SILABS C8051F344 On-chip debug circuity facilitates full speed non-intru-sive in-system debug (no emulatr required) Datasheet

C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Full Speed USB Flash MCU Family
Analog Peripherals
- 10-Bit ADC (C8051F340/1/2/3/4/5/6/7/A/B only)
•
•
-
Instructions in 1 or 2 system clocks
- 48 MIPS and 25 MIPS versions available.
- Expanded interrupt handler
Memory
- 4352 or 2304 Bytes RAM
- 64 or 32 kB Flash; In-system programmable in 512-byte
Two comparators
Internal voltage reference
(C8051F340/1/2/3/4/5/6/7/A/B only)
Brown-out detector and POR Circuitry
sectors
USB Function Controller
- USB specification 2.0 compliant
- Full speed (12 Mbps) or low speed (1.5 Mbps) operation
- Integrated clock recovery; no external crystal required for
full speed or low speed
- Supports eight flexible endpoints
- 1 kB USB buffer memory
- Integrated transceiver; no external resistors required
On-Chip Debug
- On-chip debug circuitry facilitates full speed, non-intru-
sive in-system debug (No emulator required)
Provides breakpoints, single stepping, 
inspect/modify memory and registers
Superior performance to emulation systems using
ICE-chips, target pods, and sockets
Voltage Regulator
ANALOG
PERIPHERALS
10-bit
200 ksps
ADC
TEMP
SENSOR
-
+
-
+
-
VREG
VREF
enhanced UART serial ports
Four general purpose 16-bit counter/timers
16-bit programmable counter array (PCA) with five capture/compare modules
External Memory Interface (EMIF)
Clock Sources
- Internal Oscillator: ±0.25% accuracy with clock recovery
-
Voltage Supply Input: 2.7 to 5.25 V
- Voltages from 3.6 to 5.25 V supported using On-Chip 
A
M
U
X
Digital Peripherals
- 40/25 Port I/O; All 5 V tolerant with high sink current
- Hardware enhanced SPI™, SMBus™, and one or two
enabled. Supports all USB and UART modes
External Oscillator: Crystal, RC, C, or clock (1 or 2 Pin
modes)
Low Frequency (80 kHz) Internal Oscillator
Can switch between clock sources on-the-fly
Packages
- 48-pin TQFP (C8051F340/1/4/5/8/C)
- 32-pin LQFP (C8051F342/3/6/7/9/A/B/D)
- 5x5 mm 32-pin QFN (C8051F342/3/6/7/9/A/B)
Temperature Range: –40 to +85 °C
DIGITAL I/O
UART0
UART1*
SPI
SMBus
PCA
Port 0
4 Timers
48 Pin Only
C8051F340/1/2/34/5/6/7/A/B Only
Ext. Memory I/F
•
Up to 200 ksps
Built-in analog multiplexer with single-ended and 
differential mode
VREF from external pin, internal reference, or VDD
Built-in temperature sensor
External conversion start input option
CROSSBAR
•
•
HIgh Speed 8051 µC Core
- Pipelined instruction architecture; executes 70% of
Port 1
Port 2
Port 3
Port 4
* C8051F340/1/4/5/8/A/B/C Only
PRECISION INTERNAL
OSCILLATORS
USB Controller /
Transceiver
HIGH-SPEED CONTROLLER CORE
64/32 kB
ISP FLASH
FLEXIBLE
INTERRUPTS
Rev. 1.4 9/09
8051 CPU
(48/25 MIPS)
DEBUG
CIRCUITRY
4/2 kB RAM
POR
Copyright © 2009 by Silicon Laboratories
WDT
C8051F34x
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
2
Rev. 1.4
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table of Contents
1.
2.
3.
4.
5.
System Overview.................................................................................................... 17
Absolute Maximum Ratings .................................................................................. 24
Global DC Electrical Characteristics .................................................................... 25
Pinout and Package Definitions............................................................................ 28
10-Bit ADC (ADC0, C8051F340/1/2/3/4/5/6/7/A/B Only)........................................ 41
5.1. Analog Multiplexer ............................................................................................ 42
5.2. Temperature Sensor ......................................................................................... 43
5.3. Modes of Operation .......................................................................................... 45
5.3.1. Starting a Conversion............................................................................... 45
5.3.2. Tracking Modes........................................................................................ 46
5.3.3. Settling Time Requirements ..................................................................... 47
5.4. Programmable Window Detector ...................................................................... 52
5.4.1. Window Detector In Single-Ended Mode ................................................. 54
5.4.2. Window Detector In Differential Mode...................................................... 55
6. Voltage Reference (C8051F340/1/2/3/4/5/6/7/A/B Only)....................................... 57
7. Comparators ........................................................................................................... 59
8. Voltage Regulator (REG0)...................................................................................... 69
8.1. Regulator Mode Selection................................................................................. 69
8.2. VBUS Detection ................................................................................................ 69
9. CIP-51 Microcontroller ........................................................................................... 73
9.1. Instruction Set ................................................................................................... 74
9.1.1. Instruction and CPU Timing ..................................................................... 74
9.1.2. MOVX Instruction and Program Memory ................................................. 75
9.2. Memory Organization........................................................................................ 79
9.2.1. Program Memory...................................................................................... 80
9.2.2. Data Memory............................................................................................ 81
9.2.3. General Purpose Registers ...................................................................... 81
9.2.4. Bit Addressable Locations........................................................................ 81
9.2.5. Stack ....................................................................................................... 81
9.2.6. Special Function Registers....................................................................... 82
9.2.7. Register Descriptions ............................................................................... 86
9.3. Interrupt Handler ............................................................................................... 88
9.3.1. MCU Interrupt Sources and Vectors ........................................................ 88
9.3.2. External Interrupts .................................................................................... 88
9.3.3. Interrupt Priorities ..................................................................................... 89
9.3.4. Interrupt Latency ...................................................................................... 89
9.3.5. Interrupt Register Descriptions................................................................. 90
9.4. Power Management Modes .............................................................................. 97
9.4.1. Idle Mode.................................................................................................. 97
9.4.2. Stop Mode ................................................................................................ 97
10. Prefetch Engine ...................................................................................................... 99
11. Reset Sources....................................................................................................... 100
11.1.Power-On Reset ............................................................................................. 101
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11.2.Power-Fail Reset / VDD Monitor .................................................................... 102
11.3.External Reset ................................................................................................ 103
11.4.Missing Clock Detector Reset ........................................................................ 103
11.5.Comparator0 Reset ........................................................................................ 103
11.6.PCA Watchdog Timer Reset .......................................................................... 103
11.7.Flash Error Reset ........................................................................................... 103
11.8.Software Reset ............................................................................................... 104
11.9.USB Reset...................................................................................................... 104
12. Flash Memory ....................................................................................................... 107
12.1.Programming The Flash Memory ................................................................... 107
12.1.1.Flash Lock and Key Functions ............................................................... 107
12.1.2.Flash Erase Procedure .......................................................................... 107
12.1.3.Flash Write Procedure ........................................................................... 108
12.2.Non-Volatile Data Storage.............................................................................. 109
12.3.Security Options ............................................................................................. 109
13. External Data Memory Interface and On-Chip XRAM........................................ 114
13.1.Accessing XRAM............................................................................................ 114
13.1.1.16-Bit MOVX Example ........................................................................... 114
13.1.2.8-Bit MOVX Example ............................................................................. 114
13.2.Accessing USB FIFO Space .......................................................................... 115
13.3.Configuring the External Memory Interface .................................................... 116
13.4.Port Configuration........................................................................................... 116
13.5.Multiplexed and Non-multiplexed Selection.................................................... 119
13.5.1.Multiplexed Configuration....................................................................... 119
13.5.2.Non-multiplexed Configuration............................................................... 120
13.6.Memory Mode Selection................................................................................. 120
13.6.1.Internal XRAM Only ............................................................................... 121
13.6.2.Split Mode without Bank Select.............................................................. 121
13.6.3.Split Mode with Bank Select................................................................... 122
13.6.4.External Only.......................................................................................... 122
13.7.Timing .......................................................................................................... 122
13.7.1.Non-multiplexed Mode ........................................................................... 124
13.7.2.Multiplexed Mode ................................................................................... 127
14. Oscillators ............................................................................................................. 131
14.1.Programmable Internal High-Frequency (H-F) Oscillator ............................... 132
14.1.1.Internal H-F Oscillator Suspend Mode ................................................... 132
14.2.Programmable Internal Low-Frequency (L-F) Oscillator ................................ 133
14.2.1.Calibrating the Internal L-F Oscillator..................................................... 133
14.3.External Oscillator Drive Circuit...................................................................... 135
14.3.1.Clocking Timers Directly Through the External Oscillator...................... 135
14.3.2.External Crystal Example....................................................................... 135
14.3.3.External RC Example............................................................................. 136
14.3.4.External Capacitor Example................................................................... 136
14.4.4x Clock Multiplier .......................................................................................... 138
14.5.System and USB Clock Selection .................................................................. 139
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14.5.1.System Clock Selection ......................................................................... 139
14.5.2.USB Clock Selection .............................................................................. 139
15. Port Input/Output.................................................................................................. 142
15.1.Priority Crossbar Decoder .............................................................................. 144
15.2.Port I/O Initialization ....................................................................................... 147
15.3.General Purpose Port I/O ............................................................................... 150
16. Universal Serial Bus Controller (USB0).............................................................. 159
16.1.Endpoint Addressing ...................................................................................... 160
16.2.USB Transceiver ............................................................................................ 160
16.3.USB Register Access ..................................................................................... 162
16.4.USB Clock Configuration................................................................................ 166
16.5.FIFO Management ......................................................................................... 167
16.5.1.FIFO Split Mode ..................................................................................... 167
16.5.2.FIFO Double Buffering ........................................................................... 168
16.5.3.FIFO Access .......................................................................................... 168
16.6.Function Addressing....................................................................................... 169
16.7.Function Configuration and Control................................................................ 169
16.8.Interrupts ........................................................................................................ 172
16.9.The Serial Interface Engine ............................................................................ 176
16.10.Endpoint0 ..................................................................................................... 176
16.10.1.Endpoint0 SETUP Transactions .......................................................... 177
16.10.2.Endpoint0 IN Transactions................................................................... 177
16.10.3.Endpoint0 OUT Transactions............................................................... 178
16.11.Configuring Endpoints1-3 ............................................................................. 180
16.12.Controlling Endpoints1-3 IN.......................................................................... 180
16.12.1.Endpoints1-3 IN Interrupt or Bulk Mode............................................... 180
16.12.2.Endpoints1-3 IN Isochronous Mode..................................................... 181
16.13.Controlling Endpoints1-3 OUT...................................................................... 183
16.13.1.Endpoints1-3 OUT Interrupt or Bulk Mode........................................... 183
16.13.2.Endpoints1-3 OUT Isochronous Mode................................................. 184
17. SMBus ................................................................................................................... 188
17.1.Supporting Documents ................................................................................... 189
17.2.SMBus Configuration...................................................................................... 189
17.3.SMBus Operation ........................................................................................... 189
17.3.1.Arbitration............................................................................................... 190
17.3.2.Clock Low Extension.............................................................................. 191
17.3.3.SCL Low Timeout................................................................................... 191
17.3.4.SCL High (SMBus Free) Timeout .......................................................... 191
17.4.Using the SMBus............................................................................................ 191
17.4.1.SMBus Configuration Register............................................................... 192
17.4.2.SMB0CN Control Register ..................................................................... 195
17.4.3.Data Register ......................................................................................... 198
17.5.SMBus Transfer Modes.................................................................................. 198
17.5.1.Master Transmitter Mode ....................................................................... 198
17.5.2.Master Receiver Mode ........................................................................... 200
Rev. 1.3
5
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
17.5.3.Slave Receiver Mode ............................................................................. 201
17.5.4.Slave Transmitter Mode ......................................................................... 202
17.6.SMBus Status Decoding................................................................................. 202
18. UART0.................................................................................................................... 205
18.1.Enhanced Baud Rate Generation................................................................... 206
18.2.Operational Modes ......................................................................................... 206
18.2.1.8-Bit UART ............................................................................................. 207
18.2.2.9-Bit UART ............................................................................................. 208
18.3.Multiprocessor Communications .................................................................... 208
19. UART1 (C8051F340/1/4/5/8/A/B/C Only).............................................................. 213
19.1.Baud Rate Generator ..................................................................................... 214
19.2.Data Format.................................................................................................... 215
19.3.Configuration and Operation .......................................................................... 216
19.3.1.Data Transmission ................................................................................. 216
19.3.2.Data Reception ...................................................................................... 216
19.3.3.Multiprocessor Communications ............................................................ 217
20. Enhanced Serial Peripheral Interface (SPI0)...................................................... 222
20.1.Signal Descriptions......................................................................................... 223
20.1.1.Master Out, Slave In (MOSI).................................................................. 223
20.1.2.Master In, Slave Out (MISO).................................................................. 223
20.1.3.Serial Clock (SCK) ................................................................................. 223
20.1.4.Slave Select (NSS) ................................................................................ 223
20.2.SPI0 Master Mode Operation ......................................................................... 224
20.3.SPI0 Slave Mode Operation ........................................................................... 226
20.4.SPI0 Interrupt Sources ................................................................................... 226
20.5.Serial Clock Timing......................................................................................... 227
20.6.SPI Special Function Registers ...................................................................... 229
21. Timers.................................................................................................................... 235
21.1.Timer 0 and Timer 1 ....................................................................................... 235
21.1.1.Mode 0: 13-bit Counter/Timer ................................................................ 235
21.1.2.Mode 1: 16-bit Counter/Timer ................................................................ 236
21.1.3.Mode 2: 8-bit Counter/Timer with Auto-Reload...................................... 237
21.1.4.Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................. 238
21.2.Timer 2 .......................................................................................................... 243
21.2.1.16-bit Timer with Auto-Reload................................................................ 243
21.2.2.8-bit Timers with Auto-Reload................................................................ 244
21.2.3.Timer 2 Capture Modes: USB Start-of-Frame or LFO Falling Edge ...... 245
21.3.Timer 3 .......................................................................................................... 249
21.3.1.16-bit Timer with Auto-Reload................................................................ 249
21.3.2.8-bit Timers with Auto-Reload................................................................ 250
21.3.3.USB Start-of-Frame Capture.................................................................. 251
22. Programmable Counter Array (PCA0) ................................................................ 255
22.1.PCA Counter/Timer ........................................................................................ 256
22.2.Capture/Compare Modules ............................................................................ 257
22.2.1.Edge-triggered Capture Mode................................................................ 258
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22.2.2.Software Timer (Compare) Mode........................................................... 259
22.2.3.High Speed Output Mode....................................................................... 260
22.2.4.Frequency Output Mode ........................................................................ 261
22.2.5.8-Bit Pulse Width Modulator Mode......................................................... 262
22.2.6.16-Bit Pulse Width Modulator Mode....................................................... 263
22.3.Watchdog Timer Mode ................................................................................... 264
22.3.1.Watchdog Timer Operation .................................................................... 264
22.3.2.Watchdog Timer Usage ......................................................................... 265
22.4.Register Descriptions for PCA........................................................................ 266
23. C2 Interface ........................................................................................................... 271
23.1.C2 Interface Registers.................................................................................... 271
23.2.C2 Pin Sharing ............................................................................................... 273
Document Change List............................................................................................. 274
Contact Information.................................................................................................. 276
Rev. 1.3
7
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
List of Figures
1. System Overview
Figure 1.1. C8051F340/1/4/5 Block Diagram ........................................................... 19
Figure 1.2. C8051F342/3/6/7 Block Diagram ........................................................... 20
Figure 1.3. C8051F348/C Block Diagram................................................................. 21
Figure 1.4. C8051F349/D Block Diagram................................................................. 22
Figure 1.5. C8051F34A/B Block Diagram ................................................................ 23
4. Pinout and Package Definitions
Figure 4.1. TQFP-48 Pinout Diagram (Top View) .................................................... 31
Figure 4.2. TQFP-48 Package Diagram ................................................................... 32
Figure 4.3. TQFP-48 Recommended PCB Land Pattern ......................................... 33
Figure 4.4. LQFP-32 Pinout Diagram (Top View)..................................................... 34
Figure 4.5. LQFP-32 Package Diagram ................................................................... 35
Figure 4.6. LQFP-32 Recommended PCB Land Pattern ......................................... 36
Figure 4.7. QFN-32 Pinout Diagram (Top View) ...................................................... 37
5. 10-Bit ADC (ADC0, C8051F340/1/2/3/4/5/6/7/A/B Only)
Figure 5.1. ADC0 Functional Block Diagram............................................................ 41
Figure 5.2. Temperature Sensor Transfer Function ................................................. 43
Figure 5.3. Temperature Sensor Error with 1-Point Calibration (VREF = 2.40 V) .... 44
Figure 5.4. 10-Bit ADC Track and Conversion Example Timing .............................. 46
Figure 5.5. ADC0 Equivalent Input Circuits .............................................................. 47
Figure 5.6. ADC Window Compare Example: Right-Justified Single-Ended Data ... 54
Figure 5.7. ADC Window Compare Example: Left-Justified Single-Ended Data...... 54
Figure 5.8. ADC Window Compare Example: Right-Justified Differential Data........ 55
Figure 5.9. ADC Window Compare Example: Left-Justified Differential Data .......... 55
6. Voltage Reference (C8051F340/1/2/3/4/5/6/7/A/B Only)
Figure 6.1. Voltage Reference Functional Block Diagram........................................ 57
7. Comparators
Figure 7.1. Comparator Functional Block Diagram .................................................. 60
Figure 7.2. Comparator Hysteresis Plot ................................................................... 61
8. Voltage Regulator (REG0)
Figure 8.1. REG0 Configuration: USB Bus-Powered ............................................... 70
Figure 8.2. REG0 Configuration: USB Self-Powered ............................................... 70
Figure 8.3. REG0 Configuration: USB Self-Powered, Regulator Disabled............... 71
Figure 8.4. REG0 Configuration: No USB Connection ............................................. 71
9. CIP-51 Microcontroller
Figure 9.1. CIP-51 Block Diagram............................................................................ 73
Figure 9.2. On-Chip Memory Map for 64 kB Devices............................................... 79
Figure 9.3. On-Chip Memory Map for 32 kB Devices............................................... 80
11. Reset Sources
Figure 11.1. Reset Sources.................................................................................... 100
Figure 11.2. Power-On and VDD Monitor Reset Timing ........................................ 101
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C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
12. Flash Memory
Figure 12.1. Flash Program Memory Map and Security Byte................................. 110
13. External Data Memory Interface and On-Chip XRAM
Figure 13.1. USB FIFO Space and XRAM Memory Map 
with USBFAE set to ‘1’ ...................................................................................... 115
