – – – – – – – – (0xD9) Reserved – – – – – – – – (0xD8) Reserved – – – – – – – – (0xD7) Reserved – – – – – – – – (0xD6) Reserved – – – – – – – – (0xD5) Reserved – – – – – – – – (0xD4) Reserved – – – – – – – – (0xD3) Reserved – – – – – – – – (0xD2) Reserved – – – – – – – – (0xD1) Reserved – – – – – – – – (0xD0) Reserved – – – – – – – – (0xCF) Reserved – – – – – – – – (0xCE) Reserved – – – – – – – – (0xCD) Reserved – – – – – – – – (0xCC) Reserved – – – – – – – – (0xCB) Reserved – – – – – – – – (0xCA) Reserved – – – – – – – – (0xC9) Reserved – – – – – – – – (0xC8) Reserved – – – – – – – – (0xC7) Reserved – – – – – – – – (0xC6) Reserved – – – – – – – – (0xC5) Reserved – – – – – – – – (0xC4) Reserved – – – – – – – – (0xC3) Reserved – – – – – – – – (0xC2) Reserved – – – – – – – – (0xC1) Reserved – – – – – – – – (0xC0) Reserved – – – – – – – – Page AT90PWM81 7734P–AVR–08/10 AT90PWM81 Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 (0xBF) Reserved – – – – – – – – Page (0xBE) Reserved – – – – – – – – (0xBD) Reserved – – – – – – – – (0xBC) Reserved – – – – – – – – (0xBB) Reserved – – – – – – – – (0xBA) Reserved – – – – – – – – (0xB9) Reserved – – – – – – – – (0xB8) Reserved – – – – – – – – (0xB7) Reserved – – – – – – – – (0xB6) Reserved – – – – – – – – (0xB5) Reserved – – – – – – – – (0xB4) Reserved – – – – – – – – (0xB3) Reserved – – – – – – – – (0xB2) Reserved – – – – – – – – (0xB1) Reserved – – – – – – – – (0xB0) Reserved – – – – – – – – (0xAF) Reserved – – – – – – – – (0xAE) Reserved – – – – – – – – (0xAD) Reserved – – – – – – – – (0xAC) Reserved – – – – – – – – (0xAB) Reserved – – – – – – – – (0xAA) Reserved – – – – – – – – (0xA9) Reserved – – – – – – – – (0xA8) Reserved – – – – – – – – (0xA7) Reserved – – – – – – – – (0xA6) Reserved – – – – – – – – (0xA5) Reserved – – – – – – – – (0xA4) Reserved – – – – – – – – (0xA3) Reserved – – – – – – – – (0xA2) Reserved – – – – – – – – (0xA1) Reserved – – – – – – – – (0xA0) Reserved – – – – – – – – (0x9F) Reserved – – – – – – – – (0x9E) Reserved – – – – – – – – (0x9D) Reserved – – – – – – – – (0x9C) Reserved – – – – – – – – (0x9B) Reserved – – – – – – – – (0x9A) Reserved – – – – – – – – (0x99) Reserved – – – – – – – – (0x98) Reserved – – – – – – – – (0x97) Reserved – – – – – – – – (0x96) Reserved – – – – – – – – (0x95) Reserved – – – – – – – – (0x94) Reserved – – – – – – – – (0x93) Reserved – – – – – – – – (0x9r) Reserved – – – – – – – – (0x91) Reserved – – – – – – – – (0x90) Reserved – – – – – – – – (0x8F) Reserved – – – – – – – – (0x8E) Reserved – – – – – – – – (0x8D) ICR1H ICR115 ICR114 ICR113 ICR112 ICR111 ICR110 ICR19 ICR18 page 97 (0x8C) ICR1L ICR17 ICR16 ICR15 ICR14 ICR13 ICR12 ICR11 ICR10 page 97 (0x8B) Reserved – – – – – – – – (0x8A) TCCR1B ICNC1 ICES1 – WGM13 – CS12 CS11 CS10 page 96 (0x89) EICRA – – ISC21 ISC20 ISC11 ISC10 ISC01 ISC00 page 82 (0x88) OSCCAL – CAL6 CAL5 CAL4 CAL3 CAL2 CAL1 CAL0 page 38 (0x87) PLLCSR - - PLLF3 PLLF2 PLLF1 PLLF0 PLLE PLOCK page 40 (0x86) PRR PRPSC2 – PRPSCR PRTIM1 – PRSPI – PRADC page 47 (0x85) CLKSELR – (0x84) CLKCSR (0x83) CLKPR (0x82) WDTCSR (0x81) BGCCR CLKCCE COUT CSUT1 CSUT0 CLKRDY CSEL3 CLKC3 CSEL2 CLKC2 CSEL1 CLKC1 CSEL0 CLKC0 – – CLKPCE – – – CLKPS3 CLKPS2 CLKPS1 CLKPS0 WDIF WDIE WDP3 WDCE WDE WDP2 WDP1 WDP0 – – – BGCC3 BGCR3 BGCC2 BGCR2 BGCC1 BGCR1 BGCC0 BGCR0 page 42 page 41 page 41 page 46 page 191 (0x80) BGCRR – – – – (0x7F) AC3CON AC3EN AC3IE AC3IS1 AC3IS0 AC3OEA AC3M2 AC3M1 AC3M0 page 191 page 199 (0x7E) AC2CON AC2EN AC2IE AC2IS1 AC2IS0 – AC2M2 AC2M1 AC2M0 page 199 299 7734P–AVR–08/10 Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Page (0x7D) AC1CON AC1EN AC1IE AC1IS1 AC1IS0 – AC1M2 AC1M1 AC1M0 page 197 (0x7C) AC3ECON – – AC3OI AC3OE – AC3H2 AC3H1 AC3H0 page 197 (0x7B) AC2ECON – – AC2OI AC2OE – AC2H2 AC2H1 AC2H0 page 197 (0x7A) AC1ECON – – AC1OI AC1OE AC1ICE AC1H2 AC1H1 AC1H0 page 197 (0x79) AMP0CSR AMP0EN AMP0IS AMP0G1 AMP0G0 AMP0GS – AMP0TS1 AMP0TS0 page 224 (0x78) DIDR1 – – – – (0x77) DIDR0 (0x76) DACON ADC8D/AMP3D ADC7D/AMP0-D DAATE DATS2 ADC5D/ACMP2D DATS1 (0x75) ACMP1MD AMP0+D ADC10D ADC9D page 221 ADC4D/ACMP3M ADC3D/ACMPMD ADC2D/ACMP2M ADC1D ADC0D/ACMP1D page 221 DATS0 – DALA – DAEN page 228 Room for analog test registers (0x74) (0x73) (0x72) (0x71) PASDLY2 (0x70) PCNFE2 (0x6F) PASDLY2[7:0] PBFMn1 page 135 PASDLKn2 PASDLKn1 PASDLKn0 PELEVnA1 PELEVnB1 POMV2A3 POEN2D POMV2A2 POM2 POMV2B3 POMV2B2 POMV2B1 POMV2B0 (0x6E) PSOC2 POS22 PSYNC21 PSYNC20 (0x6D) PICR2H POS23 PCST2 – – – (0x6C) PICR2L (0x6B) Reserved – – – – – – – – (0x6A) PSOC0 PISEL0A1 PISEL0B1 PSYNC01 PSYNC00 – POEN0B – POEN0A (0x69) PICR0H PCST0 – – – (0x68) PICR0L (0x67) PFRC2B PCAE2B PISEL2B PELEV2B PFLTE2B PRFM2B3 PRFM2B2 PRFM2B1 PRFM2B0 page 140 (0x66) PFRC2A PCAE2A PISEL2A PELEV2A PFLTE2A PRFM2A3 PRFM2A2 PRFM2A1 PRFM2A0 page 140 (0x65) OCR2SAH – – – – (0x64) OCR2SAL (0x63) PFRC0B PCAE0B PISEL0B PELEV0B PFLTE0B PRFM0B3 PRFM0B2 PRFM0B1 PRFM0B0 page 175 (0x62) PFRC0A PCAE0A PISEL0A PELEV0A PFLTE0A PRFM0A3 PRFM0A2 PRFM0A1 PRFM0A0 page 175 (0x61) OCR0SAH – – – – (0x60) OCR0SAL 0x3F (0x5F) SREG I T H S V N Z C page 9 0x3E (0x5E) SPH – – – – SP11 SP10 SP9 SP8 page 12 0x3D (0x5D) SPL SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0 page 12 0x3C (0x5C) Reserved – – – – – – – – 0x3B (0x5B) TCNT1H TCNT115 TCNT114 TCNT113 TCNT112 TCNT111 TCNT110 TCNT19 TCNT18 page 97 0x3A (0x5A) TCNT1L TCNT17 TCNT16 TCNT15 TCNT14 TCNT13 TCNT12 TCNT11 TCNT10 page 97 0x39 (0x59) DACH - / DAC9 - / DAC8 - / DAC7 - / DAC6 - / DAC5 - / DAC4 DAC9 / DAC3 DAC8 / DAC2 page 229 0x38 (0x58) DACL DAC7 / DAC1 DAC6 /DAC0 DAC5 / - DAC4 / - DAC3 / - DAC2 / - DAC1 / - DAC0 / page 229 0x37 (0x57) SPMCSR SPMIE RWWSB SIGRD RWWSRE BLBSET PGWRT PGERS SPMEN page 238 0x36 (0x56) SPDR SPD7 SPD6 SPD5 SPD4 SPD3 SPD2 SPD1 SPD0 page 188 0x35 (0x55) MCUCR – – – PUD RSTDIS CKRC81 IVSEL IVCE page 54 & page 72 0x34 (0x54) MCUSR – – – – WDRF BORF EXTRF PORF page 53 0x33 (0x53) SMCR – – – – SM2 SM1 SM0 SE 0x32 (0x52) MSMCR POEN2B PISEL0A1 POMV2A1 POEN2C PISEL0B1 page 142 POEN2A page 133 PICR2[11:8] page 142 PICR2[7:0] page 142 PICR0[11:8] page 177 OCR2SA[11:8] page 134 OCR2SA[7:0] page 134 OCR0SA[11:8] page 172 OCR0SA[7:0] page 172 Monitor Stop Mode Control Register DWDR 0x30 (0x50) Reserved – – – – – – – – page 171 page 177 PICR0[7:0] 0x31 (0x51) page 135 POMV2A0 page 47 reserved DWDR[7:0] page 232 – – – – 0x2F (0x4F) OCR2RAH 0x2E (0x4E) OCR2RAL 0x2D (0x4D) ADCH - / ADC9 - / ADC8 - / ADC7 - / ADC6 - / ADC5 - / ADC4 ADC9 / ADC3 ADC8 / ADC2 page 220 0x2C (0x4C) ADCL ADC7 / ADC1 ADC6 / ADC0 ADC5 / - ADC4 / - ADC3 / - ADC2 / - ADC1 / - ADC0 / page 220 0x2B (0x4B) OCR0RAH – – – – 0x2A (0x4A) OCR0RAL 0x29 (0x49) OCR2RBH 0x28 (0x48) OCR2RBL 0x27 (0x47) OCR2SBH 0x26 (0x46) OCR2SBL 0x25 (0x45) OCR0RBH 0x24 (0x44) OCR0RBL 0x23 (0x43) OCR0SBH 0x22 (0x42) OCR0SBL 0x21 (0x41) EIMSK – – – – – INT2 INT1 INT0 page 83 0x20 (0x40) EIFR – – – – – INTF2 INTF1 INTF0 page 83 0x1F (0x3F) EEARH – – – – – – – EEAR8 page 19 0x1E (0x3E) EEARL EEAR7 EEAR6 EEAR5 EEAR4 EEAR3 EEAR2 EEAR1 EEAR0 page 19 0x1D (0x3D) EEDR EEDR7 EEDR6 EEDR5 EEDR4 EEDR3 EEDR2 EEDR1 EEDR0 page 19 0x1C (0x3C) EECR NVMBSY EEPAGE EEPM1 EEPM0 EERIE EEMWE EEWE EERE page 19 300 OCR2RA[11:8] page 134 OCR2RA[7:0] page 134 OCR0RA[11:8] page 172 OCR0RA[7:0] page 172 OCR2RB[15:12] OCR2RB[11:8] page 135 OCR2RB[7:0] – – – page 135 – OCR2SB[11:8] page 135 OCR2SB[7:0] page 135 OCR0RB[15:12] OCR0RB[11:8] page 173 OCR0RB[7:0] – – – page 173 – OCR0SB[11:8] page 172 OCR0SB[7:0] page 172 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Page 0x1B (0x3B) GPIOR2 GPIOR27 GPIOR26 GPIOR25 GPIOR24 GPIOR23 GPIOR22 GPIOR21 GPIOR20 page 26 0x1A (0x3A) GPIOR1 GPIOR17 GPIOR16 GPIOR15 GPIOR14 GPIOR13 GPIOR12 GPIOR11 GPIOR10 page 26 0x19 (0x39) GPIOR0 GPIOR07 GPIOR06 GPIOR05 GPIOR04 GPIOR03 GPIOR02 GPIOR01 GPIOR00 page 26 0x18 (0x38) SPSR SPIF WCOL – – – – – SPI2X page 188 0x17 (0x37) SPCR SPIE SPE DORD MSTR CPOL CPHA SPR1 SPR0 page 186 0x16 (0x36) PCTL2 PPRE21 PPRE20 PBFM2 PAOC2B PAOC2A PARUN2 PCCYC2 PRUN2 page 139 0x15 (0x35) PCNF2 0x14 (0x34) PIFR2 PFIFTY2 POAC2B PALOCK2 POAC2A PLOCK2 PSEI2 PMODE21 PEV2B PMODE20 PEV2A POP2 PRN21 PCLKSEL2 PRN20 POME2 PEOP2 page 144 page 135 0x13 (0x33) PIM2 - - PSEIE2 PEVE2B PEVE2A - PEOEPE2 PEOPE2 page 143 0x12 (0x32) PCTL0 PPRE01 PPRE00 PBFM01 PAOC0B PAOC0A PBFM00 PCCYC0 PRUN0 page 174 0x11 (0x31) PCNF0 PFIFTY0 PALOCK0 PLOCK0 PIFR0 – PCLKSEL0 PRN00 – PEOP0 PIM0 POAC0A - POP0 PRN01 0x0F (0x2F) POAC0B - PMODE00 PEV0A page 173 0x10 (0x30) PMODE01 PEV0B – PEVE0B PEVE0A – PEOEPE0 PEOPE0 page 178 0x0E (0x2E) PORTE – – – – – PORTE2 PORTE1 PORTE0 page 80 0x0D (0x2D) DDRE – – – – – DDE2 DDE1 DDE0 page 81 0x0C (0x2C) PINE – – – – – PINE2 PINE1 PINE0 page 81 0x0B (0x2B) PORTD PORTD7 PORTD6 PORTD5 PORTD4 PORTD3 PORTD2 PORTD1 PORTD0 page 80 0x0A (0x2A) DDRD DDD7 DDD6 DDD5 DDD4 DDD3 DDD2 DDD1 DDD0 page 80 0x09 (0x29) PIND PIND7 PIND6 PIND5 PIND4 PIND3 PIND2 PIND1 PIND0 page 80 0x08 (0x28) ADMUX REFS1 REFS0 ADLAR – MUX3 MUX2 MUX1 MUX0 page 216 0x07 (0x27) ADCSRB ADHSM ADNCDIS – ADSSEN ADTS3 ADTS2 ADTS1 ADTS0 page 219 0x06 (0x26) ADCSRA ADEN ADSC ADATE ADIF ADIE ADPS2 ADPS1 ADPS0 page 218 0x05 (0x25) PORTB PORTB7 PORTB6 PORTB5 PORTB4 PORTB3 PORTB2 PORTB1 PORTB0 page 80 0x04 (0x24) DDRB DDB7 DDB6 DDB5 DDB4 DDB3 DDB2 DDB1 DDB0 page 80 0x03 (0x23) PINB PINB7 PINB6 PINB5 PINB4 PINB3 PINB2 PINB1 PINB0 page 80 0x02 (0x22) TIFR1 – – ICF1 – – – – TOV1 page 98 0x01 (0x21) TIMSK1 – – ICIE1 – – – – TOIE1 page 97 0x00 (0x20) ACSR AC3IF AC2IF AC1IF – AC3O AC2O AC1O – page 201 Note: page 178 1. For compatibility with future devices, reserved bits should be written to zero if accessed. Reserved I/O memory addresses should never be written. 2. I/O Registers within the address range 0x00 - 0x1F are directly bit-accessible using the SBI and CBI instructions. In these registers, the value of single bits can be checked by using the SBIS and SBIC instructions. 3. Some of the status flags are cleared by writing a logical one to them. Note that, unlike most other AVRs, the CBI and SBI instructions will only operate on the specified bit, and can therefore be used on registers containing such status flags. The CBI and SBI instructions work with registers 0x00 to 0x1F only. 4. When using the I/O specific commands IN and OUT, the I/O addresses 0x00 - 0x3F must be used. When addressing I/O Registers as data space using LD and ST instructions, 0x20 must be added to these addresses. The AT90PWM81 is a complex microcontroller with more peripheral units than can be supported within the 64 location reserved in Opcode for the IN and OUT instructions. For the Extended I/O space from 0x60 - 0xFF in SRAM, only the ST/STS/STD and LD/LDS/LDD instructions can be used. 301 7734P–AVR–08/10 25. Instruction Set Summary Mnemonics Operands Description Operation Flags #Clocks ARITHMETIC AND LOGIC INSTRUCTIONS ADD Rd, Rr Add two Registers Rd ← Rd + Rr Z,C,N,V,H 1 ADC Rd, Rr Add with Carry two Registers Rd ← Rd + Rr + C Z,C,N,V,H 1 ADIW Rdl,K Add Immediate to Word Rdh:Rdl ← Rdh:Rdl + K Z,C,N,V,S 2 SUB Rd, Rr Subtract two Registers Rd ← Rd - Rr Z,C,N,V,H 1 SUBI Rd, K Subtract Constant from Register Rd ← Rd - K Z,C,N,V,H 1 SBC Rd, Rr Subtract with Carry two Registers Rd ← Rd - Rr - C Z,C,N,V,H 1 SBCI Rd, K Subtract with Carry Constant from Reg. Rd ← Rd - K - C Z,C,N,V,H 1 SBIW Rdl,K Subtract Immediate from Word Rdh:Rdl ← Rdh:Rdl - K Z,C,N,V,S 2 AND Rd, Rr Logical AND Registers Rd ← Rd • Rr Z,N,V 1 ANDI Rd, K Logical AND Register and Constant Rd ← Rd • K Z,N,V 1 OR Rd, Rr Logical OR Registers Rd ← Rd v Rr Z,N,V 1 ORI Rd, K Logical OR Register and Constant Rd ← Rd v K Z,N,V 1 EOR Rd, Rr Exclusive OR Registers Rd ← Rd ⊕ Rr Z,N,V 1 COM Rd One’s Complement Rd ← 0xFF − Rd Z,C,N,V 1 NEG Rd Two’s Complement Rd ← 0x00 − Rd Z,C,N,V,H 1 SBR Rd,K Set Bit(s) in Register Rd ← Rd v K Z,N,V 1 CBR Rd,K Clear Bit(s) in Register Rd ← Rd • (0xFF - K) Z,N,V 1 INC Rd Increment Rd ← Rd + 1 Z,N,V 1 DEC Rd Decrement Rd ← Rd − 1 Z,N,V 1 TST Rd Test for Zero or Minus Rd ← Rd • Rd Z,N,V 1 CLR Rd Clear Register Rd ← Rd ⊕ Rd Z,N,V 1 SER Rd Set Register Rd ← 0xFF None 1 MUL Rd, Rr Multiply Unsigned R1:R0 ← Rd x Rr Z,C 2 MULS Rd, Rr Multiply Signed R1:R0 ← Rd x Rr Z,C 2 MULSU Rd, Rr Multiply Signed with Unsigned R1:R0 ← Rd x Rr Z,C 2 FMUL Rd, Rr Fractional Multiply Unsigned R1:R0 ← (Rd x Rr) << 1 Z,C 2 FMULS Rd, Rr Fractional Multiply Signed R1:R0 ← (Rd x Rr) << 1 Z,C 2 FMULSU Rd, Rr Fractional Multiply Signed with Unsigned R1:R0 ← (Rd x Rr) << 1 Z,C 2 RJMP k 2 BRANCH INSTRUCTIONS IJMP RCALL PC ← PC + k + 1 None PC ← Z None 2 Relative Subroutine Call PC ← PC + k + 1 None 3 ICALL Indirect Call to (Z) PC ← Z None 3 RET Subroutine Return PC ← STACK None 4 RETI Interrupt Return PC ← STACK I 4 Compare, Skip if Equal if (Rd = Rr) PC ← PC + 2 or 3 None 1/2/3 CPSE 302 k Relative Jump Indirect Jump to (Z) Rd,Rr CP Rd,Rr Compare Rd − Rr Z, N,V,C,H 1 CPC Rd,Rr Compare with Carry Rd − Rr − C Z, N,V,C,H 1 CPI Rd,K Compare Register with Immediate Rd − K Z, N,V,C,H 1 SBRC Rr, b Skip if Bit in Register Cleared if (Rr(b)=0) PC ← PC + 2 or 3 None 1/2/3 SBRS Rr, b Skip if Bit in Register is Set if (Rr(b)=1) PC ← PC + 2 or 3 None 1/2/3 SBIC P, b Skip if Bit in I/O Register Cleared if (P(b)=0) PC ← PC + 2 or 3 None 1/2/3 SBIS P, b Skip if Bit in I/O Register is Set if (P(b)=1) PC ← PC + 2 or 3 None 1/2/3 BRBS s, k Branch if Status Flag Set if (SREG(s) = 1) then PC←PC+k + 1 None 1/2 BRBC s, k Branch if Status Flag Cleared if (SREG(s) = 0) then PC←PC+k + 1 None 1/2 BREQ k Branch if Equal if (Z = 1) then PC ← PC + k + 1 None 1/2 BRNE k Branch if Not Equal if (Z = 0) then PC ← PC + k + 1 None 1/2 BRCS k Branch if Carry Set if (C = 1) then PC ← PC + k + 1 None 1/2 BRCC k Branch if Carry Cleared if (C = 0) then PC ← PC + k + 1 None 1/2 BRSH k Branch if Same or Higher if (C = 0) then PC ← PC + k + 1 None 1/2 BRLO k Branch if Lower if (C = 1) then PC ← PC + k + 1 None 1/2 BRMI k Branch if Minus if (N = 1) then PC ← PC + k + 1 None 1/2 BRPL k Branch if Plus if (N = 0) then PC ← PC + k + 1 None 1/2 BRGE k Branch if Greater or Equal, Signed if (N ⊕ V= 0) then PC ← PC + k + 1 None 1/2 BRLT k Branch if Less Than Zero, Signed if (N ⊕ V= 1) then PC ← PC + k + 1 None 1/2 BRHS k Branch if Half Carry Flag Set if (H = 1) then PC ← PC + k + 1 None 1/2 BRHC k Branch if Half Carry Flag Cleared if (H = 0) then PC ← PC + k + 1 None 1/2 BRTS k Branch if T Flag Set if (T = 1) then PC ← PC + k + 1 None 1/2 BRTC k Branch if T Flag Cleared if (T = 0) then PC ← PC + k + 1 None 1/2 BRVS k Branch if Overflow Flag is Set if (V = 1) then PC ← PC + k + 1 None 1/2 BRVC k Branch if Overflow Flag is Cleared if (V = 0) then PC ← PC + k + 1 None 1/2 BRIE k Branch if Interrupt Enabled if ( I = 1) then PC ← PC + k + 1 None 1/2 BRID k Branch if Interrupt Disabled if ( I = 0) then PC ← PC + k + 1 None 1/2 AT90PWM81 7734P–AVR–08/10 AT90PWM81 Mnemonics Operands Description Operation Flags #Clocks BIT AND BIT-TEST INSTRUCTIONS SBI P,b Set Bit in I/O Register I/O(P,b) ← 1 None 2 CBI P,b Clear Bit in I/O Register I/O(P,b) ← 0 None 2 LSL Rd Logical Shift Left Rd(n+1) ← Rd(n), Rd(0) ← 0 Z,C,N,V 1 LSR Rd Logical Shift Right Rd(n) ← Rd(n+1), Rd(7) ← 0 Z,C,N,V 1 ROL Rd Rotate Left Through Carry Rd(0)←C,Rd(n+1)← Rd(n),C←Rd(7) Z,C,N,V 1 ROR Rd Rotate Right Through Carry Rd(7)←C,Rd(n)← Rd(n+1),C←Rd(0) Z,C,N,V 1 ASR Rd Arithmetic Shift Right Rd(n) ← Rd(n+1), n=0..6 Z,C,N,V 1 SWAP Rd Swap Nibbles Rd(3..0)←Rd(7..4),Rd(7..4)←Rd(3..0) None 1 BSET s Flag Set SREG(s) ← 1 SREG(s) 1 BCLR s Flag Clear SREG(s) ← 0 SREG(s) 1 BST Rr, b Bit Store from Register to T T ← Rr(b) T 1 BLD Rd, b Bit load from T to Register Rd(b) ← T None 1 1 SEC Set Carry C←1 C CLC Clear Carry C←0 C 1 SEN Set Negative Flag N←1 N 1 CLN Clear Negative Flag N←0 N 1 SEZ Set Zero Flag Z←1 Z 1 CLZ Clear Zero Flag Z←0 Z 1 SEI Global Interrupt Enable I←1 I 1 CLI Global Interrupt Disable I←0 I 1 SES Set Signed Test Flag S←1 S 1 CLS Clear Signed Test Flag S←0 S 1 SEV Set Twos Complement Overflow. V←1 V 1 CLV Clear Twos Complement Overflow V←0 V 1 SET Set T in SREG T←1 T 1 CLT Clear T in SREG T←0 T 