WINBOND W79E648

Preliminary W79E648 Data Sheet
8-BIT MICROCONTROLLER
Table of Contents1.
GENERAL DESCRIPTION .................................................................................................................... 2
2.
FEATURES............................................................................................................................................ 2
3.
PIN CONFIGURATION.......................................................................................................................... 3
4.
PIN DESCRIPTION ............................................................................................................................... 4
5.
BLOCK DIAGRAM ................................................................................................................................. 6
6.
FUNCTIONAL DESCRIPTION .............................................................................................................. 7
7.
MEMORY ORGANIZATION .................................................................................................................. 8
8.
INSTRUCTION .................................................................................................................................... 28
8.1
Instruction Timing .......................................................................................................... 28
9.
POWER MANAGEMENT..................................................................................................................... 34
10.
INTERRUPTS...................................................................................................................................... 37
11.
PROGRAMMABLE TIMERS/COUNTERS .......................................................................................... 39
11.1
11.2
11.3
12.
Timer/Counters 0 & 1..................................................................................................... 39
Timer/Counter 2 ............................................................................................................. 42
Watchdog Timer ............................................................................................................ 45
SERIAL PORT ..................................................................................................................................... 52
12.1
12.2
Framing Error Detection ................................................................................................ 58
Multiprocessor Communications ................................................................................... 58
13.
TIMED ACCESS PROTECTION ......................................................................................................... 59
14.
H/W REBOOT MODE (BOOT FROM 4K BYTES OF LDFLASH) ....................................................... 61
15.
IN-SYSTEM PROGRAMMING ............................................................................................................ 62
15.1
15.2
The Loader Program Locates at LDFlash Memory ....................................................... 62
The Loader Program Locates at APFlash Memory ....................................................... 62
16.
H/W WRITER MODE........................................................................................................................... 62
17.
SECURITY BITS.................................................................................................................................. 63
18.
ELECTRICAL CHARACTERISTICS.................................................................................................... 65
18.1
18.2
18.3
Absolute Maximum Ratings ........................................................................................... 65
DC Characteristics......................................................................................................... 66
AC Characteristics ......................................................................................................... 67
19.
TYPICAL APPLICATION CIRCUITS ................................................................................................... 72
20.
PACKAGE DIMENSIONS.................................................................................................................... 73
21.
APPLICATION NOTE .......................................................................................................................... 75
22.
REVISION HISTORY........................................................................................................................... 80
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
1. GENERAL DESCRIPTION
The W79E648 is a fast 8051 compatible microcontroller with a redesigned processor core without
wasted clock and memory cycles. As a result, it executes every 8051 instruction faster than the
original 8051 for the same crystal speed. Typically, the instruction executing time of W79E648 is 1.5 to
3 times faster than that of traditional 8051, depending on the type of instruction. In general, the overall
performance is about 2.5 times better than the original for the same crystal speed. Giving the same
throughput with lower clock speed, power consumption has been improved. Consequently, the
W79E648 is a fully static CMOS design; it can also be operated at a lower crystal clock. The
W79E648 contains In-System Programmable (ISP) 128 KB bank-addressed Flash EPROM; 4KB
auxiliary Flash EPROM for loader program; on-chip 1 KB MOVX SRAM; power saving modes.
2. FEATURES
•
8-bit CMOS microcontroller
•
High speed architecture of 4 clocks/machine cycle runs up to 40 MHz
•
Instruction-set compatible with MCS-51
•
Seven 8-bit I/O Ports
•
One extra 4-bit I/O ports, chip select, reboot fuction
•
Three 16-bit Timers
•
7 interrupt sources with two levels of priority
•
On-chip oscillator and clock circuitry
•
One enhanced full duplex serial port
• Dual 64KB In-System Programmable Flash EPROM banks (AP Flash EPROM 0 and AP Flash
EPROM 1)
•
4KB Auxiliary Flash EPROM for loader program (LD Flash EPROM)
•
256 bytes scratch-pad RAM
•
1 KB on-chip SRAM for MOVX instruction
•
Programmable Watchdog Timer
•
6 channels of 8 bit PWM
•
Software Reset
•
Software programmable access cycle to external RAM/peripherals
•
Code protection
•
Packages:
− PLCC 68: W79E648X40PX
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Preliminary W79E648
PIN CONFIGURATION
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
3. PIN DESCRIPTION
SYMBOL
TYPE
DESCRIPTIONS
EA
I
EXTERNAL ACCESS ENABLE: This pin forces the processor to execute out of
external ROM. It should be kept high to access internal ROM. The ROM
address and data will not be present on the bus if EA pin is high and the
program counter is within 128 KB area. Otherwise they will be present on the
bus.
PSEN
O
PROGRAM STORE ENABLE: PSEN enables the external ROM data onto the
Port 0 address/data bus during fetch and MOVC operations. When internal
ROM access is performed, no PSEN strobe signal outputs from this pin.
ALE
O
ADDRESS LATCH ENABLE: ALE is used to enable the address latch that
separates the address from the data on Port 0.
RST
I
RESET: A high on this pin for two machine cycles while the oscillator is running
resets the device.
XTAL1
I
CRYSTAL1: This is the crystal oscillator input. This pin may be driven by an
external clock.
XTAL2
O
CRYSTAL2: This is the crystal oscillator output. It is the inversion of XTAL1.
VSS
I
GROUND: Ground potential
VDD
I
POWER SUPPLY: Supply voltage for operation.
P0.0 − P0.7
I/O
P1.0 − P1.7
PORT 0: Port 0 is an open-drain bi-directional I/O port. This port also provides a
multiplexed low order address/data bus during accesses to external memory.
PORT 1: Port 1 is a bi-directional I/O port with internal pull-ups. The bits have
alternate functions which are described below:
I/O
T2(P1.0): Timer/Counter 2 external count input
T2EX(P1.1): Timer/Counter 2 Reload/Capture/Direction control
P2.0 − P2.7
I/O
PORT 2: Port 2 is a bi-directional I/O port with internal pull-ups. This port also
provides the upper address bits for accesses to external memory.
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Preliminary W79E648
Pin Description, continued
SYMBOL
TYPE
DESCRIPTIONS
PORT 3: Port 3 is a bi-directional I/O port with internal pull-ups. All bits have
alternate functions, which are described below:
RXD(P3.0) : Serial Port 0 input
TXD(P3.1) : Serial Port 0 output
INT0 (P3.2) : External Interrupt 0
P3.0 − P3.7
I/O
INT1 (P3.3) : External Interrupt 1
T0(P3.4)
: Timer 0 External Input
T1(P3.5)
: Timer 1 External Input
WR (P3.6) : External Data Memory Write Strobe
RD (P3.7) : External Data Memory Read Strobe
PORT 4: Port 4 is a 4-bit bi-directional I/O port. The P4.3 also provide the
P4.0 − P4.3
I/O
P5.0 – P5.7
I/O
PORT 5: Port 5 is a bi-directional I/O port with internal pull-ups.
P6.0 – P6.7
I/O
PORT6: Port 6 is a bi-directional I/O port with internal pull-ups.
P7.0 – P7.7
I/O
PORT 7: Port 7 is a bi-directional I/O port with internal pull-ups.
alternate function REBOOT which is H/W reboot from LD flash.
* Note: TYPE I : input, O: output, I/O: bi-directional.
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
4. BLOCK DIAGRAM
5.
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Preliminary W79E648
FUNCTIONAL DESCRIPTION
The W79E648 is 8052 pin compatible and instruction set compatible. It includes the resources of the
standard 8052 such as four 8-bit I/O Ports, three 16-bit timer/counters, full duplex serial port and
interrupt sources.
The W79E648 features a faster running and better performance 8-bit CPU with a redesigned core
processor without wasted clock and memory cycles. it improves the performance not just by running at
high frequency but also by reducing the machine cycle duration from the standard 8052 period of
twelve clocks to four clock cycles for the majority of instructions. This improves performance by an
average of 1.5 to 3 times. It can also adjust the duration of the MOVX instruction (access to off-chip
data memory) between two machine cycles and nine machine cycles. This flexibility allows the
W79E648 to work efficiently with both fast and slow RAMs and peripheral devices. In addition, the
W79E648 contains on-chip 1KB MOVX SRAM, the address of which is between 0000H and 03FFH. It
only can be accessed by MOVX instruction; this on-chip SRAM is optional under software control.
The W79E648 is an 8052 compatible device that gives the user the features of the original 8052
device, but with improved speed and power consumption characteristics. It has the same instruction
set as the 8051 family. While the original 8051 family was designed to operate at 12 clock periods per
machine cycle, the W79E648 operates at a much reduced clock rate of only 4 clock periods per
machine cycle. This naturally speeds up the execution of instructions. Consequently, the W79E648
can run at a higher speed as compared to the original 8052, even if the same crystal is used. Since
the W79E648 is a fully static CMOS design, it can also be operated at a lower crystal clock, giving the
same throughput in terms of instruction execution, yet reducing the power consumption.
The 4 clocks per machine cycle feature in the W79E648 is responsible for a three-fold increase in
execution speed. The W79E648 has all the standard features of the 8052, and has a few extra
peripherals and features as well.
I/O Ports
The W79E648 has four 8-bit ports and one extra 4-bit port. Port 0 can be used as an Address/Data
bus when external program is running or external memory/device is accessed by MOVC or MOVX
instruction. In these cases, it has strong pull-ups and pull-downs, and does not need any external pullups. Otherwise it can be used as a general I/O port with open-drain circuit. Port 2 is used chiefly as
the upper 8-bits of the Address bus when port 0 is used as an address/data bus. It also has strong
pull-ups and pull-downs when it serves as an address bus. Port 1 and 3 act as I/O ports with alternate
functions. Port 4 serves as a general purpose I/O port as Port 1 and Port 3.
Serial I/O
The W79E648 has one enhanced serial ports that are functionally similar to the serial port of the
original 8052 family. However the serial ports on the W79E648 can operate in different modes in order
to obtain timing similarity as well. The serial port has the enhanced features of Automatic Address
recognition and Frame Error detection.
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Preliminary W79E648
Timers
The W79E648 has three 16-bit timers that are functionally similar to the timers of the 8052 family.
When used as timers, they can be set to run at either 4 clocks or 12 clocks per count, thus providing
the user with the option of operating in a mode that emulates the timing of the original 8052. The
W79E648 has an additional feature, the watchdog timer. This timer is used as a System Monitor or as
a very long time period timer.
Interrupts
The Interrupt structure in the W79E648 is slightly different from that of the standard 8052. Due to the
presence of additional features and peripherals, the number of interrupt sources and vectors has been
increased. The W79E648 provides 7 interrupt resources with two priority level, including 2 external
interrupt sources, timer interrupts, serial I/O interrupts.
Power Management
Like the standard 80C52, the W79E648 also has IDLE and POWER DOWN modes of operation. The
W79E648 provides a new Economy mode which allow user to switch the internal clock rate divided by
either 4, 64 or 1024. In the IDLE mode, the clock to the CPU core is stopped while the timers, serial
port and interrupts clock continue to operate. In the POWER DOWN mode, all the clock are stopped
and the chip operation is completely stopped. This is the lowest power consumption state.
On-chip Data SRAM
The W79E648 has 1K Bytes of data space SRAM which is read/write accessible and is memory
mapped. This on-chip MOVX SRAM is reached by the MOVX instruction. It is not used for executable
program memory. There is no conflict or overlap among the 256 bytes Scratchpad RAM and the 1K
Bytes MOVX SRAM as they use different addressing modes and separate instructions. The on-chip
MOVX SRAM is enabled by setting the DME0 bit in the PMR register. After a reset, the DME0 bit is
cleared such that the on-chip MOVX SRAM is disabled, and all data memory spaces 0000H − FFFFH
access to the external memory.
6. MEMORY ORGANIZATION
The W79E648 separates the memory into two separate sections, the Program Memory and the Data
Memory. The Program Memory is used to store the instruction op-codes, while the Data Memory is
used to store data or for memory mapped devices.
Program Memory
The Program Memory on the standard 8052 can only be addressed to 64 Kbytes long. By invoking the
banking methodology, W79E648 can extend to two 64KB flash EPROM banks, APFlash0 and
APFlash1. There are on-chip ROM banks which can be used similarly to that of the 8052. All
instructions are fetched for execution from this memory area. The MOVC instruction can also access
this memory region. There is an auxiliary 4KB Flash EPROM bank (LDFlash) resided user loader
program for In-System Programming (ISP). Both APFlashs allow serial or parallel download according
to user loader program in LDFlash.
Data Memory
The W79E648 can access up to 64Kbytes of external Data Memory. This memory region is accessed
by the MOVX instructions. Unlike the 8051 derivatives, the W79E648 contains on-chip 1K bytes
MOVX SRAM of Data Memory, which can only be accessed by MOVX instructions. These 1K bytes of
SRAM are between address 0000H and 03FFH. Access to the on-chip MOVX SRAM is optional under
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Preliminary W79E648
software control. When enabled by software, any MOVX instruction that uses this area will go to the
on-chip RAM. MOVX addresses greater than 03FFH automatically go to external memory through
Port 0 and 2. When disabled, the 1KB memory area is transparent to the system memory map. Any
MOVX directed to the space between 0000H and FFFFH goes to the expanded bus on Port 0 and 2.
This is the default condition. In addition, the W79E648 has the standard 256 bytes of on-chip
Scratchpad RAM. This can be accessed either by direct addressing or by indirect addressing. There
are also some Special Function Registers (SFRs), which can only be accessed by direct addressing.
Since the Scratchpad RAM is only 256 bytes, it can be used only when data contents are small. In the
event that larger data contents are present, two selections can be used. One is on-chip MOVX SRAM,
the other is the external Data Memory. The on-chip MOVX SRAM can only be accessed by a MOVX
instruction, the same as that for external Data Memory. However, the on-chip RAM has the fastest
access times.
FFh
Indirect
Addressing
RAM
80h
7Fh
00h
64 K
Bytes
External
Data
Memory
Direct &
Indirect
Addressing
RAM
03FFh
0000h
FFFFh
SFRs
Direct
Addressing
64K Bytes
On-chip
Program
Memory
64K Bytes
On-chip
Program
Memory
APROM0
APROM1
4K Bytes
1K Bytes
On-chip SRAM
0000h
0FFFh
LDROM
Figure 1. Memory Map
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
Special Function Registers
The W79E648 uses Special Function Registers (SFRs) to control and monitor peripherals and their
Modes.
The SFRs reside in the register locations 80-FFh and are accessed by direct addressing only. Some
of the SFRs are bit addressable. This is very useful in cases where one wishes to modify a particular
bit without changing the others. The SFRs that are bit addressable are those whose addresses end in
0 or 8. The W79E648 contains all the SFRs present in the standard 8052. However, some additional
SFRs have been added. In some cases unused bits in the original 8052 have been given new
functions. The list of SFRs is as follows. The table is condensed with eight locations per row. Empty
locations indicate that there are no registers at these addresses. When a bit or register is not
implemented, it will read high.
Table 1. Special Function Register Location Table
F8
EIP
F0
B
E8
EIE
E0
ACC
D8
WDCON
D0
PSW
C8
T2CON
PWMP
PWM0
PWM1
PWMCON1 PWM2
PWM3
T2MOD
RCAP2L
RCAP2H
TL2
TH2
PWMCON2 PWM4
PWM5
PMR
STATUS
SFRAL
SFRAH
C0
TA
B8
IP
SADEN
B0
P3
P5
A8
IE
SADDR
A0
P2
XRAMAH
P4CSIN
98
SCON0
SBUF
P42AL
P42AH
P43AL
P43AH
90
P1
P4CONA
P4CONB
P40AL
P40AH
P41AL
88
TCON
TMOD
TL0
TL1
TH0
TH1
CKCON
80
P0
SP
DPL
DPH
P6
P7
ROMCON
SFDFD
SFRCN
P4
CHPCON
P41AH
PCON
Note: The SFRs in the column with dark borders are bit-addressable.
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Preliminary W79E648
A brief description of the SFRs now follows.
Port 0
Bit:
7
6
5
4
3
2
1
0
P0.7
P0.6
P0.5
P0.4
P0.3
P0.2
P0.1
P0.0
Mnemonic: P0
Address: 80h
Port 0 is an open-drain bi-directional I/O port. This port also provides a multiplexed low order
address/data bus during accesses to external memory.
Stack Pointer
Bit:
7
6
5
4
3
2
1
0
SP.7
SP.6
SP.5
SP.4
SP.3
SP.2
SP.1
SP.0
Mnemonic: SP
Address: 81h
The Stack Pointer stores the Scratchpad RAM address where the stack begins. In other words, it
always points to the top of the stack.
Data Pointer Low
Bit:
7
6
5
4
3
2
1
0
DPL.7
DPL.6
DPL.5
DPL.4
DPL.3
DPL.2
DPL.1
DPL.0
Mnemonic: DPL
Address: 82h
This is the low byte of the standard 8052 16-bit data pointer.
Data Pointer High
Bit:
7
6
5
4
3
2
1
0
DPH.7
DPH.6
DPH.5
DPH.4
DPH.3
DPH.2
DPH.1
DPH.0
Mnemonic: DPH
Address: 83h
This is the high byte of the standard 8052 16-bit data pointer.
Power Control
Bit:
7
6
5
4
3
2
1
0
SM0D
SMOD0
-
-
GF1
GF0
PD
IDL
Mnemonic: PCON
Address: 87h
SMOD : This bit doubles the serial port baud rate in mode 1, 2, and 3 when set to 1.
SMOD0: Framing Error Detection Enable: When SMOD0 is set to 1, then SCON.7 indicates a Frame
Error and acts as the FE flag. When SMOD0 is 0, then SCON.7 acts as per the standard
8052 function.
GF1-0: These two bits are general purpose user flags.
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Revision A1
Preliminary W79E648
PD:
Setting this bit causes the W79E648 to go into the POWER DOWN mode. In this mode all the
clocks are stopped and program execution is frozen.