Figure 13.2. Multiplexed Configuration Example.................................................... 119
Figure 13.3. Non-multiplexed Configuration Example ............................................ 120
Figure 13.4. EMIF Operating Modes ...................................................................... 120
Figure 13.5. Non-multiplexed 16-bit MOVX Timing ................................................ 124
Figure 13.6. Non-multiplexed 8-bit MOVX without Bank Select Timing ................. 125
Figure 13.7. Non-multiplexed 8-bit MOVX with Bank Select Timing ...................... 126
Figure 13.8. Multiplexed 16-bit MOVX Timing........................................................ 127
Figure 13.9. Multiplexed 8-bit MOVX without Bank Select Timing ......................... 128
Figure 13.10. Multiplexed 8-bit MOVX with Bank Select Timing ............................ 129
14. Oscillators
Figure 14.1. Oscillator Diagram.............................................................................. 131
15. Port Input/Output
Figure 15.1. Port I/O Functional Block Diagram (Port 0 through Port 3) ................ 142
Figure 15.2. Port I/O Cell Block Diagram ............................................................... 143
Figure 15.3. Peripheral Availability on Port I/O Pins............................................... 144
Figure 15.4. Crossbar Priority Decoder in Example Configuration
(No Pins Skipped) ............................................................................................. 145
Figure 15.5. Crossbar Priority Decoder in 
Example Configuration (3 Pins Skipped) .......................................................... 146
16. Universal Serial Bus Controller (USB0)
Figure 16.1. USB0 Block Diagram.......................................................................... 159
Figure 16.2. USB0 Register Access Scheme......................................................... 162
Figure 16.3. USB FIFO Allocation .......................................................................... 167
17. SMBus
Figure 17.1. SMBus Block Diagram ....................................................................... 188
Figure 17.2. Typical SMBus Configuration ............................................................. 189
Figure 17.3. SMBus Transaction ............................................................................ 190
Figure 17.4. Typical SMBus SCL Generation......................................................... 193
Figure 17.5. Typical Master Transmitter Sequence................................................ 199
Figure 17.6. Typical Master Receiver Sequence.................................................... 200
Figure 17.7. Typical Slave Receiver Sequence...................................................... 201
Figure 17.8. Typical Slave Transmitter Sequence.................................................. 202
18. UART0
Figure 18.1. UART0 Block Diagram ....................................................................... 205
Figure 18.2. UART0 Baud Rate Logic .................................................................... 206
Figure 18.3. UART Interconnect Diagram .............................................................. 207
Figure 18.4. 8-Bit UART Timing Diagram............................................................... 207
Figure 18.5. 9-Bit UART Timing Diagram............................................................... 208
Figure 18.6. UART Multi-Processor Mode Interconnect Diagram .......................... 209
19. UART1 (C8051F340/1/4/5/8/A/B/C Only)
Rev. 1.3
9
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Figure 19.1. UART1 Block Diagram ....................................................................... 213
Figure 19.2. UART1 Timing Without Parity or Extra Bit.......................................... 215
Figure 19.3. UART1 Timing With Parity ................................................................. 215
Figure 19.4. UART1 Timing With Extra Bit ............................................................. 215
Figure 19.5. Typical UART Interconnect Diagram.................................................. 216
Figure 19.6. UART Multi-Processor Mode Interconnect Diagram .......................... 218
20. Enhanced Serial Peripheral Interface (SPI0)
Figure 20.1. SPI Block Diagram ............................................................................. 222
Figure 20.2. Multiple-Master Mode Connection Diagram ....................................... 225
Figure 20.3. 3-Wire Single Master and Slave Mode Connection Diagram ............. 225
Figure 20.4. 4-Wire Single Master Mode and Slave Mode Connection Diagram ... 225
Figure 20.5. Master Mode Data/Clock Timing ........................................................ 227
Figure 20.6. Slave Mode Data/Clock Timing (CKPHA = 0) .................................... 228
Figure 20.7. Slave Mode Data/Clock Timing (CKPHA = 1) .................................... 228
Figure 20.8. SPI Master Timing (CKPHA = 0)........................................................ 232
Figure 20.9. SPI Master Timing (CKPHA = 1)........................................................ 232
Figure 20.10. SPI Slave Timing (CKPHA = 0)........................................................ 233
Figure 20.11. SPI Slave Timing (CKPHA = 1)........................................................ 233
21. Timers
Figure 21.1. T0 Mode 0 Block Diagram.................................................................. 236
Figure 21.2. T0 Mode 2 Block Diagram.................................................................. 237
Figure 21.3. T0 Mode 3 Block Diagram.................................................................. 238
Figure 21.4. Timer 2 16-Bit Mode Block Diagram .................................................. 243
Figure 21.5. Timer 2 8-Bit Mode Block Diagram .................................................... 244
Figure 21.6. Timer 2 Capture Mode (T2SPLIT = ‘0’) .............................................. 245
Figure 21.7. Timer 2 Capture Mode (T2SPLIT = ‘1’) .............................................. 246
Figure 21.8. Timer 3 16-Bit Mode Block Diagram .................................................. 249
Figure 21.9. Timer 3 8-Bit Mode Block Diagram .................................................... 250
Figure 21.10. Timer 3 Capture Mode (T3SPLIT = ‘0’) ............................................ 251
Figure 21.11. Timer 3 Capture Mode (T3SPLIT = ‘1’) ............................................ 252
22. Programmable Counter Array (PCA0)
Figure 22.1. PCA Block Diagram............................................................................ 255
Figure 22.2. PCA Counter/Timer Block Diagram.................................................... 256
Figure 22.3. PCA Interrupt Block Diagram ............................................................. 257
Figure 22.4. PCA Capture Mode Diagram.............................................................. 258
Figure 22.5. PCA Software Timer Mode Diagram .................................................. 259
Figure 22.6. PCA High Speed Output Mode Diagram............................................ 260
Figure 22.7. PCA Frequency Output Mode ............................................................ 261
Figure 22.8. PCA 8-Bit PWM Mode Diagram ......................................................... 262
Figure 22.9. PCA 16-Bit PWM Mode...................................................................... 263
Figure 22.10. PCA Module 4 with Watchdog Timer Enabled ................................. 264
23. C2 Interface
Figure 23.1. Typical C2 Pin Sharing....................................................................... 273
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Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
List of Tables
1. System Overview
Table 1.1. Product Selection Guide ......................................................................... 18
2. Absolute Maximum Ratings
Table 2.1. Absolute Maximum Ratings* .................................................................. 24
3. Global DC Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics ....................................................... 25
Table 3.2. Index to Electrical Characteristics Tables ............................................... 27
4. Pinout and Package Definitions
Table 4.1. Pin Definitions for the C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D ................. 28
Table 4.2. TQFP-48 Package Dimensions .............................................................. 32
Table 4.3. TQFP-48 PCB Land Pattern Dimensions ............................................... 33
Table 4.4. LQFP-32 Package Dimensions .............................................................. 35
Table 4.5. LQFP-32 PCB Land Pattern Dimensions ............................................... 36
5. 10-Bit ADC (ADC0, C8051F340/1/2/3/4/5/6/7/A/B Only)
Table 5.1. ADC0 Electrical Characteristics .............................................................. 56
6. Voltage Reference (C8051F340/1/2/3/4/5/6/7/A/B Only)
Table 6.1. Voltage Reference Electrical Characteristics ......................................... 58
7. Comparators
Table 7.1. Comparator Electrical Characteristics .................................................... 68
8. Voltage Regulator (REG0)
Table 8.1. Voltage Regulator Electrical Specifications ............................................ 69
9. CIP-51 Microcontroller
Table 9.1. CIP-51 Instruction Set Summary ............................................................ 75
Table 9.2. Special Function Register (SFR) Memory Map ...................................... 82
Table 9.3. Special Function Registers ..................................................................... 83
Table 9.4. Interrupt Summary .................................................................................. 90
11. Reset Sources
Table 11.1. Reset Electrical Characteristics .......................................................... 106
12. Flash Memory
Table 12.1. Flash Electrical Characteristics .......................................................... 109
13. External Data Memory Interface and On-Chip XRAM
Table 13.1. AC Parameters for External Memory Interface ................................... 130
14. Oscillators
Table 14.1. Oscillator Electrical Characteristics .................................................... 141
15. Port Input/Output
Table 15.1. Port I/O DC Electrical Characteristics ................................................. 158
16. Universal Serial Bus Controller (USB0)
Table 16.1. Endpoint Addressing Scheme ............................................................ 160
Table 16.2. USB0 Controller Registers ................................................................. 165
Table 16.3. FIFO Configurations ........................................................................... 168
Table 16.4. USB Transceiver Electrical Characteristics ........................................ 187
17. SMBus
Table 17.1. SMBus Clock Source Selection .......................................................... 192
Rev. 1.3
11
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 17.2. Minimum SDA Setup and Hold Times ................................................ 193
Table 17.3. Sources for Hardware Changes to SMB0CN ..................................... 197
Table 17.4. SMBus Status Decoding ..................................................................... 203
18. UART0
Table 18.1. Timer Settings for Standard Baud Rates 
Using the Internal Oscillator ............................................................... 212
19. UART1 (C8051F340/1/4/5/8/A/B/C Only)
Table 19.1. Baud Rate Generator Settings for Standard Baud Rates ................... 214
20. Enhanced Serial Peripheral Interface (SPI0)
Table 20.1. SPI Slave Timing Parameters ............................................................ 234
22. Programmable Counter Array (PCA0)
Table 22.1. PCA Timebase Input Options ............................................................. 256
Table 22.2. PCA0CPM Register Settings for PCA Capture/Compare Modules .... 257
Table 22.3. Watchdog Timer Timeout Intervals1 ................................................... 265
12
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
List of Registers
SFR Definition 5.1. AMX0P: AMUX0 Positive Channel Select . . . . . . . . . . . . . . . . . . . 48
SFR Definition 5.2. AMX0N: AMUX0 Negative Channel Select . . . . . . . . . . . . . . . . . . 49
SFR Definition 5.3. ADC0CF: ADC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
SFR Definition 5.4. ADC0H: ADC0 Data Word MSB . . . . . . . . . . . . . . . . . . . . . . . . . . 50
SFR Definition 5.5. ADC0L: ADC0 Data Word LSB . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
SFR Definition 5.6. ADC0CN: ADC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte . . . . . . . . . . . . . 52
SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte . . . . . . . . . . . . . . 52
SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte . . . . . . . . . . . . . . . . 53
SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte . . . . . . . . . . . . . . . 53
SFR Definition 6.1. REF0CN: Reference Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
SFR Definition 7.1. CPT0CN: Comparator0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
SFR Definition 7.2. CPT0MX: Comparator0 MUX Selection . . . . . . . . . . . . . . . . . . . . 63
SFR Definition 7.3. CPT0MD: Comparator0 Mode Selection . . . . . . . . . . . . . . . . . . . . 64
SFR Definition 7.4. CPT1CN: Comparator1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
SFR Definition 7.5. CPT1MX: Comparator1 MUX Selection . . . . . . . . . . . . . . . . . . . . 66
SFR Definition 7.6. CPT1MD: Comparator1 Mode Selection . . . . . . . . . . . . . . . . . . . . 67
SFR Definition 8.1. REG0CN: Voltage Regulator Control . . . . . . . . . . . . . . . . . . . . . . 72
SFR Definition 9.1. DPL: Data Pointer Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
SFR Definition 9.2. DPH: Data Pointer High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
SFR Definition 9.3. SP: Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
SFR Definition 9.4. PSW: Program Status Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
SFR Definition 9.5. ACC: Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
SFR Definition 9.6. B: B Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
SFR Definition 9.7. IE: Interrupt Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
SFR Definition 9.8. IP: Interrupt Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
SFR Definition 9.9. EIE1: Extended Interrupt Enable 1 . . . . . . . . . . . . . . . . . . . . . . . . 93
SFR Definition 9.10. EIP1: Extended Interrupt Priority 1 . . . . . . . . . . . . . . . . . . . . . . . 94
SFR Definition 9.11. EIE2: Extended Interrupt Enable 2 . . . . . . . . . . . . . . . . . . . . . . . 95
SFR Definition 9.12. EIP2: Extended Interrupt Priority 2 . . . . . . . . . . . . . . . . . . . . . . . 95
SFR Definition 9.13. IT01CF: INT0/INT1 Configuration . . . . . . . . . . . . . . . . . . . . . . . . 96
SFR Definition 9.14. PCON: Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
SFR Definition 10.1. PFE0CN: Prefetch Engine Control . . . . . . . . . . . . . . . . . . . . . . . 99
SFR Definition 11.1. VDM0CN: VDD Monitor Control . . . . . . . . . . . . . . . . . . . . . . . . . 102
SFR Definition 11.2. RSTSRC: Reset Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
SFR Definition 12.1. PSCTL: Program Store R/W Control . . . . . . . . . . . . . . . . . . . . . 112
SFR Definition 12.2. FLKEY: Flash Lock and Key . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
SFR Definition 12.3. FLSCL: Flash Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
SFR Definition 13.1. EMI0CN: External Memory Interface Control . . . . . . . . . . . . . . 117
SFR Definition 13.2. EMI0CF: External Memory Configuration . . . . . . . . . . . . . . . . . 118
SFR Definition 13.3. EMI0TC: External Memory Timing Control . . . . . . . . . . . . . . . . 123
SFR Definition 14.1. OSCICN: Internal H-F Oscillator Control . . . . . . . . . . . . . . . . . . 132
SFR Definition 14.2. OSCICL: Internal H-F Oscillator Calibration . . . . . . . . . . . . . . . 133
Rev. 1.3
13
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 14.3. OSCLCN: Internal L-F Oscillator Control . . . . . . . . . . . . . . . . . . 134
SFR Definition 14.4. OSCXCN: External Oscillator Control . . . . . . . . . . . . . . . . . . . . 137
SFR Definition 14.5. CLKMUL: Clock Multiplier Control . . . . . . . . . . . . . . . . . . . . . . . 138
SFR Definition 14.6. CLKSEL: Clock Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
SFR Definition 15.1. XBR0: Port I/O Crossbar Register 0 . . . . . . . . . . . . . . . . . . . . . 148
SFR Definition 15.2. XBR1: Port I/O Crossbar Register 1 . . . . . . . . . . . . . . . . . . . . . 149
SFR Definition 15.3. XBR2: Port I/O Crossbar Register 2 . . . . . . . . . . . . . . . . . . . . . 149
SFR Definition 15.4. P0: Port0 Latch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
SFR Definition 15.5. P0MDIN: Port0 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
SFR Definition 15.6. P0MDOUT: Port0 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 151
SFR Definition 15.7. P0SKIP: Port0 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
SFR Definition 15.8. P1: Port1 Latch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
SFR Definition 15.9. P1MDIN: Port1 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
SFR Definition 15.10. P1MDOUT: Port1 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 152
SFR Definition 15.11. P1SKIP: Port1 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
SFR Definition 15.12. P2: Port2 Latch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
SFR Definition 15.13. P2MDIN: Port2 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
SFR Definition 15.14. P2MDOUT: Port2 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 154
SFR Definition 15.15. P2SKIP: Port2 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
SFR Definition 15.16. P3: Port3 Latch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
SFR Definition 15.17. P3MDIN: Port3 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
SFR Definition 15.18. P3MDOUT: Port3 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 155
SFR Definition 15.19. P3SKIP: Port3 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
SFR Definition 15.20. P4: Port4 Latch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
SFR Definition 15.21. P4MDIN: Port4 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
SFR Definition 15.22. P4MDOUT: Port4 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 157
SFR Definition 16.1. USB0XCN: USB0 Transceiver Control . . . . . . . . . . . . . . . . . . . 161
SFR Definition 16.2. USB0ADR: USB0 Indirect Address . . . . . . . . . . . . . . . . . . . . . . 163
SFR Definition 16.3. USB0DAT: USB0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
USB Register Definition 16.4. INDEX: USB0 Endpoint Index . . . . . . . . . . . . . . . . . . . 165
USB Register Definition 16.5. CLKREC: Clock Recovery Control . . . . . . . . . . . . . . . 166
USB Register Definition 16.6. FIFOn: USB0 Endpoint FIFO Access . . . . . . . . . . . . . 168
USB Register Definition 16.7. FADDR: USB0 Function Address . . . . . . . . . . . . . . . . 169
USB Register Definition 16.8. POWER: USB0 Power . . . . . . . . . . . . . . . . . . . . . . . . 171
USB Register Definition 16.9. FRAMEL: USB0 Frame Number Low . . . . . . . . . . . . . 172
USB Register Definition 16.10. FRAMEH: USB0 Frame Number High . . . . . . . . . . . 172
USB Register Definition 16.11. IN1INT: USB0 IN Endpoint Interrupt . . . . . . . . . . . . . 173
USB Register Definition 16.12. OUT1INT: USB0 Out Endpoint Interrupt . . . . . . . . . . 173
USB Register Definition 16.13. CMINT: USB0 Common Interrupt . . . . . . . . . . . . . . . 174
USB Register Definition 16.14. IN1IE: USB0 IN Endpoint Interrupt Enable . . . . . . . . 175
USB Register Definition 16.15. OUT1IE: USB0 Out Endpoint Interrupt Enable . . . . . 175
USB Register Definition 16.16. CMIE: USB0 Common Interrupt Enable . . . . . . . . . . 176
USB Register Definition 16.17. E0CSR: USB0 Endpoint0 Control . . . . . . . . . . . . . . . 179
USB Register Definition 16.18. E0CNT: USB0 Endpoint 0 Data Count . . . . . . . . . . . 180
14
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
USB Register Definition 16.19. EINCSRL: USB0 IN Endpoint Control Low Byte . . . . 182
USB Register Definition 16.20. EINCSRH: USB0 IN Endpoint Control High Byte . . . 183
USB Register Definition 16.21. EOUTCSRL: USB0 OUT 
Endpoint Control Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
USB Register Definition 16.22. EOUTCSRH: USB0 OUT 
Endpoint Control High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
USB Register Definition 16.23. EOUTCNTL: USB0 OUT Endpoint Count Low . . . . . 186
USB Register Definition 16.24. EOUTCNTH: USB0 OUT Endpoint Count High . . . . 186
SFR Definition 17.1. SMB0CF: SMBus Clock/Configuration . . . . . . . . . . . . . . . . . . . 194
SFR Definition 17.2. SMB0CN: SMBus Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
SFR Definition 17.3. SMB0DAT: SMBus Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
SFR Definition 18.1. SCON0: Serial Port 0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . 210
SFR Definition 18.2. SBUF0: Serial (UART0) Port Data Buffer . . . . . . . . . . . . . . . . . 211
SFR Definition 19.1. SCON1: UART1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
SFR Definition 19.2. SMOD1: UART1 Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
SFR Definition 19.3. SBUF1: UART1 Data Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
SFR Definition 19.4. SBCON1: UART1 Baud Rate Generator Control . . . . . . . . . . . 220
SFR Definition 19.5. SBRLH1: UART1 Baud Rate Generator High Byte . . . . . . . . . . 221
SFR Definition 19.6. SBRLL1: UART1 Baud Rate Generator Low Byte . . . . . . . . . . . 221
SFR Definition 20.1. SPI0CFG: SPI0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 229
SFR Definition 20.2. SPI0CN: SPI0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
SFR Definition 20.3. SPI0CKR: SPI0 Clock Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
SFR Definition 20.4. SPI0DAT: SPI0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
SFR Definition 21.1. TCON: Timer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
SFR Definition 21.2. TMOD: Timer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
SFR Definition 21.3. CKCON: Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
SFR Definition 21.4. TL0: Timer 0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
SFR Definition 21.5. TL1: Timer 1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
SFR Definition 21.6. TH0: Timer 0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
SFR Definition 21.7. TH1: Timer 1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
SFR Definition 21.8. TMR2CN: Timer 2 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
SFR Definition 21.9. TMR2RLL: Timer 2 Reload Register Low Byte . . . . . . . . . . . . . 248
SFR Definition 21.10. TMR2RLH: Timer 2 Reload Register High Byte . . . . . . . . . . . 248
SFR Definition 21.11. TMR2L: Timer 2 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
SFR Definition 21.12. TMR2H Timer 2 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
SFR Definition 21.13. TMR3CN: Timer 3 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
SFR Definition 21.14. TMR3RLL: Timer 3 Reload Register Low Byte . . . . . . . . . . . . 254
SFR Definition 21.15. TMR3RLH: Timer 3 Reload Register High Byte . . . . . . . . . . . 254
SFR Definition 21.16. TMR3L: Timer 3 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
SFR Definition 21.17. TMR3H Timer 3 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
SFR Definition 22.1. PCA0CN: PCA Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
SFR Definition 22.2. PCA0MD: PCA Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
SFR Definition 22.3. PCA0CPMn: PCA Capture/Compare Mode . . . . . . . . . . . . . . . 268
SFR Definition 22.4. PCA0L: PCA Counter/Timer Low Byte . . . . . . . . . . . . . . . . . . . 269
SFR Definition 22.5. PCA0H: PCA Counter/Timer High Byte . . . . . . . . . . . . . . . . . . . 269
Rev. 1.3
15
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 22.6. PCA0CPLn: PCA Capture Module Low Byte . . . . . . . . . . . . . . . 269
SFR Definition 22.7. PCA0CPHn: PCA Capture Module High Byte . . . . . . . . . . . . . . 270
C2 Register Definition 23.1. C2ADD: C2 Address . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
C2 Register Definition 23.2. DEVICEID: C2 Device ID . . . . . . . . . . . . . . . . . . . . . . . . 271
C2 Register Definition 23.3. REVID: C2 Revision ID . . . . . . . . . . . . . . . . . . . . . . . . . 272
C2 Register Definition 23.4. FPCTL: C2 Flash Programming Control . . . . . . . . . . . . 272
C2 Register Definition 23.5. FPDAT: C2 Flash Programming Data . . . . . . . . . . . . . . 272
16
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
1.
System Overview
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D devices are fully integrated mixed-signal System-on-a-Chip MCUs.
Highlighted features are listed below. Refer to Table 1.1 for specific product feature selection.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
High-speed pipelined 8051-compatible microcontroller core (up to 48 MIPS)
In-system, full-speed, non-intrusive debug interface (on-chip)
Universal Serial Bus (USB) Function Controller with eight flexible endpoint pipes, integrated transceiver, and 1 kB FIFO RAM
Supply Voltage Regulator
True 10-bit 200 ksps differential / single-ended ADC with analog multiplexer
On-chip Voltage Reference and Temperature Sensor
On-chip Voltage Comparators (2)
Precision internal calibrated 12 MHz internal oscillator and 4x clock multiplier
Internal low-frequency oscillator for additional power savings
Up to 64 kB of on-chip Flash memory
Up to 4352 Bytes of on-chip RAM (256 + 4 kB)
External Memory Interface (EMIF) available on 48-pin versions.
SMBus/I2C, up to 2 UARTs, and Enhanced SPI serial interfaces implemented in hardware
Four general-purpose 16-bit timers
Programmable Counter/Timer Array (PCA) with five capture/compare modules and Watchdog Timer
function
On-chip Power-On Reset, VDD Monitor, and Missing Clock Detector
Up to 40 Port I/O (5 V tolerant)
With on-chip Power-On Reset, VDD monitor, Voltage Regulator, Watchdog Timer, and clock oscillator,
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D devices are truly stand-alone System-on-a-Chip solutions. The
Flash memory can be reprogrammed in-circuit, providing non-volatile data storage, and also allowing field
upgrades of the 8051 firmware. User software has complete control of all peripherals, and may individually
shut down any or all peripherals for power savings.
The on-chip Silicon Labs 2-Wire (C2) Development Interface allows non-intrusive (uses no on-chip
resources), full speed, in-circuit debugging using the production MCU installed in the final application. This
debug logic supports inspection and modification of memory and registers, setting breakpoints, single
stepping, run and halt commands. All analog and digital peripherals are fully functional while debugging
using C2. The two C2 interface pins can be shared with user functions, allowing in-system debugging without occupying package pins.
Each device is specified for 2.7–5.25 V operation over the industrial temperature range (–40 to +85 °C).
For voltages above 3.6 V, the on-chip Voltage Regulator must be used. A minimum of 3.0 V is required for
USB communication. The Port I/O and RST pins are tolerant of input signals up to 5 V. C8051F340/1/2/3/
4/5/6/7/8/9/A/B/C/D devices are available in 48-pin TQFP, 32-pin LQFP, or 32-pin QFN packages. See
Table 1.1, “Product Selection Guide,” on page 18 for feature and package choices.
Rev. 1.3
17
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Flash Memory (Bytes)
RAM
Calibrated Internal Oscillator
Low Frequency Oscillator
USB with 1k Endpoint RAM
Supply Voltage Regulator
SMBus/I2C
Enhanced SPI
UARTs
Timers (16-bit)
Programmable Counter Array
Digital Port I/Os
External Memory Interface (EMIF)
10-bit 200 ksps ADC
Temperature Sensor
Voltage Reference
Analog Comparators
Package
C8051F340-GQ
48
64k
4352