1 SEH CLH Set Half Carry Flag in SREG Clear Half Carry Flag in SREG H←1 H←0 H H 1 1 DATA TRANSFER INSTRUCTIONS MOV Rd, Rr Move Between Registers 1 Rd, Rr Copy Register Word Rd ← Rr Rd+1:Rd ← Rr+1:Rr None MOVW None 1 LDI Rd, K Load Immediate Rd ← K None 1 LD Rd, X Load Indirect Rd ← (X) None 2 LD Rd, X+ Load Indirect and Post-Inc. Rd ← (X), X ← X + 1 None 2 LD Rd, - X Load Indirect and Pre-Dec. X ← X - 1, Rd ← (X) None 2 LD Rd, Y Load Indirect Rd ← (Y) None 2 LD Rd, Y+ Load Indirect and Post-Inc. Rd ← (Y), Y ← Y + 1 None 2 2 LD Rd, - Y Load Indirect and Pre-Dec. Y ← Y - 1, Rd ← (Y) None LDD Rd,Y+q Load Indirect with Displacement Rd ← (Y + q) None 2 LD Rd, Z Load Indirect Rd ← (Z) None 2 LD Rd, Z+ Load Indirect and Post-Inc. Rd ← (Z), Z ← Z+1 None 2 LD Rd, -Z Load Indirect and Pre-Dec. Z ← Z - 1, Rd ← (Z) None 2 LDD Rd, Z+q Load Indirect with Displacement Rd ← (Z + q) None 2 LDS Rd, k Load Direct from SRAM Rd ← (k) None 2 ST X, Rr Store Indirect (X) ← Rr None 2 ST X+, Rr Store Indirect and Post-Inc. (X) ← Rr, X ← X + 1 None 2 ST - X, Rr Store Indirect and Pre-Dec. X ← X - 1, (X) ← Rr None 2 ST Y, Rr Store Indirect (Y) ← Rr None 2 ST Y+, Rr Store Indirect and Post-Inc. (Y) ← Rr, Y ← Y + 1 None 2 2 ST - Y, Rr Store Indirect and Pre-Dec. Y ← Y - 1, (Y) ← Rr None STD Y+q,Rr Store Indirect with Displacement (Y + q) ← Rr None 2 ST Z, Rr Store Indirect (Z) ← Rr None 2 ST Z+, Rr Store Indirect and Post-Inc. (Z) ← Rr, Z ← Z + 1 None 2 ST -Z, Rr Store Indirect and Pre-Dec. Z ← Z - 1, (Z) ← Rr None 2 STD Z+q,Rr Store Indirect with Displacement (Z + q) ← Rr None 2 STS k, Rr Store Direct to SRAM (k) ← Rr None 2 Load Program Memory R0 ← (Z) None 3 LPM LPM Rd, Z Load Program Memory Rd ← (Z) None 3 LPM Rd, Z+ Load Program Memory and Post-Inc Rd ← (Z), Z ← Z+1 None 3 Store Program Memory (Z) ← R1:R0 None - In Port Rd ← P None 1 1 SPM IN Rd, P OUT P, Rr Out Port P ← Rr None PUSH Rr Push Register on Stack STACK ← Rr None 2 POP Rd Pop Register from Stack Rd ← STACK None 2 MCU CONTROL INSTRUCTIONS 303 7734P–AVR–08/10 Mnemonics 304 Operands Description Operation Flags #Clocks None 1 NOP No Operation SLEEP Sleep (see specific descr. for Sleep function) None 1 WDR BREAK Watchdog Reset Break (see specific descr. for WDR/timer) For On-chip Debug Only None None 1 N/A AT90PWM81 7734P–AVR–08/10 AT90PWM81 26. Ordering Information Speed (MHz) Power Supply Ordering Code Package (1) Operation Range 16 2.7 - 5.5V AT90PWM81-16ME QFN32 Engineering Samples 16 2.7 - 5.5V AT90PWM81-16SE SO20 Engineering Samples (2) 16 2.7 - 5.5V AT90PWM81-16MN QFN32 Extended (-40°C to 105°C) 16 2.7 - 5.5V AT90PWM81-16SN SO20 Extended (-40°C to 105°C) (3) 16 2.7 - 5.5V AT90PWM81-16MF QFN32 Extended (-40°C to 125°C) 16 2.7 - 5.5V AT90PWM81-16SF SO20 Extended (-40°C to 125°C) Note: All packages are Pb free, fully LHF Note: This device can also be supplied in wafer form. Please contact your local Atmel sales office for detailed ordering information and minimum quantities. Note: Parts numbers are for shipping in sticks (SO) or in trays (QFN). Thes devices can also be supplied in Tape and Reel. Please contact your local Atmel sales office for detailed ordering information and minimum quantities. Note: P/N for Extended -40°C to 125°C are not yet defined Note: 1. Marking on the package is PWM81-ME. 2. Marking on the package is PWM81-MN. 3. Marking on the package is PWM81-MF. 305 7734P–AVR–08/10 27. Package Information Package Type SO20 TG, 20-Lead, 0.300” Body Width Plastic Gull Wing Small Outline Package (SOIC) QFN32 PN, 32-Lead, 5.0 x 5.0 mm Body, 0.50mm Pitch Quad Flat No lead Package (QFN) 306 AT90PWM81 7734P–AVR–08/10 AT90PWM81 27.1 SO20 307 7734P–AVR–08/10 27.2 308 QFN32 AT90PWM81 7734P–AVR–08/10 AT90PWM81 28. Errata 28.1 Errata AT90PWM81 revA • 28.2 Available on request Errata AT90PWM81 revB • Clock Switch disable • Crystal oscillator control with Clock Switch • BOD disable fuse • PSC output at Reset • Flash and EEPROM programming failure if CPU clock is switched • ADC AMPlifier measurement is unstable • ADC measurement reports abnormal values with PSC2-synchronized conversions • Over-consumption in power down sleep mode 1. Clock Switch enable & disable After a “Enable Clock Source” or a “Disable Clock Source” command, the command is still active until the next access of CLKCSR register. If CLKSEL is written with a new value, the corresponding clock will be unintentionnaly enabled or disabled. Work around: After the Enable or Disable command, write CLKCSR with value 1<<CLKCCE 2. Crystal oscillator control with Clock Switch When a Xtal oscillator is active and CLKSELR is written with a new value for the selection of another clock source (for instance RC or WD) , the Xtal oscillator gain is not correct. Work around: After the commands “Enable Clock Source” and “Clock Source Switching”, write back CLKSELR with the values corresponding to the active Xtal oscillator 3. BOD disable fuse It is strongly advised to keep the BOD active. Indeed, the RC oscillator may lock if it is activated when the power suppy goes at a low voltage. Work around: If it is mandatory to disable the BOD, do not set the RC oscillator as clock source during reset and makes sure the RC oscillator is never active when the power supply is below the lowest POR voltage (2.6V). 4. PSC output at Reset At Reset, the PSC outputs may be set at a value different from the PSC Fuse configuration (Bit 4 of Extended Fuse Byte). Work around: Initiate PSC output states from source code. 309 7734P–AVR–08/10 5. Flash and EEPROM programming failure if CPU clock is switched If Clock switching is used in the Application, the memory programming is only possible when the internal RC oscillator is selected as System clock. If the Application requires a memory programming on a clock source different from the internal RC oscillator, do not switch to this clock source. Work around: - Use internal RC oscillator when programming Flash and EEPROM, or - Do not use clock switching. 6. ADC AMPlifier measurement is unstable When switching from a single-ended ADC channel to an Amplified channel, noise can appear on ADC conversion. Work around: After switching from a single ended to an amplified channel, discard the first ADC conversion. 7. ADC measurement reports abnormal values with PSC2-synchronized conversions When using ADC in synchronized mode, an unexpected extra Single ended conversion can spuriously re-start.This can occur when the End of conversion and the Trigger event occur at the same time. Work around: No workaround 8. Over-consumption in power down sleep mode. In Power-down mode, an extra power consumption up to 500µA may occur. Work around: No workaround 28.3 310 Errata AT90PWM81 revC • Clock Switch disable • Crystal oscillator control with Clock Switch • BOD disable fuse • PSC output at Reset • Flash and EEPROM programming failure if CPU clock is switched • ADC AMPlifier measurement is unstable • ADC measurement reports abnormal values with PSC2-synchronized conversions • Over-consumption in power down sleep mode. AT90PWM81 7734P–AVR–08/10 AT90PWM81 1. Clock Switch enable & disable After a “Enable Clock Source” or a “Disable Clock Source” command, the command is still active until the next access of CLKCSR register. If CLKSEL is written with a new value, the corresponding clock will be unintentionnaly enabled or disabled. Work around: Atter the Enable or Disable command, write CLKCSR with value 1<<CLKCCE 2. Crystal oscillator control with Clock Switch When a Xtal oscillator is active and CLKSELR is written with a new value for the selection of another clock source (for instance RC or WD) , the Xtal oscillator gain is not correct. Work around: After the commands “Enable Clock Source” and “Clock Source Switching”, write back CLKSELR with the values corresponding to the active Xtal oscillator 3. BOD disable fuse It is strongly advised to keep the BOD active. Indeed, the RC oscillator may lock if it is activated when the power suppy goes at a low voltage. Work around: If it is mandatory to disable the BOD, do not set the RC oscillator as clock source during reset and makes sure the RC oscillator is never active when the power supply is below the lowest POR voltage (2.6V). 