IDL:
Setting this bit causes the W79E648 to go into the IDLE mode. In this mode the clocks to the
CPU are stopped, so program execution is frozen. But the clock to the serial, timer and
interrupt blocks is not stopped, and these blocks continue operating.
Timer Control
Bit:
7
6
5
4
3
2
1
0
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
Mnemonic: TCON
Address: 88h
TF1:
Timer 1 overflow flag: This bit is set when Timer 1 overflows. It is cleared automatically when
the program does a timer 1 interrupt service routine. Software can also set or clear this bit.
TR1:
Timer 1 run control: This bit is set or cleared by software to turn timer/counter on or off.
TF0:
Timer 0 overflow flag: This bit is set when Timer 0 overflows. It is cleared automatically when
the program does a timer 0 interrupt service routine. Software can also set or clear this bit.
TR0:
Timer 0 run control: This bit is set or cleared by software to turn timer/counter on or off.
IE1:
Interrupt 1 edge detect: Set by hardware when an edge/level is detected on INT1 . This bit is
cleared by hardware when the service routine is vectored to only if the interrupt was edge
triggered. Otherwise it follows the pin.
IT1:
Interrupt 1 type control: Set/cleared by software to specify falling edge/ low level triggered
external inputs.
IE0:
Interrupt 0 edge detect: Set by hardware when an edge/level is detected on INT0 . This bit is
cleared by hardware when the service routine is vectored to only if the interrupt was edge
triggered. Otherwise it follows the pin.
IT0:
Interrupt 0 type control: Set/cleared by software to specify falling edge/ low level triggered
external inputs.
Timer Mode Control
Bit:
7
6
5
4
3
2
1
0
GATE
C/T
M1
M0
GATE
C/T
M1
M0
TIMER1
TIMER0
Mnemonic: TMOD
Address: 89h
GATE: Gating control: When this bit is set, Timer/counter x is enabled only while INTx pin is high and
TRx control bit is set. When cleared, Timer x is enabled whenever TRx control bit is set.
C / T : Timer or Counter Select: When cleared, the timer is incremented by internal clocks. When set
, the timer counts high-to-low edges of the Tx pin.
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Preliminary W79E648
M1, M0: Mode Select bits:
M1
M0
MODE
0
0
Mode 0: 8-bits with 5-bit prescale.
0
1
Mode 1: 18-bits, no prescale.
1
0
Mode 2: 8-bits with auto-reload from THx
1
1
Mode 3: (Timer 0) TL0 is an 8-bit timer/counter controlled by the standard Timer 0
control bits. TH0 is a 8-bit timer only controlled by Timer 1 control bits. (Timer 1)
Timer/counter is stopped.
Timer 0 LSB
Bit:
7
6
5
4
3
2
1
0
TL0.7
TL0.6
TL0.5
TL0.4
TL0.3
TL0.2
TL0.1
TL0.0
Mnemonic: TL0
Address: 8Ah
TL0.7−0: Timer 0 LSB
Timer 1 LSB
Bit:
7
6
5
4
3
2
1
0
TL1.7
TL1.6
TL1.5
TL1.4
TL1.3
TL1.2
TL1.1
TL1.0
Mnemonic: TL1
Address: 8Bh
TL1.7−0: Timer 1 LSB
Timer 0 MSB
Bit:
7
6
5
4
3
2
1
0
TH0.7
TH0.6
TH0.5
TH0.4
TH0.3
TH0.2
TH0.1
TH0.0
Mnemonic: TH0
Address: 8Ch
TH0.7−0: Timer 0 MSB
Timer 1 MSB
Bit:
7
6
5
4
3
2
1
0
TH1.7
TH1.6
TH1.5
TH1.4
TH1.3
TH1.2
TH1.1
TH1.0
Mnemonic: TH1
Address: 8Dh
TH1.7−0: Timer 1 MSB
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
Clock Control
Bit:
7
6
5
4
3
2
1
0
WD1
WD0
T2M
T1M
T0M
MD2
MD1
MD0
Mnemonic: CKCON
Address: 8Eh
WD1−0: Watchdog timer mode select bits: These bits determine the time-out period for the watchdog
timer. In all four time-out options the reset time-out is 512 clocks more than the interrupt timeout period.
WD1
0
WD0
0
Interrupt time-out
2
0
1
2
1
0
2
1
1
2
17
20
23
26
Reset time-out
2
2
2
2
17
20
23
26
+ 512
+ 512
+ 512
+ 512
T2M:
Timer 2 clock select: When T2M is set to 1, timer 2 uses a divide by 4 clock, and when set to
0 it uses a divide by 12 clock.
T1M:
Timer 1 clock select: When T1M is set to 1, timer 1 uses a divide by 4 clock, and when set to
0 it uses a divide by 12 clock.
T0M:
Timer 0 clock select: When T0M is set to 1, timer 0 uses a divide by 4 clock, and when set to
0 it uses a divide by 12 clock.
MD2−0: Stretch MOVX select bits: These three bits are used to select the stretch value for the MOVX
instruction. Using a variable MOVX length enables the user to access slower external
memory devices or peripherals without the need for external circuits. The RD or WR strobe
will be stretched by the selected interval. When accessing the on-chip SRAM, the MOVX
instruction is always in 2 machine cycles regardless of the stretch setting. By default, the
stretch has value of 1. If the user needs faster accessing, then a stretch value of 0 should be
selected.
MD2
MD1
MD0
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
Stretch value MOVX duration
0
1
2
3
4
5
6
7
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2 machine cycles
3 machine cycles (Default)
4 machine cycles
5 machine cycles
6 machine cycles
7 machine cycles
8 machine cycles
9 machine cycles
Preliminary W79E648
Port 1
Bit:
7
6
5
4
3
2
1
0
P1.7
P1.6
P1.5
P1.4
P1.3
P1.2
P1.1
P1.0
Mnemonic: P1
Address: 90h
P1.7−0: General purpose I/O port. Most instructions will read the port pins in case of a port read
access, however in case of read-modify-write instructions, the port latch is read. Some pins
also have alternate input or output functions. This alternate functions are described below:
P1.0 : T2
P1.1 : T2EX
External I/O for Timer/Counter 2
Timer/Counter 2 Capture/Reload Trigger
Port 4 Control Register A
Bit:
7
6
5
4
3
2
1
0
P41M1
P41M0
P41C1
P41C0
P40M1
P40M0
P40C1
P40C0
Mnemonic: P4CONA
Address: 92h
Port 4 Control Register B
Bit:
7
6
5
4
3
2
1
0
P43M1
P43M0
P43C1
P43C0
P42M1
P42M0
P42C1
P42C0
Mnemonic: P4CONB
Address: 93h
BIT NAME
P4xM1, P4xM0
FUNCTION
Port 4 alternate modes.
=00: Mode 0. P4.x is a general purpose I/O port which is the same as Port 1.
=01: Mode 1. P4.x is a Read Strobe signal for chip select purpose. The address
range depends on the SFR P4xAH, P4xAL and bits P4xC1, P4xC0.
=10: Mode 2. P4.x is a Write Strobe signal for chip select purpose. The address
range depends on the SFR P4xAH, P4xAL and bits P4xC1, P4xC0.
=11: Mode 3. P4.x is a Read/Write Strobe signal for chip select purpose. The
address range depends on the SFR P4xAH, P4xAL and bits P4xC1, P4xC0
P4xC1, P4xC0
Port 4 Chip-select Mode address comparison:
=00: Compare the full address (16 bits length) with the base address registers
P4xAH and P4xAL.
=01: Compare the 15 high bits (A15-A1) of address bus with the base address
registers P4xAH and P4xAL.
=10: Compare the 14 high bits (A15-A2) of address bus with the base address
registers P4xAH and P4xAL.
=11: Compare the 8 high bits (A15-A8) of address bus with the base address
registers P4xAH and P4xAL.
- 15 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
P4.0 Base Address Low Byte Register
Bit:
7
6
5
4
3
2
1
0
A7
A6
A5
A4
A3
A2
A1
A0
Mnemonic: P40AL
Address: 94h
P4.0 Base Address High Byte Register
Bit:
7
6
5
4
3
2
1
0
A15
A14
A13
A12
A11
A10
A9
A8
Mnemonic: P40AH
Address: 95h
P4.1 Base Address Low Byte Register
Bit:
7
6
5
4
3
2
1
0
A7
A6
A5
A4
A3
A2
A1
A0
Mnemonic: P41AL
Address: 96h
P4.1 Base Address High Byte Register
Bit:
7
6
5
4
3
2
1
0
A15
A14
A13
A12
A11
A10
A9
A8
Mnemonic: P41AH
Address: 97h
Serial Port Control
Bit:
7
6
5
4
3
2
1
0
SM0/FE
SM1
SM2
REN
TB8
RB8
TI
RI
Mnemonic: SCON
Address: 98h
SM0/FE: Serial port 0, Mode 0 bit or Framing Error Flag: The SMOD0 bit in PCON SFR determines
whether this bit acts as SM0 or as FE. The operation of SM0 is described below. When
used
as FE, this bit will be set to indicate an invalid stop bit. This bit must be manually cleared in
software to clear the FE condition.
SM1:
Serial port Mode bit 1:
SM0
0
0
1
1
SM2:
SM1
0
1
0
1
Mode
0
1
2
3
Description
Length
Synchronous
8
Asynchronous 10
Asynchronous 11
Asynchronous 11
Baud rate
4/12 Tclk
Variable
64/32 Tclk
Variable
Multiple processors communication. Setting this bit to 1 enables the multiprocessor
communication feature in mode 2 and 3. In mode 2 or 3, if SM2 is set to 1, then RI will not be
activated if the received 9th data bit (RB8) is 0. In mode 1, if SM2 = 1, then RI will not be
activated if a valid stop bit was not received. In mode 0, the SM2 bit controls the serial port
clock. If set to 0, then the serial port runs at a divide by 12 clock of the oscillator. This gives
- 16 -
Preliminary W79E648
compatibility with the standard 8052. When set to 1, the serial clock become divide by 4 of the
oscillator clock. This results in faster synchronous serial communication.
REN:
Receive enable: When set to 1 serial reception is enabled, otherwise reception is disabled.
TB8:
This is the 9th bit to be transmitted in modes 2 and 3. This bit is set and cleared by software
as desired.
In modes 2 and 3 this is the received 9th data bit. In mode 1, if SM2 = 0, RB8 is the stop bit
that was received. In mode 0 it has no function.
Transmit interrupt flag: This flag is set by hardware at the end of the 8th bit time in mode 0, or
at the beginning of the stop bit in all other modes during serial transmission. This bit must be
cleared by software.
Receive interrupt flag: This flag is set by hardware at the end of the 8th bit time in mode 0, or
halfway through the stop bits time in the other modes during serial reception. However the
restrictions of SM2 apply to this bit. This bit can be cleared only by software.
RB8:
TI:
RI:
Serial Data Buffer
Bit:
7
6
5
4
3
2
1
0
SBUF.7 SBUF.6 SBUF.5 SBUF.4 SBUF.3 SBUF.2 SBUF.1 SBUF.0
Mnemonic: SBUF
Address: 99h
SBUF.7-0: Serial data on the serial port 0 is read from or written to this location. It actually consists of
two separate internal 8-bit registers. One is the receive resister, and the other is the
transmit buffer. Any read access gets data from the receive data buffer, while write access
is to the transmit data buffer.
P4.2 Base Address Low Byte Register
Bit:
7
6
5
4
3
2
1
0
A7
A6
A5
A4
A3
A2
A1
A0
Mnemonic: P42AL
Address: 9Ah
P4.2 Base Address High Byte Register
Bit:
7
6
5
4
3
2
1
0
A15
A14
A13
A12
A11
A10
A9
A8
Mnemonic: P42AH
Address: 9Bh
P4.3 Base Address Low Byte Register
Bit:
7
6
5
4
3
2
1
0
A7
A6
A5
A4
A3
A2
A1
A0
Mnemonic: P43AL
Address: 9Ch
- 17 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
P4.3 Base Address High Byte Register
Bit:
7
6
5
4
3
2
1
0
A15
A14
A13
A12
A11
A10
A9
A8
Mnemonic: P43AH
Address: 9Dh
ISP Control Register
Bit:
7
6
5
4
3
2
1
0
SWRST/HWB
-
LDAP
-
-
-
LDSEL
ENP
Mnemonic: CHPCON
Address: 9Fh
SWRST/HWB: Set this bit to launch a whole device reset that is same as asserting high to RST pin,
micro controller will be back to initial state and clear this bit automatically. To read this
bit, its alternate function to indicate the ISP hardware reboot mode is invoking when
read it in high.
LDAP: This bit is Read Only. High: device is executing the program in LDFlash. Low: device is
executing the program in APFlashs.
LDSEL: Loader program residence selection. Set to high to route the device fetching code from
LDFlash.
ENP: In System Programming Mode Enable. Set this be to launch the ISP mode. Device will operate
ISP procedures, such as Erase, Program and Read operations, according to correlative SFRs
settings. During ISP mode, device achieves ISP operations by the way of IDLE state. In the
other words, device is not indeed in IDLE mode is set bit PCON.1 while ISP is enabled. Clear
this bit to disable ISP mode, device get back to normal operation including IDLE state.
- 18 -
Preliminary W79E648
Software Reset
Set CHPCON = 0X83, timer and enter IDLE mode. CPU will reset and restart from APFlash after time
out.
Port 2
Bit:
7
6
5
4
3
2
1
0
P2.7
P2.6
P2.5
P2.4
P2.3
P2.2
P2.1
P2.0
Mnemonic: P2
Address: A0h
P2.7-0: Port 2 is a bi-directional I/O port with internal pull-ups. This port also provides the upper
address bits for accesses to external memory.
Port 4 Chip-select Polarity
Bit:
7
6
5
4
P43INV P42INV P42INV P40INV
6.1.1
3
2
1
0
-
-
-
PUP0
Mnemonic: P4CSIN
Address: A2h
P4xINV: The active polarity of P4.x when set it as chip-select signal. High = Active High. Low = Active
Low.
PUP0: Enable Port 0 weak pull up.
Port 4
Bit:
7
6
5
4
3
2
1
0
-
-
-
-
P4.3
P4.2
P4.1
P4.0
Mnemonic: P4
Address: A5h
P4.3-0: Port 4 is a bi-directional I/O port with internal pull-ups. Port 4 can not use bit-addressable
instruction (SETB or CLR).
Interrupt Enable
Bit:
7
6
5
4
3
2
1
0
EA
ES1
ET2
ES
ET1
EX1
ET0
EX0
Mnemonic: IE
EA:
ET2:
ES:
ET1:
EX1:
ET0:
EX0:
Address: A8h
Global enable. Enable/disable all interrupts.
Enable Timer 2 interrupt.
Enable Serial Port 0 interrupt.
Enable Timer 1 interrupt
Enable external interrupt 1
Enable Timer 0 interrupt
Enable external interrupt 0
- 19 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
Slave Address
Bit:
7
6
5
4
3
Mnemonic: SADDR
2
1
0
Address: A9h
SADDR: The SADDR should be programmed to the given or broadcast address for serial port 0 to
which the slave processor is designated.
ROM Banking Control
Bit:
7
6
5
4
-
-
-
-
3
2
1
EN128K DCP12
Mnemonic: ROMCON
0
DCP11 DCP10
Address: ABh
EN128K: On-chip ROM banking enable. Set this bit to enable APFlash0 and APFlash1 by banking
mechanism. The P1.x is selected to be the auxiliary highest address line A16.
DCP1x: A16 selection. By default, P1.7 is defined as A16.
A16
DCP12
DCP11
DCP10
P1.0
0
0
0
P1.1
0
0
1
P1.2
0
1
0
P1.3
0
1
1
P1.4
1
0
0
P1.5
1
0
1
P1.6
1
1
0
P1.7
1
1
1
ISP Address Low Byte
Bit:
7
6
5
4
3
2
1
0
A7
A6
A5
A4
A3
A2
A1
A0
Mnemonic: SFRAL
Address: ACh
Low byte destination address for In System Programming operations. SFRAH and SFRAL address a
specific ROM bytes for erasure, porgramming or read.
ISP Address High Byte
Bit:
7
6
5
4
3
2
1
0
A15
A14
A13
A12
A11
A10
A9
A8
Mnemonic: SFRAH
Address: ADh
High byte destination address for In System Programming operations. SFRAH and SFRAL address a
specific ROM bytes for erasure, porgramming or read.
ISP Data Buffer
Bit:
7
6
5
4
3
2
1
0
D7
D6
D5
D4
D3
D2
D1
D0
Mnemonic: SFRFD
Address: AEh
In ISP mode, read/write a specific byte ROM content must go through SFRFD register.
- 20 -
Preliminary W79E648
ISP Operation Modes
Bit:
7
6
5
4
3
2
1
0
BANK
WFWIN
NOE
NCE
CTRL3
CTRL2
CTRL1
CTRL0
Mnemonic: SFRCN
Address: AFh
BANK: Select APFlash banks for ISP. Set it 1 access to APFlash1, clear it to APFlash0.
WFWIN: Destenation ROM bank for programming, erasure and read. 0 = APFlashx, 1 = LDFlash.
NOE: Flash EPROM output enable.
NCE: Flash EPROM chip enable.
CTRL[3:0]: Mode Selection.
BANK
WFWIN
NOE
NCE
CTRL<3:0>
SFRAH,
SFRAL
SFRFD
Erase 4KB LDFlash
0
1
1
0
0010
X
X
Erase 64K APFlash0
0
0
1
0
0010
X
X
Erase 64K APFlash1
1
0
1
0
0010
X
X
Program 4KB LDFlash
0
1
1
0
0001
Address in
Data in
Program 64KB APFlash0
0
0
1
0
0001
Address in
Data in
Program 64KB APFlash1
1
0
1
0
0001
Address in
Data in
Read 4KB LDFlash
0
1
0
0
0000
Address in
Data out
Read 64KB APFlash0
0
0
0
0
0000
Address in
Data out
Read 64KB APFlash1
1
0
0
0
0000
Address in
Data out
7
6
5
4
3
2
1
0
P3.7
P3.6
P3.5
P3.4
P3.3
P3.2
P3.1
P3.0
ISP Mode
Port 3
Bit:
Mnemonic: P3
Address: B0h
P3.7-0: General purpose I/O port. Each pin also has an alternate input or output function. The
alternate functions are described below.