2
4

40




2
TQFP48
C8051F341-GQ
48
32k
2304






2
4

40




2
TQFP48
C8051F342-GQ
48
64k
4352






1
4

25
—



2
LQFP32
C8051F342-GM
48
64k
4352






1
4

25
—



2
QFN32
C8051F343-GQ
48
32k
2304






1
4

25
—



2
LQFP32
C8051F343-GM
48
32k
2304






1
4

25
—



2
QFN32
C8051F344-GQ
25
64k
4352






2
4

40




2
TQFP48
C8051F345-GQ
25
32k
2304






2
4

40




2
TQFP48
C8051F346-GQ
25
64k
4352

—




1
4

25
—



2
LQFP32
C8051F346-GM
25
64k
4352

—




1
4

25
—



2
QFN32
C8051F347-GQ
25
32k
2304

—




1
4

25
—



2
LQFP32
C8051F347-GM
25
32k
2304

—




1
4

25
—



2
QFN32
C8051F348-GQ
25
32k
2304






2
4

40

—
—
—
2
TQFP48
C8051F349-GQ
25
32k
2304






1
4

25
—
—
—
—
2
LQFP32
C8051F349-GM
25
32k
2304






1
4

25
—
—
—
—
2
QFN32
C8051F34A-GQ
48
64k
4352






2
4

25
—



2
LQFP32
C8051F34A-GM
48
64k
4352






2
4

25
—



2
QFN32
C8051F34B-GQ
48
32k
2304






2
4

25
—



2
LQFP32
C8051F34B-GM
48
32k
2304






2
4

25
—



2
QFN32
C8051F34C-GQ
48
64k
4352






2
4

40

—
—
—
2
TQFP48
C8051F34D-GQ
48
64k
4352






1
4

25
—
—
—
—
2
LQFP32
Ordering Part Number
MIPS (Peak)
Table 1.1. Product Selection Guide
18
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
C2D
Port I/O Configuration
Debug / Programming
Hardware
C2CK/RST
UART0
Reset
Power-On
Reset
Supply
Monitor
VDD
Power
Net
VREG
Voltage
Regulator
Port 0
Drivers
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6/XTAL1
P0.7/XTAL2
Port 1
Drivers
P1.0
P1.1
P1.2
P1.3
P1.4/CNVSTR
P1.5/VREF
P1.6
P1.7
Port 2
Drivers
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
Port 3
Drivers
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
Port 4
Drivers
P4.0
P4.1
P4.2
P4.3
P4.4
P4.5
P4.6
P4.7
Digital Peripherals
CIP-51 8051
Controller Core
UART1
Timers 0, 1,
2, 3
64/32k Byte ISP FLASH
Program Memory
Priority
Crossbar
Decoder
PCA/WDT
256 Byte RAM
SMBus
SPI
4/2k Byte XRAM
Crossbar Control
GND
System Clock Setup
XTAL1
XTAL2
External
Oscillator
Internal
Oscillator
SFR
Bus
External Memory
Interface
P1
Control
Clock
Multiplier
P2 / P3
Address
P4
Data
Clock
Recovery
Low Freq.
Oscillator
Analog Peripherals
CP0
VREF
USB Peripheral
D+
D-
VBUS
Full / Low
Speed
Transceiver
VDD
VREF
+
+
-
2 Comparators
Controller
1k Byte
RAM
CP1
10-bit
200ksps
ADC
A
M
U
X
VDD
AIN0 - AIN19
Temp
Sensor
Figure 1.1. C8051F340/1/4/5 Block Diagram
Rev. 1.3
19
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
C2D
Port I/O Configuration
Debug / Programming
Hardware
C2CK/RST
UART0
Reset
Power-On
Reset
Supply
Monitor
VDD
Power
Net
VREG
Voltage
Regulator
Port 0
Drivers
P0.0
P0.1
P0.2/XTAL1
P0.3/XTAL2
P0.4
P0.5
P0.6/CNVSTR
P0.7/VREF
Port 1
Drivers
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
Port 2
Drivers
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
Digital Peripherals
CIP-51 8051
Controller Core
Timers 0, 1,
2, 3
64/32 kB ISP FLASH
Program Memory
Priority
Crossbar
Decoder
PCA/WDT
256 Byte RAM
SMBus
SPI
4/2 kB XRAM
Crossbar Control
GND
System Clock Setup
XTAL1
XTAL2
External
Oscillator
Internal
Oscillator
Clock
Recovery
SFR
Bus
P3.0/C2D
Port 3
Drivers
Clock
Multiplier
Low Freq.
Oscillator*
Analog Peripherals
CP0
VREF
USB Peripheral
D+
D-
VBUS
Full / Low
Speed
Transceiver
VDD
VREF
CP1
+
+
-
2 Comparators
Controller
10-bit
200 ksps
ADC
1 kB RAM
A
M
U
X
VDD
AIN0 - AIN20
Temp
Sensor
*Low Frequency Oscillator option not available on C8051F346/7
Figure 1.2. C8051F342/3/6/7 Block Diagram
20
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
C2D
Port I/O Configuration
Debug / Programming
Hardware
C2CK/RST
UART0
Reset
Power-On
Reset
Supply
Monitor
VDD
Power
Net
VREG
Voltage
Regulator
Port 0
Drivers
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6/XTAL1
P0.7/XTAL2
Port 1
Drivers
P1.0
P1.1
P1.2
P1.3
P1.4/CNVSTR
P1.5/VREF
P1.6
P1.7
Port 2
Drivers
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
Port 3
Drivers
P3.0
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7
Port 4
Drivers
P4.0
P4.1
P4.2
P4.3
P4.4
P4.5
P4.6
P4.7
Digital Peripherals
CIP-51 8051
Controller Core
UART1
Timers 0, 1,
2, 3
64/32 kB ISP FLASH
Program Memory
Priority
Crossbar
Decoder
PCA/WDT
256 Byte RAM
SMBus
SPI
4/2 kB XRAM
Crossbar Control
GND
System Clock Setup
XTAL1
XTAL2
External
Oscillator
Internal
Oscillator
SFR
Bus
External Memory
Interface
P1
Control
Clock
Multiplier
Address
P4
Data
Clock
Recovery
P2 / P3
Low Freq.
Oscillator
Analog Peripherals
USB Peripheral
D+
D-
VBUS
Full / Low
Speed
Transceiver
CP0
Controller
CP1
1k Byte
RAM
+
+
-
2 Comparators
Figure 1.3. C8051F348/C Block Diagram
Rev. 1.3
21
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
C2D
Port I/O Configuration
Debug / Programming
Hardware
C2CK/RST
UART0
Reset
Power-On
Reset
Supply
Monitor
VDD
Power
Net
VREG
Voltage
Regulator
Port 0
Drivers
P0.0
P0.1
P0.2/XTAL1
P0.3/XTAL2
P0.4
P0.5
P0.6/CNVSTR
P0.7/VREF
Port 1
Drivers
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
Port 2
Drivers
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
Digital Peripherals
CIP-51 8051
Controller Core
Timers 0, 1,
2, 3
64/32 kB ISP FLASH
Program Memory
Priority
Crossbar
Decoder
PCA/WDT
256 Byte RAM
SMBus
SPI
4/2 kB XRAM
Crossbar Control
GND
System Clock Setup
XTAL1
XTAL2
External
Oscillator
Internal
Oscillator
Clock
Recovery
SFR
Bus
P3.0/C2D
Port 3
Drivers
Clock
Multiplier
Low Freq.
Oscillator
Analog Peripherals
USB Peripheral
D+
D-
VBUS
Full / Low
Speed
Transceiver
CP0
Controller
CP1
+
+
-
2 Comparators
1 kB RAM
Figure 1.4. C8051F349/D Block Diagram
22
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
C2D
Port I/O Configuration
Debug / Programming
Hardware
C2CK/RST
UART0
Reset
Power-On
Reset
Supply
Monitor
VDD
Power
Net
VREG
Voltage
Regulator
Port 0
Drivers
P0.0
P0.1
P0.2/XTAL1
P0.3/XTAL2
P0.4
P0.5
P0.6/CNVSTR
P0.7/VREF
Port 1
Drivers
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
Port 2
Drivers
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
Digital Peripherals
CIP-51 8051
Controller Core
UART1
Timers 0, 1,
2, 3
64/32 kB ISP FLASH
Program Memory
Priority
Crossbar
Decoder
PCA/WDT
256 Byte RAM
SMBus
SPI
4/2 kB XRAM
Crossbar Control
GND
System Clock Setup
XTAL1
XTAL2
External
Oscillator
Internal
Oscillator
Clock
Recovery
SFR
Bus
P3.0/C2D
Port 3
Drivers
Clock
Multiplier
Low Freq.
Oscillator*
Analog Peripherals
CP0
VREF
USB Peripheral
D+
D-
VBUS
Full / Low
Speed
Transceiver
VDD
VREF
+
+
-
2 Comparators
Controller
1 kB RAM
CP1
10-bit
200 ksps
ADC
A
M
U
X
VDD
AIN0 - AIN20
Temp
Sensor
Figure 1.5. C8051F34A/B Block Diagram
Rev. 1.3
23
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
2.
Absolute Maximum Ratings
Table 2.1. Absolute Maximum Ratings*
Parameter
Conditions
Min
Typ
Max
Units
Ambient temperature under bias
–55
125
°C
Storage Temperature
–65
150
°C
Voltage on any Port I/O Pin or RST with
respect to GND
–0.3
5.8
V
Voltage on VDD with respect to GND
–0.3
4.2
V
Maximum Total current through VDD and
GND
500
mA
Maximum output current sunk by RST or any
Port pin
100
mA
*Note: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the
device. This is a stress rating only and functional operation of the devices at those or any other conditions
above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating
conditions for extended periods may affect device reliability.
24
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
3.
Global DC Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics
–40 to +85 °C, 25 MHz System Clock unless otherwise specified.
Parameter
Conditions
Digital Supply Voltage1
Min
Typ
Max
Units
VRST
3.3
3.6
V
Digital Supply RAM Data
Retention Voltage
SYSCLK (System Clock)2
1.5
C8051F340/1/2/3/A/B/C/D
C8051F344/5/6/7/8/9
Specified Operating 
Temperature Range
V
0
0
48
25
MHz
–40
+85
°C
Digital Supply Current - CPU Active (Normal Mode, accessing Flash)
IDD3
IDD Supply Sensitivity3,4
IDD Frequency Sensitivity3,5
VDD = 3.3 V, SYSCLK = 48 MHz
VDD = 3.3 V, SYSCLK = 24 MHz
VDD = 3.3 V, SYSCLK = 1 MHz
VDD = 3.3 V, SYSCLK = 80 kHz
25.9
13.9
0.69
55
28.5
15.7
mA
mA
mA
µA
VDD = 3.6 V, SYSCLK = 48 MHz
VDD = 3.6 V, SYSCLK = 24 MHz
29.7
15.9
32.3
18
mA
mA
SYSCLK = 1 MHz, 
relative to VDD = 3.3 V
SYSCLK = 24 MHz, 
relative to VDD = 3.3 V
47
%/V
46
%/V
VDD = 3.3 V, SYSCLK < 30 MHz, 
T = 25 ºC
VDD = 3.3 V, SYSCLK > 30 MHz, 
T = 25 ºC
0.69
mA/MHz
0.44
mA/MHz
VDD = 3.6 V, SYSCLK < 30 MHz, 
T = 25 ºC
VDD = 3.6 V, SYSCLK > 30 MHz, 
T = 25 ºC
0.80
mA/MHz
0.50
mA/MHz
Digital Supply Current - CPU Inactive (Idle Mode, not accessing Flash)
IDD3
IDD Supply Sensitivity3,4
VDD = 3.3 V, SYSCLK = 48 MHz
VDD = 3.3 V, SYSCLK = 24 MHz
VDD = 3.3 V, SYSCLK = 1 MHz
VDD = 3.3 V, SYSCLK = 80 kHz
16.6
8.25
0.44
35
18.75
9.34
mA
mA
mA
µA
VDD = 3.6 V, SYSCLK = 48 MHz
VDD = 3.6 V, SYSCLK = 24 MHz
18.6
9.26
20.9
10.5
mA
mA
SYSCLK = 1 MHz, 
relative to VDD = 3.3 V
SYSCLK = 24 MHz, 
relative to VDD = 3.3 V
Rev. 1.3
41
%/V
39
%/V
25
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 3.1. Global DC Electrical Characteristics (Continued)
–40 to +85 °C, 25 MHz System Clock unless otherwise specified.
Parameter
IDD Frequency
Sensitivity3,6
Digital Supply Current (Stop
Mode, shutdown)
Conditions
Min
Typ
Max
Units
VDD = 3.3 V, SYSCLK < 1 MHz, 
T = 25 ºC
VDD = 3.3 V, SYSCLK > 1 MHz, 
T = 25 ºC
0.44
mA/MHz
0.32
mA/MHz
VDD = 3.6 V, SYSCLK < 1 MHz, 
T = 25 ºC
VDD = 3.6 V, SYSCLK > 1 MHz, 
T = 25 ºC
0.49
mA/MHz
0.36
mA/MHz
< 0.1
µA
8.69
mA
9.59
mA
< 0.1
µA
Oscillator not running, 
VDD monitor disabled
Digital Supply Current for USB VDD = 3.3 V, USB Clock = 48 MHz
Module (USB Active Mode)
VDD = 3.6 V, USB Clock = 48 MHz
Digital Supply Current for USB Oscillator not running
Module (USB Suspend Mode) VDD monitor disabled
Notes:
1. USB Requires 3.0 V Minimum Supply Voltage.
2. SYSCLK must be at least 32 kHz to enable debugging.
3. Based on device characterization of data; Not production tested.
4. Active and Inactive IDD at voltages and frequencies other than those specified can be calculated using the IDD
Supply Sensitivity. For example, if the VDD is 3.0 V instead of 3.3 V at 24 MHz: IDD = 13.9 mA typical at 3.3 V
and SYSCLK = 24 MHz. From this, IDD = 13.9 mA + 0.46 x (3.0 V – 3.3 V) = 13.76 mA at 3.0 V and SYSCLK
= 24 MHz.
5. IDD can be estimated for frequencies < 30 MHz by multiplying the frequency of interest by the frequency
sensitivity number for that range. When using these numbers to estimate IDD for > 30 MHz, the estimate should
be the current at 24 MHz (or 48 MHz) minus the difference in current indicated by the frequency sensitivity
number. For example: VDD = 3.3 V; SYSCLK = 35 MHz, IDD = 13.9 mA – (24 MHz – 35 MHz) x 0.44 mA/MHz =
18.74 mA.
6. Idle IDD can be estimated for frequencies < 1 MHz by multiplying the frequency of interest by the frequency
sensitivity number for that range. When using these numbers to estimate Idle IDD for > 1 MHz, the estimate
should be the current at 24 MHz (or 48 MHz) minus the difference in current indicated by the frequency
sensitivity number. For example: VDD = 3.3 V; SYSCLK = 5 MHz, Idle IDD = 8.25 mA – (24 MHz – 5 MHz) x
0.32 mA/MHz = 2.17 mA.
Other electrical characteristics tables are found in the data sheet section corresponding to the associated
peripherals. For more information on electrical characteristics for a specific peripheral, refer to the page
indicated in Table 3.2.
26
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 3.2. Index to Electrical Characteristics Tables
Table Title
ADC0 Electrical Characteristics
Voltage Reference Electrical Characteristics
Comparator Electrical Characteristics
Voltage Regulator Electrical Specifications
Reset Electrical Characteristics
Flash Electrical Characteristics
AC Parameters for External Memory Interface
Oscillator Electrical Characteristics
Port I/O DC Electrical Characteristics
USB Transceiver Electrical Characteristics
Page No.
56
58
68
69
106
109
130
141
158
187
Rev. 1.3
27
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
4.
Pinout and Package Definitions
Table 4.1. Pin Definitions for the C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Name
VDD
Pin Numbers
48-pin 32-pin
10
6
Type
Power In 2.7–3.6 V Power Supply Voltage Input.
Power
Out
GND
7
3
RST/
13
9
C2CK
Description
3.3 V Voltage Regulator Output. See Section 8.
Ground.
D I/O
Device Reset. Open-drain output of internal POR or VDD
monitor. An external source can initiate a system reset by
driving this pin low for at least 15 µs. See Section 11.
D I/O
Clock signal for the C2 Debug Interface.
C2D
14
—
D I/O
Bi-directional data signal for the C2 Debug Interface.
P3.0 /
—
10
D I/O
Port 3.0. See Section 15 for a complete description of Port
3.
C2D
D I/O
Bi-directional data signal for the C2 Debug Interface.
28
REGIN
11
7
Power In 5 V Regulator Input. This pin is the input to the on-chip voltage regulator.
VBUS
12
8
D In
VBUS Sense Input. This pin should be connected to the
VBUS signal of a USB network. A 5 V signal on this pin indicates a USB network connection.
D+
8
4
D I/O
USB D+.
D-
9
5
D I/O
USB D–.
P0.0
6
2
D I/O or Port 0.0. See Section 15 for a complete description of Port
A In
0.
P0.1
5
1
D I/O or Port 0.1.
A In
P0.2
4
32
D I/O or Port 0.2.
A In
P0.3
3
31
D I/O or Port 0.3.
A In
P0.4
2
30
D I/O or Port 0.4.
A In
P0.5
1
29
D I/O or Port 0.5.
A In
P0.6
48
28
D I/O or Port 0.6.
A In
P0.7
47
27
D I/O or Port 0.7.
A In
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 4.1. Pin Definitions for the C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D (Continued)
Name
Pin Numbers
48-pin 32-pin
Type
Description
P1.0
46
26
D I/O or Port 1.0. See Section 15 for a complete description of Port
A In
1.
P1.1
45
25
D I/O or Port 1.1.
A In
P1.2
44
24
D I/O or Port 1.2.
A In
P1.3
43
23
D I/O or Port 1.3.
A In
P1.4
42
22
D I/O or Port 1.4.
A In
P1.5
41
21
D I/O or Port 1.5.
A In
P1.6
40
20
D I/O or Port 1.6.
A In
P1.7
39
19
D I/O or Port 1.7.
A In
P2.0
38
18
D I/O or Port 2.0. See Section 15 for a complete description of Port
A In
2.
P2.1
37
17
D I/O or Port 2.1.
A In
P2.2
36
16
D I/O or Port 2.2.
A In
P2.3
35
15
D I/O or Port 2.3.
A In
P2.4
34
14
D I/O or Port 2.4.
A In
P2.5
33
13
D I/O or Port 2.5.
A In
P2.6
32
12
D I/O or Port 2.6.
A In
P2.7
31
11
D I/O or Port 2.7.
A In
P3.0
30
—
D I/O or Port 3.0. See Section 15 for a complete description of Port
A In
3.
P3.1
29
—
D I/O or Port 3.1.
A In
P3.2
28
—
D I/O or Port 3.2.
A In
Rev. 1.3
29
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 4.1. Pin Definitions for the C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D (Continued)
Name
30
Pin Numbers
48-pin 32-pin
Type
Description
P3.3
27
—
D I/O or Port 3.3.
A In
P3.4
26
—
D I/O or Port 3.4.
A In
P3.5
25
—
D I/O or Port 3.5.
A In
P3.6
24
—
D I/O or Port 3.6.
A In
P3.7
23
—
D I/O or Port 3.7.
A In
P4.0
22
—
D I/O or Port 4.0. See Section 15 for a complete description of Port
A In
4.
P4.1
21
—
D I/O or Port 4.1.
A In
P4.2
20
—
D I/O or Port 4.2.
A In
P4.3
19
—
D I/O or Port 4.3.
A In
P4.4
18
—
D I/O or Port 4.4.
A In
P4.5
17
—
D I/O or Port 4.5.
A In
P4.6
16
—
D I/O or Port 4.6.
A In
P4.7
15
—
D I/O or Port 4.7.
A In
Rev. 1.3
P0.6
P0.7
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
48
47
46
45
44
43
42
41
40
39
38
37
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
P0.5
1
36
P2.2
P0.4
2
35
P2.3
P0.3
3
34
P2.4
P0.2
4
33
P2.5
P0.1
5
32
P2.6
P0.0
6
31
P2.7
GND
7
30
P3.0
D+
8
29
P3.1
D-
9
28
P3.2
VDD
10
27
P3.3
REGIN
11
26
P3.4
VBUS
12
25
P3.5
20
21
22
23
24
P4.2
P4.1
P4.0
P3.7
P3.6
17
P4.5
19
16
P4.6
P4.3
15
P4.7
18
14
C2D
P4.4
13
RST / C2CK
C8051F340/1/4/5/8/C-GQ
Top View
Figure 4.1. TQFP-48 Pinout Diagram (Top View)
Rev. 1.3
31
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Figure 4.2. TQFP-48 Package Diagram
Table 4.2. TQFP-48 Package Dimensions
Dimension
A
A1
A2
b
c
D
D1
e
E
E1
L
aaa
bbb
ccc
ddd

Min
—
0.05
0.95
0.17
0.09
0.45
0°
Nom
—
—
1.00
0.22
—
9.00 BSC
7.00 BSC
0.50 BSC
9.00 BSC
7.00 BSC
0.60
0.20
0.20
0.08
0.08
3.5°
Max
1.20
0.15
1.05
0.27
0.20
0.75
7°
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to JEDEC outline MS-026, variation ABC.
4. The recommended card reflow profile is per the JEDEC/IPC J-STD-020
specification for Small Body Components.
32
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Figure 4.3. TQFP-48 Recommended PCB Land Pattern
Table 4.3. TQFP-48 PCB Land Pattern Dimensions
Dimension
Min
Max
C1
C2
E
X1
Y1
8.30
8.30
8.40
8.40
0.50 BSC
0.20
1.40
0.30
1.50
Notes:
General:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. This Land Pattern Design is based on the IPC-7351 guidelines.
Solder Mask Design:
3. All metal pads are to be non-solder mask defined (NSMD). Clearance between
the solder mask and the metal pad is to be 60 µm minimum, all the way around
the pad.
Stencil Design:
4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls
should be used to assure good solder paste release.
5. The stencil thickness should be 0.125 mm (5 mils).
6. The ratio of stencil aperture to land pad size should be 1:1 for all pads.
Card Assembly:
7. A No-Clean, Type-3 solder paste is recommended.
8. The recommended card reflow profile is per the JEDEC/IPC J-STD-020
specification for Small Body Components.
Rev. 1.3
33
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
P1.0
P1.1
32
31
30
29
28
27
26
25
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
P0.1
1
24
P1.2
P0.0
2
23
P1.3
GND
3
22
P1.4
D+
4
21
P1.5
D-
5
20
P1.6
VDD
6
19
P1.7
REGIN
7
18
P2.0
VBUS
8
17
P2.1
9
10
11
12
13
14
15
16
RST / C2CK
P3.0 / C2D
P2.7
P2.6
P2.5
P2.4
P2.3
P2.2
C8051F342/3/6/7/9/A/B/D-GQ
Top View
Figure 4.4. LQFP-32 Pinout Diagram (Top View)
34
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Figure 4.5. LQFP-32 Package Diagram
Table 4.4. LQFP-32 Package Dimensions
Dimension
A
A1
A2
b
c
D
D1
e
E
E1
L
aaa
bbb
ccc
ddd