4. PSC output at Reset At Reset, the PSC outputs may be set at a value different from the PSC Fuse configuration (Bit 4 of Extended Fuse Byte). Work around: Initiate PSC output states from source code. 5. Flash and EEPROM programming failure if CPU clock is switched If Clock switching is used in the Application, the memory programming is only possible when the internal RC oscillator is selected as System clock. If the Application requires a memory programming on a clock source different from the internal RC oscillator, do not switch to this clock source. Work around: - Use internal RC oscillator when programming Flash and EEPROM, or - Do not use clock switching 6. ADC AMPlifier measurement is unstable When switching from a single-ended ADC channel to an Amplified channel, noise can appear on ADC conversion. Work around: After switching from a single ended to an amplified channel, discard the first ADC conversion. 311 7734P–AVR–08/10 7. ADC measurement reports abnormal values with PSC2-synchronized conversions When using ADC in synchronized mode, an unexpected extra Single ended conversion can spuriously re-start.This can occur when the End of conversion and the Trigger event occur at the same time. Work around: No workaround 8. Over-consumption in power down sleep mode. In Power-down mode, an extra power consumption up to 500µA may occur. Work around: No workaround 28.4 Errata AT90PWM81 revD • Clock Switch disable • Crystal oscillator control with Clock Switch • BOD disable fuse • Flash and EEPROM programming failure if CPU clock is switched • ADC Amplifier measurement is unstable • ADC measurement reports abnormal values with PSC2-synchronized conversions • Over-consumption in power down sleep mode 1. Clock Switch enable & disable After a “Enable Clock Source” or a “Disable Clock Source” command, the command is still active until the next access of CLKCSR register. If CLKSEL is written with a new value, the corresponding clock will be unintentionnaly enabled or disabled. Work around: Atter the Enable or Disable command, write CLKCSR with value 1<<CLKCCE 2. Crystal oscillator control with Clock Switch When a Xtal oscillator is active and CLKSELR is written with a new value for the selection of another clock source (for instance RC or WD) , the Xtal oscillator gain is not correct. Work around: After the commands “Enable Clock Source” and “Clock Source Switching”, write back CLKSELR with the values corresponding to the active Xtal oscillator 3. BOD disable fuse It is strongly advised to keep the BOD active. Indeed, the RC oscillator may lock if it is activated when the power suppy goes at a low voltage. Work around: If it is mandatory to disable the BOD, do not set the RC oscillator as clock source during reset and makes sure the RC oscillator is never active when the power supply is below the lowest POR voltage (2.6V). 312 AT90PWM81 7734P–AVR–08/10 AT90PWM81 4. Flash and EEPROM programming failure if CPU clock is switched If Clock switching is used in the Application, the memory programming is only possible when the internal RC oscillator is selected as System clock. If the Application requires a memory programming on a clock source different from the internal RC oscillator, do not switch to this clock source. Work around: - Use internal RC oscillator when programming Flash and EEPROM, or - Do not use clock switching 5. ADC AMPlifier measurement is unstable When switching from a single-ended ADC channel to an Amplified channel, noise can appear on ADC conversion. Work around: After switching from a single ended to an amplified channel, discard the first ADC conversion. 6. ADC measurement reports abnormal values with PSC2-synchronized conversions When using ADC in synchronized mode, an unexpected extra Single ended conversion can spuriously re-start.This can occur when the End of conversion and the Trigger event occur at the same time. Work around: No workaround 7. Over-consumption in power down sleep mode. In Power-down mode, an extra power consumption up to 500µA may occur. Work around: No workaround 28.5 Errata AT90PWM81 revE • Clock Switch disable • Crystal oscillator control with Clock Switch • BOD disable fuse 1. Clock Switch enable & disable After a “Enable Clock Source” or a “Disable Clock Source” command, the command is still active until the next access of CLKCSR register. If CLKSEL is written with a new value, the corresponding clock will be unintentionnaly enabled or disabled. Work around: Atter the Enable or Disable command, write CLKCSR with value 1<<CLKCCE 313 7734P–AVR–08/10 2. Crystal oscillator control with Clock Switch When a Xtal oscillator is active and CLKSELR is written with a new value for the selection of another clock source (for instance RC or WD) , the Xtal oscillator gain is not correct. Work around: After the commands “Enable Clock Source” and “Clock Source Switching”, write back CLKSELR with the values corresponding to the active Xtal oscillator 3. BOD disable fuse It is strongly advised to keep the BOD active. Indeed, the RC oscillator may lock if it is activated when the power suppy goes at a low voltage. Work around: If it is mandatory to disable the BOD, do not set the RC oscillator as clock source during reset and makes sure the RC oscillator is never active when the power-supply is below the lowest supply voltage (2.6V). 314 AT90PWM81 7734P–AVR–08/10 AT90PWM81 29. Datasheet Revision History for AT90PWM81 Please note that the referring page numbers in this section are referred to this document. The referring revision in this section are referring to the document revision. 29.1 Rev. 7734A 1. 29.2 Document creation. Rev. 7734B 1. GPIO3 suppressed for compatibility reason 2. Pinout: PB7 & PD7 swapped 3. CKSEL values redefined 4. Clock switching & clock monitoring added 5. PSCrOUT name changed to PSCOUTR 6. ADC Auto trigger on PSC synchro improved. 7. Parallel programming updated for 20 pins 8. Fuses updated: compatibility & potential conflict for reset levels 29.3 Rev. 7734C 1. Pin out change request 2. Several improvements on paragraph indent and numbering 3. P28-29: Device clock option select 4. P194: BGD bit suppressed 5. P311-314: Register address changed 29.4 Rev. 7734D 1. Pin name AGND 2. PSC reduced support enhanced resolution (Application request) 29.5 Rev. 7734E 1. Speed at 3V, 12 Mhz 2. Add chapter Pin description (PE request) 3. Table 7-1 : PE function for 128k RC oscillator is I/O 4. Details on RC oscillator enable page 30 5. New warnings on clock switching page 40 6. Details on CKRC81 page 45 7. Wake up source PSC not available in PowedDown page 48 8. Typos on DIDR0/1 9. ADC sample & hold time on auto conversion 10. PSC input beheavior during reset precision 11. Update using the PRR examples with exsisting peripherals 12. Parallel programing input pins 13. I/O hysteresis curve 315 7734P–AVR–08/10 29.6 Rev. 7734F 1. Clean chapter clock from all “Power save” 2. Update chapter “Calibrated Internal RC Oscillator” on page 29 3. Update Table 7-9 on page 35 : SUT for PLL 4. Update chapter Idle Mode page 48 5. Update figure “PSC Input Module A” on page 119 and “PSC Input Module B” on page 120 6. Update figure “PSC behavior versus PSCn Input B in Mode 14” on page 132 7. Update tables 14-16 ”PSC edge & level input Selection” on page 142 & 14-17 ”PSC edge & level input Selection” on page 142 8. Clean chaper PSC (no more PSC0 & PSC1 register) 9. PSCR registers and bits renamed from “r” to “0” 10. Update chapter “Digital Input Disable Register 0 – DIDR0” on page 207 & “Digital Input Disable Register 1– DIDR1” on page 208 11. Update figures on parallel programming :Figure 23-1 on page 261, Figure 23-3 on page 265,Figure 23-4 on page 266,Figure 23-5 on page 268 12. Suppress chapter ”Parallel Programing Characteristic” after Section 23.7.14, now in “Parallel Programming