P3.7
RD
Strobe for read from external RAM
P3.6
P3.5
P3.4
WR
T1
T0
Strobe for write to external RAM
Timer/counter 1 external count input
Timer/counter 0 external count input
P3.3
INT1
External interrupt 1
P3.2
P3.1
P3.0
INT0
TxD
RxD
External interrupt 0
Serial port 0 output
Serial port 0 input
- 21 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
Port 5
Bit:
7
6
5
4
3
2
1
0
P5.7
P5.6
P5.5
P5.4
P5.3
P5.2
P5.1
P5.0
Mnemonic: P5
Address: B1h
P5.7-0: General purpose I/O port. Port 5 can not use bit-addressable instruction (SETB or CLR).
Demo code:
ORL
P5,#00000010B
; Set P5.1=H
ANL
P5,#11111101B
; Clear P5.1=L
Port 6
Bit:
7
6
5
4
3
2
1
0
P6.7
P6.6
P6.5
P6.4
P6.3
P6.2
P6.1
P6.0
Mnemonic: P6
Address: B2h
P6.7-0: General purpose I/O port. Port 6 can not use bit-addressable instruction (SETB or CLR).
Port 7
Bit:
7
6
5
4
3
2
1
0
P7.7
P7.6
P7.5
P7.4
P7.3
P7.2
P7.1
P7.0
Mnemonic: P7
Address: B3h
P7.7-0: General purpose I/O port. Port 7 can not use bit-addressable instruction (SETB or CLR).
- 22 -
Preliminary W79E648
Interrupt Priority
Bit:
7
6
5
4
3
2
1
0
-
-
PT2
PS
PT1
PX1
PT0
PX0
Mnemonic: IP
IP.7:
PT2:
PS:
PT1:
PX1:
PT0:
PX0:
Address: B8h
This bit is un-implemented and will read high.
This bit defines the Timer 2 interrupt priority. PT2 = 1 sets it to higher priority level.
This bit defines the Serial port 0 interrupt priority. PS = 1 sets it to higher priority level.
This bit defines the Timer 1 interrupt priority. PT1 = 1 sets it to higher priority level.
This bit defines the External interrupt 1 priority. PX1 = 1 sets it to higher priority level.
This bit defines the Timer 0 interrupt priority. PT0 = 1 sets it to higher priority level.
This bit defines the External interrupt 0 priority. PX0 = 1 sets it to higher priority level.
Slave Address Mask Enable
Bit:
7
6
5
4
3
Mnemonic: SADEN
2
1
0
Address: B9h
SADEN: This register enables the Automatic Address Recognition feature of the Serial port 0. When
a bit in the SADEN is set to 1, the same bit location in SADDR will be compared with the
incoming serial data. When SADEN.n is 0, then the bit becomes a "don't care" in the
comparison. This register enables the Automatic Address Recognition feature of the Serial
port 0. When all the bits of SADEN are 0, interrupt will occur for any incoming address.
Power Management Register
Bit:
7
6
5
4
3
2
1
0
-
-
-
-
-
ALE-OFF
-
DME0
Mnemonic: PMR
Address: C4h
ALE0FF: This bit disables the expression of the ALE signal on the device pin during all on-board
program and data memory accesses. External memory accesses will automatically enable
ALE independent of ALEOFF.
0 = ALE expression is enable; 1 = ALE expression is disable
DME0: This bit determines the on-chip MOVX SRAM to be enabled or disabled. Set this bit to 1 will
enable the on-chip 1KB MOVX SRAM.
Status Register
Bit:
7
6
5
4
3
2
1
0
-
HIP
LIP
-
-
-
-
-
Mnemonic: STATUS
Address: C5h
- 23 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
HIP: High Priority Interrupt Status. When set, it indicates that software is servicing a high priority
interrupt. This bit will be cleared when the program executes the corresponding RETI
instruction.
LIP: Low Priority Interrupt Status. When set, it indicates that software is servicing a low priority
interrupt. This bit will be cleared when the program executes the corresponding RETI
instruction.
Timed Access
Bit:
7
6
5
4
3
2
1
0
TA.7
TA.6
TA.5
TA.4
TA.3
TA.2
TA.1
TfA.0
Mnemonic: TA
Address: C7h
TA: The Timed Access register controls the access to protected bits. To access protected bits, the
user must first write AAH to the TA. This must be immediately followed by a write of 55H to TA.
Now a window is opened in the protected bits for three machine cycles, during which the user can
write to these bits.
Timer 2 Control
Bit:
7
6
5
4
3
2
1
0
TF2
EXF2
RCLK
TCLK
EXEN2
TR2
C / T2
CP / RL2
Mnemonic: T2CON
TF2:
Address: C8h
Timer 2 overflow flag: This bit is set when Timer 2 overflows. It is also set when the count is
equal to the capture register in down count mode. It can be set only if RCLK and TCLK are
both 0. It is cleared only by software. Software can also set or clear this bit.
EXF2: Timer 2 External Flag: A negative transition on the T2EX pin (P1.1) or timer 2 overflow will
cause this flag to set based on the CP / RL2 , EXEN2 and DCEN bits. If set by a negative
transition, this flag must be cleared by software. Setting this bit in software or detection of a
negative transition on T2EX pin will force a timer interrupt if enabled.
RCLK: Receive Clock Flag: This bit determines the serial port 0 time-base when receiving data in
serial modes 1 or 3. If it is 0, then timer 1 overflow is used for baud rate generation, otherwise
timer 2 overflow is used. Setting this bit forces timer 2 in baud rate generator mode.
TCLK: Transmit Clock Flag: This bit determines the serial port 0 time-base when transmitting data in
modes 1 and 3. If it is set to 0, the timer 1 overflow is used to generate the baud rate clock
otherwise timer 2 overflow is used. Setting this bit forces timer 2 in baud rate generator mode.
EXEN2: Timer 2 External Enable. This bit enables the capture/reload function on the T2EX pin if
Timer 2 is not generating baud clocks for the serial port. If this bit is 0, then the T2EX pin will
be ignored, otherwise a negative transition detected on the T2EX pin will result in capture or
reload.
TR2:
Timer 2 Run Control. This bit enables/disables the operation of timer 2. Clearing this bit will
halt the timer 2 and preserve the current count in TH2, TL2.
C / T2 : Counter/Timer Select. This bit determines whether timer 2 will function as a timer or a counter.
Independent of this bit, the timer will run at 2 clocks per tick when used in baud rate generator
mode. If it is set to 0, then timer 2 operates as a timer at a speed depending on T2M bit
(CKCON.5), otherwise it will count negative edges on T2 pin.
- 24 -
Preliminary W79E648
CP / RL2 : Capture/Reload Select. This bit determines whether the capture or reload function will be
used for timer 2. If either RCLK or TCLK is set, this bit will be ignored and the timer will
function in an auto-reload mode following each overflow. If the bit is 0 then auto-reload will
occur when timer 2 overflows or a falling edge is detected on T2EX pin if EXEN2 = 1. If
this bit is 1, then timer 2 captures will occur when a falling edge is detected on T2EX pin if
EXEN2 = 1.
Timed 2 Mode Control
Bit:
7
6
5
4
3
2
1
0
-
-
-
-
T2CR
-
-
DCEN
Mnemonic: T2MOD
Address: C9h
T2CR: Timer 2 Capture Reset. In the Timer 2 Capture Mode this bit enables/disables hardware
automatically reset Timer 2 while the value in TL2 and TH2 have been transferred into the
capture register.
DCEN: Down Count Enable: This bit, in conjunction with the T2EX pin, controls the direction that
timer 2 counts in 16-bit auto-reload mode.
Timer 2 Capture LSB
Bit:
7
6
5
RCAP2L.7
RCAP2L.6
4
3
2
1
0
RCAP2L.5 RCAP2L.4 RCAP2L.3 RCAP2L.2 RCAP2L.1
Mnemonic: RCAP2L
RCAP2L.0
Address: CAh
RCAP2L: This register is used to capture the TL2 value when a timer 2 is configured in capture mode.
RCAP2L is also used as the LSB of a 16-bit reload value when timer 2 is configured in autoreload mode.
Timer 2 Capture MSB
Bit:
7
6
5
4
3
2
1
0
RCAP2H.7 RCAP2H.6 RCAP2H.5 RCAP2H.4 RCAP2H.3 RCAP2H.2 RCAP2H.1 RCAP2H.0
Mnemonic: RCAP2H
Address: CBh
RCAP2H: This register is used to capture the TH2 value when a timer 2 is configured in capture
mode.
RCAP2H is also used as the MSB of a 16-bit reload value when timer 2 is configured in
auto-reload mode.
Timer 2 LSB
Bit:
7
6
5
4
3
2
1
0
TL2.7
TL2.6
TL2.5
TL2.4
TL2.3
TL2.2
TL2.1
TL2.0
Mnemonic: TL2
TL2:
Address: CCh
Timer 2 LSB
- 25 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
Timer 2 MSB
Bit:
7
6
5
4
3
2
1
0
TH2.7
TH2.6
TH2.5
TH2.4
TH2.3
TH2.2
TH2.1
TH2.0
Mnemonic: TH2
TH2:
Address: CDh
Timer 2 MSB
Program Status Word
Bit:
7
6
5
4
3
2
1
0
CY
AC
F0
RS1
RS0
OV
F1
P
Mnemonic: PSW
Address: D0h
CY:
Carry flag: Set for an arithmetic operation which results in a carry being generated from the
ALU. It is also used as the accumulator for the bit operations.
AC:
Auxiliary carry: Set when the previous operation resulted in a carry from the high order nibble.
F0:
User flag 0: General purpose flag that can be set or cleared by the user.
RS.1-0: Register bank select bits:
RS1
RS0
Register bank
Address
0
0
0
00-07h
0
1
1
08-0Fh
1
0
2
10-17h
1
1
3
18-1Fh
OV:
Overflow flag: Set when a carry was generated from the seventh bit but not from the 8th bit as
a result of the previous operation, or vice-versa.
F1:
User Flag 1: General purpose flag that can be set or cleared by the user by software.
P:
Parity flag: Set/cleared by hardware to indicate odd/even number of 1's in the accumulator.
Watchdog Control
Bit:
7
6
5
4
3
2
1
0
-
POR
-
-
WDIF
WTRF
EWT
RWT
Mnemonic: WDCON
POR:
Address: D8h
Power-on reset flag. Hardware will set this flag on a power up condition. This flag can be read
or written by software. A write by software is the only way to clear this bit once it is set.
WDIF: Watchdog Timer Interrupt Flag. If the watchdog interrupt is enabled, hardware will set this bit
to indicate that the watchdog interrupt has occurred. If the interrupt is not enabled, then this bit
indicates that the time-out period has elapsed. This bit must be cleared by software.
WTRF: Watchdog Timer Reset Flag. Hardware will set this bit when the watchdog timer causes a
reset. Software can read it but must clear it manually. A power-fail reset will also clear the bit.
This bit helps software in determining the cause of a reset. If EWT = 0, the watchdog timer
will have no affect on this bit.
EWT:
Enable Watchdog timer Reset. Setting this bit will enable the Watchdog timer Reset function.
- 26 -
Preliminary W79E648
RWT: Reset Watchdog Timer. This bit helps in putting the watchdog timer into a know state. It also
helps in resetting the watchdog timer before a time-out occurs. Failing to set the EWT before
time-out will cause an interrupt, if EWDI (EIE.4) is set, and 512 clocks after that a watchdog
timer reset will be generated if EWT is set. This bit is self-clearing by hardware.
The WDCON SFR is set to a 0x0x0xx0b on an external reset. WTRF is set to a 1 on a Watchdog timer
reset, but to a 0 on power on/down resets. WTRF is not altered by an external reset. POR is set to 1
by a power-on reset. EWT is set to 0 on a Power-on reset and unaffected by other resets.
All the bits in this SFR have unrestricted read access. POR, EWT, WDIF and RWT require Timed
Access procedure to write. The remaining bits have unrestricted write accesses. Please refer TA
register discription.
TA
EG
C7H
WDCON
REG
D8H
CKCON
REG
8EH
MOV TA, #AAH
MOV TA, #55H
SETB WDCON.0
ORL CKCON, #11000000B
MOV TA, #AAH
MOV TA, #55H
ORL WDCON, #00000010B
; Reset watchdog timer
; Select 26 bits watchdog timer
; Enable watchdog
Accumulator
Bit:
7
6
5
4
3
2
1
0
ACC.7
ACC.6
ACC.5
ACC.4
ACC.3
ACC.2
ACC.1
ACC.0
Mnemonic: ACC
Address: E0h
ACC.7-0: The A (or ACC) register is the standard 8052 accumulator.
Extended Interrupt Enable
Bit:
7
6
5
4
3
2
1
0
-
-
-
EWDI
-
-
-
-
Mnemonic: EIE
Address: E8h
EIE.7-5: Reserved bits, will read high
EWDI: Enable Watchdog timer interrupt
B Register
Bit:
7
6
5
4
3
2
1
0
B.7
B.6
B.5
B.4
B.3
B.2
B.1
B.0
Mnemonic: B
Address: F0h
- 27 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
B.7-0: The B register is the standard 8052 register that serves as a second accumulator.
Extended Interrupt Priority
Bit:
7
6
5
4
3
2
1
0
-
-
-
PWDI
-
-
-
-
Mnemonic: EIP
Address: F8h
EIP.7-5: Reserved bits.
PWDI: Watchdog timer interrupt priority.
7. INSTRUCTION
The W79E648 executes all the instructions of the standard 8032 family. The operation of these
instructions, their effect on the flag bits and the status bits is exactly the same. However, timing of
these instructions is different. The reason for this is two fold. Firstly, in the W79E648, each machine
cycle consists of 4 clock periods, while in the standard 8032 it consists of 12 clock periods. Also, in the
W79E648 there is only one fetch per machine cycle i.e. 4 clocks per fetch, while in the standard 8032
there can be two fetches per machine cycle, which works out to 6 clocks per fetch.
The advantage the W79E648 has is that since there is only one fetch per machine cycle, the number
of machine cycles in most cases is equal to the number of operands that the instruction has. In case
of jumps and calls there will be an additional cycle that will be needed to calculate the new address.
But overall the W79E648 reduces the number of dummy fetches and wasted cycles, thereby
improving efficiency as compared to the standard 8032.
7.1
Instruction Timing
The instruction timing for the W79E648 is an important aspect, especially for those users who wish to
use software instructions to generate timing delays. Also, it provides the user with an insight into the
timing differences between the W79E648 and the standard 8032. In the W79E648 each machine
cycle is four clock periods long. Each clock period is designated a state. Thus each machine cycle is
made up of four states, C1, C2 C3 and C4, in that order. Due to the reduced time for each instruction
execution, both the clock edges are used for internal timing. Hence it is important that the duty cycle of
the clock be as close to 50% as possible to avoid timing conflicts. As mentioned earlier, the W79E648
does one op-code fetch per machine cycle. Therefore, in most of the instructions, the number of
machine cycles needed to execute the instruction is equal to the number of bytes in the instruction. Of
the 256 available op-codes, 128 of them are single cycle instructions. Thus more than half of all opcodes in the W79E648 are executed in just four clock periods. Most of the two-cycle instructions are
those that have two byte instruction codes. However there are some instructions that have only one
byte instructions, yet they are two cycle instructions. One instruction which is of importance is the
MOVX instruction. In the standard 8032, the MOVX instruction is always two machine cycles long.
However in the W79E648, the user has a facility to stretch the duration of this instruction from 2
machine cycles to 9 machine cycles. The RD and WR strobe lines are also proportionately
elongated. This gives the user flexibility in accessing both fast and slow peripherals without the use of
external circuitry and with minimum software overhead. The rest of the instructions are either three,
four or five machine cycle instructions. Note that in the W79E648, based on the number of machine
cycles, there are five different types, while in the standard 8032 there are only three. However, in the
W79E648 each machine cycle is made of only 4 clock periods compared to the 12 clock periods for
- 28 -
Preliminary W79E648
the standard 8032. Therefore, even though the number of categories has increased, each instruction
is at least 1.5 to 3 times faster than the standard 8032 in terms of clock periods.
Single Cycle
C1
C2
C4
C3
CLK
ALE
PSEN
A7-0
AD7-0
Data_ in D7-0
Address A15-8
PORT 2
Figure 3. Single Cycle Instruction Timing
Operand Fetch
Instruction Fetch
C1
C2
C3
C4
C1
C2
C3
C4
CLK
ALE
PSEN
AD7-0
PORT 2
PC
OP-CODE
PC+1
Address A15-8
OPERAND
Address A15-8
Figure 4. Two Cycle Instruction Timing
- 29 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
Instruction Fetch
C1
C2
C3
Operand Fetch
C4
C1
C2
Operand Fetch
C3
C4
C1
C2
C3
C4
CLK
ALE
PSEN
A7-0
AD7-0
PORT 2
OP-CODE
A7-0
Address A15-8
OPERAND
A7-0
Address A15-8
OPERAND
Address A15-8
Figure 5. Three Cycle Instruction Timing
Instruction Fetch
C1
C2
C3
C4
Operand Fetch
C1
C2
C3
C4
Operand Fetch
C1
C2
C3
C4
Operand Fetch
C1
C2
C3
C4
CLK
ALE
PSEN
AD7-0
A7-0 OP-CODE
A7-0 OPERAND
A7-0 OPERAND
A7-0 OPERAND
Port 2
Address A15-8
Address A15-8
Address A15-8
Address A15-8
Figure 6. Four Cycle Instruction Timing
- 30 -
Preliminary W79E648
Instruction Fetch
C1
C2
C3
Operand Fetch
C4
C1
C2
C3
C4
Operand Fetch
C1
C2
C3
C4
Operand Fetch
Operand Fetch
C1
C2
C3
C4
C1
C2
C3
C4
CLK
ALE
PSEN
AD7-0
A7-0 OP-CODE
A7-0 OPERAND
A7-0 OPERAND
A7-0 OPERAND
A7-0 OPERAND
PORT 2
Address A15-8
Address A15-8
Address A15-8
Address A15-8
Address A15-8
Figure 7. Five Cycle Instruction Timing
7.1.1
External Data Memory Access Timing
The timing for the MOVX instruction is another feature of the W79E648. In the standard 8032, the
MOVX instruction has a fixed execution time of 2 machine cycles. However in the W79E648, the
duration of the access can be varied by the user.