Min
—
0.05
1.35
0.30
0.09
0.45
0°
Nom
—
—
1.40
0.37
—
9.00 BSC
7.00 BSC
0.80 BSC
9.00 BSC
7.00 BSC
0.60
0.20
0.20
0.10
0.20
3.5°
Max
1.60
0.15
1.45
0.45
0.20
0.75
7°
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to JEDEC outline MS-026, variation BBA.
4. The recommended card reflow profile is per the JEDEC/IPC J-STD-020
specification for Small Body Components.
Rev. 1.3
35
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Figure 4.6. LQFP-32 Recommended PCB Land Pattern
Table 4.5. LQFP-32 PCB Land Pattern Dimensions
Dimension
Min
Max
C1
C2
E
X1
Y1
8.40
8.40
8.50
8.50
0.80 BSC
0.40
1.25
0.50
1.35
Notes:
General:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. This Land Pattern Design is based on the IPC-7351 guidelines.
Solder Mask Design:
3. All metal pads are to be non-solder mask defined (NSMD). Clearance between
the solder mask and the metal pad is to be 60 µm minimum, all the way around
the pad.
Stencil Design:
4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls
should be used to assure good solder paste release.
5. The stencil thickness should be 0.125 mm (5 mils).
6. The ratio of stencil aperture to land pad size should be 1:1 for all pads.
Card Assembly:
7. A No-Clean, Type-3 solder paste is recommended.
8. The recommended card reflow profile is per the JEDEC/IPC J-STD-020
specification for Small Body Components.
36
Rev. 1.3
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
P1.0
P1.1
32
31
30
29
28
27
26
25
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
P0.1
1
24
P1.2
P0.0
2
23
P1.3
GND
3
22
P1.4
D+
4
21
P1.5
D-
5
20
P1.6
VDD
6
19
P1.7
REGIN
7
18
P2.0
17
P2.1
C8051F342/3/6/7/9/A/B-GM
Top View
GND (optional)
13
14
15
16
P2.5
P2.4
P2.3
P2.2
11
P2.7
12
10
P3.0 / C2D
P2.6
9
8
RST / C2CK
VBUS
Figure 4.7. QFN-32 Pinout Diagram (Top View)
Rev. 1.3
37
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Figure 4.8. QFN-32 Package Drawing
Table 4.6. QFN-32 Package Dimensions
Dimension
Min
Nom
Max
A
0.80
0.9
1.00
A1
0.00
0.02
0.05
b
0.18
0.25
0.30
D
D2
5.00 BSC
3.20
3.30
e
0.50 BSC
E
5.00 BSC
3.40
E2
3.20
3.30
3.40
L
0.30
0.40
0.50
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to the JEDEC Solid State Outline MO-220,
variation VHHD except for custom features D2, E2, and L which are
toleranced per supplier designation.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020
specification for Small Body Components.
38
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 4.6. QFN-32 Package Dimensions (Continued)
Dimension
Min
Nom
Max
L1
0.00
—
0.15
aaa
—
—
0.15
bbb
—
—
0.10
ddd
—
—
0.05
eee
—
—
0.08
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to the JEDEC Solid State Outline MO-220,
variation VHHD except for custom features D2, E2, and L which are
toleranced per supplier designation.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020
specification for Small Body Components.
Rev. 1.3
39
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Figure 4.9. QFN-32 Recommended PCB Land Pattern
Table 4.7. QFN-32 PCB Land Pattern Dimesions
Dimension
Min
Max
Dimension
Min
Max
C1
C2
E
X1
4.80
4.80
4.90
4.90
X2
Y1
Y2
3.20
0.75
3.20
3.40
0.85
3.40
0.50 BSC
0.20
0.30
Notes:
General:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. This Land Pattern Design is based on the IPC-7351 guidelines.
Solder Mask Design:
3. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder
mask and the metal pad is to be 60m minimum, all the way around the pad.
Stencil Design:
4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used
to assure good solder paste release.
5. The stencil thickness should be 0.125 mm (5 mils).
6. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pins.
7. A 3x3 array of 1.0 mm openings on a 1.2mm pitch should be used for the center pad to assure
the proper paste volume.
Card Assembly:
8. A No-Clean, Type-3 solder paste is recommended.
9. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small
Body Components.
40
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
5.
10-Bit ADC (ADC0, C8051F340/1/2/3/4/5/6/7/A/B Only)
The ADC0 subsystem for the C8051F34x devices consists of two analog multiplexers (referred to collectively as AMUX0), and a 200 ksps, 10-bit successive-approximation-register ADC with integrated
track-and-hold and programmable window detector. The AMUX0, data conversion modes, and window
detector are all configured under software control via the Special Function Registers shown in Figure 5.1.
ADC0 operates in both Single-ended and Differential modes, and may be configured to measure voltages
at port pins, the Temperature Sensor output, or VDD with respect to a port pin, VREF, or GND. The connection options for AMUX0 are detailed in SFR Definition 5.1 and SFR Definition 5.2. The ADC0 subsystem is
enabled only when the AD0EN bit in the ADC0 Control register (ADC0CN) is set to logic 1. The ADC0 subsystem is in low power shutdown when this bit is logic 0.
AD0CM0
AD0CM1
AD0CM2
AD0WINT
AD0INT
ADC0L
10-Bit
SAR
AIN+
ADC
AIN-
Negative
Input
(AIN-)
AMUX
SYSCLK
VREF
AD0BUSY
AD0EN
Start
Conversion
Temp
Sensor
Port I/O
Pins*
AD0TM
AMX0P0
AMX0P1
AMX0P2
VDD
Positive
Input
(AIN+)
AMUX
000
AD0BUSY (W)
001
Timer 0 Overflow
010
Timer 2 Overflow
011
Timer 1 Overflow
100
CNVSTR Input
101
Timer 3 Overflow
ADC0H
VDD
ADC0CN
REF
Port I/O
Pins*
AMX0P3
AMX0P4
AMX0P
AD0WINT
* 21 Selections on 32-pin package
20 Selections on 48-pin package
AMX0N
AD0SC0
AD0LJST
AD0SC1
AD0SC2
AD0SC3
AD0SC4
AMX0N0
AMX0N1
AMX0N2
AMX0N3
AMX0N4
GND
ADC0CF
32
ADC0LTH ADC0LTL
Window
Compare
Logic
ADC0GTH ADC0GTL
Figure 5.1. ADC0 Functional Block Diagram
Rev. 1.3
41
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
5.1.
Analog Multiplexer
AMUX0 selects the positive and negative inputs to the ADC. The positive input (AIN+) can be connected to
individual Port pins, the on-chip temperature sensor, or the positive power supply (VDD). The negative
input (AIN-) can be connected to individual Port pins, VREF, or GND. When GND is selected as the negative input, ADC0 operates in Single-ended Mode; at all other times, ADC0 operates in Differential
Mode. The ADC0 input channels are selected in the AMX0P and AMX0N registers as described in SFR
Definition 5.1 and SFR Definition 5.2.
The conversion code format differs between Single-ended and Differential modes. The registers ADC0H
and ADC0L contain the high and low bytes of the output conversion code from the ADC at the completion
of each conversion. Data can be right-justified or left-justified, depending on the setting of the AD0LJST bit
(ADC0CN.0). When in Single-ended Mode, conversion codes are represented as 10-bit unsigned integers.
Inputs are measured from ‘0’ to VREF x 1023/1024. Example codes are shown below for both right-justified and left-justified data. Unused bits in the ADC0H and ADC0L registers are set to ‘0’.
Input Voltage
(Single-Ended)
VREF x 1023/1024
VREF x 512/1024
VREF x 256/1024
0
Right-Justified ADC0H:ADC0L
(AD0LJST = 0)
0x03FF
0x0200
0x0100
0x0000
Left-Justified ADC0H:ADC0L
(AD0LJST = 1)
0xFFC0
0x8000
0x4000
0x0000
When in Differential Mode, conversion codes are represented as 10-bit signed 2’s complement numbers.
Inputs are measured from –VREF to VREF x 511/512. Example codes are shown below for both right-justified and left-justified data. For right-justified data, the unused MSBs of ADC0H are a sign-extension of the
data word. For left-justified data, the unused LSBs in the ADC0L register are set to ‘0’.
Input Voltage
(Differential)
VREF x 511/512
VREF x 256/512
0
–VREF x 256/512
–VREF
Right-Justified ADC0H:ADC0L
(AD0LJST = 0)
0x01FF
0x0100
0x0000
0xFF00
0xFE00
Left-Justified ADC0H:ADC0L
(AD0LJST = 1)
0x7FC0
0x4000
0x0000
0xC000
0x8000
Important Note About ADC0 Input Configuration: Port pins selected as ADC0 inputs should be configured as analog inputs, and should be skipped by the Digital Crossbar. To configure a Port pin for analog
input, set to ‘0’ the corresponding bit in register PnMDIN (for n = 0,1,2,3). To force the Crossbar to skip a
Port pin, set to ‘1’ the corresponding bit in register PnSKIP (for n = 0,1,2). See Section “15. Port Input/
Output” on page 142 for more Port I/O configuration details.
42
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
5.2.
Temperature Sensor
The temperature sensor transfer function is shown in Figure 5.2. The output voltage (VTEMP) is the positive
ADC input when the temperature sensor is selected by bits AMX0P4-0 in register AMX0P. Values for the
Offset and Slope parameters can be found in Table 5.1.
VTEMP = (Gain x TempC) + Offset
Voltage
TempC = (VTEMP - Offset) / Gain
Gain (V / deg C)
Offset (V at 0 Celsius)
Temperature
Figure 5.2. Temperature Sensor Transfer Function
The uncalibrated temperature sensor output is extremely linear and suitable for relative temperature measurements (see Table 5.1 for linearity specifications). For absolute temperature measurements, offset and/
or gain calibration is recommended. Typically a 1-point (offset) calibration includes the following steps:
Step 1. Control/measure the ambient temperature (this temperature must be known).
Step 2. Power the device, and delay for a few seconds to allow for self-heating.
Step 3. Perform an ADC conversion with the temperature sensor selected as the positive input
and GND selected as the negative input.
Step 4. Calculate the offset characteristics, and store this value in non-volatile memory for use
with subsequent temperature sensor measurements.
Figure 5.3 shows the typical temperature sensor error assuming a 1-point calibration at 25 °C. Note that
parameters which affect ADC measurement, in particular the voltage reference value, will also
affect temperature measurement.
Rev. 1.3
43
Error (degrees C)
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
5.0
0
5.0
0
4.0
0
4.0
0
3.0
0
3.0
0
2.0
0
2.0
0
1.0
0
1.0
0
0.0
0-40.00
-20.00
0.0
0
20.0
0
40.0
0
60.0
0
0.0
0
-1.00
-1.00
-2.00
-2.00
-3.00
-3.00
-4.00
-4.00
-5.00
-5.00
Temperature (degrees C)
Figure 5.3. Temperature Sensor Error with 1-Point Calibration (VREF = 2.40 V)
44
80.0
0
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
5.3.
Modes of Operation
ADC0 has a maximum conversion speed of 200 ksps. The ADC0 conversion clock is a divided version of
the system clock, determined by the AD0SC bits in the ADC0CF register (system clock divided by
(AD0SC + 1) for 0  AD0SC 31).
5.3.1. Starting a Conversion
A conversion can be initiated in one of five ways, depending on the programmed states of the ADC0 Start
of Conversion Mode bits (AD0CM2–0) in register ADC0CN. Conversions may be initiated by one of the following:
1.
2.
3.
4.
5.
6.
Writing a ‘1’ to the AD0BUSY bit of register ADC0CN
A Timer 0 overflow (i.e., timed continuous conversions)
A Timer 2 overflow
A Timer 1 overflow
A rising edge on the CNVSTR input signal
A Timer 3 overflow
Writing a ‘1’ to AD0BUSY provides software control of ADC0 whereby conversions are performed
"on-demand". During conversion, the AD0BUSY bit is set to logic 1 and reset to logic 0 when the conversion is complete. The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the ADC0
interrupt flag (AD0INT). Note: When polling for ADC conversion completions, the ADC0 interrupt flag
(AD0INT) should be used. Converted data is available in the ADC0 data registers, ADC0H:ADC0L, when
bit AD0INT is logic 1. Note that when Timer 2 or Timer 3 overflows are used as the conversion source, Low
Byte overflows are used if Timer 2/3 is in 8-bit mode; High byte overflows are used if Timer 2/3 is in 16-bit
mode. See Section “21. Timers” on page 235 for timer configuration.
Important Note About Using CNVSTR: The CNVSTR input pin also functions as a Port pin. When the
CNVSTR input is used as the ADC0 conversion source, the associated Port pin should be skipped by the
Digital Crossbar. To configure the Crossbar to skip a pin, set the corresponding bit in the PnSKIP register
to ‘1’. See Section “15. Port Input/Output” on page 142 for details on Port I/O configuration.
Rev. 1.3
45
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
5.3.2. Tracking Modes
The AD0TM bit in register ADC0CN controls the ADC0 track-and-hold mode. In its default state, the ADC0
input is continuously tracked, except when a conversion is in progress. When the AD0TM bit is logic 1,
ADC0 operates in low-power track-and-hold mode. In this mode, each conversion is preceded by a tracking period of 3 SAR clocks (after the start-of-conversion signal). When the CNVSTR signal is used to initiate conversions in low-power tracking mode, ADC0 tracks only when CNVSTR is low; conversion begins
on the rising edge of CNVSTR (see Figure 5.4). Tracking can also be disabled (shutdown) when the device
is in low power standby or sleep modes. Low-power track-and-hold mode is also useful when AMUX settings are frequently changed, due to the settling time requirements described in Section “5.3.3. Settling
Time Requirements” on page 47.
A. ADC0 Timing for External Trigger Source
CNVSTR
(AD0CM[2:0]=100)
1
2
3
4
5
6
7
8
9
10 11
SAR Clocks
AD0TM=1
AD0TM=0
Write '1' to AD0BUSY,
Timer 0, Timer 2,
Timer 1, Timer 3 Overflow
(AD0CM[2:0]=000, 001,010
011, 101)
Low Power
or Convert
Track
Track or Convert
Convert
Low Power
Mode
Convert
Track
B. ADC0 Timing for Internal Trigger Source
1
2
3
4
5
6
7
8
9
10 11 12 13 14
SAR Clocks
AD0TM=1
Low Power
or Convert
Track
1
2
3
Convert
4
5
6
7
8
9
Low Power Mode
10 11
SAR Clocks
AD0TM=0
Track or
Convert
Convert
Track
Figure 5.4. 10-Bit ADC Track and Conversion Example Timing
46
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
5.3.3. Settling Time Requirements
When the ADC0 input configuration is changed (i.e., a different AMUX0 selection is made), a minimum
tracking time is required before an accurate conversion can be performed. This tracking time is determined
by the AMUX0 resistance, the ADC0 sampling capacitance, any external source resistance, and the accuracy required for the conversion. Note that in low-power tracking mode, three SAR clocks are used for
tracking at the start of every conversion. For most applications, these three SAR clocks will meet the minimum tracking time requirements.
Figure 5.5 shows the equivalent ADC0 input circuits for both Differential and Single-ended modes. Notice
that the equivalent time constant for both input circuits is the same. The required ADC0 settling time for a
given settling accuracy (SA) may be approximated by Equation 5.1. When measuring the Temperature
Sensor output or VDD with respect to GND, RTOTAL reduces to RMUX. See Table 5.1 for ADC0 minimum
settling time requirements.
n
2
t = ln  -------  R TOTAL C SAMPLE
SA
Equation 5.1. ADC0 Settling Time Requirements
Where:
SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB)
t is the required settling time in seconds
RTOTAL is the sum of the AMUX0 resistance and any external source resistance.
n is the ADC resolution in bits (10).
Differential Mode
Single-Ended Mode
MUX
Select
MUX Select
Px.x
Px.x
RMUX = 5k
RMUX = 5k
CSAMPLE = 5pF
CSAMPLE = 5pF
RCInput= RMUX * CSAMPLE
RCInput= RMUX * CSAMPLE
CSAMPLE = 5pF
Px.x
RMUX = 5k
MUX Select
Figure 5.5. ADC0 Equivalent Input Circuits
Rev. 1.3
47
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 5.1. AMX0P: AMUX0 Positive Channel Select
R
R
R
R/W
R/W
R/W
R/W
-
-
-
AMX0P4
AMX0P3
AMX0P2
AMX0P1
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
AMX0P0 00000000
Bit0
SFR Address:
0xBB
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bits4–0: AMX0P4–0: AMUX0 Positive Input Selection
AMX0P4-0
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
10000
10001
10010
10011
10100
10101 - 11101
11110
11111
48
ADC0 Positive Input
(32-pin Package)
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0
P0.0
P0.1
P0.4
P0.5
RESERVED
Temp Sensor
VDD
Rev. 1.3
ADC0 Positive Input
(48-pin Package)
P2.0
P2.1
P2.2
P2.3
P2.5
P2.6
P3.0
P3.1
P3.4
P3.5
P3.7
P4.0
P4.3
P4.4
P4.5
P4.6
RESERVED
P0.3
P0.4
P1.1
P1.2
RESERVED
Temp Sensor
VDD
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 5.2. AMX0N: AMUX0 Negative Channel Select
R
R
R
R/W
R/W
R/W
R/W
-
-
-
AMX0N4
AMX0N3
AMX0N2
AMX0N1
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
AMX0N0 00000000
Bit0
SFR Address:
0xBA
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bits4–0: AMX0N4–0: AMUX0 Negative Input Selection.
Note that when GND is selected as the Negative Input, ADC0 operates in Single-ended
mode. For all other Negative Input selections, ADC0 operates in Differential mode.
AMX0N4-0
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
10000
10001
10010
10011
10100
10101 - 11101
11110
11111
ADC0 Negative Input
(32-pin Package)
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7
P3.0
P0.0
P0.1
P0.4
P0.5
RESERVED
VREF
GND (Single-Ended Mode)
Rev. 1.3
ADC0 Negative Input
(48-pin Package)
P2.0
P2.1
P2.2
P2.3
P2.5
P2.6
P3.0
P3.1
P3.4
P3.5
P3.7
P4.0
P4.3
P4.4
P4.5
P4.6
RESERVED
P0.3
P0.4
P1.1
P1.2
RESERVED
VREF
GND (Single-Ended Mode)
49
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 5.3. ADC0CF: ADC0 Configuration
R/W
R/W
R/W
R/W
AD0SC4
AD0SC3
AD0SC2
AD0SC1
Bit7
Bit6
Bit5
Bit4
R/W
R/W
AD0SC0 AD0LJST
Bit3
Bit2
R/W
R/W
Reset Value
-
-
11111000
Bit1
Bit0
SFR Address:
0xBC
Bits7–3: AD0SC4–0: ADC0 SAR Conversion Clock Period Bits.
SAR Conversion clock is derived from system clock by the following equation, where
AD0SC refers to the 5-bit value held in bits AD0SC4-0. SAR Conversion clock requirements
are given in Table 5.1.
SYSCLK
AD0SC = ---------------------- – 1
CLK SAR
Bit2:
AD0LJST: ADC0 Left Justify Select.
0: Data in ADC0H:ADC0L registers are right-justified.
1: Data in ADC0H:ADC0L registers are left-justified.
Bits1–0: UNUSED. Read = 00b; Write = don’t care.
SFR Definition 5.4. ADC0H: ADC0 Data Word MSB
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xBE
Bits7–0: ADC0 Data Word High-Order Bits.
For AD0LJST = 0: Bits 7–2 are the sign extension of Bit1. Bits 1-0 are the upper 2 bits of the
10-bit ADC0 Data Word.
For AD0LJST = 1: Bits 7–0 are the most-significant bits of the 10-bit ADC0 Data Word.
SFR Definition 5.5. ADC0L: ADC0 Data Word LSB
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xBD
Bits7–0: ADC0 Data Word Low-Order Bits.
For AD0LJST = 0: Bits 7–0 are the lower 8 bits of the 10-bit Data Word.
For AD0LJST = 1: Bits 7–6 are the lower 2 bits of the 10-bit Data Word. Bits 5–0 will always
read ‘0’.
50
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 5.6. ADC0CN: ADC0 Control
R/W
R/W
AD0EN
AD0TM
Bit7
Bit6
R/W
R/W
R/W
R/W
AD0INT AD0BUSY AD0WINT AD0CM2
Bit5
Bit4
Bit3
R/W
R/W
Reset Value
AD0CM1 AD0CM0 00000000
Bit2
Bit1
Bit0
(bit addressable)
SFR Address:
0xE8
Bit7:
AD0EN: ADC0 Enable Bit.
0: ADC0 Disabled. ADC0 is in low-power shutdown.
1: ADC0 Enabled. ADC0 is active and ready for data conversions.
Bit6:
AD0TM: ADC0 Track Mode Bit.
0: Normal Track Mode: When ADC0 is enabled, tracking is continuous unless a conversion
is in progress.
1: Low-power Track Mode: Tracking Defined by AD0CM2-0 bits (see below).
Bit5:
AD0INT: ADC0 Conversion Complete Interrupt Flag.
0: ADC0 has not completed a data conversion since the last time AD0INT was cleared.
1: ADC0 has completed a data conversion.
Bit4:
AD0BUSY: ADC0 Busy Bit.
Read:
0: ADC0 conversion is complete or a conversion is not currently in progress. AD0INT is set
to logic 1 on the falling edge of AD0BUSY.
1: ADC0 conversion is in progress.
Write:
0: No Effect.
1: Initiates ADC0 Conversion if AD0CM2-0 = 000b
Bit3:
AD0WINT: ADC0 Window Compare Interrupt Flag.
0: ADC0 Window Comparison Data match has not occurred since this flag was last cleared.
1: ADC0 Window Comparison Data match has occurred.
Bits2–0: AD0CM2–0: ADC0 Start of Conversion Mode Select.
When AD0TM = 0:
000: ADC0 conversion initiated on every write of ‘1’ to AD0BUSY.
001: ADC0 conversion initiated on overflow of Timer 0.
010: ADC0 conversion initiated on overflow of Timer 2.
011: ADC0 conversion initiated on overflow of Timer 1.
100: ADC0 conversion initiated on rising edge of external CNVSTR.
101: ADC0 conversion initiated on overflow of Timer 3.
11x: Reserved.
When AD0TM = 1:
000: Tracking initiated on write of ‘1’ to AD0BUSY and lasts 3 SAR clocks, followed by conversion.
001: Tracking initiated on overflow of Timer 0 and lasts 3 SAR clocks, followed by conversion.
010: Tracking initiated on overflow of Timer 2 and lasts 3 SAR clocks, followed by conversion.
011: Tracking initiated on overflow of Timer 1 and lasts 3 SAR clocks, followed by conversion.
100: ADC0 tracks only when CNVSTR input is logic low; conversion starts on rising CNVSTR edge.
101: Tracking initiated on overflow of Timer 3 and lasts 3 SAR clocks, followed by conversion.
11x: Reserved.
Rev. 1.3
51
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
5.4.
Programmable Window Detector
The ADC Programmable Window Detector continuously compares the ADC0 conversion results to
user-programmed limits, and notifies the system when a desired condition is detected. This is especially
effective in an interrupt-driven system, saving code space and CPU bandwidth while delivering faster system response times. The window detector interrupt flag (AD0WINT in register ADC0CN) can also be used
in polled mode. The ADC0 Greater-Than (ADC0GTH, ADC0GTL) and Less-Than (ADC0LTH, ADC0LTL)
registers hold the comparison values. The window detector flag can be programmed to indicate when measured data is inside or outside of the user-programmed limits, depending on the contents of the ADC0
Less-Than and ADC0 Greater-Than registers.
The Window Detector registers must be written with the same format (left/right justified, signed/unsigned)
as that of the current ADC configuration (left/right justified, single-ended/differential).
SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
11111111
0xC4
Bits7–0: High byte of ADC0 Greater-Than Data Word.
SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
11111111
0xC3
Bits7–0: Low byte of ADC0 Greater-Than Data Word.
52
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
00000000
0xC6
Bits7–0: High byte of ADC0 Less-Than Data Word.
SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xC5
Bits7–0: Low byte of ADC0 Less-Than Data Word.
Rev. 1.3
53
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
5.4.1. Window Detector In Single-Ended Mode
Figure 5.6 shows two example window comparisons for right-justified, single-ended data, with
ADC0LTH:ADC0LTL = 0x0080 (128d) and ADC0GTH:ADC0GTL = 0x0040 (64d). In single-ended mode,
the input voltage can range from ‘0’ to VREF x (1023/1024) with respect to GND, and is represented by a
10-bit unsigned integer value. In the left example, an AD0WINT interrupt will be generated if the ADC0
conversion word (ADC0H:ADC0L) is within the range defined by ADC0GTH:ADC0GTL and
ADC0LTH:ADC0LTL (if 0x0040 < ADC0H:ADC0L < 0x0080). In the right example, and AD0WINT interrupt
will be generated if the ADC0 conversion word is outside of the range defined by the ADC0GT and
ADC0LT registers (if ADC0H:ADC0L < 0x0040 or ADC0H:ADC0L > 0x0080). Figure 5.7 shows an example using left-justified data with equivalent ADC0GT and ADC0LT register settings.
ADC0H:ADC0L
ADC0H:ADC0L
Input Voltage
(Px.x - GND)
VREF x (1023/1024)
Input Voltage
(Px.x - GND)
VREF x (1023/1024)
0x03FF
0x03FF
AD0WINT
not affected
AD0WINT=1
0x0081
VREF x (128/1024)
0x0080
0x0081
ADC0LTH:ADC0LTL
VREF x (128/1024)
0x007F
0x0080
0x007F
AD0WINT=1
VREF x (64/1024)
0x0041
0x0040
ADC0GTH:ADC0GTL
VREF x (64/1024)
0x003F