Characteristics” on page 282 29.7 Rev. 7734G 1. Update pin out definitions with PE3 as AREF pin: Figures “20 Pin Packages” on page 4, “32Pin Packages” on page 5,Table “Pin out description” on page 7, Chapter “Port E (P32..0) RESET/ XTAL1/ XTAL2/AREF” on page 8 and Chapter “Alternate Functions of Port E” on page 82 2. Update Table 7-1 on page 28 , for CKSEL 0111, 1100 & 1101 3. Update figure “Analog to Digital Converter Block Schematic” on page 210 4. Update Table 19-3 on page 224; warning no more errata 29.8 Rev. 7734H 1. Udate Product configurationTable 2-1 on page 2 2. Add chapter “RC Oscillator calibration” on page 31 3. Update chapter “Internal Voltage Reference” on page 58 4. Update chapter “On Chip voltage Reference and Temperature sensor overview” on page 192 5. Update chapter “Temperature Measurement” on page 196 6. Update Figure “Analog Comparator Block Diagram” on page 201 7. Update chapter “Reading the Signature Row from Software” on page 250 8. Update chapter “Calibrated Internal RC Oscillator Accuracy” on page 277 9. Add chapter “Power consumption estimation with clock prescaling” on page 290 10. Update chapter “Errata” on page 325 29.9 Rev. 7734I 1. Remove PE3 I/O function (Only AREF and ADC functions) : Pages 3,4,6,7,80,81,223 2. Remove the ‘Enable Watchdog in Automatic Reload Mode’ Page 34 and in Table 6-12 on Page 18 3. Update RC Calibartion section 6.2.2.1 page 30 4. Remove chapter 6.3.7 on Page 36 5. Remove chapter 16.3 Band Gap calibration procedure on Page 191 6. Update Temperature calibration on Page 191 7. Remove chapter 16.4.3 Two Points Temperature sensor calibration on Page 197 316 AT90PWM81 7734P–AVR–08/10 AT90PWM81 8. Update Signature Row Addressing on Page249 9. Update DC Characteristics : Update table 23-1 Page 275 : RC calibartion @25°C Update Table 23.2 page 272 : -40°C in place of -45°C New Table in 23.2 : -40°C to +125°C 10. Update Erratasheet 29.10 Rev. 7734J 1. Page 2 Table 2-1 : QFN32 : 32 Pins 2. Page 6 Table 3-2 : SO24 and QFN20 are removed 3. Page 30 section 6.2.2.1 : RC Osc. is monitored @125°C 4. Page 51 : Table 8.2 : BODenable is mandatory 5. Page 166 : removed AT90PWM2/3 comments 6. Page 267 Table 23-1 : User Calibration at +5% 7. Page 271 Update of ADC Characteristics 8. Page 273 Add the DAC Characteristics 29.11 Rev. 7734K 1. Page 193 §16.4.1 : removed the last sentence about reading of the temperature sensor during Hot testing 2. Page 193 §16.4.1 : T formula modifed with new TSGAIN 3. Page 244 Table 21.5 : Signature row adressing table updated with right address 29.12 Rev. 7734L 1. Update Errata Rev E 29.13 Rev. 7734M 1. Page 204 : Figure 18-1 removed REFS2 bit 2. .Pages 277 to 294 : update of Typical characteristics 29.14 Rev. 7734N 1. Page 52 : update of BOD levels 2. .Pages 267,268,269,270 : update of Vref, Icc power-down, Icc operating, Icc Idle and Watchdog oscillator characteristics 29.15 Rev. 7734O 1. Pages 275,276 Table 23-6: update of ADC characteristics 2. .Page 270: add a new line in Table 23-1(Calibrated Internal RC oscillator Accuracy ) 3. .Pages 267, 269,279 : update of Analog comparator characteristics 29.16 Rev. 7734P 1. Updated “Electrical Characteristics(1)” on page 265 and “AT90PWM81 Typical Characteristics” on page 280 317 7734P–AVR–08/10 Table Of Contents 1 Products Configuration ..........................................................................................2 2 Pin Configurations .................................................................................................3 2.1Pin Descriptions ....................................................................................................................... 6 3 AVR CPU Core .......................................................................................................8 3.1Introduction .............................................................................................................................. 8 3.2Architectural Overview ............................................................................................................ 8 3.3ALU – Arithmetic Logic Unit .................................................................................................. 9 3.4Status Register .......................................................................................................................... 9 3.5General Purpose Register File ................................................................................................ 11 3.6Stack Pointer .......................................................................................................................... 12 3.7Instruction Execution Timing ................................................................................................. 12 3.8Reset and Interrupt Handling ................................................................................................. 13 4 Memories ...............................................................................................................16 4.1In-System Reprogrammable Flash Program Memory ........................................................... 16 4.2SRAM Data Memory ............................................................................................................. 16 4.3EEPROM Data Memory ........................................................................................................ 18 4.4Fuse Bits ................................................................................................................................. 22 4.5I/O Memory ............................................................................................................................ 26 4.6General Purpose I/O Registers ............................................................................................... 26 5 System Clock and Clock Options .........................................................................27 5.1Clock Systems and their Distribution ..................................................................................... 27 5.2Clock Sources ......................................................................................................................... 28 5.3Dynamic Clock Switch ........................................................................................................... 35 5.4System Clock Prescaler .......................................................................................................... 38 5.5Register Description ............................................................................................................... 38 6 Power Management and Sleep Modes .................................................................44 6.1Sleep Modes ........................................................................................................................... 44 6.2Idle Mode ............................................................................................................................... 44 6.3ADC Noise Reduction Mode ................................................................................................. 45 6.4Power-down Mode ................................................................................................................. 45 6.5Standby Mode ........................................................................................................................ 45 6.6Power Reduction Register ...................................................................................................... 45 6.7Minimizing Power Consumption ........................................................................................... 45 i AT90PWM81 7734P–AVR–08/10 AT90PWM81 6.8Register description ................................................................................................................ 47 7 System Control and Reset .....................................................................................49 7.1System Control overview ....................................................................................................... 