The instruction starts off as a normal op-code fetch of 4 clocks. In the next machine cycle, the
W79E648 puts out the address of the external Data Memory and the actual access occurs here. The
user can change the duration of this access time by setting the STRETCH value. The Clock Control
SFR (CKCON) has three bits that control the stretch value. These three bits are M2-0 (bits 2-0 of
CKCON). These three bits give the user 8 different access time options. The stretch can be varied
from 0 to 7, resulting in MOVX instructions that last from 2 to 9 machine cycles in length. Note that the
stretching of the instruction only results in the elongation of the MOVX instruction, as if the state of the
CPU was held for the desired period. There is no effect on any other instruction or its timing. By
default, the Stretch value is set at 1, giving a MOVX instruction of 3 machine cycles. If desired by the
user the stretch value can be set to 0 to give the fastest MOVX instruction of only 2 machine cycles.
Table 4. Data Memory Cycle Stretch Values
M2
M1
M0
Machine
Cycles
0
0
0
0
0
1
0
1
0
2
3 (default)
4
RD or WR
strobe width
in Clocks
2
4
8
- 31 -
RD or WR
strobe width
@ 25 MHz
80 nS
160 nS
320 nS
RD or WR
strobe width
@ 40 MHz
50 nS
100 nS
200 nS
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
Continued
M2
M1
M0
Machine
Cycles
0
1
1
1
1
1
0
0
1
1
1
0
1
0
1
5
6
7
8
9
RD or WR
strobe width
@ 25 MHz
480 nS
640 nS
800 nS
960 nS
1120 nS
First
Second
Machine cycle
Machine cycle
Last Cycle
of Previous
Instruction
RD or WR
strobe width
in Clocks
12
16
20
24
28
RD or WR
strobe width
@ 40 MHz
300 nS
400 nS
500 nS
600 nS
700 nS
Next Instruction
Machine Cycle
MOVX instruction cycle
C1 C2 C3 C4 C1 C2 C3 C4 C1 C2 C3 C4 C1 C2 C3 C4
CLK
ALE
PSEN
WR
PORT 0
A0-A7
D0-D7
D0-D7
Next Inst.
Address
MOVX Inst.
Address
MOVX Inst.
PORT 2
A0-A7
A15-A8
D0-D7
A0-A7
D0-D7
MOVX Data
Address
Next Inst. Read
MOVX Data out
A15-A8
A15-A8
Figure 8. Data Memory Write with Stretch Value = 0
- 32 -
A0-A7
A15-A8
Preliminary W79E648
Last Cycle
First
of Previous
Instruction
Second
Third
Machine Cycle Machine Cycle Machine Cycle
Next Instruction
Machine Cycle
MOVX instruction cycle
C1 C2 C3 C4 C1 C2 C3 C4 C1 C2 C3 C4 C1 C2 C3 C4 C1 C2 C3 C4
CLK
ALE
PSEN
WR
D0-D7
A0-A7
PORT 0
MOVX Inst.
Address
D0-D7
A0-A7
Next Inst.
Address
A15-A8
MOVX Data
Address
A0-A7
D0-D7
MOVX Data out
Next Inst.
Read
MOVX Inst.
PORT 2
D0-D7
A0-A7
A15-A8
A15-A8
A15-A8
Figure 9. Data Memory Write with Stretch Value = 1
Last Cycle
First
Second
Third
Fourth
of Previous
Instruction
Machine Cycle
Machine Cycle
Machine Cycle
Machine Cycle
Next
Instruction
Machine Cycle
MOVX instruction cycle
C1 C2 C3 C4 C1 C2 C3 C4 C1 C2 C3 C4 C1 C2 C3 C4 C1 C2 C3 C4 C1 C2 C3 C4
CLK
ALE
PSEN
WR
PORT 0
D0-D7
A0-A7
MOVX Inst.
Address
Next Inst.
Address
MOVX Inst.
PORT 2
D0-D7
A0-A7
A15-A8
A0-A7
MOVX Data
Address
D0-D7
A0-A7
D0-D7
MOVX Data out
Next Inst.
Read
A15-A8
A15-A8
A15-A8
Figure 10. Data Memory Write with Stretch Value = 2
- 33 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
8. POWER MANAGEMENT
The W79E648 has several features that help the user to control the power consumption of the device.
The power saving features are basically the POWER DOWN mode, ECONOMY mode and the IDLE
mode of operation.
Idle Mode
The user can put the device into idle mode by writing 1 to the bit PCON.0. The instruction that sets the
idle bit is the last instruction that will be executed before the device goes into Idle Mode. In the Idle
mode, the clock to the CPU is halted, but not to the Interrupt, Timer, Watchdog timer and Serial port
blocks. This forces the CPU state to be frozen; the Program counter, the Stack Pointer, the Program
Status Word, the Accumulator and the other registers hold their contents. The ALE and PSEN pins are
held high during the Idle state. The port pins hold the logical states they had at the time Idle was
activated. The Idle mode can be terminated in two ways. Since the interrupt controller is still active, the
activation of any enabled interrupt can wake up the processor. This will automatically clear the Idle bit,
terminate the Idle mode, and the Interrupt Service Routine(ISR) will be executed. After the ISR,
execution of the program will continue from the instruction which put the device into Idle mode.
The Idle mode can also be exited by activating the reset. The device can be put into reset either by
applying a high on the external RST pin, a Power on reset condition or a Watchdog timer reset. The
external reset pin has to be held high for at least two machine cycles i.e. 8 clock periods to be
recognized as a valid reset. In the reset condition the program counter is reset to 0000h and all the
SFRs are set to the reset condition. Since the clock is already running there is no delay and execution
starts immediately. In the Idle mode, the Watchdog timer continues to run, and if enabled, a time-out
will cause a watchdog timer interrupt which will wake up the device. The software must reset the
Watchdog timer in order to preempt the reset which will occur after 512 clock periods of the time-out.
When the W79E648 is exiting from an Idle mode with a reset, the instruction following the one which
put the device into Idle mode is not executed. So there is no danger of unexpected writes.
Power Down Mode
The device can be put into Power Down mode by writing 1 to bit PCON.1. The instruction that does
this will be the last instruction to be executed before the device goes into Power Down mode. In the
Power Down mode, all the clocks are stopped and the device comes to a halt. All activity is completely
stopped and the power consumption is reduced to the lowest possible value. In this state the ALE and
PSEN pins are pulled low. The port pins output the values held by their respective SFRs.
The W79E648 will exit the Power Down mode with a reset or by an external interrupt pin enabled as
level detect. An external reset can be used to exit the Power down state. The high on RST pin
terminates the Power Down mode, and restarts the clock. The program execution will restart from
0000h. In the Power down mode, the clock is stopped, so the Watchdog timer cannot be used to
provide the reset to exit Power down mode.
The W79E648 can be woken from the Power Down mode by forcing an external interrupt pin
activated, provided the corresponding interrupt is enabled, while the global enable(EA) bit is set and
the external input has been set to a level detect mode. If these conditions are met, then the low level
on the external pin re-starts the oscillator. Then device executes the interrupt service routine for the
corresponding external interrupt. After the interrupt service routine is completed, the program
execution returns to the instruction after the one which put the device into Power Down mode and
continues from there.
- 34 -
Preliminary W79E648
Table 5. Status of external pins during Idle and Power Down
Program
Memory
ALE
PSEN
PORT0
PORT1
PORT2
PORT3
Idle
Internal
1
1
Data
Data
Data
Data
Idle
External
1
1
Float
Data
Address
Data
Power Down
Internal
0
0
Data
Data
Data
Data
Power Down
External
0
0
Float
Data
Data
Data
Mode
Reset Conditions
The user has several hardware related options for placing the W79E648 into reset condition. In
general, most register bits go to their reset value irrespective of the reset condition, but there are a few
flags whose state depends on the source of reset. The user can use these flags to determine the
cause of reset using software. There are two ways of putting the device into reset state. They are
External reset and Watchdog reset.
External Reset
The device continuously samples the RST pin at state C4 of every machine cycle. Therefore the RST
pin must be held for at least 2 machine cycles to ensure detection of a valid RST high. The reset
circuitry then synchronously applies the internal reset signal. Thus the reset is a synchronous
operation and requires the clock to be running to cause an external reset.
Once the device is in reset condition, it will remain so as long as RST is 1. Even after RST is
deactivated, the device will continue to be in reset state for up to two machine cycles, and then begin
program execution from 0000h. There is no flag associated with the external reset condition. However
since the other two reset sources have flags, the external reset can be considered as the default reset
if those two flags are cleared.
The software must clear the POR flag after reading it, otherwise it will not be possible to correctly
determine future reset sources. If the power fails, i.e. falls below Vrst, then the device will once again
go into reset state. When the power returns to the proper operating levels, the device will again
perform a power on reset delay and set the POR flag.
Watchdog Timer Reset
The Watchdog timer is a free running timer with programmable time-out intervals. The user can clear
the watchdog timer at any time, causing it to restart the count. When the time-out interval is reached
an interrupt flag is set. If the Watchdog reset is enabled and the watchdog timer is not cleared, then
512 clocks from the flag being set, the watchdog timer will generate a reset . This places the device
into the reset condition. The reset condition is maintained by hardware for two machine cycles. Once
the reset is removed the device will begin execution from 0000h.
- 35 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
Reset State
Most of the SFRs and registers on the device will go to the same condition in the reset state. The
Program Counter is forced to 0000h and is held there as long as the reset condition is applied.
However, the reset state does not affect the on-chip RAM. The data in the RAM will be preserved
during the reset. However, the stack pointer is reset to 07h, and therefore the stack contents will be
lost. The RAM contents will be lost if the VDD falls below approximately 2V, as this is the minimum
voltage level required for the RAM to operate normally. Therefore after a first time power on reset the
RAM contents will be indeterminate. During a power fail condition, if the power falls below 2V, the
RAM contents are lost.
After a reset most SFRs are cleared. Interrupts and Timers are disabled. The Watchdog timer is
disabled if the reset source was a POR. The port SFRs have FFh written into them which puts the port
pins in a high state. Port 0 floats as it does not have on-chip pull-ups.
Table 6. SFR Reset Value
SFR Name
Reset Value
SFR Name
Reset Value
P0
11111111b
IE
00000000b
SP
00000111b
SADDR
00000000b
DPL
00000000b
P3
11111111b
DPH
00000000b
IP
x0000000b
PMR
010xx0x0b
SADEN
00000000b
STATUS
000x0000b
T2CON
00000000b
PC
00000000b
T2MOD
00000x00b
PCON
00xx0000b
RCAP2L
00000000b
TCON
00000000b
RCAP2H
00000000b
TMOD
00000000b
TL2
00000000b
TL0
00000000b
TH2
00000000b
TL1
00000000b
TA
11111111b
TH0
00000000b
PSW
00000000b
TH1
00000000b
WDCON
0x0x0xx0b
CKCON
00000001b
ACC
00000000b
P1
11111111b
EIE
xxx00000b
P4CONA
00000000b
P4CONB
00000000b
P40AL
00000000b
P40AH
00000000b
P41AL
00000000b
P41AH
00000000b
P42AL
00000000b
P42AH
00000000b
P43Al
00000000b
P43AH
00000000b
CHPCON
00000000b
P4CSIN
00000000b
ROMCON
00000111b
SFRAL
00000000b
SFRAH
00000000b
SFRFD
00000000b
SFRCN
00111111b
P4
xxxx1111b
- 36 -
Preliminary W79E648
Table 6. SFR Reset Value, continued
SFR Name
Reset Value
SFR Name
Reset Value
SCON
00000000b
B
00000000b
SBUF
xxxxxxxxb
EIP
xxx00000b
P2
11111111b
PWMCON1
00000000b
PWMCON2
00000000b
PWM0
00000000b
PWM1
00000000b
PWM2
00000000b
PWM3
00000000b
PWM4
00000000b
PWM5
00000000b
The WDCON SFR bits are set/cleared in reset condition depending on the source of the reset.
WDCON
External reset
Watchdog reset
Power on reset
0x0x0xx0b
0x0x01x0b
01000000b
The POR bit WDCON.6 is set only by the power on reset. The WTRF bit WDCON.2 is set when the
Watchdog timer causes a reset. A power on reset will also clear this bit. The EWT bit WDCON.1 is
cleared by power on resets. This disables the Watchdog timer resets. A watchdog or external reset
does not affect the EWT bit.
9. INTERRUPTS
The W79E648 has a two priority level interrupt structure with 11 interrupt sources. Each of the
interrupt sources has an individual priority bit, flag, interrupt vector and enable bit. In addition, the
interrupts can be globally enabled or disabled.
Interrupt Sources
The External Interrupts INT0 and INT1 can be either edge triggered or level triggered, depending on
bits IT0 and IT1. The bits IE0 and IE1 in the TCON register are the flags which are checked to
generate the interrupt. In the edge triggered mode, the INTx inputs are sampled in every machine
cycle. If the sample is high in one cycle and low in the next, then a high to low transition is detected
and the interrupts request flag IEx in TCON is set. The flag bit requests the interrupt. Since the
external interrupts are sampled every machine cycle, they have to be held high or low for at least one
complete machine cycle. The IEx flag is automatically cleared when the service routine is called. If the
level triggered mode is selected, then the requesting source has to hold the pin low till the interrupt is
serviced. The IEx flag will not be cleared by the hardware on entering the service routine. If the
interrupt continues to be held low even after the service routine is completed, then the processor may
acknowledge another interrupt request from the same source.
- 37 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
The Timer 0 and 1 Interrupts are generated by the TF0 and TF1 flags. These flags are set by the
overflow in the Timer 0 and Timer 1. The TF0 and TF1 flags are automatically cleared by the
hardware when the timer interrupt is serviced. The Timer 2 interrupt is generated by a logical OR of
the TF2 and the EXF2 flags. These flags are set by overflow or capture/reload events in the timer 2
operation. The hardware does not clear these flags when a timer 2 interrupt is executed. Software has
to resolve the cause of the interrupt between TF2 and EXF2 and clear the appropriate flag.
The Watchdog timer can be used as a system monitor or a simple timer. In either case, when the
time-out count is reached, the Watchdog timer interrupt flag WDIF (WDCON.3) is set. If the interrupt is
enabled by the enable bit EIE.4, then an interrupt will occur.
All the bits that generate interrupts can be set or reset by hardware, and thereby software initiated
interrupts can be generated. Each of the individual interrupts can be enabled or disabled by setting or
clearing a bit in the IE SFR. IE also has a global enable/disable bit EA, which can be cleared to
disable all the interrupts.
Priority Level Structure
There are three priority levels for the interrupts, highest, high and low. The interrupt sources can be
individually set to either high or low levels. Naturally, a higher priority interrupt cannot be interrupted
by a lower priority interrupt. However there exists a pre-defined hierarchy amongst the interrupts
themselves. This hierarchy comes into play when the interrupt controller has to resolve simultaneous
requests having the same priority level. This hierarchy is defined as shown below; the interrupts are
numbered starting from the highest priority to the lowest.
Table 7. Priority structure of interrupts
Source
Flag
Vector Address
Priority level
External Interrupt 0
IE0
0003h
1(highest)
Timer 0 Overflow
TF0
000Bh
2
External Interrupt 1
IE1
0013h
3
Timer 1 Overflow
TF1
001Bh
4
RI + TI
0023h
5
Timer 2 Overflow
TF2 + EXF2
002Bh
6
Watchdog Timer
WDIF
0063h
7 (lowest)
Serial Port
- 38 -
Preliminary W79E648
10. PROGRAMMABLE TIMERS/COUNTERS
The W79E648 has three 16-bit programmable timer/counters and one programmable Watchdog timer.
The Watchdog timer is operationally quite different from the other two timers.
10.1 Timer/Counters 0 & 1
The W79E648 has two 16-bit Timer/Counters. Each of these Timer/Counters has two 8 bit registers
which form the 16 bit counting register. For Timer/Counter 0 they are TH0, the upper 8 bits register,
and TL0, the lower 8 bit register. Similarly Timer/Counter 1 has two 8 bit registers, TH1 and TL1. The
two can be configured to operate either as timers, counting machine cycles or as counters counting
external inputs.
When configured as a "Timer", the timer counts clock cycles. The timer clock can be programmed to
be thought of as 1/12 of the system clock or 1/4 of the system clock. In the "Counter" mode, the
register is incremented on the falling edge of the external input pin, T0 in case of Timer 0, and T1 for
Timer 1. The T0 and T1 inputs are sampled in every machine cycle at C4. If the sampled value is high
in one machine cycle and low in the next, then a valid high to low transition on the pin is recognized
and the count register is incremented. Since it takes two machine cycles to recognize a negative
transition on the pin, the maximum rate at which counting will take place is 1/24 of the master clock
frequency. In either the "Timer" or "Counter" mode, the count register will be updated at C3.
Therefore, in the "Timer" mode, the recognized negative transition on pin T0 and T1 can cause the
count register value to be updated only in the machine cycle following the one in which the negative
edge was detected.