0x0041
0x0040
ADC0GTH:ADC0GTL
AD0WINT
not affected
ADC0LTH:ADC0LTL
0x003F
AD0WINT=1
AD0WINT
not affected
0
0x0000
0
0x0000
Figure 5.6. ADC Window Compare Example: Right-Justified Single-Ended Data
ADC0H:ADC0L
ADC0H:ADC0L
Input Voltage
(Px.x - GND)
VREF x (1023/1024)
Input Voltage
(Px.x - GND)
0xFFC0
VREF x (1023/1024)
0xFFC0
AD0WINT
not affected
AD0WINT=1
0x2040
VREF x (128/1024)
0x2000
0x2040
ADC0LTH:ADC0LTL
VREF x (128/1024)
0x1FC0
0x2000
0x1FC0
AD0WINT=1
0x1040
VREF x (64/1024)
0x1000
0x1040
ADC0GTH:ADC0GTL
VREF x (64/1024)
0x0FC0
0x1000
AD0WINT
not affected
ADC0LTH:ADC0LTL
0x0FC0
AD0WINT=1
AD0WINT
not affected
0
ADC0GTH:ADC0GTL
0x0000
0
0x0000
Figure 5.7. ADC Window Compare Example: Left-Justified Single-Ended Data
54
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
5.4.2. Window Detector In Differential Mode
Figure 5.8 shows two example window comparisons for right-justified, differential data, with
ADC0LTH:ADC0LTL = 0x0040 (+64d) and ADC0GTH:ADC0GTH = 0xFFFF (-1d). In differential mode, the
measurable voltage between the input pins is between -VREF and VREF*(511/512). Output codes are represented as 10-bit 2’s complement signed integers. In the left example, an AD0WINT interrupt will be generated if the ADC0 conversion word (ADC0H:ADC0L) is within the range defined by ADC0GTH:ADC0GTL
and ADC0LTH:ADC0LTL (if 0xFFFF (-1d) < ADC0H:ADC0L < 0x0040 (64d)). In the right example, an
AD0WINT interrupt will be generated if the ADC0 conversion word is outside of the range defined by the
ADC0GT and ADC0LT registers (if ADC0H:ADC0L < 0xFFFF (-1d) or ADC0H:ADC0L > 0x0040 (+64d)).
Figure 5.9 shows an example using left-justified data with equivalent ADC0GT and ADC0LT register settings.
ADC0H:ADC0L
ADC0H:ADC0L
Input Voltage
(Px.x - Px.x)
VREF x (511/512)
Input Voltage
(Px.x - Px.x)
0x01FF
VREF x (511/512)
0x01FF
AD0WINT
not affected
AD0WINT=1
0x0041
VREF x (64/512)
0x0040
0x0041
ADC0LTH:ADC0LTL
VREF x (64/512)
0x003F
0x0040
0x003F
AD0WINT=1
0x0000
VREF x (-1/512)
0xFFFF
0x0000
ADC0GTH:ADC0GTL
VREF x (-1/512)
0xFFFE
0xFFFF
ADC0GTH:ADC0GTL
AD0WINT
not affected
ADC0LTH:ADC0LTL
0xFFFE
AD0WINT=1
AD0WINT
not affected
-VREF
0x0200
-VREF
0x0200
Figure 5.8. ADC Window Compare Example: Right-Justified Differential Data
ADC0H:ADC0L
ADC0H:ADC0L
Input Voltage
(Px.x - Px.x)
VREF x (511/512)
Input Voltage
(Px.x - Px.y)
0x7FC0
VREF x (511/512)
0x7FC0
AD0WINT
not affected
AD0WINT=1
0x1040
VREF x (64/512)
0x1000
0x1040
ADC0LTH:ADC0LTL
VREF x (64/512)
0x0FC0
0x1000
0x0FC0
AD0WINT=1
0x0000
VREF x (-1/512)
0xFFC0
0x0000
ADC0GTH:ADC0GTL
VREF x (-1/512)
0xFF80
0xFFC0
AD0WINT
not affected
ADC0LTH:ADC0LTL
0xFF80
AD0WINT=1
AD0WINT
not affected
-VREF
ADC0GTH:ADC0GTL
0x8000
-VREF
0x8000
Figure 5.9. ADC Window Compare Example: Left-Justified Differential Data
Rev. 1.3
55
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 5.1. ADC0 Electrical Characteristics
VDD = 3.0 V, VREF = 2.40 V, –40 to +85 °C unless otherwise specified
Parameter
Conditions
Min
Typ
Max
Units
DC Accuracy
Resolution
10
Integral Nonlinearity
Differential Nonlinearity
Guaranteed Monotonic
bits
±0.5
±1
LSB
±0.5
±1
LSB
Offset Error
–15
0
+15
LSB
Full Scale Error
–15
–1
+15
LSB
Offset Temperature Coefficient
10
ppm/°C
Dynamic Performance (10 kHz sine-wave Single-ended input, 1 dB below Full Scale, 200 ksps)
Signal-to-Noise Plus Distortion
Total Harmonic Distortion
51
Up to the 5th harmonic
Spurious-Free Dynamic Range
52.5
dB
–67
dB
78
dB
Conversion Rate
SAR Conversion Clock
3
MHz
Conversion Time in SAR Clocks
10
clocks
Track/Hold Acquisition Time
300
ns
Throughput Rate
200
ksps
0
–VREF
VREF
VREF
V
V
0
VDD
V
Analog Inputs
ADC Input Voltage Range
Single Ended (AIN+ – GND)
Differential (AIN+ – AIN–)
Absolute Pin Voltage with respect
Single Ended or Differential
to GND
Input Capacitance
5
pF
±0.1
°C
Gain
2.86
mV/°C
Gain Error2
±33.5
µV/ºC
776
mV
±8.51
mV
Temperature Sensor
Linearity
1
Offset1
(Temp = 0 °C)
Offset Error2
Power Specifications
Power Supply Current (VDD supOperating Mode, 200 ksps
plied to ADC0)
400
Power Supply Rejection
±0.3
Notes:
1. Includes ADC offset, gain, and linearity variations.
2. Represents one standard deviation from the mean.
56
Rev. 1.3
900
µA
mV/V
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
6.
Voltage Reference (C8051F340/1/2/3/4/5/6/7/A/B Only)
The Voltage reference MUX on C8051F34x devices is configurable to use an externally connected voltage
reference, the on-chip reference voltage generator, or the power supply voltage VDD (see Figure 6.1). The
REFSL bit in the Reference Control register (REF0CN) selects the reference source. For the internal reference or an external source, REFSL should be set to ‘0’; For VDD as the reference source, REFSL should
be set to ‘1’.
The BIASE bit enables the internal ADC bias generator, which is used by the ADC and Internal Oscillator.
This enable is forced to logic 1 when either of the aforementioned peripherals is enabled. The ADC bias
generator may be enabled manually by writing a ‘1’ to the BIASE bit in register REF0CN; see SFR Definition 6.1 for REF0CN register details. The Reference bias generator (see Figure 6.1) is used by the Internal
Voltage Reference, Temperature Sensor, and Clock Multiplier. The Reference bias is automatically
enabled when any of the aforementioned peripherals are enabled. The electrical specifications for the voltage reference and bias circuits are given in Table 6.1.
Important Note About the VREF Pin: The VREF pin, when not using the on-chip voltage reference or an
external precision reference, can be configured as a GPIO Port pin. When using an external voltage reference or the on-chip reference, the VREF pin should be configured as analog pin and skipped by the Digital
Crossbar. To configure the VREF pin for analog mode, set the corresponding bit in the PnMDIN register to
‘0’. To configure the Crossbar to skip the VREF pin, set the corresponding bit in register PnSKIP to ‘1’.
Refer to Section “15. Port Input/Output” on page 142 for complete Port I/O configuration details.
The temperature sensor connects to the ADC0 positive input multiplexer (see Section “5.1. Analog Multiplexer” on page 42 for details). The TEMPE bit in register REF0CN enables/disables the temperature
sensor. While disabled, the temperature sensor defaults to a high impedance state and any ADC0 measurements performed on the sensor result in meaningless data.
REFSL
TEMPE
BIASE
REFBE
REF0CN
AD0EN
EN
ADC Bias
To ADC,
Internal Oscillator
IOSCEN
VDD
R1
External
Voltage
Reference
Circuit
EN
VREF
Temp Sensor
To Analog Mux
0
VREF
(to ADC)
GND
VDD
1
CLKMUL
Enable
EN
TEMPE
Reference
Bias
To Clock Multiplier,
Temp Sensor
REFBE
EN
Internal
Reference
Figure 6.1. Voltage Reference Functional Block Diagram
Rev. 1.3
57
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 6.1. REF0CN: Reference Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
-
-
-
REFSL
TEMPE
BIASE
REFBE
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xD1
Bits7–3: UNUSED. Read = 00000b; Write = don’t care.
Bit3:
REFSL: Voltage Reference Select.
This bit selects the source for the internal voltage reference.
0: VREF pin used as voltage reference.
1: VDD used as voltage reference.
Bit2:
TEMPE: Temperature Sensor Enable Bit.
0: Internal Temperature Sensor off.
1: Internal Temperature Sensor on.
Bit1:
BIASE: Internal Analog Bias Generator Enable Bit.
0: Internal Bias Generator off.
1: Internal Bias Generator on.
Bit0:
REFBE: Internal Reference Buffer Enable Bit.
0: Internal Reference Buffer disabled.
1: Internal Reference Buffer enabled. Internal voltage reference driven on the VREF pin.
Table 6.1. Voltage Reference Electrical Characteristics
VDD = 3.0 V; –40 to +85 °C Unless Otherwise Specified
Parameter
Conditions
Min
Internal Reference (REFBE = 1)
25 °C ambient
2.38
Output Voltage
VREF Short-Circuit Current
VREF Temperature Coefficient
Load Regulation
Load = 0 to 200 µA to GND
4.7 µF tantalum, 0.1 µF ceramic
VREF Turn-on Time 1
bypass
VREF Turn-on Time 2
0.1 µF ceramic bypass
VREF Turn-on Time 3
no bypass cap
Power Supply Rejection
External Reference (REFBE = 0)
Input Voltage Range
Input Current
ADC Bias Generator
Reference Bias Generator
58
Typ
Max
Units
2.44
2.50
10
V
mA
15
ppm/°C
1.5
ppm/µA
2
ms
20
10
140
µs
µs
ppm/V
VDD
0
Sample Rate = 200 ksps; VREF =
3.0 V
Bias Generators
BIASE = ‘1’
Rev. 1.3
V
12
µA
100
40
µA
µA
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
7.
Comparators
C8051F34x devices include two on-chip programmable voltage Comparators. A block diagram of the comparators is shown in Figure 7.1, where “n” is the comparator number (0 or 1). The two Comparators operate identically with the following exceptions: (1) Their input selections differ, and (2) Comparator0 can be
used as a reset source. For input selection details, refer to SFR Definition 7.2 and SFR Definition 7.5.
Each Comparator offers programmable response time and hysteresis, an analog input multiplexer, and two
outputs that are optionally available at the Port pins: a synchronous “latched” output (CP0, CP1), or an
asynchronous “raw” output (CP0A, CP1A). The asynchronous signal is available even when the system
clock is not active. This allows the Comparators to operate and generate an output with the device in
STOP mode. When assigned to a Port pin, the Comparator outputs may be configured as open drain or
push-pull (see Section “15.2. Port I/O Initialization” on page 147). Comparator0 may also be used as a
reset source (see Section “11.5. Comparator0 Reset” on page 103).
The Comparator0 inputs are selected in the CPT0MX register (SFR Definition 7.2). The CMX0P1-CMX0P0
bits select the Comparator0 positive input; the CMX0N1-CMX0N0 bits select the Comparator0 negative
input. The Comparator1 inputs are selected in the CPT1MX register (SFR Definition 7.5). The
CMX1P1-CMX1P0 bits select the Comparator1 positive input; the CMX1N1-CMX1N0 bits select the
Comparator1 negative input.
Important Note About Comparator Inputs: The Port pins selected as Comparator inputs should be configured as analog inputs in their associated Port configuration register, and configured to be skipped by the
Crossbar (for details on Port configuration, see Section “15.3. General Purpose Port I/O” on page 150).
Rev. 1.3
59
CMXnN2
CMXnN1
CMXnN0
CPTnCN
CPTnMX
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
CPnEN
CPnOUT
CPnRIF
CPnFIF
CPnHYP1
VDD
CPn
Interrupt
CPnHYP0
CPnHYN1
CPnHYN0
CMXnP2
CMXnP1
CMXnP0
CPn
Rising-edge
CPn
Falling-edge
Interrupt
Logic
CPn +
CPnRIE
CPnFIE
+
D
-
SET
CLR
Q
Q
D
SET
CLR
CPn
Q
Q
Crossbar
(SYNCHRONIZER)
GND
CPnA
CPn -
Port I/O connection options vary with
package (32-pin or 48-pin)
CPTnMD
Reset Decision Tree
(Comprator 0 Only)
CPnRIE
CPnFIE
CPnMD1
CPnMD0
Figure 7.1. Comparator Functional Block Diagram
Comparator outputs can be polled in software, used as an interrupt source, and/or routed to a Port pin.
When routed to a Port pin, Comparator outputs are available asynchronous or synchronous to the system
clock; the asynchronous output is available even in STOP mode (with no system clock active). When disabled, the Comparator output (if assigned to a Port I/O pin via the Crossbar) defaults to the logic low state,
and supply current falls to less than 100 nA. See Section “15.1. Priority Crossbar Decoder” on
page 144 for details on configuring Comparator outputs via the digital Crossbar. Comparator inputs can be
externally driven from –0.25 V to (VDD) + 0.25 V without damage or upset. The complete Comparator electrical specifications are given in Table 7.1.
Comparator response time may be configured in software via the CPTnMD registers (see SFR Definition
7.3 and SFR Definition 7.6). Selecting a longer response time reduces the Comparator supply current. See
Table 7.1 for complete timing and supply current specifications.
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VIN+
VIN-
CP0+
CP0-
+
CP0
_
OUT
CIRCUIT CONFIGURATION
Positive Hysteresis Voltage
(Programmed with CP0HYP Bits)
VIN-
INPUTS
Negative Hysteresis Voltage
(Programmed by CP0HYN Bits)
VIN+
VOH
OUTPUT
VOL
Negative Hysteresis
Disabled
Positive Hysteresis
Disabled
Maximum
Negative Hysteresis
Maximum
Positive Hysteresis
Figure 7.2. Comparator Hysteresis Plot
Comparator hysteresis is programmed using Bits3-0 in the Comparator Control Register CPTnCN (shown
in SFR Definition 7.1 and SFR Definition 7.4). The amount of negative hysteresis voltage is determined by
the settings of the CPnHYN bits. As shown in Figure 7.2, various levels of negative hysteresis can be
programmed, or negative hysteresis can be disabled. In a similar way, the amount of positive hysteresis is
determined by the setting the CPnHYP bits.
Comparator interrupts can be generated on both rising-edge and falling-edge output transitions. (For Interrupt enable and priority control, see Section “9.3. Interrupt Handler” on page 88.) The CPnFIF flag is set
to ‘1’ upon a Comparator falling-edge, and the CPnRIF flag is set to ‘1’ upon the Comparator rising-edge.
Once set, these bits remain set until cleared by software. The output state of the Comparator can be
obtained at any time by reading the CPnOUT bit. The Comparator is enabled by setting the CPnEN bit to
‘1’, and is disabled by clearing this bit to ‘0’.
Rev. 1.3
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C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 7.1. CPT0CN: Comparator0 Control
R/W
R
R/W
R/W
CP0EN
CP0OUT
CP0RIF
CP0FIF
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
Reset Value
CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0 00000000
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x9B
Bit7:
CP0EN: Comparator0 Enable Bit.
0: Comparator0 Disabled.
1: Comparator0 Enabled.
Bit6:
CP0OUT: Comparator0 Output State Flag.
0: Voltage on CP0+ < CP0–.
1: Voltage on CP0+ > CP0–.
Bit5:
CP0RIF: Comparator0 Rising-Edge Flag.
0: No Comparator0 Rising Edge has occurred since this flag was last cleared.
1: Comparator0 Rising Edge has occurred.
Bit4:
CP0FIF: Comparator0 Falling-Edge Flag.
0: No Comparator0 Falling-Edge has occurred since this flag was last cleared.
1: Comparator0 Falling-Edge Interrupt has occurred.
Bits3–2: CP0HYP1–0: Comparator0 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 20 mV.
Bits1–0: CP0HYN1–0: Comparator0 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hysteresis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 20 mV.
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SFR Definition 7.2. CPT0MX: Comparator0 MUX Selection
R/W
Bit7
R/W
R/W
R/W
CMX0N2 CMX0N1 CMX0N0
Bit6
Bit5
Bit4
R/W
R/W
R/W
-
CMX0P2
CMX0P1
Bit3
Bit2
Bit1
R/W
Reset Value
CMX0P0 00000000
Bit0
SFR Address:
0x9F
Bit7:
UNUSED. Read = 0b, Write = don’t care.
Bits6–4: CMX0N2–CMX0N0: Comparator0 Negative Input MUX Select.
These bits select which Port pin is used as the Comparator0 negative input.
CMX0N1 CMX0N1 CMX0N0
0
0
0
0
1
0
0
1
1
0
0
1
0
1
0
Negative Input
(32-pin Package)
P1.1
P1.5
P2.1
P2.5
P0.1
Negative Input
(48-pin Package)
P2.1
P2.6
P3.5
P4.4
P0.4
Bit3:
UNUSED. Read = 0b, Write = don’t care.
Bits2–0: CMX0P2–CMX0P0: Comparator0 Positive Input MUX Select.
These bits select which Port pin is used as the Comparator0 positive input.
CMX0P1 CMX0P1 CMX0P0
0
0
0
0
1
0
0
1
1
0
0
1
0
1
0
Positive Input
(32-pin Package)
P1.0
P1.4
P2.0
P2.4
P0.0
Positive Input
(48-pin Package)
P2.0
P2.5
P3.4
P4.3
P0.3
Note that the port pins used by the comparator depend on the package type (32-pin or 48-pin).
Rev. 1.3
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C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 7.3. CPT0MD: Comparator0 Mode Selection
R/W
R/W
R/W
R/W
R/W
R/W
-
-
CP0RIE
CP0FIE
-
-
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
R/W
R/W
Reset Value
CP0MD1 CP0MD0 00000010
Bit1
Bit0
SFR Address:
0x9D
Bits7–6: UNUSED. Read = 00b. Write = don’t care.
Bit5:
CP0RIE: Comparator0 Rising-Edge Interrupt Enable.
0: Comparator0 rising-edge interrupt disabled.
1: Comparator0 rising-edge interrupt enabled.
Bit4:
CP0FIE: Comparator0 Falling-Edge Interrupt Enable.
0: Comparator0 falling-edge interrupt disabled.
1: Comparator0 falling-edge interrupt enabled.
Bits3–2: UNUSED. Read = 00b. Write = don’t care.
Bits1–0: CP0MD1–CP0MD0: Comparator0 Mode Select
These bits select the response time for Comparator0.
Mode
0
1
2
3
CP0MD1
0
0
1
1
CP0MD0
0
1
0
1
CP0 Response Time*
Fastest Response
Lowest Power
* See Table 7.1 for response time parameters.
64
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SFR Definition 7.4. CPT1CN: Comparator1 Control
R/W
R
R/W
R/W
CP1EN
CP1OUT
CP1RIF
CP1FIF
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
Reset Value
CP1HYP1 CP1HYP0 CP1HYN1 CP1HYN0 00000000
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x9A
Bit7:
CP1EN: Comparator1 Enable Bit.
0: Comparator1 Disabled.
1: Comparator1 Enabled.
Bit6:
CP1OUT: Comparator1 Output State Flag.
0: Voltage on CP1+ < CP1–.
1: Voltage on CP1+ > CP1–.
Bit5:
CP1RIF: Comparator1 Rising-Edge Flag.
0: No Comparator1 Rising Edge has occurred since this flag was last cleared.
1: Comparator1 Rising Edge has occurred.
Bit4:
CP1FIF: Comparator1 Falling-Edge Flag.
0: No Comparator1 Falling-Edge has occurred since this flag was last cleared.
1: Comparator1 Falling-Edge has occurred.
Bits3–2: CP1HYP1–0: Comparator1 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 20 mV.
Bits1–0: CP1HYN1–0: Comparator1 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hysteresis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 20 mV.
Rev. 1.3
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C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 7.5. CPT1MX: Comparator1 MUX Selection
R/W
Bit7
R/W
R/W
R/W
CMX1N2 CMX1N1 CMX1N0
Bit6
Bit5
Bit4
R/W
R/W
R/W
-
CMX1P2
CMX1P1
Bit3
Bit2
Bit1
R/W
Reset Value
CMX1P0 00000000
Bit0
SFR Address:
0x9E
Bit7:
UNUSED. Read = 0b, Write = don’t care.
Bits6–4: CMX1N2–CMX1N0: Comparator1 Negative Input MUX Select.
These bits select which Port pin is used as the Comparator1 negative input.
CMX1N2 CMX1N1 CMX1N0
0
0
0
0
1
0
0
1
1
0
0
1
0
1
0
Negative Input
(32-pin Package)
P1.3
P1.7
P2.3
P2.7
P0.5
Negative Input
(48-pin Package)
P2.3
P3.1
P4.0
P4.6
P1.2
Bit3:
UNUSED. Read = 0b, Write = don’t care.
Bits2–0: CMX1P1–CMX1P0: Comparator1 Positive Input MUX Select.
These bits select which Port pin is used as the Comparator1 positive input.
CMX1P2 CMX1P1 CMX1P0
0
0
0
0
1
0
0
1
1
0
0
1
0
1
0
Positive Input
(32-pin Package)
P1.2
P1.6
P2.2
P2.6
P0.4
Positive Input
(48-pin Package)
P2.2
P3.0
P3.7
P4.5
P1.1
Note that the port pins used by the comparator depend on the package type (32-pin or 48-pin).
66
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SFR Definition 7.6. CPT1MD: Comparator1 Mode Selection
R/W
R/W
R/W
R/W
R/W
R/W
-
-
CP1RIE
CP1FIE
-
-
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
R/W
R/W
Reset Value
CP1MD1 CP1MD0 00000010
Bit1
Bit0
SFR Address:
0x9C
Bits7–6: UNUSED. Read = 00b, Write = don’t care.
Bit5:
CP1RIE: Comparator1 Rising-Edge Interrupt Enable.
0: Comparator1 rising-edge interrupt disabled.
1: Comparator1 rising-edge interrupt enabled.
Bit4:
CP1FIE: Comparator1 Falling-Edge Interrupt Enable.
0: Comparator1 falling-edge interrupt disabled.
1: Comparator1 falling-edge interrupt enabled.
Bits1–0: CP1MD1–CP1MD0: Comparator1 Mode Select.
These bits select the response time for Comparator1.
Mode
0
1
2
3
CP1MD1
0
0
1
1
CP1MD0
0
1
0
1
CP1 Response Time*
Fastest Response
Lowest Power
* See Table 7.1 for response time parameters.
Rev. 1.3
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C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 7.1. Comparator Electrical Characteristics
VDD = 3.0 V, –40 to +85 °C unless otherwise noted.
All specifications apply to both Comparator0 and Comparator1 unless otherwise noted.
Parameter
Conditions
Min
Typ
Max
Units
Response Time:
Mode 0, Vcm* = 1.5 V
CP0+ – CP0– = 100 mV
100
ns
CP0+ – CP0– = –100 mV
250
ns
Response Time:
Mode 1, Vcm* = 1.5 V
CP0+ – CP0– = 100 mV
175
ns
CP0+ – CP0– = –100 mV
500
ns
Response Time:
Mode 2, Vcm* = 1.5 V
CP0+ – CP0– = 100 mV
320
ns
CP0+ – CP0– = –100 mV
1100
ns
Response Time:
Mode 3, Vcm* = 1.5 V
CP0+ – CP0– = 100 mV
1050
ns
CP0+ – CP0– = –100 mV
5200
ns
Common-Mode Rejection
Ratio
1.5
4
mV/V
0
1
mV
Positive Hysteresis 1
CP0HYP1–0 = 00
Positive Hysteresis 2
CP0HYP1–0 = 01
2
5
10
mV
Positive Hysteresis 3
CP0HYP1–0 = 10
7
10
20
mV
Positive Hysteresis 4
CP0HYP1–0 = 11
15
20
30
mV
Negative Hysteresis 1
CP0HYN1–0 = 00
0
1
mV
Negative Hysteresis 2
CP0HYN1–0 = 01
2
5
10
mV
Negative Hysteresis 3
CP0HYN1–0 = 10
7
10
20
mV
Negative Hysteresis 4
CP0HYN1–0 = 11
15
20
30
mV
VDD + 0.25
V
Inverting or Non-Inverting
Input Voltage Range
–0.25
Input Capacitance
3
pF
Input Bias Current
0.001
nA
Input Offset Voltage
–5
+5
mV
Power Supply
Power Supply Rejection
0.1
mV/V
Power-up Time
10
µs
Mode 0
7.6
µA
Mode 1
3.2
µA
Mode 2
1.3
µA
Mode 3
0.4
µA
Supply Current at DC
*Note: Vcm is the common-mode voltage on CP0+ and CP0–.
68
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8.
Voltage Regulator (REG0)
C8051F34x devices include a voltage regulator (REG0). When enabled, the REG0 output appears on the
VDD pin and can be used to power external devices. REG0 can be enabled/disabled by software using bit
REGEN in register REG0CN. See Table 8.1 for REG0 electrical characteristics.
Note that the VBUS signal must be connected to the VBUS pin when using the device in a USB network.
The VBUS signal should only be connected to the REGIN pin when operating the device as a bus-powered
function. REG0 configuration options are shown in Figure 8.1–Figure 8.4.
8.1.
Regulator Mode Selection
REG0 offers a low power mode intended for use when the device is in suspend mode. In this low power
mode, the REG0 output remains as specified; however the REG0 dynamic performance (response time) is
degraded. See Table 8.1 for normal and low power mode supply current specifications. The REG0 mode
selection is controlled via the REGMOD bit in register REG0CN.
8.2.
VBUS Detection
When the USB Function Controller is used (see section Section “16. Universal Serial Bus Controller
(USB0)” on page 159), the VBUS signal should be connected to the VBUS pin. The VBSTAT bit (register
REG0CN) indicates the current logic level of the VBUS signal. If enabled, a VBUS interrupt will be generated when the VBUS signal matches the polarity selected by the VBPOL bit in register REG0CN. The
VBUS interrupt is level-sensitive, and has no associated interrupt pending flag. The VBUS interrupt will be
active as long as the VBUS signal matches the polarity selected by VBPOL. See Table 8.1 for VBUS input
parameters.
Important Note: When USB is selected as a reset source, a system reset will be generated when the
VBUS signal matches the polarity selected by the VBPOL bit. See Section “11. Reset Sources” on
page 100 for details on selecting USB as a reset source
Table 8.1. Voltage Regulator Electrical Specifications
–40 to +85 °C unless otherwise specified.
Parameter
Conditions
Max
Units
5.25
V
3.6
V
Output Current2
100
mA
VBUS Detection Input Low Voltage
1.0
V
Input Voltage Range1
Output Voltage (VDD)2
Typ
2.7
Output Current = 1 to 100 mA
VBUS Detection Input High Voltage
Bias Current
Min
3.0
3.3
3.0
Normal Mode (REGMOD = ‘0’)
Low Power Mode (REGMOD = ‘1’)
Dropout Voltage (VDO)3
V
65
35
111
61
1
µA
mV/mA
Notes:
1. Input range specified for regulation. When an external regulator is used, should be tied to VDD.