49 7.2System Control registers ........................................................................................................ 53 7.3Internal Voltage Reference ..................................................................................................... 54 7.4Watchdog Timer ..................................................................................................................... 55 8 Interrupts ..............................................................................................................61 8.1Interrupt Vectors in AT90PWM81 ........................................................................................ 61 9 I/O-Ports ................................................................................................................66 9.1Introduction ............................................................................................................................ 66 9.2Ports as General Digital I/O ................................................................................................... 67 9.3Alternate Port Functions ......................................................................................................... 71 9.4Register Description for I/O-Ports ......................................................................................... 80 10 External Interrupts ...............................................................................................82 11 Reduced 16-bit Timer/Counter1 ..........................................................................84 11.1Overview .............................................................................................................................. 84 11.2Accessing 16-bit Registers ................................................................................................... 86 11.3Timer/Counter Clock Sources .............................................................................................. 89 11.4Counter Unit ......................................................................................................................... 90 11.5Input Capture Unit ................................................................................................................ 91 11.6Modes of Operation .............................................................................................................. 93 11.7Timer/Counter Timing Diagrams ......................................................................................... 94 11.816-bit Timer/Counter Register Description .......................................................................... 95 12 Power Stage Controller – (PSCn) ........................................................................99 12.1Features ................................................................................................................................ 99 12.2Overview .............................................................................................................................. 99 12.3PSC Description ................................................................................................................. 100 12.4Signal Description .............................................................................................................. 102 12.5Functional Description ....................................................................................................... 104 12.6Update of Values ................................................................................................................ 109 12.7Enhanced Resolution .......................................................................................................... 110 12.8PSC Inputs .......................................................................................................................... 113 12.9PSC Input Mode 1: Stop signal, Jump to Opposite Dead-Time and Wait ......................... 120 12.10PSC Input Mode 2: Stop signal, Execute Opposite Pulse and Wait ................................ 121 ii 7734P–AVR–08/10 12.11PSC Input Mode 3: Stop signal, Execute Opposite Pulse while Fault active .................. 122 12.12PSC Input Mode 4: Deactivate outputs without changing timing. ................................... 123 12.13PSC Input Mode 5: Stop signal and Insert Dead-Time .................................................... 123 12.14PSC Input Mode 6: Stop signal, Jump to Opposite Dead-Time and Wait. ...................... 124 12.15PSC Input Mode 7: Halt PSC and Wait for Software Action .......................................... 124 12.16PSC Input Mode 8: Edge Retrigger PSC ......................................................................... 125 12.17PSC Input Mode 9: Fixed Frequency Edge Retrigger PSC ............................................. 126 12.18PSC Input Mode 14: Fixed Frequency Edge Retrigger PSC and Deactivate Output ...... 127 12.19PSC2 Outputs ................................................................................................................... 129 12.20Analog Synchronization ................................................................................................... 130 12.21Interrupt Handling ............................................................................................................ 130 12.22PSC Synchronization ........................................................................................................ 131 12.23PSC Clock Sources ........................................................................................................... 132 12.24Interrupts .......................................................................................................................... 132 12.25PSC Register Definition ................................................................................................... 133 12.26PSC2 Specific Register .................................................................................................... 142 13 Reduced Power Stage Controller – (PSCR) .......................................................147 13.1Features .............................................................................................................................. 147 13.2Overview ............................................................................................................................ 147 13.3PSCR Description ............................................................................................................. 148 13.4Signal Description .............................................................................................................. 149 13.5Functional Description ....................................................................................................... 151 13.6Update of Values ................................................................................................................ 154 13.7Enhanced resolution ........................................................................................................... 155 13.8PSCR Inputs ....................................................................................................................... 155 13.9PSCR Input Mode 1: Stop signal, Jump to Opposite Dead-Time and Wait ...................... 161 13.10PSCR Input Mode 2: Stop signal, Execute Opposite Dead-Time and Wait .................... 162 13.11PSCR Input Mode 3: Stop signal, Execute Opposite while Fault active ......................... 163 13.12PSCR Input Mode 4: Deactivate outputs without changing timing. ................................ 164 13.13PSCR Input Mode 5: Stop signal and Insert Dead-Time ................................................. 164 13.14PSCR Input Mode 6: Stop signal, Jump to Opposite Dead-Time and Wait. ................... 165 13.15PSCR Input Mode 7: Halt PSCR and Wait for Software Action ..................................... 