The "Timer" or "Counter" function is selected by the " C / T " bit in the TMOD Special Function
Register. Each Timer/Counter has one selection bit for its own; bit 2 of TMOD selects the function for
Timer/Counter 0 and bit 6 of TMOD selects the function for Timer/Counter 1. In addition each
Timer/Counter can be set to operate in any one of four possible modes. The mode selection is done
by bits M0 and M1 in the TMOD SFR.
Time-Base Selection
The W79E648 gives the user two modes of operation for the timer. The timers can be programmed to
operate like the standard 8051 family, counting at the rate of 1/12 of the clock speed. This will ensure
that timing loops on the W79E648 and the standard 8051 can be matched. This is the default mode of
operation of the W79E648 timers. The user also has the option to count in the turbo mode, where the
timers will increment at the rate of 1/4 clock speed. This will straight-away increase the counting
speed three times. This selection is done by the T0M and T1M bits in CKCON SFR. A reset sets these
bits to 0, and the timers then operate in the standard 8051 mode. The user should set these bits to 1 if
the timers are to operate in turbo mode.
Mode 0
In Mode 0, the timer/counters act as a 8 bit counter with a 5 bit, divide by 32 pre-scale. In this mode
we have a 13 bit timer/counter. The 13 bit counter consists of 8 bits of THx and 5 lower bits of TLx.
The upper 3 bits of TLx are ignored.
The negative edge of the clock increments the count in the TLx register. When the fifth bit in TLx
moves from 1 to 0, then the count in the THx register is incremented. When the count in THx moves
from FFh to 00h, then the overflow flag TFx in TCON SFR is set. The counted input is enabled only if
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
TRx is set and either GATE = 0 or INTx = 1. When C / T is set to 0, then it will count clock cycles,
and if C / T is set to 1, then it will count 1 to 0 transitions on T0 (P3.4) for timer 0 and T1 (P3.5) for
timer 1. When the 13 bit count reaches 1FFFh the next count will cause it to roll-over to 0000h. The
timer overflow flag TFx of the relevant timer is set and if enabled an interrupts will occur. Note that
when used as a timer, the time-base may be either clock cycles/12 or clock cycles/4 as selected by
the bits TxM of the CKCON SFR.
Timer 1 functions are shown in brackets
T0M = CKCON.3
(T1M = CKCON.4)
1/4
osc
1
1/12
T0 = P3.4
(T1 = P3.5)
0
M1,M0 = TMOD.1,TMOD.0
(M1,M0 = TMOD.5,TMOD.4)
C/T = TMOD.2
(C/T = TMOD.6)
00
0
1
0
4
7
0
01
TL0
(TL1)
7
TH0
(TH1)
TR0 = TCON.4
(TR1 = TCON.6)
GATE = TMOD.3
TFx
(GATE = TMOD.7)
INT0 = P3.2
Interrupt
TF0
(INT1 = P3.3)
(TF1)
Figure 11. Timer/Counter Mode 0 & Mode 1
Mode 1
Mode 1 is similar to Mode 0 except that the counting register forms a 16 bit counter, rather than a 13
bit counter. This means that all the bits of THx and TLx are used. Roll-over occurs when the timer
moves from a count of FFFFh to 0000h. The timer overflow flag TFx of the relevant timer is set and if
enabled an interrupt will occur. The selection of the time-base in the timer mode is similar to that in
Mode 0. The gate function operates similarly to that in Mode 0.
Mode 2
In Mode 2, the timer/counter is in the Auto Reload Mode. In this mode, TLx acts as a 8 bit count
register, while THx holds the reload value. When the TLx register overflows from FFh to 00h, the TFx
bit in TCON is set and TLx is reloaded with the contents of THx, and the counting process continues
from here. The reload operation leaves the contents of the THx register unchanged. Counting is
enabled by the TRx bit and proper setting of GATE and INTx pins. As in the other two modes 0 and 1
mode 2 allows counting of either clock cycles (clock/12 or clock/4) or pulses on pin Tn.
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Preliminary W79E648
T0M = CKCON.3
(T1M = CKCON.4)
1/4
osc
1/12
T0 = P3.4
(T1 = P3.5)
1
0
Timer 1 functions are shown in brackets
C/T = TMOD.2
(C/T = TMOD.6)
0
TL0
(TL1)
0
1
7
TFx
Interrupt
TF0
(TF1)
TR0 = TCON.4
(TR1 = TCON.6)
GATE = TMOD.3
(GATE = TMOD.7)
0
7
TH0
(TH1)
INT0 = P3.2
(INT1 = P3.3)
Figure 12. Timer/Counter Mode 2.
Mode 3
Mode 3 has different operating methods for the two timer/counters. For timer/counter 1, mode 3 simply
freezes the counter. Timer/Counter 0, however, configures TL0 and TH0 as two separate 8 bit count
registers in this mode. The logic for this mode is shown in the figure. TL0 uses the Timer/Counter 0
control bits C / T , GATE, TR0, INT0 and TF0. The TL0 can be used to count clock cycles (clock/12
or clock/4) or 1-to-0 transitions on pin T0 as determined by C/T (TMOD.2). TH0 is forced as a clock
cycle counter (clock/12 or clock/4) and takes over the use of TR1 and TF1 from Timer/Counter 1.
Mode 3 is used in cases where an extra 8 bit timer is needed. With Timer 0 in Mode 3, Timer 1 can
still be used in Modes 0, 1 and 2., but its flexibility is somewhat limited. While its basic functionality is
maintained, it no longer has control over its overflow flag TF1 and the enable bit TR1. Timer 1 can still
be used as a timer/counter and retains the use of GATE and INT1 pin. In this condition it can be
turned on and off by switching it out of and into its own Mode 3. It can also be used as a baud rate
generator for the serial port.
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
10.2 Timer/Counter 2
Timer/Counter 2 is a 16 bit up/down counter which is configured by the T2MOD register and controlled
by the T2CON register. Timer/Counter 2 is equipped with a capture/reload capability. As with the
Timer 0 and Timer 1 counters, there exists considerable flexibility in selecting and controlling the
clock, and in defining the operating mode. The clock source for Timer/Counter 2 may be selected for
either the external T2 pin (C/T2 = 1) or the crystal oscillator, which is divided by 12 or 4 (C/T2 = 0).
The clock is then enabled when TR2 is a 1, and disabled when TR2 is a 0.
T0M = CKCON.3
1/4
osc
1/12
T0 = P3.4
1
C/T = TMOD.2
0
TL0
0
0
1
7
TF0
Interrupt
TR0 = TCON.4
GATE = TMOD.3
INT0 = P3.2
TH0
0
TR1 = TCON.6
7
TF1
Interrupt
Figure 13. Timer/Counter 0 Mode 3
Capture Mode
The capture mode is enabled by setting the CP / RL2 bit in the T2CON register to a 1. In the capture
mode, Timer/Counter 2 serves as a 16 bit up counter. When the counter rolls over from FFFFh to
0000h, the TF2 bit is set, which will generate an interrupt request. If the EXEN2 bit is set, then a
negative transition of T2EX pin will cause the value in the TL2 and TH2 register to be captured by the
RCAP2L and RCAP2H registers. This action also causes the EXF2 bit in T2CON to be set, which will
also generate an interrupt. Setting the T2CR bit (T2MOD.3), the W79E648 allows hardware to reset
timer 2 automatically after the value of TL2 and TH2 have been captured.
- 42 -
Preliminary W79E648
1/4
osc
T2M = CKCON.5
1
C/T2 = T2CON.1
0
T2CON.7
0
1/12
TL2
1
TH2
TF2
T2 = P1.0
TR2 = T2CON.2
Timer 2
Interrupt
T2EX = P1.1
RCAP2L RCAP2H
EXEN2 = T2CON.3
EXF2
T2CON.6
Figure 14. 16-Bit Capture Mode
Auto-reload Mode, Counting up
The auto-reload mode as an up counter is enabled by clearing the CP / RL2 bit in the T2CON register
and clearing the DCEN bit in T2MOD register. In this mode, Timer/Counter 2 is a 16 bit up counter.
When the counter rolls over from FFFFh, a reload is generated that causes the contents of the
RCAP2L and RCAP2H registers to be reloaded into the TL2 and TH2 registers. The reload action also
sets the TF2 bit. If the EXEN2 bit is set, then a negative transition of T2EX pin will also cause a
reload. This action also sets the EXF2 bit in T2CON.
T2M = CKCON.5
1/4
1
1/12
0
osc
C/T2 = T2CON.1
T2CON.7
0
TL2
1
TH2
TF2
T2 = P1.0
TR2 = T2CON.2
Timer 2
Interrupt
T2EX = P1.1
RCAP2L RCAP2H
EXF2
EXEN2 = T2CON.3
T2CON.6
Figure 15. 16-Bit Auto-reload Mode, Counting Up
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
Auto-reload Mode, Counting Up/Down
Timer/Counter 2 will be in auto-reload mode as an up/down counter if CP / RL2 bit in T2CON is
cleared and the DCEN bit in T2MOD is set. In this mode, Timer/Counter 2 is an up/down counter
whose direction is controlled by the T2EX pin. A 1 on this pin cause the counter to count up. An
overflow while counting up will cause the counter to be reloaded with the contents of the capture
registers. The next down count following the case where the contents of Timer/Counter equal the
capture registers will load an FFFFh into Timer/Counter 2. In either event a reload will set the TF2 bit.
A reload will also toggle the EXF2 bit. However, the EXF2 bit can not generate an interrupt while in
this mode.
Down Counting Reload Value
0FFh
T2M = CKCON.5
1/4
1
osc
0FFh
C/T = T2CON.1
0
1/12
T2CON.7
0
TL2
1
Timer 2
Interrupt
TF2
TH2
T2 = P1.0
TR2 = T2CON.2
RCAP2L
RCAP2H
Up Counting Reload Value
EXF2
T2EX = P1.1
DCEN = 1
T2CON.6
Figure 16. 16-Bit Auto-reload Up/Down Counter
Baud Rate Generator Mode
The baud rate generator mode is enabled by setting either the RCLK or TCLK bits in T2CON register.
While in the baud rate generator mode, Timer/Counter 2 is a 16 bit counter with auto reload when the
count rolls over from FFFFh. However, rolling over does not set the TF2 bit. If EXEN2 bit is set, then a
negative transition of the T2EX pin will set EXF2 bit in the T2CON register and cause an interrupt
request.
osc
C/T = T2CON.1
0
TL2
1
TH2
Timer 2
overflow
T2 = P1.0
TR2 = T2CON.2
T2EX = P1.1
RCAP2L RCAP2H
EXF2
T2CON.6
EXEN2 = T2CON.3
Figure 17. Baud Rate Generator Mode
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Timer 2
Interrupt
Preliminary W79E648
10.3 Pulse Width Modulated Outputs (PWM)
There are six pulse width modulated output channels to generate pulses of programmable length and
interval. The repetition frequency is defined by an 8-bit prescaler PWMP, which supplies the clock for
the counter. The prescaler and counter are common to both PWM channels. The 8-bit counter counts
modular 255 (0 ~ 254). The value of the 8-bit counter compared to the contents of six registers:
PWM0, PWM1, PWM2, PWM3 and PWM4. Provided the contents of either these registers is greater
than the counter value, the corresponding PWM0, PWM1, PWM2, PWM3, PWM4 or PWM5 output is
set HIGH. If the contents of these registers are equal to, or less than the counter value, the output will
be LOW. The pulse-width-ratio is defined by the contents of the registers PWM0, PWM1, PWM2,
PWM3, PWM4 and PWM5. The pulse-width-ratio is in the range of 0 to 1 and may be programmed in
increments of 1/255. ENPWM0, ENPWM1, ENPWM2, ENPWM3, ENPWM4 and ENPWM5 bit will
enable or disable PWM output.
Buffered PWM outputs may be used to drive DC motors. The rotation speed of the motor would be
proportional to the contents of PWM0/1/2/3/4/5.
The repetition frequency fpwm , at the
PWM0/1/2/3/4/5 output is given by:
fpwm =
fosc
2 × (1 + PWMP) × 255
Prescaler division factor = PWM + 1
PWMn high/low ratio of PWMn =
(PWMn)
255 - (PWMn)
This gives a repetition frequency range of 123 Hz to 31.4K Hz ( fosc = 16M Hz). By loading the PWM
registers with either 00H or FFH, the PWM channels will output a constant HIGH or LOW level,
respectively. Since the 8-bit counter counts modulo 255, it can never actually reach the value of the
PWM registers when they are loaded with FFH.
When a compare register (PWM0, PWM1, PWM2, PWM3, PWM4, PWM5) is loaded with a new value,
the associated output updated immediately. It does not have to wait until the end of the current
counter period. There is weakly pulled high on PWM output.
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
comparator
ENPWM0/1/2/3/4
PWM0OE
PWM0
f osc
PWM0
(P1.0)
1/2
Prescaler
8bit counter
PWM1OE
PWMP
PWM1
(P1.1)
PWM1
comparator
comparator
PWM2OE
PWM2
PWM2
(P1.2)
8bit counter
PWM3OE
PWM3
(P1.3)
PWM3
comparator
comparator
PWM4OE
PWM4
PWM4
(P1.4)
8bit counter
PWM5OE
PWM5
(P1.5)
PWM5
comparator
FIGURE 1 PWM DIAGRAM
Please refer as below code.
mov
mov
mov
mov
mov
mov
mov
mov
mov
pwmcon1, #00110011b
pwmcon2, #00000101b
pwmp, #40h
pwm0, #14h
pwm1, #18h
pwm2, #20h
pwm3, #b0h
pwm4, #40h
pwmcon1, #11111111b
; enable pwm3, 2, 1, 0
; enable pwm4
; Fpwm = XT/(2*(1+pwmp)*255)
; duty cycle high/low = pwm0/(255-pmw0)
; output enable pwm3, 2, 1, 0
- 46 -
Preliminary W79E648
PWM3 Register
Bit:
7
6
5
4
3
2
Mnemonic: PWM3
1
0
Address: DEH
PWM2 Register
Bit:
7
6
5
4
3
2
Mnemonic: PWM2
1
0
Address: DDH
PWM Control 1 Register
Bit:
7
6
5
4
3
2
1
0
PWM3OE
PWM2OE
ENPWM3
ENPWM2
PWM1OE
PWM0OE
ENPWM1
ENWPM0
Mnemonic: PWMCON1
Address: DCH
PWM3OE: Output enable for PWM3
PWM2OE: Output enable for PWM2
ENPWM3: Enable PWM3
ENPWM2: Enable PWM2
PWM1OE: Output enable for PWM1
PWM0OE: Output enable for PWM0
ENPWM1: Enable PWM1
ENPWM0: Enable PWM0
PWM1 Register
Bit:
7
6
5
4
3
2
Mnemonic: PWM1
PWM0 Register
Bit:
7
6
7
6
0
Address: DBH
5
4
3
2
Mnemonic: PWM0
PWMP Register
Bit:
1
1
0
Address: DAH
5
4
Mnemonic: PWMP
3
2
1
0
Address: D9H
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
PWM4 Register
Bit:
7
6
5
4
3
2
Mnemonic: PWM4
1
0
Address: CFH
PWM Control 2 Register
Bit:
7
6
5
4
3
2
1
0
-
-
-
-
PWM5
OE-
PWM4
OE
ENWP
M5
ENWP
M4
Mnemonic: PWMCON2
Address: CEH
PWM5OE: Output enable for PWM5
PWM4OE: Output enable for PWM4
ENPWM5: Enable for PWM5
ENPWM4: Enable for PWM4
PWM5 Register
Bit:
7
6
5
4
Mnemonic: PWM5
3
2
1
0
Address: C3H
10.4 Watchdog Timer
The Watchdog timer is a free-running timer which can be programmed by the user to serve as a
system monitor, a time-base generator or an event timer. It is basically a set of dividers that divide the
system clock. The divider output is selectable and determines the time-out interval. When the time-out
occurs a flag is set, which can cause an interrupt if enabled, and a system reset can also be caused if
it is enabled. The interrupt will occur if the individual interrupt enable and the global enable are set.
The interrupt and reset functions are independent of each other and may be used separately or
together depending on the users software.
- 48 -
Preliminary W79E648
XT
0
16
WD1,WD0
WDIF
Interrupt
EWDI(EIE.4)
17
20
19
22
00
01
10
11
WTRF
Time-out
512 clock
delay
Reset Watchdog
RWT (WDCON.0)
23
25
Reset
Enable Watchdog timer reset
EWT(WDCON.1)
Figure 19. Watchdog Timer
The Watchdog timer should first be restarted by using RWT. This ensures that the timer starts from a
known state. The RWT bit is used to restart the watchdog timer. This bit is self clearing, i.e. after
writing a 1 to this bit the software will automatically clear it. The watchdog timer will now count clock
cycles. The time-out interval is selected by the two bits WD1 and WD0 (CKCON.7 and CKCON.6).
When the selected time-out occurs, the Watchdog interrupt flag WDIF (WDCON.3) is set. After the
time-out has occurred, the watchdog timer waits for an additional 512 clock cycles. If the Watchdog
Reset EWT (WDCON.1) is enabled, then 512 clocks after the time-out, if there is no RWT, a system
reset due to Watchdog timer will occur. This will last for two machine cycles, and the Watchdog timer
reset flag WTRF (WDCON.2) will be set. This indicates to the software that the watchdog was the
cause of the reset.
When used as a simple timer, the reset and interrupt functions are disabled. The timer will set the
WDIF flag each time the timer completes the selected time interval. The WDIF flag is polled to detect a
time-out and the RWT allows software to restart the timer. The Watchdog timer can also be used as a
very long timer. The interrupt feature is enabled in this case. Every time the time-out occurs an
interrupt will occur if the global interrupt enable EA is set.