2. Output current is total regulator output, including any current required by the C8051F34x.
3. The minimum input voltage is 2.70 V or VDD + VDO (max load), whichever is greater.
Rev. 1.3
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VBUS
VBUS Sense
From VBUS
REGIN
5 V In
Voltage Regulator (REG0)
3 V Out
To 3 V
Power Net
Device
Power Net
VDD
Figure 8.1. REG0 Configuration: USB Bus-Powered
From VBUS
VBUS
VBUS Sense
From 5 V
Power Net
REGIN
5 V In
Voltage Regulator (REG0)
3 V Out
To 3 V
Power Net
Device
Power Net
VDD
Figure 8.2. REG0 Configuration: USB Self-Powered
70
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
From VBUS
VBUS
VBUS Sense
REGIN
5 V In
Voltage Regulator (REG0)
3 V Out
From 3 V
Power Net
Device
Power Net
VDD
Figure 8.3. REG0 Configuration: USB Self-Powered, Regulator Disabled
VBUS
VBUS Sense
From 5 V
Power Net
REGIN
5 V In
Voltage Regulator (REG0)
3 V Out
To 3 V
Power Net
Device
Power Net
VDD
Figure 8.4. REG0 Configuration: No USB Connection
Rev. 1.3
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C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 8.1. REG0CN: Voltage Regulator Control
R/W
R
R/W
REGDIS
VBSTAT
VBPOL
Bit7
Bit6
Bit5
R/W
R/W
R/W
R/W
R/W
Reset Value
REGMOD Reserved Reserved Reserved Reserved 00000000
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xC9
Bit7:
REGDIS: Voltage Regulator Disable.
0: Voltage Regulator Enabled.
1: Voltage Regulator Disabled.
Bit6:
VBSTAT: VBUS Signal Status.
0: VBUS signal currently absent (device not attached to USB network).
1: VBUS signal currently present (device attached to USB network).
Bit5:
VBPOL: VBUS Interrupt Polarity Select.
This bit selects the VBUS interrupt polarity.
0: VBUS interrupt active when VBUS is low.
1: VBUS interrupt active when VBUS is high.
Bit4:
REGMOD: Voltage Regulator Mode Select.
This bit selects the Voltage Regulator mode. When REGMOD is set to ‘1’, the voltage regulator operates in low power (suspend) mode.
0: USB0 Voltage Regulator in normal mode.
1: USB0 Voltage Regulator in low power mode.
Bits3–0: Reserved. Read = 0000b. Must Write = 0000b.
72
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9.
CIP-51 Microcontroller
The MCU system controller core is the CIP-51 microcontroller. The CIP-51 is fully compatible with the
MCS-51™ instruction set; standard 803x/805x assemblers and compilers can be used to develop software. The MCU family has a superset of all the peripherals included with a standard 8051. Included are
four 16-bit counter/timers (see description in Section 21), an enhanced full-duplex UART (see description
in Section 18), an Enhanced SPI (see description in Section 20), 256 bytes of internal RAM, 128 byte
Special Function Register (SFR) address space (Section 9.2.6), and 25 Port I/O (see description in Section 15). The CIP-51 also includes on-chip debug hardware (see description in Section 23), and interfaces
directly with the analog and digital subsystems providing a complete data acquisition or control-system
solution in a single integrated circuit.
The CIP-51 Microcontroller core implements the standard 8051 organization and peripherals as well as
additional custom peripherals and functions to extend its capability (see Figure 9.1 for a block diagram).
The CIP-51 includes the following features:
- Fully Compatible with MCS-51 Instruction
Set
- 0 to 48 MHz Clock Frequency
- 256 Bytes of Internal RAM
- 25 Port I/O
-
Extended Interrupt Handler
Reset Input
Power Management Modes
On-chip Debug Logic
Program and Data Memory Security
D8
D8
ACCUMULATOR
STACK POINTER
TMP1
TMP2
SRAM
ADDRESS
REGISTER
PSW
SRAM
(256 X 8)
D8
D8
D8
ALU
D8
DATA BUS
B REGISTER
D8
D8
D8
DATA BUS
DATA BUS
SFR_ADDRESS
BUFFER
D8
DATA POINTER
D8
D8
SFR
BUS
INTERFACE
SFR_CONTROL
SFR_WRITE_DATA
SFR_READ_DATA
DATA BUS
PC INCREMENTER
PROGRAM COUNTER (PC)
PRGM. ADDRESS REG.
MEM_ADDRESS
D8
MEM_CONTROL
A16
MEMORY
INTERFACE
MEM_WRITE_DATA
MEM_READ_DATA
PIPELINE
RESET
D8
CONTROL
LOGIC
SYSTEM_IRQs
CLOCK
D8
STOP
IDLE
POWER CONTROL
REGISTER
INTERRUPT
INTERFACE
EMULATION_IRQ
D8
Figure 9.1. CIP-51 Block Diagram
Rev. 1.3
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Performance
The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system
clock cycles to execute, and usually have a maximum system clock of 12 MHz. By contrast, the CIP-51
core executes 70% of its instructions in one or two system clock cycles, with no instructions taking more
than eight system clock cycles.
With the CIP-51's maximum system clock at 25 MHz, it has a peak throughput of 25 MIPS. The CIP-51 has
a total of 109 instructions. The table below shows the total number of instructions that for execution time.
Clocks to Execute
1
2
2/4
3
3/5
4
5
4/6
6
8
Number of Instructions
26
50
5
10
7
5
2
1
2
1
Programming and Debugging Support
In-system programming of the Flash program memory and communication with on-chip debug support
logic is accomplished via the Silicon Labs 2-Wire Development Interface (C2). Note that the re-programmable Flash can also be read and changed a single byte at a time by the application software using the
MOVC and MOVX instructions. This feature allows program memory to be used for non-volatile data storage as well as updating program code under software control.
The on-chip Silicon Labs 2-Wire (C2) Development Interface allows non-intrusive (uses no on-chip
resources), full speed, in-circuit debugging using the production MCU installed in the final application. This
debug logic supports inspection and modification of memory and registers, setting breakpoints, single
stepping, run and halt commands. All analog and digital peripherals are fully functional while debugging
using C2. The two C2 interface pins can be shared with user functions, allowing in-system debugging without occupying package pins. C2 details can be found in Section “23. C2 Interface” on page 271.
The CIP-51 is supported by development tools from Silicon Labs and third party vendors. Silicon Labs provides an integrated development environment (IDE) including editor, debugger, and programmer. The
IDE's debugger and programmer interface to the CIP-51 via the C2 interface to provide fast and efficient
in-system device programming and debugging. An 8051 assembler, linker and evaluation ‘C’ compiler are
included in the Development Kit. Many third party macro assemblers and C compilers are also available,
which can be used directly with the IDE.
9.1.
Instruction Set
The instruction set of the CIP-51 System Controller is fully compatible with the standard MCS-51™ instruction set. Standard 8051 development tools can be used to develop software for the CIP-51. All CIP-51
instructions are the binary and functional equivalent of their MCS-51™ counterparts, including opcodes,
addressing modes and effect on PSW flags. However, instruction timing is different than that of the standard 8051.
9.1.1. Instruction and CPU Timing
In many 8051 implementations, a distinction is made between machine cycles and clock cycles, with
machine cycles varying from 2 to 12 clock cycles in length. However, the CIP-51 implementation is based
solely on clock cycle timing. All instruction timings are specified in terms of clock cycles.
Due to the pipelined architecture of the CIP-51, most instructions execute in the same number of clock
cycles as there are program bytes in the instruction. Conditional branch instructions take two fewer clock
cycles to complete when the branch is not taken as opposed to when the branch is taken. Table 9.1 is the
CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock
cycles for each instruction.
74
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
9.1.2. MOVX Instruction and Program Memory
In the CIP-51, the MOVX instruction serves three purposes: accessing on-chip XRAM, accessing off-chip
data XRAM (only on C8051F340/1/4/5/8 devices), and accessing on-chip program Flash memory. The
Flash access feature provides a mechanism for user software to update program code and use the program memory space for non-volatile data storage (see Section “12. Flash Memory” on page 107). The
External Memory Interface (only on C8051F340/1/4/5/8 devices) provides a fast access interface to
off-chip data XRAM (or memory-mapped peripherals) via the MOVX instruction. Refer to Section
“13. External Data Memory Interface and On-Chip XRAM” on page 114. for details.
Table 9.1. CIP-51 Instruction Set Summary
Mnemonic
ADD A, Rn
ADD A, direct
ADD A, @Ri
ADD A, #data
ADDC A, Rn
ADDC A, direct
ADDC A, @Ri
ADDC A, #data
SUBB A, Rn
SUBB A, direct
SUBB A, @Ri
SUBB A, #data
INC A
INC Rn
INC direct
INC @Ri
DEC A
DEC Rn
DEC direct
DEC @Ri
INC DPTR
MUL AB
DIV AB
DA A
ANL A, Rn
ANL A, direct
ANL A, @Ri
ANL A, #data
ANL direct, A
ANL direct, #data
ORL A, Rn
ORL A, direct
ORL A, @Ri
Description
Arithmetic Operations
Add register to A
Add direct byte to A
Add indirect RAM to A
Add immediate to A
Add register to A with carry
Add direct byte to A with carry
Add indirect RAM to A with carry
Add immediate to A with carry
Subtract register from A with borrow
Subtract direct byte from A with borrow
Subtract indirect RAM from A with borrow
Subtract immediate from A with borrow
Increment A
Increment register
Increment direct byte
Increment indirect RAM
Decrement A
Decrement register
Decrement direct byte
Decrement indirect RAM
Increment Data Pointer
Multiply A and B
Divide A by B
Decimal adjust A
Logical Operations
AND Register to A
AND direct byte to A
AND indirect RAM to A
AND immediate to A
AND A to direct byte
AND immediate to direct byte
OR Register to A
OR direct byte to A
OR indirect RAM to A
Rev. 1.3
Bytes
Clock
Cycles
1
2
1
2
1
2
1
2
1
2
1
2
1
1
2
1
1
1
2
1
1
1
1
1
1
2
2
2
1
2
2
2
1
2
2
2
1
1
2
2
1
1
2
2
1
4
8
1
1
2
1
2
2
3
1
2
1
1
2
2
2
2
3
1
2
2
75
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 9.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic
ORL A, #data
ORL direct, A
ORL direct, #data
XRL A, Rn
XRL A, direct
XRL A, @Ri
XRL A, #data
XRL direct, A
XRL direct, #data
CLR A
CPL A
RL A
RLC A
RR A
RRC A
SWAP A
MOV A, Rn
MOV A, direct
MOV A, @Ri
MOV A, #data
MOV Rn, A
MOV Rn, direct
MOV Rn, #data
MOV direct, A
MOV direct, Rn
MOV direct, direct
MOV direct, @Ri
MOV direct, #data
MOV @Ri, A
MOV @Ri, direct
MOV @Ri, #data
MOV DPTR, #data16
MOVC A, @A+DPTR
MOVC A, @A+PC
MOVX A, @Ri
MOVX @Ri, A
MOVX A, @DPTR
MOVX @DPTR, A
PUSH direct
POP direct
XCH A, Rn
XCH A, direct
XCH A, @Ri
XCHD A, @Ri
76
Description
OR immediate to A
OR A to direct byte
OR immediate to direct byte
Exclusive-OR Register to A
Exclusive-OR direct byte to A
Exclusive-OR indirect RAM to A
Exclusive-OR immediate to A
Exclusive-OR A to direct byte
Exclusive-OR immediate to direct byte
Clear A
Complement A
Rotate A left
Rotate A left through Carry
Rotate A right
Rotate A right through Carry
Swap nibbles of A
Data Transfer
Move Register to A
Move direct byte to A
Move indirect RAM to A
Move immediate to A
Move A to Register
Move direct byte to Register
Move immediate to Register
Move A to direct byte
Move Register to direct byte
Move direct byte to direct byte
Move indirect RAM to direct byte
Move immediate to direct byte
Move A to indirect RAM
Move direct byte to indirect RAM
Move immediate to indirect RAM
Load DPTR with 16-bit constant
Move code byte relative DPTR to A
Move code byte relative PC to A
Move external data (8-bit address) to A
Move A to external data (8-bit address)
Move external data (16-bit address) to A
Move A to external data (16-bit address)
Push direct byte onto stack
Pop direct byte from stack
Exchange Register with A
Exchange direct byte with A
Exchange indirect RAM with A
Exchange low nibble of indirect RAM with A
Rev. 1.3
2
2
3
1
2
1
2
2
3
1
1
1
1
1
1
1
Clock
Cycles
2
2
3
1
2
2
2
2
3
1
1
1
1
1
1
1
1
2
1
2
1
2
2
2
2
3
2
3
1
2
2
3
1
1
1
1
1
1
2
2
1
2
1
1
1
2
2
2
1
2
2
2
2
3
2
3
2
2
2
3
3
3
3
3
3
3
2
2
1
2
2
2
Bytes
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 9.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic
CLR C
CLR bit
SETB C
SETB bit
CPL C
CPL bit
ANL C, bit
ANL C, /bit
ORL C, bit
ORL C, /bit
MOV C, bit
MOV bit, C
JC rel
JNC rel
JB bit, rel
JNB bit, rel
JBC bit, rel
ACALL addr11
LCALL addr16
RET
RETI
AJMP addr11
LJMP addr16
SJMP rel
JMP @A+DPTR
JZ rel
JNZ rel
CJNE A, direct, rel
CJNE A, #data, rel
CJNE Rn, #data, rel
CJNE @Ri, #data, rel
DJNZ Rn, rel
DJNZ direct, rel
NOP
Description
Boolean Manipulation
Clear Carry
Clear direct bit
Set Carry
Set direct bit
Complement Carry
Complement direct bit
AND direct bit to Carry
AND complement of direct bit to Carry
OR direct bit to carry
OR complement of direct bit to Carry
Move direct bit to Carry
Move Carry to direct bit
Jump if Carry is set
Jump if Carry is not set
Jump if direct bit is set
Jump if direct bit is not set
Jump if direct bit is set and clear bit
Program Branching
Absolute subroutine call
Long subroutine call
Return from subroutine
Return from interrupt
Absolute jump
Long jump
Short jump (relative address)
Jump indirect relative to DPTR
Jump if A equals zero
Jump if A does not equal zero
Compare direct byte to A and jump if not equal
Compare immediate to A and jump if not equal
Compare immediate to Register and jump if not equal
Compare immediate to indirect and jump if not equal
Decrement Register and jump if not zero
Decrement direct byte and jump if not zero
No operation
Rev. 1.3
Bytes
Clock
Cycles
1
2
1
2
1
2
2
2
2
2
2
2
2
2
3
3
3
1
2
1
2
1
2
2
2
2
2
2
2
2/4
2/4
3/5
3/5
3/5
2
3
1
1
2
3
2
1
2
2
3
3
3
3
2
3
1
4
5
6
6
4
5
4
4
2/4
2/4
3/5
3/5
3/5
4/6
2/4
3/5
1
77
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Notes on Registers, Operands and Addressing Modes:
Rn - Register R0-R7 of the currently selected register bank.
@Ri - Data RAM location addressed indirectly through R0 or R1.
rel - 8-bit, signed (two’s complement) offset relative to the first byte of the following instruction. Used by
SJMP and all conditional jumps.
direct - 8-bit internal data location’s address. This could be a direct-access Data RAM location
(0x00-0x7F) or an SFR (0x80-0xFF).
#data - 8-bit constant
#data16 - 16-bit constant
bit - Direct-accessed bit in Data RAM or SFR
addr11 - 11-bit destination address used by ACALL and AJMP. The destination must be within the same
2K-byte page of program memory as the first byte of the following instruction.
addr16 - 16-bit destination address used by LCALL and LJMP. The destination may be anywhere within
the 8K-byte program memory space.
There is one unused opcode (0xA5) that performs the same function as NOP.
All mnemonics copyrighted © Intel Corporation 1980.
78
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
9.2.
Memory Organization
The memory organization of the CIP-51 System Controller is similar to that of a standard 8051. There are
two separate memory spaces: program memory and data memory. Program and data memory share the
same address space but are accessed via different instruction types. The CIP-51 memory organization is
shown in Figure 9.2 and Figure 9.3.
DATA MEMORY (RAM)
INTERNAL DATA ADDRESS SPACE
PROGRAM/DATA MEMORY
(FLASH)
0xFFFF
0xFC00
0xFF
RESERVED
0xFBFF
0x80
0x7F
Upper 128 RAM
(Indirect Addressing
Only)
(Direct and Indirect
Addressing)
FLASH
(In-System
Programmable in 512
Byte Sectors)
0x30
0x2F
0x20
0x1F
0x00
Bit Addressable
Special Function
Register's
(Direct Addressing Only)
Lower 128 RAM
(Direct and Indirect
Addressing)
General Purpose
Registers
EXTERNAL DATA ADDRESS SPACE
0x0000
0xFFFF
Off-Chip XRAM
(Available only on devices
with EMIF)
0x1000
0x0FFF
XRAM - 4096 Bytes
(Accessable using MOVX
instruction)
USB FIFOs
1024 Bytes
0x07FF
0x0400
0x0000
Figure 9.2. On-Chip Memory Map for 64 kB Devices
Rev. 1.3
79
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
DATA MEMORY (RAM)
INTERNAL DATA ADDRESS SPACE
PROGRAM/DATA MEMORY
(FLASH)
0x7FFF
0xFF
FLASH
(In-System
Programmable in 512
Byte Sectors)
0x0000
0x80
0x7F
Upper 128 RAM
(Indirect Addressing
Only)
(Direct and Indirect
Addressing)
0x30
0x2F
0x20
0x1F
0x00
Bit Addressable
Special Function
Register's
(Direct Addressing Only)
Lower 128 RAM
(Direct and Indirect
Addressing)
General Purpose
Registers
EXTERNAL DATA ADDRESS SPACE
0xFFFF
Off-Chip XRAM
(Available only on devices
with EMIF)
0x0800
0x07FF
XRAM - 2048 Bytes
(Accessable using MOVX
instruction)
USB FIFOs
1024 Bytes
0x07FF
0x0400
0x0000
Figure 9.3. On-Chip Memory Map for 32 kB Devices
9.2.1. Program Memory
The CIP-51 core has a 64k-byte program memory space. The C8051F34x implements 64k or 32k bytes of
this program memory space as in-system, re-programmable Flash memory. Note that on the 64k versions
of the C8051F34x, addresses above 0xFBFF are reserved.
Program memory is normally assumed to be read-only. However, the CIP-51 can write to program memory
by setting the Program Store Write Enable bit (PSCTL.0) and using the MOVX instruction. This feature provides a mechanism for the CIP-51 to update program code and use the program memory space for
non-volatile data storage. Refer to Section “12. Flash Memory” on page 107 for further details.
80
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
9.2.2. Data Memory
The CIP-51 includes 256 of internal RAM mapped into the data memory space from 0x00 through 0xFF.
The lower 128 bytes of data memory are used for general purpose registers and scratch pad memory.
Either direct or indirect addressing may be used to access the lower 128 bytes of data memory. Locations
0x00 through 0x1F are addressable as four banks of general purpose registers, each bank consisting of
eight byte-wide registers. The next 16 bytes, locations 0x20 through 0x2F, may either be addressed as
bytes or as 128 bit locations accessible with the direct addressing mode.
The upper 128 bytes of data memory are accessible only by indirect addressing. This region occupies the
same address space as the Special Function Registers (SFR) but is physically separate from the SFR
space. The addressing mode used by an instruction when accessing locations above 0x7F determines
whether the CPU accesses the upper 128 bytes of data memory space or the SFRs. Instructions that use
direct addressing will access the SFR space. Instructions using indirect addressing above 0x7F access the
upper 128 bytes of data memory. Figure 9.2 illustrates the data memory organization of the CIP-51.
9.2.3. General Purpose Registers
The lower 32 bytes of data memory, locations 0x00 through 0x1F, may be addressed as four banks of general-purpose registers. Each bank consists of eight byte-wide registers designated R0 through R7. Only
one of these banks may be enabled at a time. Two bits in the program status word, RS0 (PSW.3) and RS1
(PSW.4), select the active register bank (see description of the PSW in SFR Definition 9.4). This allows
fast context switching when entering subroutines and interrupt service routines. Indirect addressing modes
use registers R0 and R1 as index registers.
9.2.4. Bit Addressable Locations
In addition to direct access to data memory organized as bytes, the sixteen data memory locations at 0x20
through 0x2F are also accessible as 128 individually addressable bits. Each bit has a bit address from
0x00 to 0x7F. Bit 0 of the byte at 0x20 has bit address 0x00 while bit7 of the byte at 0x20 has bit address
0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by
the type of instruction used (bit source or destination operands as opposed to a byte source or destination).
The MCS-51™ assembly language allows an alternate notation for bit addressing of the form XX.B where
XX is the byte address and B is the bit position within the byte. For example, the instruction:
MOV
C, 22h.3
moves the Boolean value at 0x13 (bit 3 of the byte at location 0x22) into the Carry flag.
9.2.5. Stack
A programmer's stack can be located anywhere in the 256-byte data memory. The stack area is designated using the Stack Pointer (SP, 0x81) SFR. The SP will point to the last location used. The next value
pushed on the stack is placed at SP+1 and then SP is incremented. A reset initializes the stack pointer to
location 0x07. Therefore, the first value pushed on the stack is placed at location 0x08, which is also the
first register (R0) of register bank 1. Thus, if more than one register bank is to be used, the SP should be
initialized to a location in the data memory not being used for data storage. The stack depth can extend up
to 256 bytes.
Rev. 1.3
81
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
9.2.6. Special Function Registers
The direct-access data memory locations from 0x80 to 0xFF constitute the special function registers
(SFRs). The SFRs provide control and data exchange with the CIP-51's resources and peripherals. The
CIP-51 duplicates the SFRs found in a typical 8051 implementation as well as implementing additional
SFRs used to configure and access the sub-systems unique to the MCU. This allows the addition of new
functionality while retaining compatibility with the MCS-51™ instruction set. Table 9.2 lists the SFRs implemented in the CIP-51 System Controller.
The SFR registers are accessed anytime the direct addressing mode is used to access memory locations
from 0x80 to 0xFF. SFRs with addresses ending in 0x0 or 0x8 (e.g. P0, TCON, SCON0, IE, etc.) are
bit-addressable as well as byte-addressable. All other SFRs are byte-addressable only. Unoccupied
addresses in the SFR space are reserved for future use. Accessing these areas will have an indeterminate
effect and should be avoided. Refer to the corresponding pages of the datasheet, as indicated in Table 9.3,
for a detailed description of each register.
Table 9.2. Special Function Register (SFR) Memory Map
F8
F0
E8
E0
D8
D0
C8
C0
B8
B0
A8
A0
98
90
88
80
SPI0CN
PCA0L
PCA0H PCA0CPL0 PCA0CPH0 PCA0CPL4 PCA0CPH4
B
P0MDIN
P1MDIN
P2MDIN
P3MDIN
P4MDIN
EIP1
ADC0CN PCA0CPL1 PCA0CPH1 PCA0CPL2 PCA0CPH2 PCA0CPL3 PCA0CPH3
ACC
XBR0
XBR1
XBR2
IT01CF
SMOD1
EIE1
PCA0CN PCA0MD PCA0CPM0 PCA0CPM1 PCA0CPM2 PCA0CPM3 PCA0CPM4
PSW
REF0CN
SCON1
SBUF1
P0SKIP
P1SKIP
P2SKIP
TMR2CN REG0CN TMR2RLL TMR2RLH
TMR2L
TMR2H
SMB0CN SMB0CF SMB0DAT ADC0GTL ADC0GTH ADC0LTL ADC0LTH
IP
CLKMUL
AMX0N
AMX0P
ADC0CF
ADC0L
ADC0H
P3
OSCXCN OSCICN
OSCICL
SBRLL1
SBRLH1
FLSCL
IE
CLKSEL
EMI0CN
SBCON1
P4MDOUT
P2
SPI0CFG SPI0CKR SPI0DAT P0MDOUT P1MDOUT P2MDOUT
SCON0
SBUF0
CPT1CN
CPT0CN
CPT1MD
CPT0MD
CPT1MX
P1
TMR3CN TMR3RLL TMR3RLH
TMR3L
TMR3H
USB0ADR
TCON
TMOD
TL0
TL1
TH0
TH1
CKCON
P0
SP
DPL
DPH
EMI0TC
EMI0CF
OSCLCN
0(8)
1(9)
2(A)
3(B)
4(C)
5(D)
6(E)
(bit addressable)
82
Rev. 1.3
VDM0CN
EIP2
RSTSRC
EIE2
P3SKIP
USB0XCN
P4
FLKEY
PFE0CN
P3MDOUT
CPT0MX
USB0DAT
PSCTL
PCON
7(F)
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 9.3. Special Function Registers
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
Register
Address
Description
ACC
0xE0
Accumulator
ADC0CF
0xBC
ADC0 Configuration
ADC0CN
0xE8
ADC0 Control
ADC0GTH
0xC4
ADC0 Greater-Than Compare High
ADC0GTL
0xC3
ADC0 Greater-Than Compare Low
ADC0H
0xBE
ADC0 High
ADC0L
0xBD
ADC0 Low
ADC0LTH
0xC6
ADC0 Less-Than Compare Word High
ADC0LTL
0xC5
ADC0 Less-Than Compare Word Low
AMX0N
0xBA
AMUX0 Negative Channel Select
AMX0P
0xBB
AMUX0 Positive Channel Select
B
0xF0
B Register
CKCON
0x8E
Clock Control
CLKMUL
0xB9
Clock Multiplier
CLKSEL
0xA9
Clock Select
CPT0CN
0x9B
Comparator0 Control
CPT0MD
0x9D
Comparator0 Mode Selection
CPT0MX
0x9F
Comparator0 MUX Selection
CPT1CN
0x9A
Comparator1 Control
CPT1MD
0x9C
Comparator1 Mode Selection
CPT1MX
0x9E
Comparator1 MUX Selection