165 13.16PSCR Input Mode 8: Edge Retrigger PSC ....................................................................... 166 13.17PSCR Input Mode 9: Fixed Frequency Edge Retrigger PSC ........................................... 167 13.18PSCR Input Mode 14: Fixed Frequency Edge Retrigger PSCR and Deactivate Output . 168 13.19Analog Synchronization ................................................................................................... 169 iii AT90PWM81 7734P–AVR–08/10 AT90PWM81 13.20Interrupt Handling ............................................................................................................ 170 13.21PSC Clock Sources ........................................................................................................... 170 13.22Interrupts .......................................................................................................................... 171 13.23PSCR Register Definition ................................................................................................ 171 14 Serial Peripheral Interface – SPI: .....................................................................180 14.1Features .............................................................................................................................. 180 14.2Overview ............................................................................................................................ 180 14.3SS Pin Functionality ........................................................................................................... 184 14.4Data Modes ........................................................................................................................ 185 14.5SPI registers ........................................................................................................................ 186 15 Voltage Reference and Temperature Sensor .....................................................189 15.1Features .............................................................................................................................. 189 15.2On Chip voltage Reference and Temperature sensor overview ......................................... 189 15.3Register Description ........................................................................................................... 190 15.4Temperature Measurement ................................................................................................. 192 16 Analog Comparator ............................................................................................194 16.1Features .............................................................................................................................. 194 16.2Overview ............................................................................................................................ 194 16.3Shared pins between Analog Comparator and ADC .......................................................... 196 16.4Analog Comparator Register Description .......................................................................... 196 17 Analog to Digital Converter - ADC ....................................................................203 17.1Features .............................................................................................................................. 203 17.2Operation ............................................................................................................................ 205 17.3Starting a Conversion ......................................................................................................... 205 17.4Prescaling and Conversion Timing .................................................................................... 206 17.5Changing Channel or Reference Selection ......................................................................... 208 17.6ADC Noise Canceler .......................................................................................................... 209 17.7ADC Conversion Result ..................................................................................................... 214 17.8ADC Register Description ................................................................................................. 216 17.9Amplifier ............................................................................................................................ 221 17.10Amplifier Control Registers ............................................................................................. 224 18 Digital to Analog Converter - DAC ....................................................................226 18.1Features .............................................................................................................................. 226 18.2Operation ............................................................................................................................ 227 iv 7734P–AVR–08/10 18.3Starting a Conversion ......................................................................................................... 227 18.4DAC Register Description ................................................................................................. 228 19 debugWIRE On-chip Debug System ..................................................................231 19.1Features .............................................................................................................................. 231 19.2Overview ............................................................................................................................ 231 19.3Physical Interface ............................................................................................................... 231 19.4Software Break Points ........................................................................................................ 232 19.5Limitations of debugWIRE ................................................................................................ 232 19.6debugWIRE Related Register in I/O Memory ................................................................... 232 20 Boot Loader Support – Read-While-Write Self-Programming .........................232 20.1Boot Loader Features ......................................................................................................... 233 20.2Application and Boot Loader Flash Sections ..................................................................... 233 20.3Read-While-Write and No Read-While-Write Flash Sections .......................................... 233 20.4Boot Loader Lock Bits ....................................................................................................... 236 20.5Entering the Boot Loader Program .................................................................................... 237 20.6Addressing the Flash During Self-Programming ............................................................... 239 20.7Self-Programming the Flash ............................................................................................... 240 21 Memory Programming .......................................................................................247 21.1Program And Data Memory Lock Bits .............................................................................. 247 21.2Fuse Bits ............................................................................................................................. 249 21.3Signature Bytes .................................................................................................................. 252 21.4Calibration Byte ................................................................................................................. 252 21.5Parallel Programming Parameters, Pin Mapping, and Commands .................................... 252 21.6Serial Programming Pin Mapping ...................................................................................... 