The main use of the Watchdog timer is as a system monitor. This is important in real-time control
applications. In case of some power glitches or electro-magnetic interference, the processor may
begin to execute errant code. If this is left unchecked the entire system may crash. Using the
watchdog timer interrupt during software development will allow the user to select ideal watchdog
reset locations. The code is first written without the watchdog interrupt or reset. Then the watchdog
interrupt is enabled to identify code locations where interrupt occurs. The user can now insert
instructions to reset the watchdog timer which will allow the code to run without any watchdog timer
interrupts. Now the watchdog timer reset is enabled and the watchdog interrupt may be disabled. If
any errant code is executed now, then the reset watchdog timer instructions will not be executed at
the required instants and watchdog reset will occur.
The watchdog time-out selection will result in different time-out values depending on the clock speed.
The reset, when enabled, will occur 512 clocks after the time-out has occurred.
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
Table 9. Time-out values for the Watchdog timer
WD1
WD0
0
0
0
1
1
1
0
1
Watchdog
Interval
17
2
2
Time
@ 1.8432 MHz
Time
@ 10 MHz
Time
@ 25 MHz
131072
71.11 mS
13.11 mS
5.24 mS
20
1048576
568.89 mS
104.86 mS
41.94 mS
23
8388608
4551.11 mS
838.86 mS
335.54 mS
26
67108864
36408.88 mS
6710.89 mS
2684.35 mS
2
2
Number of
Clocks
The Watchdog timer will de disabled by a power-on/fail reset. The Watchdog timer reset does not
disable the watchdog timer, but will restart it. In general, software should restart the timer to put it into
a known state.
The control bits that support the Watchdog timer are discussed below.
Watchdog Control
WDIF: WDCON.3 - Watchdog Timer Interrupt flag. This bit is set whenever the time-out occurs in the
watchdog timer. If the Watchdog interrupt is enabled (EIE.4), then an interrupt will occur (if the
global interrupt enable is set and other interrupt requirements are met). Software or any reset
can clear this bit.
WTRF: WDCON.2 - Watchdog Timer Reset flag. This bit is set whenever a watchdog reset occurs.
This bit is useful for determined the cause of a reset. Software must read it, and clear it
manually. A Power-fail reset will clear this bit. If EWT = 0, then this bit will not be affected by
the watchdog timer.
EWT:
WDCON.1 - Enable Watchdog timer Reset. This bit when set to 1 will enable the Watchdog
timer reset function. Setting this bit to 0 will disable the Watchdog timer reset function, but will
leave the timer running.
RWT: WDCON.0 - Reset Watchdog Timer. This bit is used to clear the Watchdog timer and to
restart it. This bit is self-clearing, so after the software writes 1 to it the hardware will
automatically clear it. If the Watchdog timer reset is enabled, then the RWT has to be set by
the user within 512 clocks of the time-out. If this is not done then a Watchdog timer reset will
occur.
- 50 -
Preliminary W79E648
Clock Control
WD1, WD0: CKCON.7, CKCON.6 - Watchdog Timer Mode select bits. These two bits select the timeout interval for the watchdog timer. The reset time is 512 clock longer than the interrupt
time-out value.
17
The default Watchdog time-out is 2 clocks, which is the shortest time-out period. The EWT, WDIF
and RWT bits are protected by the Timed Access procedure. This prevents software from accidentally
enabling or disabling the watchdog timer. More importantly, it makes it highly improbable that errant
code can enable or disable the watchdog timer. Please refer as below demo program.
org
63h
mov
TA,#AAH
mov
TA,#55H
clr
WDIF
jnb
execute_reset_flag,bypass_reset
; Test if CPU need to reset.
jmp
$
; Wait to reset
bypass_reset:
mov
TA,#AAH
mov
TA,#55H
setb
RWT
reti
org
300h
start:
mov
ckcon,#01h
; select 2 ^ 17 timer
;
mov
ckcon,#61h
; select 2 ^ 20 timer
;
mov
ckcon,#81h
; select 2 ^ 23 timer
;
mov
ckcon,#c1h
; select 2 ^ 26 timer
mov
TA,#aah
mov
TA,#55h
mov
WDCON,#00000011B
setb
EWDI
setb
ea
jmp
$
; wait time out
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
11. SERIAL PORT
Serial port in the W79E648 is a full duplex port. The W79E648 provides the user with additional
features such as the Frame Error Detection and the Automatic Address Recognition. The serial ports
are capable of synchronous as well as asynchronous communication. In Synchronous mode the
W79E648 generates the clock and operates in a half duplex mode. In the asynchronous mode, full
duplex operation is available. This means that it can simultaneously transmit and receive data. The
transmit register and the receive buffer are both addressed as SBUF Special Function Register.
However any write to SBUF will be to the transmit register, while a read from SBUF will be from the
receive buffer register. The serial port can operate in four different modes as described below.
Mode 0
This mode provides synchronous communication with external devices. In this mode serial data is
transmitted and received on the RXD line. TXD is used to transmit the shift clock. The TxD clock is
provided by the W79E648 whether the device is transmitting or receiving. This mode is therefore a
half duplex mode of serial communication. In this mode, 8 bits are transmitted or received per frame.
The LSB is transmitted/received first. The baud rate is fixed at 1/12 or 1/4 of the oscillator frequency.
This baud rate is determined by the SM2 bit (SCON.5). When this bit is set to 0, then the serial port
runs at 1/12 of the clock. When set to 1, the serial port runs at 1/4 of the clock. This additional facility
of programmable baud rate in mode 0 is the only difference between the standard 8051 and the
W79E648.
The functional block diagram is shown below. Data enters and leaves the Serial port on the RxD line.
The TxD line is used to output the shift clock. The shift clock is used to shift data into and out of the
W79E648 and the device at the other end of the line. Any instruction that causes a write to SBUF will
start the transmission. The shift clock will be activated and data will be shifted out on the RxD pin till all
8 bits are transmitted. If SM2 = 1, then the data on RxD will appear 1 clock period before the falling
edge of shift clock on TxD. The clock on TxD then remains low for 2 clock periods, and then goes high
again. If SM2 = 0, the data on RxD will appear 3 clock periods before the falling edge of shift clock on
TxD. The clock on TxD then remains low for 6 clock periods, and then goes high again. This ensures
that at the receiving end the data on RxD line can either be clocked on the rising edge of the shift
clock on TxD or latched when the TxD clock is low.
- 52 -
Preliminary W79E648
OSC
Internal
Data Bus
Write to
SBUF
PARIN
SOUT
LOAD
RXD
P3.0 Alternate
Output Function
CLOCK
12
4
TX SHIFT
TX START
TX CLOCK
SM2
Serial Port Interrupt
SERIAL
0
1
RXD
P3.0 Alternate
Iutput function
RI
CONTROLLE
RX
CLOCK
RI
REN
Transmit Shift Register
TI
RX
START
SHIFT
CLOCK
TXD
P3.1 Alternate
Output function
LOAD SBUF
RX SHIFT
CLOCK
PAROUT
SBUF
SIN
Read SBUF
SBUF
Internal
Data Bus
Receive Shift Register
Figure 20. Serial Port Mode 1
The TI flag is set high in C1 following the end of transmission of the last bit. The serial port will receive
data when REN is 1 and RI is zero. The shift clock (TxD) will be activated and the serial port will latch
data on the rising edge of shift clock. The external device should therefore present data on the falling
edge on the shift clock. This process continues till all the 8 bits have been received. The RI flag is set
in C1 following the last rising edge of the shift clock on TxD. This will stop reception, till the RI is
cleared by software.
Mode 1
In Mode 1, the full duplex asynchronous mode is used. Serial communication frames are made up of
10 bits transmitted on TXD and received on RXD. The 10 bits consist of a start bit (0), 8 data bits (LSB
first), and a stop bit (1). On receive, the stop bit goes into RB8 in the SFR SCON. The baud rate in this
mode is variable. The serial baud can be programmed to be 1/16 or 1/32 of the Timer 1 overflow.
Since the Timer 1 can be set to different reload values, a wide variation in baud rates is possible.
Transmission begins with a write to SBUF. The serial data is brought out on to TxD pin at C1 following
the first roll-over of divide by 16 counter. The next bit is placed on TxD pin at C1 following the next
rollover of the divide by 16 counter. Thus the transmission is synchronized to the divide by 16 counter
and not directly to the write to SBUF signal. After all 8 bits of data are transmitted, the stop bit is
transmitted. The TI flag is set in the C1 state after the stop bit has been put out on TxD pin. This will
be at the 10th rollover of the divide by 16 counter after a write to SBUF.
Reception is enabled only if REN is high. The serial port actually starts the receiving of serial data,
with the detection of a falling edge on the RxD pin. The 1-to-0 detector continuously monitors the RxD
line, sampling it at the rate of 16 times the selected baud rate. When a falling edge is detected, the
divide by 16 counter is immediately reset. This helps to align the bit boundaries with the rollovers of
the divide by 16 counter.
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
The 16 states of the counter effectively divide the bit time into 16 slices. The bit detection is done on a
best of three basis. The bit detector samples the RxD pin, at the 8th, 9th and 10th counter states. By
using a majority 2 of 3 voting system, the bit value is selected. This is done to improve the noise
rejection feature of the serial port. If the first bit detected after the falling edge of RxD pin is not 0, then
this indicates an invalid start bit, and the reception is immediately aborted. The serial port again looks
for a falling edge in the RxD line. If a valid start bit is detected, then the rest of the bits are also
detected and shifted into the SBUF.
After shifting in 8 data bits, there is one more shift to do, after which the SBUF and RB8 are loaded
and RI is set. However certain conditions must be met before the loading and setting of RI can be
done.
1. RI must be 0 and
2. Either SM2 = 0, or the received stop bit = 1.
If these conditions are met, then the stop bit goes to RB8, the 8 data bits go into SBUF and RI is set.
Otherwise the received frame may be lost. After the middle of the stop bit, the receiver goes back to
looking for a 1-to-0 transition on the RxD pin.
Timer 1
Overflow
SMOD=
(SMOD_1) 0
PARIN
START
LOAD
0
0
SOUT
TXD
CLOCK
1
TX START
1
16
RCLK
STOP
Internal
Data Bus
Write to
SBUF
2
TCLK
Transmit Shift Register
Timer 2 Overflow
(for Serial Port 0 only)
TX SHIFT
TX CLOCK
TI
SERIAL
CONTROLLER
1
Serial Port
Interrupt
RI
16
RX CLOCK
SAMPLE
1-TO-0
DETECTOR
RX
START
LOAD
Read
SBUF
SBUF
RX SHIFT
CLOCK
PAROUT
RXD
BIT
DETECTOR
SIN
D8
Receive Shift Register
Figure 21. Serial Port Mode 1
- 54 -
SBUF
RB8
Internal
Data
Bus
Preliminary W79E648
Mode 2
This mode uses a total of 11 bits in asynchronous full-duplex communication. The functional
description is shown in the figure below. The frame consists of one start bit (0), 8 data bits (LSB first),
a programmable 9th bit (TB8) and a stop bit (0). The 9th bit received is put into RB8. The baud rate is
programmable to 1/32 or 1/64 of the oscillator frequency, which is determined by the SMOD bit in
PCON SFR. Transmission begins with a write to SBUF. The serial data is brought out on to TxD pin at
C1 following the first roll-over of the divide by 16 counter. The next bit is placed on TxD pin at C1
following the next rollover of the divide by 16 counter. Thus the transmission is synchronized to the
divide by 16 counter, and not directly to the write to SBUF signal. After all 9 bits of data are
transmitted, the stop bit is transmitted. The TI flag is set in the C1 state after the stop bit has been put
out on TxD pin. This will be at the 11th rollover of the divide by 16 counter after a write to SBUF.
Reception is enabled only if REN is high. The serial port actually starts the receiving of serial data,
with the detection of a falling edge on the RxD pin. The 1-to-0 detector continuously monitors the RxD
line, sampling it at the rate of 16 times the selected baud rate. When a falling edge is detected, the
divide by 16 counter is immediately reset. This helps to align the bit boundaries with the rollovers of
the divide by 16 counter. The 16 states of the counter effectively divide the bit time into 16 slices. The
bit detection is done on a best of three basis. The bit detector samples the RxD pin, at the 8th, 9th and
10th counter states. By using a majority 2 of 3 voting system, the bit value is selected. This is done to
improve the noise rejection feature of the serial port.
OSC
TB8
Write to
SBUF
2
SMOD=
(SMOD_1)
0
D8
STOP
Internal
Data Bus
PARIN
START
TXD
SOUT
LOAD
1
CLOCK
TX
SHIFT
TX START
16
16
TX CLOCK
Transmit Shift Register
TI
SERIAL
CONTROLLER
Serial Port
Interrupt
RI
RX CLOCK
SAMPLE
1-TO-0
DETECTOR
RX START
LOAD
SBUF
RX SHIFT
Read
SBUF
CLOCK
PAROUT
RXD
BIT
DETECTOR
SIN
D8
SBUF
RB8
Internal
Data
Bus
Receive Shift Register
Figure 22. Serial Port Mode 2
If the first bit detected after the falling edge of RxD pin, is not 0, then this indicates an invalid start bit,
and the reception is immediately aborted. The serial port again looks for a falling edge in the RxD line.
If a valid start bit is detected, then the rest of the bits are also detected and shifted into the SBUF.
After shifting in 9 data bits, there is one more shift to do, after which the SBUF and RB8 are loaded
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
and RI is set. However certain conditions must be met before the loading and setting of RI can be
done.
- 56 -
Preliminary W79E648
1. RI must be 0 and
2. Either SM2 = 0, or the received stop bit = 1.
If these conditions are met, then the stop bit goes to RB8, the 8 data bits go into SBUF and RI is set.
Otherwise the received frame may be lost. After the middle of the stop bit, the receiver goes back to
looking for a 1-to-0 transition on the RxD pin.
Mode 3
This mode is similar to Mode 2 in all respects, except that the baud rate is programmable. The user
must first initialize the Serial related SFR SCON before any communication can take place. This
involves selection of the Mode and baud rate. The Timer 1 should also be initialized if modes 1 and 3
are used. In all four modes, transmission is started by any instruction that uses SBUF as a destination
register. Reception is initiated in Mode 0 by the condition RI = 0 and REN = 1. This will generate a
clock on the TxD pin and shift in 8 bits on the RxD pin. Reception is initiated in the other modes by the
incoming start bit if REN = 1. The external device will start the communication by transmitting the start
bit.
Timer 1
Overflow
Timer 2 Overflow
(for Serial Port 0 only)
SMOD=
(SMOD_1) 0
PARIN
START
LOAD
0
0
SOUT
TXD
CLOCK
1
TX START
1
TI
SERIAL
CONTROLLER
1
Transmit Shift Register
TX SHIFT
TX CLOCK
16
RCLK
D8
Internal
Data Bus
Write to
SBUF
2
TCLK
STOP
TB8
Serial Port
Interrupt
RI
16
RX CLOCK
SAMPLE
LOAD
SBUF
RX
1-TO-0
DETECTOR
START
Read
SBUF
RX SHIFT
CLOCK
BIT
DETECTOR
RXD
D8
SIN
Internal
Data
Bus
SBUF
PAROUT
RB8
Receive Shift Register
Figure 23. Serial Port Mode 3
Table 10. Serial Ports Modes
SM1
SM0
Mode
Type
0
0
1
1
0
1
0
1
0
1
2
3
Synch.
Asynch.
Asynch.
Asynch.
Baud Clock
4 or 12 TCLKS
Timer 1 or 2
32 or 64 TCLKS
Timer 1 or 2
- 57 -
Frame
Size
Start
Bit
Stop
Bit
9th bit
Function
8 bits
10 bits
11 bits
11 bits
No
1
1
1
No
1
1
1
None
None
0, 1
0, 1
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
11.1 Framing Error Detection
A Frame Error occurs when a valid stop bit is not detected. This could indicate incorrect serial data
communication. Typically the frame error is due to noise and contention on the serial communication
line. The W79E648 has the facility to detect such framing errors and set a flag which can be checked
by software.
The Frame Error FE(FE_1) bit is located in SCON.7. This bit is normally used as SM0 in the standard
8051 family. However, in the W79E648 it serves a dual function and is called SM0/FE. There are
actually two separate flags, one for SM0 and the other for FE. The flag that is actually accessed as
SCON.7 is determined by SMOD0 (PCON.6) bit. When SMOD0 is set to 1, then the FE flag is
indicated in SM0/FE. When SMOD0 is set to 0, then the SM0 flag is indicated in SM0/FE.
The FE bit is set to 1 by hardware but must be cleared by software. Note that SMOD0 must be 1 while
reading or writing to FE. If FE is set, then any following frames received without any error will not clear
the FE flag. The clearing has to be done by software.
11.2 Multiprocessor Communications
Multiprocessor communications makes use of the 9th data bit in modes 2 and 3. In the W79E648, the
RI flag is set only if the received byte corresponds to the Given or Broadcast address. This hardware
feature eliminates the software overhead required in checking every received address, and greatly
simplifies the software programmer task.
In the multiprocessor communication mode, the address bytes are distinguished from the data bytes
by transmitting the address with the 9th bit set high. When the master processor wants to transmit a
block of data to one of the slaves, it first sends out the address of the targeted slave (or slaves). All
the slave processors should have their SM2 bit set high when waiting for an address byte. This
ensures that they will be interrupted only by the reception of a address byte. The Automatic address
recognition feature ensures that only the addressed slave will be interrupted. The address comparison
is done in hardware not software.
The addressed slave clears the SM2 bit, thereby clearing the way to receive data bytes. With SM2 =
0, the slave will be interrupted on the reception of every single complete frame of data. The
unaddressed slaves will be unaffected, as they will be still waiting for their address. In Mode 1, the 9th
bit is the stop bit, which is 1 in case of a valid frame. If SM2 is 1, then RI is set only if a valid frame is
received and the received byte matches the Given or Broadcast address.
The Master processor can selectively communicate with groups of slaves by using the Given Address.