DPH
0x83
Data Pointer High
DPL
0x82
Data Pointer Low
EIE1
0xE6
Extended Interrupt Enable 1
EIE2
0xE7
Extended Interrupt Enable 2
EIP1
0xF6
Extended Interrupt Priority 1
EIP2
0xF7
Extended Interrupt Priority 2
EMI0CN
0xAA
External Memory Interface Control
EMI0CF
0x85
External Memory Interface Configuration
EMI0TC
0x84
External Memory Interface Timing
FLKEY
0xB7
Flash Lock and Key
FLSCL
0xB6
Flash Scale
IE
0xA8
Interrupt Enable
IP
0xB8
Interrupt Priority
IT01CF
0xE4
INT0/INT1 Configuration
OSCICL
0xB3
Internal Oscillator Calibration
OSCICN
0xB2
Internal Oscillator Control
OSCLCN
0x86
Internal Low-Frequency Oscillator Control
OSCXCN
0xB1
External Oscillator Control
P0
0x80
Port 0 Latch
P0MDIN
0xF1
Port 0 Input Mode Configuration
P0MDOUT 0xA4
Port 0 Output Mode Configuration
P0SKIP
0xD4
Port 0 Skip
P1
0x90
Port 1 Latch
Rev. 1.3
Page
87
50
51
52
52
50
50
53
53
49
48
88
241
138
140
62
64
63
65
67
66
86
86
93
95
94
95
117
118
123
112
113
91
92
96
133
132
134
137
150
150
151
151
152
83
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 9.3. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
Register
Address
Description
P1MDIN
0xF2
Port 1 Input Mode Configuration
P1MDOUT 0xA5
Port 1 Output Mode Configuration
P1SKIP
0xD5
Port 1 Skip
P2
0xA0
Port 2 Latch
P2MDIN
0xF3
Port 2 Input Mode Configuration
P2MDOUT 0xA6
Port 2 Output Mode Configuration
P2SKIP
0xD6
Port 2 Skip
P3
0xB0
Port 3 Latch
P3MDIN
0xF4
Port 3 Input Mode Configuration
P3MDOUT 0xA7
Port 3 Output Mode Configuration
P3SKIP
0xDF
Port 3Skip
P4
0xC7
Port 4 Latch
P4MDIN
0xF5
Port 4 Input Mode Configuration
P4MDOUT 0xAE
Port 4 Output Mode Configuration
PCA0CN
0xD8
PCA Control
PCA0CPH0 0xFC
PCA Capture 0 High
PCA0CPH1 0xEA
PCA Capture 1 High
PCA0CPH2 0xEC
PCA Capture 2 High
PCA0CPH3 0xEE
PCA Capture 3High
PCA0CPH4 0xFE
PCA Capture 4 High
PCA0CPL0 0xFB
PCA Capture 0 Low
PCA0CPL1 0xE9
PCA Capture 1 Low
PCA0CPL2 0xEB
PCA Capture 2 Low
PCA0CPL3 0xED
PCA Capture 3 Low
PCA0CPL4 0xFD
PCA Capture 4 Low
PCA0CPM0 0xDA
PCA Module 0 Mode Register
PCA0CPM1 0xDB
PCA Module 1 Mode Register
PCA0CPM2 0xDC
PCA Module 2 Mode Register
PCA0CPM3 0xDD
PCA Module 3 Mode Register
PCA0CPM4 0xDE
PCA Module 4 Mode Register
PCA0H
0xFA
PCA Counter High
PCA0L
0xF9
PCA Counter Low
PCA0MD
0xD9
PCA Mode
PCON
0x87
Power Control
PFE0CN
0xAF
Prefetch Engine Control
PSCTL
0x8F
Program Store R/W Control
PSW
0xD0
Program Status Word
REF0CN
0xD1
Voltage Reference Control
REG0CN
0xC9
Voltage Regulator Control
RSTSRC
0xEF
Reset Source Configuration/Status
SBCON1
0xAC
UART1 Baud Rate Generator Control
SBRLH1
0xB5
UART1 Baud Rate Generator High
SBRLL1
0xB4
UART1 Baud Rate Generator Low
SBUF1
0xD3
UART1 Data Buffer
SCON1
0xD2
UART1 Control
84
Rev. 1.3
Page
152
152
153
153
153
154
154
155
155
155
156
156
157
157
266
270
270
270
270
270
269
269
269
269
269
268
268
268
268
268
269
269
267
98
99
112
87
58
72
105
220
221
221
220
218
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 9.3. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
Register
Address
Description
SBUF0
0x99
UART0 Data Buffer
SCON0
0x98
UART0 Control
SMB0CF
0xC1
SMBus Configuration
SMB0CN
0xC0
SMBus Control
SMB0DAT
0xC2
SMBus Data
SMOD1
0xE5
UART1 Mode
SP
0x81
Stack Pointer
SPI0CFG
0xA1
SPI Configuration
SPI0CKR
0xA2
SPI Clock Rate Control
SPI0CN
0xF8
SPI Control
SPI0DAT
0xA3
SPI Data
TCON
0x88
Timer/Counter Control
TH0
0x8C
Timer/Counter 0 High
TH1
0x8D
Timer/Counter 1 High
TL0
0x8A
Timer/Counter 0 Low
TL1
0x8B
Timer/Counter 1 Low
TMOD
0x89
Timer/Counter Mode
TMR2CN
0xC8
Timer/Counter 2 Control
TMR2H
0xCD
Timer/Counter 2 High
TMR2L
0xCC
Timer/Counter 2 Low
TMR2RLH
0xCB
Timer/Counter 2 Reload High
TMR2RLL
0xCA
Timer/Counter 2 Reload Low
TMR3CN
0x91
Timer/Counter 3Control
TMR3H
0x95
Timer/Counter 3 High
TMR3L
0x94
Timer/Counter 3Low
TMR3RLH
0x93
Timer/Counter 3 Reload High
TMR3RLL
0x92
Timer/Counter 3 Reload Low
VDD Monitor Control
VDM0CN
0xFF
USB0ADR
0x96
USB0 Indirect Address Register
USB0DAT
0x97
USB0 Data Register
USB0XCN
0xD7
USB0 Transceiver Control
XBR0
0xE1
Port I/O Crossbar Control 0
XBR1
0xE2
Port I/O Crossbar Control 1
XBR2
0xE3
Port I/O Crossbar Control 2
All Other Addresses
Reserved
Rev. 1.3
Page
211
210
194
196
198
219
86
229
231
230
231
239
242
242
242
242
240
247
248
248
248
248
253
254
254
254
254
102
163
164
161
148
149
149
85
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
9.2.7. Register Descriptions
Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved bits
should not be set to logic l. Future product versions may use these bits to implement new features in which
case the reset value of the bit will be logic 0, selecting the feature's default state. Detailed descriptions of
the remaining SFRs are included in the sections of the datasheet associated with their corresponding system function.
SFR Definition 9.1. DPL: Data Pointer Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x82
Bits7–0: DPL: Data Pointer Low.
The DPL register is the low byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed memory.
SFR Definition 9.2. DPH: Data Pointer High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x83
Bits7–0: DPH: Data Pointer High.
The DPH register is the high byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed memory.
SFR Definition 9.3. SP: Stack Pointer
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
00000111
0x81
Bits7–0: SP: Stack Pointer.
The Stack Pointer holds the location of the top of the stack. The stack pointer is incremented
before every PUSH operation. The SP register defaults to 0x07 after reset.
86
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 9.4. PSW: Program Status Word
R/W
R/W
R/W
R/W
R/W
R/W
CY
Bit7
R/W
R
AC
F0
RS1
RS0
Bit6
Bit5
Bit4
Bit3
OV
F1
PARITY
00000000
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Reset Value
0xD0
Bit7:
CY: Carry Flag.
This bit is set when the last arithmetic operation resulted in a carry (addition) or a borrow
(subtraction). It is cleared to logic 0 by all other arithmetic operations.
Bit6:
AC: Auxiliary Carry Flag
This bit is set when the last arithmetic operation resulted in a carry into (addition) or a borrow
from (subtraction) the high order nibble. It is cleared to logic 0 by all other arithmetic operations.
Bit5:
F0: User Flag 0.
This is a bit-addressable, general purpose flag for use under software control.
Bits4–3: RS1–RS0: Register Bank Select.
These bits select which register bank is used during register accesses.
RS1
0
0
1
1
Bit2:
Bit1:
Bit0:
RS0
0
1
0
1
Register Bank
0
1
2
3
Address
0x00 - 0x07
0x08 - 0x0F
0x10 - 0x17
0x18 - 0x1F
OV: Overflow Flag.
This bit is set to 1 under the following circumstances:
• An ADD, ADDC, or SUBB instruction causes a sign-change overflow.
• A MUL instruction results in an overflow (result is greater than 255).
• A DIV instruction causes a divide-by-zero condition.
The OV bit is cleared to 0 by the ADD, ADDC, SUBB, MUL, and DIV instructions in all other
cases.
F1: User Flag 1.
This is a bit-addressable, general purpose flag for use under software control.
PARITY: Parity Flag.
This bit is set to logic 1 if the sum of the eight bits in the accumulator is odd and cleared if the
sum is even.
SFR Definition 9.5. ACC: Accumulator
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
ACC.7
ACC.6
ACC.5
ACC.4
ACC.3
ACC.2
ACC.1
ACC.0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
0xE0
Bits7–0: ACC: Accumulator.
This register is the accumulator for arithmetic operations.
Rev. 1.3
87
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 9.6. B: B Register
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
B.7
B.6
B.5
B.4
B.3
B.2
B.1
B.0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Reset Value
0xF0
Bits7–0: B: B Register.
This register serves as a second accumulator for certain arithmetic operations.
9.3.
Interrupt Handler
The CIP-51 includes an extended interrupt system supporting multiple interrupt sources with two priority
levels. The allocation of interrupt sources between on-chip peripherals and external inputs pins varies
according to the specific version of the device. Each interrupt source has one or more associated interrupt-pending flag(s) located in an SFR. When a peripheral or external source meets a valid interrupt condition, the associated interrupt-pending flag is set to logic 1.
If interrupts are enabled for the source, an interrupt request is generated when the interrupt-pending flag is
set. As soon as execution of the current instruction is complete, the CPU generates an LCALL to a predetermined address to begin execution of an interrupt service routine (ISR). Each ISR must end with an RETI
instruction, which returns program execution to the next instruction that would have been executed if the
interrupt request had not occurred. If interrupts are not enabled, the interrupt-pending flag is ignored by the
hardware and program execution continues as normal. (The interrupt-pending flag is set to logic 1 regardless of the interrupt's enable/disable state.)
Each interrupt source can be individually enabled or disabled through the use of an associated interrupt
enable bit in an SFR (IE-EIE2). However, interrupts must first be globally enabled by setting the EA bit
(IE.7) to logic 1 before the individual interrupt enables are recognized. Setting the EA bit to logic 0 disables
all interrupt sources regardless of the individual interrupt-enable settings.
Some interrupt-pending flags are automatically cleared by the hardware when the CPU vectors to the ISR.
However, most are not cleared by the hardware and must be cleared by software before returning from the
ISR. If an interrupt-pending flag remains set after the CPU completes the return-from-interrupt (RETI)
instruction, a new interrupt request will be generated immediately and the CPU will re-enter the ISR after
the completion of the next instruction.
9.3.1. MCU Interrupt Sources and Vectors
The MCU supports multiple interrupt sources. Software can simulate an interrupt by setting any interrupt-pending flag to logic 1. If interrupts are enabled for the flag, an interrupt request will be generated and
the CPU will vector to the ISR address associated with the interrupt-pending flag. MCU interrupt sources,
associated vector addresses, priority order and control bits are summarized in Table 9.4 on page 90. Refer
to the datasheet section associated with a particular on-chip peripheral for information regarding valid
interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s).
9.3.2. External Interrupts
The INT0 and INT1 external interrupt sources are configurable as active high or low, edge or level sensitive. The IN0PL (INT0 Polarity) and IN1PL (INT1 Polarity) bits in the IT01CF register select active high or
active low; the IT0 and IT1 bits in TCON (Section “21.1. Timer 0 and Timer 1” on page 235) select level
or edge sensitive. The following table lists the possible configurations.
88
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
IT0
1
1
0
0
IN0PL
0
1
0
1
INT0 Interrupt
Active low, edge sensitive
Active high, edge sensitive
Active low, level sensitive
Active high, level sensitive
IT1
1
1
0
0
IN1PL
0
1
0
1
INT1 Interrupt
Active low, edge sensitive
Active high, edge sensitive
Active low, level sensitive
Active high, level sensitive
INT0 and INT1 are assigned to Port pins as defined in the IT01CF register (see SFR Definition 9.13). Note
that INT0 and INT0 Port pin assignments are independent of any Crossbar assignments. INT0 and INT1
will monitor their assigned Port pins without disturbing the peripheral that was assigned the Port pin via the
Crossbar. To assign a Port pin only to INT0 and/or INT1, configure the Crossbar to skip the selected pin(s).
This is accomplished by setting the associated bit in register XBR0 (see Section “15.1. Priority Crossbar
Decoder” on page 144 for complete details on configuring the Crossbar). In the typical configuration, the
external interrupt pin should be skipped in the crossbar and configured as open-drain with the pin latch set
to '1'.
IE0 (TCON.1) and IE1 (TCON.3) serve as the interrupt-pending flags for the INT0 and INT1 external interrupts, respectively. If an INT0 or INT1 external interrupt is configured as edge-sensitive, the corresponding
interrupt-pending flag is automatically cleared by the hardware when the CPU vectors to the ISR. When
configured as level sensitive, the interrupt-pending flag remains logic 1 while the input is active as defined
by the corresponding polarity bit (IN0PL or IN1PL); the flag remains logic 0 while the input is inactive. The
external interrupt source must hold the input active until the interrupt request is recognized. It must then
deactivate the interrupt request before execution of the ISR completes or another interrupt request will be
generated.
9.3.3. Interrupt Priorities
Each interrupt source can be individually programmed to one of two priority levels: low or high. A low priority interrupt service routine can be preempted by a high priority interrupt. A high priority interrupt cannot be
preempted. Each interrupt has an associated interrupt priority bit in an SFR (IP or EIP2) used to configure
its priority level. Low priority is the default. If two interrupts are recognized simultaneously, the interrupt with
the higher priority is serviced first. If both interrupts have the same priority level, a fixed priority order is
used to arbitrate, given in Table 9.4.
9.3.4. Interrupt Latency
Interrupt response time depends on the state of the CPU when the interrupt occurs. Pending interrupts are
sampled and priority decoded each system clock cycle. Therefore, the fastest possible response time is 6
system clock cycles: 1 clock cycle to detect the interrupt and 5 clock cycles to complete the LCALL to the
ISR. If an interrupt is pending when a RETI is executed, a single instruction is executed before an LCALL
is made to service the pending interrupt. Therefore, the maximum response time for an interrupt (when no
other interrupt is currently being serviced or the new interrupt is of greater priority) occurs when the CPU is
performing an RETI instruction followed by a DIV as the next instruction. In this case, the response time is
20 system clock cycles: 1 clock cycle to detect the interrupt, 6 clock cycles to execute the RETI, 8 clock
cycles to complete the DIV instruction and 5 clock cycles to execute the LCALL to the ISR. If the CPU is
executing an ISR for an interrupt with equal or higher priority, the new interrupt will not be serviced until the
current ISR completes, including the RETI and following instruction.
Note that the CPU is stalled during Flash write/erase operations and USB FIFO MOVX accesses (see
Section “13.2. Accessing USB FIFO Space” on page 115). Interrupt service latency will be increased for
interrupts occurring while the CPU is stalled. The latency for these situations will be determined by the
standard interrupt service procedure (as described above) and the amount of time the CPU is stalled.
Rev. 1.3
89
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Bit addressable?
Cleared by HW?
Table 9.4. Interrupt Summary
Enable
Flag
N/A
N/A
Always
Enabled
IE0 (TCON.1)
Y
Y
EX0 (IE.0) PX0 (IP.0)
1
TF0 (TCON.5)
Y
Y
ET0 (IE.1) PT0 (IP.1)
0x0013
2
IE1 (TCON.3)
Y
Y
EX1 (IE.2) PX1 (IP.2)
0x001B
3
Y
Y
ET1 (IE.3) PT1 (IP.3)
UART0
0x0023
4
Y
N
ES0 (IE.4) PS0 (IP.4)
Timer 2 Overflow
0x002B
5
Y
N
ET2 (IE.5) PT2 (IP.5)
SPI0
0x0033
6
TF1 (TCON.7)
RI0 (SCON0.0)
TI0 (SCON0.1)
TF2H (TMR2CN.7)
TF2L (TMR2CN.6)
SPIF (SPI0CN.7)
WCOL (SPI0CN.6)
MODF (SPI0CN.5)
RXOVRN (SPI0CN.4)
Y
N
ESPI0
(IE.6)
SMB0
0x003B
7
SI (SMB0CN.0)
Y
USB0
0x0043
8
Special
N
0x004B
9
AD0WINT
(ADC0CN.3)
Y
0x0053
10
AD0INT (ADC0CN.5)
Y
0x005B
11
Comparator0
0x0063
12
Comparator1
0x006B
13
Timer 3 Overflow
0x0073
14
VBUS Level
0x007B
15
N/A
UART1
0x0083
16
RI1 (SCON1.0)
TI1 (SCON1.1)
Interrupt Source
Interrupt
Vector
Reset
0x0000
Top
0x0003
0
0x000B
External Interrupt 0
(INT0)
Timer 0 Overflow
External Interrupt 1
(INT1)
Timer 1 Overflow
ADC0 Window
Compare
ADC0 Conversion
Complete
Programmable Counter
Array
Priority
Pending Flag
Order
None
CF (PCA0CN.7)
CCFn (PCA0CN.n)
CP0FIF (CPT0CN.4)
CP0RIF (CPT0CN.5)
CP1FIF (CPT1CN.4)
CP1RIF (CPT1CN.5)
TF3H (TMR3CN.7)
TF3L (TMR3CN.6)
Y
N
N
N
N/A
N
ESMB0
(EIE1.0)
EUSB0
N
(EIE1.1)
EWADC0
N
(EIE1.2)
EADC0
N
(EIE1.3)
EPCA0
N
(EIE1.4)
ECP0
N
(EIE1.5)
ECP1
N
(EIE1.6)
ET3
N
(EIE1.7)
EVBUS
N/A
(EIE2.0)
ES1
N
(EIE2.1)
N
Priority
Control
Always
Highest
PSPI0
(IP.6)
PSMB0
(EIP1.0)
PUSB0
(EIP1.1)
PWADC0
(EIP1.2)
PADC0
(EIP1.3)
PPCA0
(EIP1.4)
PCP0
(EIP1.5)
PCP1
(EIP1.6)
PT3
(EIP1.7)
PVBUS
(EIP2.0)
PS1
(EIP2.1)
9.3.5. Interrupt Register Descriptions
The SFRs used to enable the interrupt sources and set their priority level are described below. Refer to the
datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt
conditions for the peripheral and the behavior of its interrupt-pending flag(s).
90
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 9.7. IE: Interrupt Enable
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
EA
ESPI0
ET2
ES0
ET1
EX1
ET0
EX0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
Reset Value
0xA8
EA: Enable All Interrupts.
This bit globally enables/disables all interrupts. It overrides the individual interrupt mask settings.
0: Disable all interrupt sources.
1: Enable each interrupt according to its individual mask setting.
ESPI0: Enable Serial Peripheral Interface (SPI0) Interrupt.
This bit sets the masking of the SPI0 interrupts.
0: Disable all SPI0 interrupts.
1: Enable interrupt requests generated by SPI0.
ET2: Enable Timer 2 Interrupt.
This bit sets the masking of the Timer 2 interrupt.
0: Disable Timer 2 interrupt.
1: Enable interrupt requests generated by the TF2L or TF2H flags.
ES0: Enable UART0 Interrupt.
This bit sets the masking of the UART0 interrupt.
0: Disable UART0 interrupt.
1: Enable UART0 interrupt.
ET1: Enable Timer 1 Interrupt.
This bit sets the masking of the Timer 1 interrupt.
0: Disable all Timer 1 interrupt.
1: Enable interrupt requests generated by the TF1 flag.
EX1: Enable External Interrupt 1.
This bit sets the masking of External Interrupt 1.
0: Disable external interrupt 1.
1: Enable interrupt requests generated by the INT1 input.
ET0: Enable Timer 0 Interrupt.
This bit sets the masking of the Timer 0 interrupt.
0: Disable all Timer 0 interrupt.
1: Enable interrupt requests generated by the TF0 flag.
EX0: Enable External Interrupt 0.
This bit sets the masking of External Interrupt 0.
0: Disable external interrupt 0.
1: Enable interrupt requests generated by the INT0 input.
Rev. 1.3
91
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 9.8. IP: Interrupt Priority
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
PSPI0
PT2
PS0
PT1
PX1
PT0
PX0
10000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
92
UNUSED. Read = 1, Write = don't care.
PSPI0: Serial Peripheral Interface (SPI0) Interrupt Priority Control.
This bit sets the priority of the SPI0 interrupt.
0: SPI0 interrupt set to low priority level.
1: SPI0 interrupt set to high priority level.
PT2: Timer 2 Interrupt Priority Control.
This bit sets the priority of the Timer 2 interrupt.
0: Timer 2 interrupt set to low priority level.
1: Timer 2 interrupts set to high priority level.
PS0: UART0 Interrupt Priority Control.
This bit sets the priority of the UART0 interrupt.
0: UART0 interrupt set to low priority level.
1: UART0 interrupts set to high priority level.
PT1: Timer 1 Interrupt Priority Control.
This bit sets the priority of the Timer 1 interrupt.
0: Timer 1 interrupt set to low priority level.
1: Timer 1 interrupts set to high priority level.
PX1: External Interrupt 1 Priority Control.
This bit sets the priority of the External Interrupt 1 interrupt.
0: External Interrupt 1 set to low priority level.
1: External Interrupt 1 set to high priority level.
PT0: Timer 0 Interrupt Priority Control.
This bit sets the priority of the Timer 0 interrupt.
0: Timer 0 interrupt set to low priority level.
1: Timer 0 interrupt set to high priority level.
PX0: External Interrupt 0 Priority Control.
This bit sets the priority of the External Interrupt 0 interrupt.
0: External Interrupt 0 set to low priority level.
1: External Interrupt 0 set to high priority level.
Rev. 1.3
0xB8
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 9.9. EIE1: Extended Interrupt Enable 1
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
ET3
ECP1
ECP0
EPCA0
EADC0
EWADC0
EUSB0
ESMB0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xE6
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
ET3: Enable Timer 3 Interrupt.
This bit sets the masking of the Timer 3 interrupt.
0: Disable Timer 3 interrupts.
1: Enable interrupt requests generated by the TF3L or TF3H flags.
ECP1: Enable Comparator1 (CP1) Interrupt.
This bit sets the masking of the CP1 interrupt.
0: Disable CP1 interrupts.
1: Enable interrupt requests generated by the CP1RIF or CP1FIF flags.
ECP0: Enable Comparator0 (CP0) Interrupt.
This bit sets the masking of the CP0 interrupt.
0: Disable CP0 interrupts.
1: Enable interrupt requests generated by the CP0RIF or CP0FIF flags.
EPCA0: Enable Programmable Counter Array (PCA0) Interrupt.
This bit sets the masking of the PCA0 interrupts.
0: Disable all PCA0 interrupts.
1: Enable interrupt requests generated by PCA0.
EADC0: Enable ADC0 Conversion Complete Interrupt.
This bit sets the masking of the ADC0 Conversion Complete interrupt.
0: Disable ADC0 Conversion Complete interrupt.
1: Enable interrupt requests generated by the AD0INT flag.
EWADC0: Enable Window Comparison ADC0 Interrupt.
This bit sets the masking of ADC0 Window Comparison interrupt.
0: Disable ADC0 Window Comparison interrupt.
1: Enable interrupt requests generated by ADC0 Window Compare flag (AD0WINT).
EUSB0: Enable USB0 Interrupt.
This bit sets the masking of the USB0 interrupt.
0: Disable all USB0 interrupts.
1: Enable interrupt requests generated by USB0.
ESMB0: Enable SMBus (SMB0) Interrupt.
This bit sets the masking of the SMB0 interrupt.
0: Disable all SMB0 interrupts.
1: Enable interrupt requests generated by SMB0.
Rev. 1.3
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C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 9.10. EIP1: Extended Interrupt Priority 1
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
PT3
PCP1
PCP0
PPCA0
PADC0
PWADC0
PUSB0
PSMB0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xF6
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
94
PT3: Timer 3 Interrupt Priority Control.
This bit sets the priority of the Timer 3 interrupt.
0: Timer 3 interrupts set to low priority level.
1: Timer 3 interrupts set to high priority level.
PCP1: Comparator1 (CP1) Interrupt Priority Control.
This bit sets the priority of the CP1 interrupt.
0: CP1 interrupt set to low priority level.
1: CP1 interrupt set to high priority level.
PCP0: Comparator0 (CP0) Interrupt Priority Control.
This bit sets the priority of the CP0 interrupt.
0: CP0 interrupt set to low priority level.
1: CP0 interrupt set to high priority level.
PPCA0: Programmable Counter Array (PCA0) Interrupt Priority Control.
This bit sets the priority of the PCA0 interrupt.
0: PCA0 interrupt set to low priority level.
1: PCA0 interrupt set to high priority level.
PADC0 ADC0 Conversion Complete Interrupt Priority Control.
This bit sets the priority of the ADC0 Conversion Complete interrupt.
0: ADC0 Conversion Complete interrupt set to low priority level.