254 21.7Parallel Programming ......................................................................................................... 255 21.8Serial Downloading ............................................................................................................ 261 22 Electrical Characteristics(1) ..................................................................................................................... 265 22.1Absolute Maximum Ratings* ............................................................................................. 265 22.2DC Characteristics .............................................................................................................. 266 22.3Clock Drive Characteristics ............................................................................................... 270 22.4Maximum Speed vs. VCC ................................................................................................................................................. 271 22.5PLL Characteristics ............................................................................................................ 272 22.6SPI Timing Characteristics ................................................................................................. 273 22.7ADC Characteristics ........................................................................................................... 275 22.8DAC Characteristics ........................................................................................................... 277 v AT90PWM81 7734P–AVR–08/10 AT90PWM81 22.9Parallel Programming Characteristics ................................................................................ 277 23 AT90PWM81 Typical Characteristics ...............................................................280 23.1Active Supply Current ........................................................................................................ 281 23.2Idle Supply Current ............................................................................................................ 283 23.3Power-Down Supply Current ............................................................................................. 285 23.4Pin Pull-up .......................................................................................................................... 286 23.5Pin output high voltage ...................................................................................................... 289 23.6Pin output low voltage ........................................................................................................ 290 23.7Pin Thresholds .................................................................................................................... 291 23.8BOD Thresholds ................................................................................................................. 292 23.9Analog Reference ............................................................................................................... 293 23.10Internal Oscillator Speed .................................................................................................. 294 23.11Current Consumption in Reset ......................................................................................... 296 24 Register Summary ..............................................................................................298 25 Instruction Set Summary ...................................................................................302 26 Ordering Information .........................................................................................305 27 Package Information ..........................................................................................306 27.1SO20 ................................................................................................................................... 307 27.2QFN32 ................................................................................................................................ 308 28 Errata ..................................................................................................................309 28.1Errata AT90PWM81 revA ................................................................................................. 309 28.2Errata AT90PWM81 revB ................................................................................................. 309 28.3Errata AT90PWM81 revC ................................................................................................. 310 28.4Errata AT90PWM81 revD ................................................................................................. 312 28.5Errata AT90PWM81 revE .................................................................................................. 313 29 Datasheet Revision History for AT90PWM81 ...................................................315 29.1Rev. 7734A ......................................................................................................................... 315 29.2Rev. 7734B ......................................................................................................................... 315 29.3Rev. 7734C ......................................................................................................................... 315 29.4Rev. 7734D ......................................................................................................................... 315 29.5Rev. 7734E ......................................................................................................................... 315 29.6Rev. 7734F ......................................................................................................................... 316 29.7Rev. 7734G ......................................................................................................................... 316 29.8Rev. 7734H ......................................................................................................................... 316 vi 7734P–AVR–08/10 29.9Rev. 7734I .......................................................................................................................... 316 29.10Rev. 7734J ........................................................................................................................ 317 29.11Rev. 7734K ....................................................................................................................... 317 29.12Rev. 7734L ....................................................................................................................... 317 29.13Rev. 7734M ...................................................................................................................... 317 29.14Rev. 7734N ....................................................................................................................... 317 29.15Rev. 7734O ....................................................................................................................... 317 29.16Rev. 7734P ....................................................................................................................... 317 vii AT90PWM81 7734P–AVR–08/10 Headquarters International Atmel Corporation 2325 Orchard Parkway San Jose, CA 95131 USA Tel: 1(408) 441-0311 Fax: 1(408) 487-2600 Atmel Asia Unit 1-5 & 16, 19/F BEA Tower, Millennium City 5 418 Kwun Tong Road Kwun Tong, Kowloon Hong Kong Tel: (852) 2245-6100 Fax: (852) 2722-1369 Atmel Europe Le Krebs 8, Rue Jean-Pierre Timbaud BP 309 78054 Saint-Quentin-enYvelines Cedex France Tel: (33) 1-30-60-70-00 Fax: (33) 1-30-60-71-11 Atmel Japan 9F, Tonetsu Shinkawa Bldg. 1-24-8 Shinkawa Chuo-ku, Tokyo 104-0033 Japan Tel: (81) 3-3523-3551 Fax: (81) 3-3523-7581 Technical Support [email protected] Sales Contact www.atmel.com/contacts Product Contact Web Site www.atmel.com Literature Requests www.atmel.com/literature Disclaimer: The information in this document is provided in connection with Atmel products. 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