All the slaves can be addressed together using the Broadcast Address. The addresses for each slave
are defined by the SADDR and SADEN SFRs. The slave address is an 8-bit value specified in the
SADDR SFR. The SADEN SFR is actually a mask for the byte value in SADDR. If a bit position in
SADEN is 0, then the corresponding bit position in SADDR is don't care. Only those bit positions in
SADDR whose corresponding bits in SADEN are 1 are used to obtain the Given Address. This gives
the user flexibility to address multiple slaves without changing the slave address in SADDR.
The following example shows how the user can define the Given Address to address different slaves.
Slave 1:
SADDR 1010 0100
SADEN 1111 1010
Given 1010 0x0x
- 58 -
Preliminary W79E648
Slave 2:
SADDR 1010 0111
SADEN 1111 1001
Given 1010 0xx1
The Given address for slave 1 and 2 differ in the LSB. For slave 1, it is a don't care, while for slave 2 it
is 1. Thus to communicate only with slave 1, the master must send an address with LSB = 0 (1010
0000). Similarly the bit 1 position is 0 for slave 1 and don't care for slave 2. Hence to communicate
only with slave 2 the master has to transmit an address with bit 1 = 1 (1010 0011). If the master
wishes to communicate with both slaves simultaneously, then the address must have bit 0 = 1 and bit
1 = 0. The bit 3 position is don't care for both the slaves. This allows two different addresses to select
both slaves (1010 0001 and 1010 0101).
The master can communicate with all the slaves simultaneously with the Broadcast Address. This
address is formed from the logical ORing of the SADDR and SADEN SFRs. The zeros in the result
are defined as don't cares In most cases the Broadcast Address is FFh. In the previous case, the
Broadcast Address is (1111111X) for slave 1 and (11111111) for slave 2.
The SADDR and SADEN SFRs are located at address A9h and B9h respectively. On reset, these two
SFRs are initialized to 00h. This results in Given Address and Broadcast Address being set as XXXX
XXXX(i.e. all bits don't care). This effectively removes the multiprocessor communications feature,
since any selectivity is disabled.
12. TIMED ACCESS PROTECTION
The W79E648 has several new features, like the Watchdog timer, on-chip ROM size adjustment, wait
state control signal and Power on/fail reset flag, which are crucial to proper operation of the system. If
left unprotected, errant code may write to the Watchdog control bits resulting in incorrect operation
and loss of control. In order to prevent this, the W79E648 has a protection scheme which controls the
write access to critical bits. This protection scheme is done using a timed access.
In this method, the bits which are to be protected have a timed write enable window. A write is
successful only if this window is active, otherwise the write will be discarded. This write enable window
is open for 3 machine cycles if certain conditions are met. After 3 machine cycles, this window
automatically closes. The window is opened by writing AAh and immediately 55h to the Timed
Access(TA) SFR. This SFR is located at address C7h. The suggested code for opening the timed
access window is
TA
REG
0C7h
MOV
TA, #0AAh
MOV
TA, #055h
;define new register TA, located at 0C7h
When the software writes AAh to the TA SFR, a counter is started. This counter waits for 3 machine
cycles looking for a write of 55h to TA. If the second write (55h) occurs within 3 machine cycles of the
first write (AAh), then the timed access window is opened. It remains open for 3 machine cycles,
during which the user may write to the protected bits. Once the window closes the procedure must be
repeated to access the other protected bits.
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
Examples of Timed Assessing are shown below.
Example 1: Valid access
MOV
MOV
MOV
TA, #0AAh
3 M/C
TA, #055h
3 M/C
WDCON, #00h 3 M/C
Note: M/C = Machine Cycles
Example 2: Valid access
MOV TA, #0AAh
MOV TA, #055h
NOP
SETB EWT
3 M/C
3 M/C
1 M/C
2 M/C
Example 3: Valid access
MOV
MOV
ORL
TA, #0Aah
3 M/C
TA, #055h
3 M/C
WDCON, #00000010B 3M/C
Example 4: Invalid access
MOV
MOV
NOP
NOP
CLR
TA, #0AAh
TA, #055h
POR
3 M/C
3 M/C
1 M/C
1 M/C
2 M/C
Example 5: Invalid Access
MOV TA, #0AAh
NOP
MOV TA, #055h
SETB EWT
3 M/C
1 M/C
3 M/C
2 M/C
In the first two examples, the writing to the protected bits is done before the 3 machine cycle window
closes. In Example 3, however, the writing to the protected bit occurs after the window has closed,
and so there is effectively no change in the status of the protected bit. In Example 4, the second write
to TA occurs 4 machine cycles after the first write, therefore the timed access window in not opened at
all, and the write to the protected bit fails.
- 60 -
Preliminary W79E648
13. H/W REBOOT MODE (BOOT FROM 4K BYTES OF LDFLASH)
The W79E648 boots from APFlash program (64K bytes) by default at the external reset. On some
occasions, user can force W79E648 to boot from the LDFlash program (4K bytes) at the external
reset. The settings for this special mode is as follow. It is necessary to add 10K resistor on these P2.6,
P2.7 and P4.3 pins.
Reboot Mode
OPTION BITS
RST
P4.3
P2.7
P2.6
MODE
Bit4 L
H↓
X
L
L
REBOOT
Bit5 L
H↓
L
X
X
REBOOT
The Reset Timing For Entering
REBOOT Mode
P2.7
Hi-Z
P2.6
Hi-Z
RST
20 US
10 mS
Notes:
1. The possible situation that you need to enter REBOOT mode is when the APFlash program can not run normally and
W79E648 can not jump to LDFlash to execute on chip programming function. Then you can use this REBOOT mode to force
the CPU jump to LDFlash and run on chip programming procedure. When you design your system, you can connect the pins
P26, P27 to switches or jumpers. For example in a CD ROM system, you can connect the P26 and P27 to PLAY and EJECT
buttons on the panel. When the APFlash program is fail to execute the normal application program. User can press both two
buttons at the same time and then switch on the power of the personal computer to force the W79E648 to enter the
REBOOT mode. After power on of personal computer, you can release both PLAY and EJECT button. And re-run the on
chip programming procedure to let the APFlash have the normal program code. Then you can back to normal condition of
CD ROM.
2: In application system design, user must take care the P4.3, P2, P3, ALE, /EA and /PSEN pin value at reset to avoid
W79E648 entering the programming mode or REBOOT mode in normal operation.
- 61 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
14. IN-SYSTEM PROGRAMMING
14.1
The Loader Program Locates at LDFlash Memory
CPU is Free Run at APFlash memory. CHPCON register had been set #03H value before CPU has
entered idle state. CPU will switch to LDFlash memory and execute a reset action. H/W reboot mode
will switch to LDFlash memory, too. Set SFRCN register where it locates at user's loader program to
update APFlash bank 0 or bank 1 memory. Set a SWRESET ( CHPCON=#83H) to switch back
APFlash after CPU has updated APFlash program. CPU will restart to run program from reset state.
14.2
The Loader Program Locates at APFlash Memory
CPU is Free Run at APFlash memory. CHPCON register had been set #01H value before CPU has
entered idle state. Set SFRCN register to update LDFlash or another bank of APFlash program. CPU
will continue to run user's APFlash program after CPU has updated program. Please refer
demonstrative code to understand other detail description.
15. H/W WRITER MODE
This mode is for the writer to write / read Flash EPROM operation. A general user may not enter this
mode.
The Timing For Entering Flash EPROM
Mode on the Programmer
Hi-Z
EA
Hi-Z
PSEN
ALE
Hi-Z
P2.7
Hi-Z
P2.6
Hi-Z
P3.7
Hi-Z
P3.6
Hi-Z
RST
10ms
300ms
- 62 -
Preliminary W79E648
16. SECURITY BITS
1. Using device programmer, the Flash EPROM can be programmed and verified repeatedly. Until
the code inside the Flash EPROM is confirmed OK, the code can be protected. The protection of
Flash EPROM and those operations on it are described below. The W79E648 has Special Setting
Register which can be accessed by device programmer. The register can only be accessed from
the Flash EPROM operation mode. Those bits of the Security Registers can not be changed once
they have been programmed from high to low. They can only be reset through erase-all operation.
If you needn’t have ISP function, please don’t fill “FF” code on LD memory. The writer always
writes AP and LD flashs every time.
B7 B6
B5 B4 B3 B2
B1 B0
Security Bits
B7: 1: XT > 24M hz, 0: XT < 24M hz.
B5: 0 -> Eable H/W reboot with P4.3
B4: 0 -> Enable H/W reboot with P2.6, P2.7
B1: 0 -> Movc Inhibited
B0 : 0-> Data out lock
Default 1 for each bit.
Option Bits
B0: Lock bit
This bit is used to protect the customer's program code in the W79E648. It may be set after the
programmer finishes the programming and verifies sequence. Once this bit is set to logic 0, both the
Flash EPROM data and Special Setting Registers can not be accessed again.
B1: MOVC Inhibit
This bit is used to restrict the accessible region of the MOVC instruction. It can prevent the MOVC
instruction in external program memory from reading the internal program code. When this bit is set to
logic 0, a MOVC instruction in external program memory space will be able to access code only in the
external memory, not in the internal memory. A MOVC instruction in internal program memory space
will always be able to access the ROM data in both internal and external memory. If this bit is logic 1,
there are no restrictions on the MOVC instruction.
B4: H/W Reboot with P2.6 and P2.7
If this bit is set to logic 0, enable to reboot 4k LDFlash mode while RST =H, P2.6 = L and P2.7 = L
state. CPU will start from LDFlash to update the user’s program.
B5: H/W Reboot with P4.3
If this bit is set to logic 0, enable to reboot 4k LDFlash mode while RST =H and P4.3 = L state. CPU
will start from LDFlash to update the user’s program
B7: Select clock freqency.
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Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
If clock freqency is over 24M hz, then set this bit is H. If clock frequency is less than 24M hz, then
clear this bit.
- 64 -
Preliminary W79E648
17. ELECTRICAL CHARACTERISTICS
17.1 Absolute Maximum Ratings
SYMBOL
PARAMETER
CONDITION
RATING
UNIT
VDD − VSS
-0.3
+7.0
V
Input Voltage
VIN
VSS -0.3
VDD +0.3
V
Operating Temperature
TA
0
+70
°C
Storage Temperatute
Tst
-55
+150
°C
DC Power Supply
Note: Exposure to conditions beyond those listed under Absolute Maximum Ratings may adversely affect the life and reliability
of the device.
- 65 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
17.2 DC Characteristics
(VDD − VSS = 5V ±10%, TA = 25°C, Fosc = 20 MHz, unless otherwise specified.)
PARAMETER
SYMBOL
SPECIFICATION
MIN.
MAX.
UNIT
TEST CONDITIONS
Operating Voltage
VDD
4.5
5.5
V
Operating Current
IDD
-
30
mA
IIDLE
-
14
mA
IPWDN
-
10
µA
Input Current
P1, P2, P3,P4, P5, P6, P7
IIN1
-50
+10
µA
VDD = 5.5V
VIN = 0V or VDD
Input Current RST[*1]
IIN2
0
+1000
µA
VDD = 5.5V
0<VIN<VDD
ILK
-10
+10
µA
VDD = 5.5V
0V<VIN<VDD
ITL[*4]
-500
-200
µA
VDD = 5.5V
VIN = 2.0V
VIL1
0
0.8
V
VDD = 4.5V
VIL2
0
0.8
V
VDD = 4.5V
VIL3
0
0.8
V
VDD = 4.5V
VIH1
2.4
VDD +0.2
V
VDD = 5.5V
VIH2
3.5
VDD +0.2
V
VDD = 5.5V
VIH3
3.5
VDD +0.2
V
VDD = 5.5V
Idle Current
Power Down Current
Input Leakage Current
P0, EA
Logic 1 to 0 Transition
Current P1, P2, P3, P4,
P5, P6, P7
Input Low Voltage
P0, P1, P2, P3, EA
Input Low Voltage
RST[*1]
Input Low Voltage
XTAL1[*3]
Input High Voltage
P0, P1, P2, P3, P4, P5, P6,
P7, EA
Input High Voltage RST
Input High Voltage
XTAL1[*3]
- 66 -
No load
VDD = RST = 5.5V
Idle mode
VDD = 5.5V
Power-down mode
VDD = 5.5V
Preliminary W79E648
DC Characteristics, continued
PARAMETER
SYMBOL
SPECIFICATION
TEST CONDITIONS
MIN.
MAX.
UNIT
Isk1
4
8
mA
VDD =4.5V
Vs = 0.45V
Isk2
10
14
mA
VDD =4.5V
VOL = 0.45V
Isr1
-180
-360
uA
VDD =4.5V
VOL = 2.4V
Isr2
-10
-14
mA
VDD =4.5V
VOL = 2.4V
VOL1
-
0.45
V
VDD = 4.5V
IOL = +6 mA
VOL2
-
0.45
V
VDD = 4.5V
IOL = +10 mA
Output High Voltage
P1, P3, P4, P5, P6, P7
VOH1
2.4
-
V
VDD = 4.5V
IOH = -180 µA
Output High Voltage
P0, P2, ALE, PSEN [*2]
VOH2
2.4
-
V
VDD = 4.5V
IOH = -10mA
Sink current
P1, P3, P4,P5, P6, P7
Sink current
P0,P2, ALE, PSEN
Source current
P1, P3, P4, P5, P6, P7
Source current
P0, P2, ALE, PSEN
Output Low Voltage
P1, P3, P4, P5, P6, P7
Output Low Voltage
P0, P2, ALE, PSEN [*2]
Notes:
*1. RST pin is a Schmitt trigger input.
*2. P0, ALE and PSEN are tested in the external access mode.
*3. XTAL1 is a CMOS input.
*4. Pins of P1, P2, P3 can source a transition current when they are being externally driven from 1 to 0. The transition
current reaches its maximum value when VIN approximates to 2V.
17.3 AC Characteristics
tCLCL
tCLCH
tCLCX
Clock
tCHCL
tCHCX
Note: Duty cycle is 50%.
- 67 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
External Clock Characteristics
PARAMETER
SYMBOL
MIN.
TYP.
MAX.
UNITS
Clock High Time
tCHCX
12
-
-
nS
Clock Low Time
tCLCX
12
-
-
nS
Clock Rise Time
tCLCH
-
-
10
nS
Clock Fall Time
tCHCL
-
-
10
nS
NOTES
17.3.1 AC Specification
SYMBOL
VARIABLE
CLOCK
MIN.
VARIABLE
CLOCK
MAX.
UNITS
1/tCLCL
0
40
MHz
ALE Pulse Width
tLHLL
1.5tCLCL - 5
nS
Address Valid to ALE Low
tAVLL
0.5tCLCL - 5
nS
Address Hold After ALE Low
tLLAX1
0.5tCLCL - 5
nS
Address Hold After ALE Low for
MOVX Write
tLLAX2
0.5tCLCL - 5
nS
ALE Low to Valid Instruction In
tLLIV
ALE Low to PSEN Low
tLLPL
0.5tCLCL - 5
nS
PSEN Pulse Width
tPLPH
2.0tCLCL - 5
nS
PSEN Low to Valid Instruction In
tPLIV
Input Instruction Hold After PSEN
tPXIX
Input Instruction Float After PSEN
tPXIZ
tCLCL - 5
nS
Port 0 Address to Valid Instr. In
tAVIV1
3.0tCLCL - 20
nS
Port 2 Address to Valid Instr. In
tAVIV2
3.5tCLCL - 20
nS
PSEN Low to Address Float
tPLAZ
0
nS
Data Hold After Read
tRHDX
0
nS
Data Float After Read
tRHDZ
tCLCL - 5
nS
RD Low to Address Float
tRLAZ
0.5tCLCL - 5
nS
PARAMETER
Oscillator Frequency
- 68 -
2.5tCLCL - 20
2.0tCLCL - 20
0
nS
nS
nS
Preliminary W79E648
17.3.2 MOVX Characteristics Using Strech Memory Cycle
PARAMETER
Data Access ALE Pulse Width
tLLHL2
Address Hold After ALE Low for
MOVX write
tLLAX2
RD Pulse Width
tRLRH
WR Pulse Width
tWLWH
RD Low to Valid Data In
tRLDV
Data Hold after Read
tRHDX
Data Float after Read
tRHDZ
ALE Low to Valid Data In
tLLDV
Port 0 Address to Valid Data In
tAVDV1
ALE Low to RD or WR Low
tLLWL
Port 0 Address to RD or WR
tAVWL
Low
Port 2 Address to RD or WR
VARIABLE
CLOCK
MIN.
SYMBOL
tAVWL2
Low
Data Valid to WR Transition
tQVWX
Data Hold after Write
tWHQX
RD Low to Address Float
tRLAZ
RD or WR high to ALE high
tWHLH
VARIABLE
CLOCK
MAX.
1.5tCLCL - 5
UNITS
nS
2.0tCLCL - 5
0.5tCLCL - 5
STRECH
tMCS = 0
tMCS>0
nS
2.0tCLCL - 5
nS
tMCS - 10
2.0tCLCL - 5
nS
tMCS - 10
2.0tCLCL - 20
tMCS - 20
0
nS
tMCS = 0
tMCS>0
tMCS = 0
tMCS>0
tMCS = 0
tMCS>0
nS
tCLCL - 5
2.0tCLCL - 5
2.5tCLCL - 5
tMCS + 2tCLCL - 40
3.0tCLCL - 20
2.0tCLCL - 5
0.5tCLCL - 5
0.5tCLCL + 5
1.5tCLCL - 5
1.5tCLCL + 5
tCLCL - 5
nS
nS
nS
nS
nS
2.0tCLCL - 5
1.5tCLCL - 5
nS
2.5tCLCL - 5
-5
nS
1.0tCLCL - 5
tCLCL - 5
nS
2.0tCLCL - 5
0.5tCLCL - 5
0
10
1.0tCLCL - 5
1.0tCLCL + 5
tMCS = 0
tMCS>0
tMCS = 0
tMCS>0
tMCS = 0
tMCS>0
tMCS = 0
tMCS>0
tMCS = 0
tMCS>0
tMCS = 0
tMCS>0
tMCS = 0
tMCS>0
tMCS = 0
tMCS>0
nS
nS
tMCS = 0
tMCS>0
Note: tMCS is a time period related to the Stretch memory cycle selection. The following table shows the time period of tMCS
for each selection of the Stretch value.
- 69 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
M2
M1
M0
MOVX Cycles
tMCS
0
0
0
2 machine cycles
0
0
0
1
3 machine cycles
4 tCLCL
0
1
0
4 machine cycles
8 tCLCL
0
1
1
5 machine cycles
12 tCLCL
1
0
0
6 machine cycles
16 tCLCL
1
0
1
7 machine cycles
20 tCLCL
1
1
0
8 machine cycles
24 tCLCL
1
1
1
9 machine cycles
28 tCLCL
Explanation of Logics Symbols
In order to maintain compatibility with the original 8051 family, this device specifies the same
parameter for each device, using the same symbols. The explanation of the symbols is as follows.
t
C
H
Time
Clock
Logic level high
A
D
L
Address
Input Data
Logic level low
I
Instruction
P
PSEN
Q
Output Data
R
RD signal
V
X
Valid
No longer a valid state
W
Z
WR signal
Tri-state
17.3.3 Program Memory Read Cycle
tLHLL
tLLIV
ALE
tAVLL
tPLPH
tPLIV
PSEN
tLLPL
tPXIZ
tPLAZ
tPXIX
tLLAX1
PORT 0
ADDRESS
A0-A7
INSTRUCTION
IN
ADDRESS
A0-A7
tAVIV1
tAVIV2
PORT 2
ADDRESS A8-A15
- 70 -
ADDRESS A8-A15
Preliminary W79E648
17.3.4 Data Memory Read Cycle
tLLDV
ALE
tWHLH
tLLWL
PSEN
tLLAX1
tRLRH
tRLDV
tAVLL
RD
tAVWL1
PORT 0
INSTRUCTION
IN
tRHDZ
tRLAZ
tRHDX
ADDRESS
A0-A7
DATA
IN
ADDRESS
A0-A7
tAVDV1
tAVDV2
PORT 2
ADDRESS A8-A15
17.3.5 Data Memory Write Cycle
ALE
tWHLH
tLLWL
PSEN
tWLWH
tLLAX2
tAVLL
WR
tAVWL1
tWHQX
tQVWX
PORT 0
INSTRUCTION
IN
ADDRESS
A0-A7
DATA OUT
ADDRESS
A0-A7
t AVDV2
PORT 2
ADDRESS A8-A15
- 71 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
18. TYPICAL APPLICATION CIRCUITS
Expanded External Program Memory and Crystal
VCC
VCC
31
19
10 u
R
EA
XTAL1
18
XTAL2
9
RST
12
13
14
15
INT0
INT1
T0
T1
1
2
3
4
5
6
7
8
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
CRYSTAL
8.2 K
C1
C2
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
39
38
37
36
35
34
33
32
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
21
22
23
24
25
26
27
28
RD
WR
PSEN
ALE
TXD
RXD
17
16
29
30
11
10
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
A8
A9
A10
A11
A12
A13
A14
A15
GND
3
4
7
8
13
14
17
18
1
11
D0
D1
D2
D3
D4
D5
D6
D7
Q0
Q1
Q2
Q3
Q4
Q5
Q6
Q7
2
5
6
9
12
15
16
19
A0 10
A1
9
A2
8
A3
7
A4
6
A5
5
A6
4
A7
3
A8 25
A9 24
A10 21
A11 23
A12 2
A13 26
A14 27
A15 1
A0
A1
A2
A3
A4
A5
A6
A7
OC
G
74F373
GND
20
22
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
CE
OE
27512
Figure A
CRYSTAL
C1
C2
R
16 MHz
20P
20P
-
24 MHz
12P
12P
-
33 MHz
10P
10P
3.3K
40 MHz
1P
1P
3.3K
The above table shows the reference values for crystal applications.
Note: C1, C2, R components refer to Figure A.
- 72 -
O0
O1
O2
O3
O4
O5
O6
O7
11
12
13
15
16
17
18
19
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
Preliminary W79E648
Typical Application Circuits, continued
Expanded External Data Memory and Oscillator
VCC
VCC
31
10 u
EA
19
XTAL1
18
XTAL2
9
RST
12
13
14
15
INT0
OSCILLATOR
8.2 K
1
2
3
4
5
6
7
8
INT1
T0
T1
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
39
38
37
36
35
34
33
32
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
21
22
23
24
25
26
27
28
A8
A9
A10
A11
A12
A13
A14
RD
17
16
29
30
11
10
WR
PSEN
ALE
TXD
RXD
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
GND
3
4
7
8
13
14
17
18
D0
D1
D2
D3
D4
D5
D6
D7
1
11
OC
G
Q0
Q1
Q2
Q3
Q4
Q5
Q6
Q7
74F373
2
5
6
9
12
15
16
19
A0
A1
A2
A3
A4
A5
A6
A7
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
10
9
8
7
6
5
4
3
25
24
21
23
2
26
1
GND 20
22
27
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
D0
D1
D2
D3
D4
D5
D6
D7
11
12
13
15
16
17
18
19
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
CE
OE
WR
20256
Figure B
19. PACKAGE DIMENSIONS
- 73 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
68 pin PLCC
H
D
D
1
9
68
61
10
60
E
E
26
H
44
27
43
c
L
2
A
0
e
b
b
Seating Plane
A
1
A
1
y
G
D
Symbol
A
A1
A2
b1
b
c
D
E
e
GD
GE
HD
HE
L
y
0
Dimension in inch
Min
Dimension in mm
Nom
Max
Min
Nom
0.185
0.020
Max
4.70
0.51
0.143
0.148
0.153
3.63
3.76
3.89
0.026
0.028
0.032
0.66
0.71
0.81
0.016
0.018
0.022
0.41
0.46
0.56
0.006
0.008
0.012
0.15
0.20
0.30
0.949
0.954
0.959
24.10
24.23
24.36
0.949
0.954
0.959
24.10
24.23
24.36
0.044
0.050
0.056
1.12
1.27
1.42
0.895
0.915
0.935
22.73
23.24
23.75
0.895
0.915
0.935
22.73
23.24
23.75
0.980
0.990
1.000
24.90
25.15
25.40
0.980
0.990
1.000
24.90
25.15
25.40
0.090
0.100
0.110
2.29
2.54
2.79
0.10
0.004
10
0
- 74 -
0
10
Preliminary W79E648
20. APPLICATION NOTE
In-system Programming Software Examples
This application note illustrates the in-system programmability of the Winbond W79E648 Flash
EPROM microcontroller. In this example, microcontroller will boot from 64 KB APFlash bank and
waiting for a key to enter in-system programming mode for re-programming the contents of 64 KB
APFlash. While entering in-system programming mode, microcontroller executes the loader program
in 4KB LDFlash bank. The loader program erases the 64 KB APFlash then reads the new code data
from external SRAM buffer (or through other interfaces) to update the 64KB APFlash.
If the customer uses the reboot mode to update his program, please enable this b3 or b4 of security
bits from the writer. Please refer security bits for detail descrption
EXAMPLE 1:
;*******************************************************************************************************************
;* Example of 64K APFlash program: Program will scan the P1.0. if P1.0 = 0, enters in-system
;* programming mode for updating the content of APFlash code else executes the current ROM code.
;* XTAL = 24 MHz
;*******************************************************************************************************************
.chip 8052
.RAMCHK OFF
.symbols
CHPCON
TA
SFRAL
SFRAH
SFRFD
SFRCN
EQU
EQU
EQU
EQU
EQU
EQU
9FH
C7H
ACH
ADH
AEH
AFH
ORG
0H
LJMP 100H
; JUMP TO MAIN PROGRAM
;************************************************************************
;* TIMER0 SERVICE VECTOR ORG = 000BH
;************************************************************************
ORG 00BH
CLR TR0
; TR0 = 0, STOP TIMER0
MOV TL0,R6
MOV TH0,R7
RETI
;************************************************************************
;* 64K APFlash MAIN PROGRAM
;************************************************************************
ORG
100H
MAIN_64K:
MOV A,P1
ANL A,#01H
CJNE A,#01H,PROGRAM_64K
JMP NORMAL_MODE
; SCAN P1.0
; IF P1.0 = 0, ENTER IN-SYSTEM PROGRAMMING MODE
- 75 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
PROGRAM_64:
MOV TA, #AAH
; CHPCON register is written protect by TA register.
MOV TA, #55H
MOV CHPCON, #03H
; CHPCON = 03H, ENTER IN-SYSTEM PROGRAMMING MODE
MOV SFRCN, #0H
MOV TCON, #00H
; TR = 0 TIMER0 STOP
MOV IP, #00H
; IP = 00H
MOV IE, #82H
; TIMER0 INTERRUPT ENABLE FOR WAKE-UP FROM IDLE MODE
MOV R6, #F0H
; TL0 = F0H
MOV R7, #FFH
; TH0 = FFH
MOV TL0, R6
MOV TH0, R7
MOV TMOD, #01H
; TMOD = 01H, SET TIMER0 A 16-BIT TIMER
MOV TCON, #10H
; TCON = 10H, TR0 = 1,GO
MOV PCON, #01H
; ENTER IDLE MODE FOR LAUNCHING THE IN-SYSTEM PROGRAMMING
;************** ******************************************************************
;* Normal mode 64KB APFlash program: depending user's application
;********************************************************************************
NORMAL_MODE:
.
; User's application program
.
.
.
EXAMPLE 2:
;***************************************************************************************************************************** ;*
Example of 4KB LDFlash program: This loader program will erase the 64KB APFlash first, then reads the new ;*
code from external SRAM and program them into 64KB APFlash bank. XTAL = 24 MHz
;*****************************************************************************************************************************
.chip 8052
.RAMCHK OFF
.symbols
CHPCON
TA
SFRAL
SFRAH
SFRFD
SFRCN
EQU
EQU
EQU
EQU
EQU
EQU
ORG 000H
LJMP 100H
9FH
C7H
ACH
ADH
AEH
AFH
; JUMP TO MAIN PROGRAM
;************************************************************************
;* 1. TIMER0 SERVICE VECTOR ORG = 0BH
;************************************************************************
ORG 000BH
CLR TR0
; TR0 = 0, STOP TIMER0
MOV TL0, R6
MOV TH0, R7
- 76 -
Preliminary W79E648
RETI
;************************************************************************
;* 4KB LDFlash MAIN PROGRAM
;************************************************************************
ORG 100H
MAIN_4K:
MOV TA,#AAH
MOV TA,#55H
MOV CHPCON,#03H
; CHPCON = 03H, ENABLE IN-SYSTEM PROGRAMMING.
MOV SFRCN,#0H
MOV TCON,#00H
; TCON = 00H, TR = 0 TIMER0 STOP
MOV TMOD,#01H
; TMOD = 01H, SET TIMER0 A 16BIT TIMER
MOV IP,#00H
; IP = 00H
MOV IE,#82H
; IE = 82H, TIMER0 INTERRUPT ENABLED
MOV R6,#F0H
MOV R7,#FFH
MOV TL0,R6
MOV TH0,R7
MOV TCON,#10H
; TCON = 10H, TR0 = 1, GO
MOV PCON,#01H
; ENTER IDLE MODE
UPDATE_64K:
MOV TCON,#00H
MOV IP,#00H
MOV IE,#82H
MOV TMOD,#01H
MOV R6,#D0H
; TCON = 00H , TR = 0 TIM0 STOP
; IP = 00H
; IE = 82H, TIMER0 INTERRUPT ENABLED
; TMOD = 01H, MODE1
; SET WAKE-UP TIME FOR ERASE OPERATION, ABOUT 15 ms
DEPENDING ON USER'S SYSTEM CLOCK RATE.
MOV R7,#8AH
MOV TL0,R6
MOV TH0,R7
ERASE_P_4K:
MOV SFRCN,#22H
MOV TCON,#10H
MOV PCON,#01H
; SFRCN = 22H, ERASE 64K APFlash0
; SFRCN = A2H, ERASE 64K APFlash1
; TCON = 10H, TR0 = 1,GO
; ENTER IDLE MODE (FOR ERASE OPERATION)
;*********************************************************************
;* BLANK CHECK
;*********************************************************************
MOV SFRCN,#0H
; SFRCN = 00H, READ 64KB APFlash0
; SFRCN = 80H, READ 64KB APFlash1
MOV SFRAH,#0H
; START ADDRESS = 0H
MOV SFRAL,#0H
MOV R6,#FDH
; SET TIMER FOR READ OPERATION, ABOUT 1.5 µS.
MOV R7,#FFH
MOV TL0,R6
MOV TH0,R7
BLANK_CHECK_LOOP:
SETB TR0
MOV PCON,#01H
MOV A,SFRFD
; ENABLE TIMER 0
; ENTER IDLE MODE
; READ ONE BYTE
- 77 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
CJNE A,#FFH,BLANK_CHECK_ERROR
INC SFRAL
; NEXT ADDRESS
MOV A,SFRAL
JNZ BLANK_CHECK_LOOP
INC SFRAH
MOV A,SFRAH
CJNE A,#0H,BLANK_CHECK_LOOP ; END ADDRESS = FFFFH
JMP PROGRAM_64KROM
BLANK_CHECK_ERROR:
JMP $
;*******************************************************************************
;* RE-PROGRAMMING 64KB APFlash BANK
;*******************************************************************************
PROGRAM_64KROM:
MOV R2,#00H
; TARGET LOW BYTE ADDRESS
MOV R1,#00H
; TARGET HIGH BYTE ADDRESS
MOV DPTR,#0H
MOV SFRAH,R1
; SFRAH, TARGET HIGH ADDRESS
MOV SFRCN,#21H
; SFRCN = 21H, PROGRAM 64K APFLASH0
; SFRCN = A1H, PROGRAM 64K APFLASH1
MOV R6,#9CH
; SET TIMER FOR PROGRAMMING, ABOUT 50 µS.
MOV R7,#FFH
MOV TL0,R6
MOV TH0,R7
PROG_D_64K:
MOV SFRAL,R2
; SFRAL = LOW BYTE ADDRESS
CALL GET_BYTE_FROM_PC_TO_ACC
; THIS PROGRAM IS BASED ON USER’S CIRCUIT.
MOV @DPTR,A
; SAVE DATA INTO SRAM TO VERIFY CODE.
MOV SFRFD,A
; SFRFD = DATA IN
MOV TCON,#10H
; TCON = 10H, TR0 = 1,GO
MOV PCON,#01H
; ENTER IDLE MODE (PRORGAMMING)
INC DPTR
INC R2
CJNE R2,#0H,PROG_D_64K
INC R1
MOV SFRAH,R1
CJNE R1,#0H,PROG_D_64K
;*****************************************************************************
; * VERIFY 64KB APFLASH BANK
;*****************************************************************************
MOV R4,#03H
; ERROR COUNTER
MOV R6,#FDH
; SET TIMER FOR READ VERIFY, ABOUT 1.5 µS.
MOV R7,#FFH
MOV TL0,R6
MOV TH0,R7
MOV DPTR,#0H
; The start address of sample code
MOV R2,#0H
; Target low byte address
MOV R1,#0H
; Target high byte address
MOV SFRAH,R1
; SFRAH, Target high address
MOV SFRCN,#00H
; SFRCN = 00H, Read APFlash0
- 78 -
Preliminary W79E648
; SFRCN = 80H , Read APFlash1
READ_VERIFY_64K:
MOV SFRAL,R2
; SFRAL = LOW ADDRESS
MOV TCON,#10H
; TCON = 10H, TR0 = 1,GO
MOV PCON,#01H
INC R2
MOVX A,@DPTR
INC DPTR
CJNE A,SFRFD,ERROR_64K
CJNE R2,#0H,READ_VERIFY_64K
INC R1
MOV SFRAH,R1
CJNE R1,#0H,READ_VERIFY_64K
;******************************************************************************
;* PROGRAMMING COMPLETLY, SOFTWARE RESET CPU
;******************************************************************************
MOV TA,#AAH
MOV TA,#55H
MOV CHPCON,#83H
; SOFTWARE RESET. CPU will restart from APFlash0
ERROR_64K:
DJNZ R4,UPDATE_64K ; IF ERROR OCCURS, REPEAT 3 TIMES.
.
; IN-SYST PROGRAMMING FAIL, USER'S PROCESS TO DEAL WITH IT.
.
.
.
- 79 -
Publication Release Date: 05/31/2004
Revision A1
Preliminary W79E648
21. REVISION HISTORY
VERSION
DATE
PAGE
A1
July 8, 2003
-
DESCRIPTION
Initial Issued
Headquarters
Winbond Electronics Corporation America
Winbond Electronics (Shanghai) Ltd.
No. 4, Creation Rd. III,
Science-Based Industrial Park,
Hsinchu, Taiwan
TEL: 886-3-5770066
FAX: 886-3-5665577
http://www.winbond.com.tw/
2727 North First Street, San Jose,
CA 95134, U.S.A.
TEL: 1-408-9436666
FAX: 1-408-5441798
27F, 2299 Yan An W. Rd. Shanghai,
200336 China
TEL: 86-21-62365999
FAX: 86-21-62365998
Taipei Office
Winbond Electronics Corporation Japan
Winbond Electronics (H.K.) Ltd.
9F, No.480, Rueiguang Rd.,
Neihu District, Taipei, 114,
Taiwan, R.O.C.
TEL: 886-2-8177-7168
FAX: 886-2-8751-3579
7F Daini-ueno BLDG, 3-7-18
Shinyokohama Kohoku-ku,
Yokohama, 222-0033
TEL: 81-45-4781881
FAX: 81-45-4781800
Unit 9-15, 22F, Millennium City,
No. 378 Kwun Tong Rd.,
Kowloon, Hong Kong
TEL: 852-27513100
FAX: 852-27552064
Please note that all data and specifications are subject to change without notice.
All the trade marks of products and companies mentioned in this data sheet belong to their respective owners.
- 80 -