1: ADC0 Conversion Complete interrupt set to high priority level.
PWADC0: ADC0 Window Comparator Interrupt Priority Control.
This bit sets the priority of the ADC0 Window interrupt.
0: ADC0 Window interrupt set to low priority level.
1: ADC0 Window interrupt set to high priority level.
PUSB0: USB0 Interrupt Priority Control.
This bit sets the priority of the USB0 interrupt.
0: USB0 interrupt set to low priority level.
1: USB0 interrupt set to high priority level.
PSMB0: SMBus (SMB0) Interrupt Priority Control.
This bit sets the priority of the SMB0 interrupt.
0: SMB0 interrupt set to low priority level.
1: SMB0 interrupt set to high priority level.
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 9.11. EIE2: Extended Interrupt Enable 2
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
-
-
-
-
-
ES1
EVBUS
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xE7
Bits7–2: UNUSED. Read = 000000b. Write = don’t care.
Bit1:
ES1: Enable UART1 Interrupt.
This bit sets the masking of the UART1 interrupt.
0: Disable UART1 interrupt.
1: Enable UART1 interrupt.
Bit0:
EVBUS: Enable VBUS Level Interrupt.
This bit sets the masking of the VBUS interrupt.
0: Disable all VBUS interrupts.
1: Enable interrupt requests generated by VBUS level sense.
SFR Definition 9.12. EIP2: Extended Interrupt Priority 2
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
-
-
-
-
-
PS1
PVBUS
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xF7
Bits7–2: UNUSED. Read = 000000b. Write = don’t care.
Bit1:
PS1: UART1 Interrupt Priority Control.
This bit sets the priority of the UART1 interrupt.
0: UART1 interrupt set to low priority level.
1: UART1 interrupts set to high priority level.
Bit0:
PVBUS: VBUS Level Interrupt Priority Control.
This bit sets the priority of the VBUS interrupt.
0: VBUS interrupt set to low priority level.
1: VBUS interrupt set to high priority level.
Rev. 1.3
95
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 9.13. IT01CF: INT0/INT1 Configuration
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
IN1PL
IN1SL2
IN1SL1
IN1SL0
IN0PL
IN0SL2
IN0SL1
IN0SL0
00000001
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xE4
Note: Refer to SFR Definition 21.1 for INT0/1 edge- or level-sensitive interrupt selection.
Bit7:
IN1PL: INT1 Polarity
0: INT1 input is active low.
1: INT1 input is active high.
Bits6–4: IN1SL2–0: INT1 Port Pin Selection Bits
These bits select which Port pin is assigned to INT1. Note that this pin assignment is independent of the Crossbar; INT1 will monitor the assigned Port pin without disturbing the
peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not
assign the Port pin to a peripheral if it is configured to skip the selected pin (accomplished by
setting to ‘1’ the corresponding bit in register P0SKIP).
IN1SL2–0
000
001
010
011
100
101
110
111
INT1 Port Pin
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
IN0PL: INT0 Polarity
0: INT0 interrupt is active low.
1: INT0 interrupt is active high.
Bits2–0: INT0SL2–0: INT0 Port Pin Selection Bits
These bits select which Port pin is assigned to INT0. Note that this pin assignment is independent of the Crossbar. INT0 will monitor the assigned Port pin without disturbing the
peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not
assign the Port pin to a peripheral if it is configured to skip the selected pin (accomplished by
setting to ‘1’ the corresponding bit in register P0SKIP).
Bit3:
IN0SL2–0
000
001
010
011
100
101
110
111
96
INT0 Port Pin
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
9.4.
Power Management Modes
The CIP-51 core has two software programmable power management modes: Idle and Stop. Idle mode
halts the CPU while leaving the peripherals and clocks active. In Stop mode, the CPU is halted, all interrupts, are inactive, and the internal oscillator is stopped (analog peripherals remain in their selected states;
the external oscillator is not affected). Since clocks are running in Idle mode, power consumption is dependent upon the system clock frequency and the number of peripherals left in active mode before entering
Idle. Stop mode consumes the least power. Figure 1.15 describes the Power Control Register (PCON)
used to control the CIP-51's power management modes.
Although the CIP-51 has Idle and Stop modes built in (as with any standard 8051 architecture), power
management of the entire MCU is better accomplished through system clock and individual peripheral
management. Each analog peripheral can be disabled when not in use and placed in low power mode.
Digital peripherals, such as timers or serial buses, draw little power when they are not in use. Turning off
the oscillators lowers power consumption considerably; however a reset is required to restart the MCU.
The internal oscillator can be placed in Suspend mode (see Section “14. Oscillators” on page 131). In
Suspend mode, the internal oscillator is stopped until a non-idle USB event is detected, or the VBUS input
signal matches the polarity selected by the VBPOL bit in register REG0CN (SFR Definition 8.1).
9.4.1. Idle Mode
Setting the Idle Mode Select bit (PCON.0) causes the CIP-51 to halt the CPU and enter Idle mode as soon
as the instruction that sets the bit completes execution. All internal registers and memory maintain their
original data. All analog and digital peripherals can remain active during Idle mode.
Idle mode is terminated when an enabled interrupt is asserted or a reset occurs. The assertion of an
enabled interrupt will cause the Idle Mode Selection bit (PCON.0) to be cleared and the CPU to resume
operation. The pending interrupt will be serviced and the next instruction to be executed after the return
from interrupt (RETI) will be the instruction immediately following the one that set the Idle Mode Select bit.
If Idle mode is terminated by an internal or external reset, the CIP-51 performs a normal reset sequence
and begins program execution at address 0x0000.
If enabled, the Watchdog Timer (WDT) will eventually cause an internal watchdog reset and thereby terminate the Idle mode. This feature protects the system from an unintended permanent shutdown in the event
of an inadvertent write to the PCON register. If this behavior is not desired, the WDT may be disabled by
software prior to entering the Idle mode if the WDT was initially configured to allow this operation. This provides the opportunity for additional power savings, allowing the system to remain in the Idle mode indefinitely, waiting for an external stimulus to wake up the system. Refer to Section “11.6. PCA Watchdog
Timer Reset” on page 103 for more information on the use and configuration of the WDT.
9.4.2. Stop Mode
Setting the Stop Mode Select bit (PCON.1) causes the CIP-51 to enter Stop mode as soon as the instruction that sets the bit completes execution. In Stop mode the internal oscillator, CPU, and all digital peripherals are stopped; the state of the external oscillator circuit is not affected. Each analog peripheral (including
the external oscillator circuit) may be shut down individually prior to entering Stop Mode. Stop mode can
only be terminated by an internal or external reset. On reset, the CIP-51 performs the normal reset
sequence and begins program execution at address 0x0000.
If enabled, the Missing Clock Detector will cause an internal reset and thereby terminate the Stop mode.
The Missing Clock Detector should be disabled if the CPU is to be put to in STOP mode for longer than the
MCD timeout of 100 µsec.
Rev. 1.3
97
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 9.14. PCON: Power Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
GF5
GF4
GF3
GF2
GF1
GF0
STOP
IDLE
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x87
Bits7–2: GF5–GF0: General Purpose Flags 5–0.
These are general purpose flags for use under software control.
Bit1:
STOP: Stop Mode Select.
Setting this bit will place the CIP-51 in Stop mode. This bit will always be read as 0.
1: CPU goes into Stop mode (internal oscillator stopped).
Bit0:
IDLE: Idle Mode Select.
Setting this bit will place the CIP-51 in Idle mode. This bit will always be read as 0.
1: CPU goes into Idle mode. (Shuts off clock to CPU, but clock to Timers, Interrupts, Serial
Ports, and Analog Peripherals are still active.)
98
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
10. Prefetch Engine
The 48 MHz versions of the C8051F34x family of devices incorporate a 2-byte prefetch engine. Because
the access time of the FLASH memory is 40 ns, and the minimum instruction time is roughly 20 ns, the
prefetch engine is necessary for full-speed code execution. Instructions are read from FLASH memory two
bytes at a time by the prefetch engine, and given to the CIP-51 processor core to execute. When running
linear code (code without any jumps or branches), the prefetch engine allows instructions to be executed
at full speed. When a code branch occurs, the processor may be stalled for up to two clock cycles while the
next set of code bytes is retrieved from FLASH memory. The FLRT bit (FLSCL.4) determines how many
clock cycles are used to read each set of two code bytes from FLASH. When operating from a system
clock of 25 MHz or less, the FLRT bit should be set to ‘0’ so that the prefetch engine takes only one clock
cycle for each read. When operating with a system clock of greater than 25 MHz (up to 48 MHz), the FLRT
bit should be set to ‘1’, so that each prefetch code read lasts for two clock cycles.
SFR Definition 10.1. PFE0CN: Prefetch Engine Control
R
R
R/W
R
R
R
R
PFEN
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
FLBWE
00100000
Bit0
SFR Address: 0xAF
Bits 7–6: Unused. Read = 00b; Write = Don’t Care
Bit 5:
PFEN: Prefetch Enable.
This bit enables the prefetch engine.
0: Prefetch engine is disabled.
1: Prefetch engine is enabled.
Bits 4–1: Unused. Read = 0000b; Write = Don’t Care
Bit 0:
FLBWE: FLASH Block Write Enable.
This bit allows block writes to FLASH memory from software.
0: Each byte of a software FLASH write is written individually.
1: FLASH bytes are written in groups of two.
Rev. 1.3
99
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
11. Reset Sources
Reset circuitry allows the controller to be easily placed in a predefined default condition. On entry to this
reset state, the following occur:
•
•
•
•
CIP-51 halts program execution
Special Function Registers (SFRs) are initialized to their defined reset values
External Port pins are forced to a known state
Interrupts and timers are disabled.
All SFRs are reset to the predefined values noted in the SFR detailed descriptions. The contents of internal
data memory are unaffected during a reset; any previously stored data is preserved. However, since the
stack pointer SFR is reset, the stack is effectively lost even though the data on the stack is not altered.
The Port I/O latches are reset to 0xFF (all logic ones) in open-drain mode. Weak pull-ups are enabled during and after the reset. For VDD Monitor and Power-On Resets, the RST pin is driven low until the device
exits the reset state.
On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to the internal oscillator. Refer to Section “14. Oscillators” on page 131 for information on selecting and configuring
the system clock source. The Watchdog Timer is enabled with the system clock divided by 12 as its clock
source (Section “22.3. Watchdog Timer Mode” on page 264 details the use of the Watchdog Timer).
Program execution begins at location 0x0000.
VDD
Supply
Monitor
+
-
Software Reset (SWRSF)
Errant
FLASH
Operation
MCD
Enable
System
Clock
WDT
Enable
EN
Internal LF
Oscillator
External
Oscillator
Drive
Reset
Funnel
PCA
WDT
CIP-51
Microcontroller
Core
USB
Controller
System Reset
Clock Select
Extended Interrupt
Handler
Figure 11.1. Reset Sources
100
Enable
EN
XTAL2
(wired-OR)
C0RSEF
Missing
Clock
Detector
(oneshot)
XTAL1
'0'
+
-
Px.x
Clock
Multiplier
Power On
Reset
Comparator 0
Px.x
Internal HF
Oscillator
Enable
Rev. 1.3
VBUS
Transition
RST
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
11.1. Power-On Reset
During power-up, the device is held in a reset state and the RST pin is driven low until VDD settles above
VRST. A Power-On Reset delay (TPORDelay) occurs before the device is released from reset; this delay is
typically less than 0.3 ms. Figure 11.2. plots the power-on and VDD monitor reset timing.
On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. When PORSF is
set, all of the other reset flags in the RSTSRC Register are indeterminate (PORSF is cleared by all other
resets). Since all resets cause program execution to begin at the same location (0x0000) software can
read the PORSF flag to determine if a power-up was the cause of reset. The content of internal data memory should be assumed to be undefined after a power-on reset. The VDD monitor is enabled following a
power-on reset.
volts
Software can force a power-on reset by writing ‘1’ to the PINRSF bit in register RSTSRC.
VDD
2.70
2.4
VRST
VD
D
2.0
1.0
t
Logic HIGH
RST
TPORDelay
Logic LOW
VDD
Monitor
Reset
Power-On
Reset
Figure 11.2. Power-On and VDD Monitor Reset Timing
Rev. 1.3
101
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
11.2. Power-Fail Reset / VDD Monitor
When a power-down transition or power irregularity causes VDD to drop below VRST, the power supply
monitor will drive the RST pin low and hold the CIP-51 in a reset state (see Figure 11.2). When VDD returns
to a level above VRST, the CIP-51 will be released from the reset state. Note that even though internal data
memory contents are not altered by the power-fail reset, it is impossible to determine if VDD dropped below
the level required for data retention. If the PORSF flag reads ‘1’, the data may no longer be valid. The VDD
monitor is enabled after power-on resets; however its defined state (enabled/disabled) is not altered by any
other reset source. For example, if the VDD monitor is enabled and a software reset is performed, the VDD
monitor will still be enabled after the reset. It is strongly recommended that the VDD monitor be left enabled
at all times for any system that contains code to write to Flash memory.
Important Note: The VDD monitor must be enabled before it is selected as a reset source. Selecting the
VDD monitor as a reset source before it is enabled and stabilized may cause a system reset. In applications where this reset is undesirable, a delay can be implemented between enabling the VDD monitor and
selecting it as a reset source. The procedure for configuring the VDD monitor as a reset source is shown
below:
Step 1. Enable the VDD monitor (VDM0CN.7 = ‘1’).
Step 2. If desired, wait for the VDD monitor to stabilize (see Table 11.1 for the VDD Monitor turn-on
time).
Step 3. Select the VDD monitor as a reset source (RSTSRC.1 = ‘1’).
See Figure 11.2 for VDD monitor timing. See Table 11.1 for complete electrical characteristics of the VDD
monitor.
SFR Definition 11.1. VDM0CN: VDD Monitor Control
R/W
VDMEN
Bit7
R
R
R
R
R
R
R
VDDSTAT Reserved Reserved Reserved Reserved Reserved Reserved
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
Variable
SFR Address:
0xFF
Bit7:
VDMEN: VDD Monitor Enable.
This bit turns the VDD monitor circuit on/off. The VDD Monitor cannot generate system resets
until it is also selected as a reset source in register RSTSRC (SFR Definition 11.2). The VDD
Monitor must be allowed to stabilize before it is selected as a reset source. Selecting the
VDD monitor as a reset source before it has stabilized will generate a system reset.
See Table 11.1 for the minimum VDD Monitor turn-on time. The VDD Monitor is enabled following all POR resets.
0: VDD Monitor Disabled.
1: VDD Monitor Enabled.
Bit6:
VDDSTAT: VDD Status.
This bit indicates the current power supply status (VDD Monitor output).
0: VDD is at or below the VDD monitor threshold.
1: VDD is above the VDD monitor threshold.
Bits5–0: Reserved. Read = Variable. Write = don’t care.
102
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
11.3. External Reset
The external RST pin provides a means for external circuitry to force the device into a reset state. Asserting an active-low signal on the RST pin generates a reset; an external pull-up and/or decoupling of the
RST pin may be necessary to avoid erroneous noise-induced resets. See Table 11.1 for complete RST pin
specifications. The PINRSF flag (RSTSRC.0) is set on exit from an external reset.
11.4. Missing Clock Detector Reset
The Missing Clock Detector (MCD) is a one-shot circuit that is triggered by the system clock. If more than
100 µs pass between rising edges on the system clock, the one-shot will time out and generate a reset.
After a MCD reset, the MCDRSF flag (RSTSRC.2) will read ‘1’, signifying the MCD as the reset source;
otherwise, this bit reads ‘0’. Writing a ‘1’ to the MCDRSF bit enables the Missing Clock Detector; writing a
‘0’ disables it. The state of the RST pin is unaffected by this reset.
11.5. Comparator0 Reset
Comparator0 can be configured as a reset source by writing a ‘1’ to the C0RSEF flag (RSTSRC.5).
Comparator0 should be enabled and allowed to settle prior to writing to C0RSEF to prevent any turn-on
chatter on the output from generating an unwanted reset. The Comparator0 reset is active-low: if the
non-inverting input voltage (on CP0+) is less than the inverting input voltage (on CP0-), a system reset is
generated. After a Comparator0 reset, the C0RSEF flag (RSTSRC.5) will read ‘1’ signifying Comparator0
as the reset source; otherwise, this bit reads ‘0’. The state of the RST pin is unaffected by this reset.
11.6. PCA Watchdog Timer Reset
The programmable Watchdog Timer (WDT) function of the Programmable Counter Array (PCA) can be
used to prevent software from running out of control during a system malfunction. The PCA WDT function
can be enabled or disabled by software as described in Section “22.3. Watchdog Timer Mode” on
page 264; the WDT is enabled and clocked by SYSCLK / 12 following any reset. If a system malfunction
prevents user software from updating the WDT, a reset is generated and the WDTRSF bit (RSTSRC.5) is
set to ‘1’. The state of the RST pin is unaffected by this reset.
11.7. Flash Error Reset
If a Flash read/write/erase or program read targets an illegal address, a system reset is generated. This
may occur due to any of the following:
•
•
•
•
•
A Flash write or erase is attempted above user code space. This occurs when PSWE is set to “1”, and
a MOVX write operation is attempted above address 0x7FFF (32 kB Flash devices) or 0xFBFF (64 kB
Flash devices).
A Flash read is attempted above user code space. This occurs when a MOVC operation is attempted
above address 0x7FFF (32 kB Flash devices) or 0xFBFF (64 kB Flash devices).
A Program read is attempted above user code space. This occurs when user code attempts to branch
to an address above 0x7FFF (32 kB Flash devices) or 0xFBFF (64 kB Flash devices).
A Flash read, write or erase attempt is restricted due to a Flash security setting (see Section
“12.3. Security Options” on page 109).
A Flash Write or Erase is attempted when the VDD monitor is not enabled.
The FERROR bit (RSTSRC.6) is set following a Flash error reset. The state of the RST pin is unaffected by
this reset.
Rev. 1.3
103
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
11.8. Software Reset
Software may force a reset by writing a ‘1’ to the SWRSF bit (RSTSRC.4). The SWRSF bit will read ‘1’ following a software forced reset. The state of the RST pin is unaffected by this reset.
11.9. USB Reset
Writing ‘1’ to the USBRSF bit in register RSTSRC selects USB0 as a reset source. With USB0 selected as
a reset source, a system reset will be generated when either of the following occur:
1. RESET signaling is detected on the USB network. The USB Function Controller (USB0) must
be enabled for RESET signaling to be detected. See Section “16. Universal Serial Bus Controller (USB0)” on page 159 for information on the USB Function Controller.
2. The voltage on the VBUS pin matches the polarity selected by the VBPOL bit in register
REG0CN. See Section “8. Voltage Regulator (REG0)” on page 69 for details on the VBUS
detection circuit.
The USBRSF bit will read ‘1’ following a USB reset. The state of the RST pin is unaffected by this reset.
104
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 11.2. RSTSRC: Reset Source
R/W
R
R/W
USBRSF FERROR C0RSEF
Bit7
Bit6
Bit5
R/W
SWRSF
Bit4
R
R/W
WDTRSF MCDRSF
Bit3
Bit2
R/W
R
Reset Value
PORSF
PINRSF
Variable
Bit1
Bit0
SFR Address:
0xEF
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
USBRSF: USB Reset Flag
0: Read: Last reset was not a USB reset; Write: USB resets disabled.
1: Read: Last reset was a USB reset; Write: USB resets enabled.
FERROR: Flash Error Indicator.
0: Source of last reset was not a Flash read/write/erase error.
1: Source of last reset was a Flash read/write/erase error.
C0RSEF: Comparator0 Reset Enable and Flag.
0: Read: Source of last reset was not Comparator0; Write: Comparator0 is not a reset
source.
1: Read: Source of last reset was Comparator0; Write: Comparator0 is a reset source
(active-low).
SWRSF: Software Reset Force and Flag.
0: Read: Source of last reset was not a write to the SWRSF bit; Write: No Effect.
1: Read: Source of last was a write to the SWRSF bit; Write: Forces a system reset.
WDTRSF: Watchdog Timer Reset Flag.
0: Source of last reset was not a WDT timeout.
1: Source of last reset was a WDT timeout.
MCDRSF: Missing Clock Detector Flag.
0: Read: Source of last reset was not a Missing Clock Detector timeout; Write: Missing
Clock Detector disabled.
1: Read: Source of last reset was a Missing Clock Detector timeout; Write: Missing Clock
Detector enabled; triggers a reset if a missing clock condition is detected.
PORSF: Power-On / VDD Monitor Reset Flag.
This bit is set anytime a power-on reset occurs. Writing this bit selects/deselects the VDD
monitor as a reset source. Note: writing ‘1’ to this bit before the VDD monitor is enabled
and stabilized can cause a system reset. See register VDM0CN (SFR Definition 11.1).
0: Read: Last reset was not a power-on or VDD monitor reset; Write: VDD monitor is not a
reset source.
1: Read: Last reset was a power-on or VDD monitor reset; all other reset flags indeterminate;
Write: VDD monitor is a reset source.
PINRSF: HW Pin Reset Flag.
0: Source of last reset was not RST pin.
1: Source of last reset was RST pin.
Note: For bits that act as both reset source enables (on a write) and reset indicator flags (on a
read), read-modify-write instructions read and modify the source enable only. This applies to
bits: USBRSF, C0RSEF, SWRSF, MCDRSF, PORSF.
Rev. 1.3
105
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 11.1. Reset Electrical Characteristics
–40 to +85 °C unless otherwise specified.
Parameter
RST Output Low Voltage
Conditions
Min
Typ
IOL = 8.5 mA, VDD = 2.7 to 3.6 V
Units
0.6
V
0.7 x VDD
RST Input High Voltage
V
0.3 x VDD
RST Input Low Voltage
RST Input Pull-Up Current
Max
RST = 0.0 V
VDD POR Threshold (VRST)
25
40
µA
2.40
2.55
2.70
V
220
500
µs
Missing Clock Detector Timeout
Time from last system clock rising edge to reset initiation
100
Reset Time Delay
Delay between release of any
reset source and code execution
at location 0x0000
5.0
µs
Minimum RST Low Time to
Generate a System Reset
15
µs
VDD Monitor Turn-on Time
100
µs
VDD Monitor Supply Current
106
20
Rev. 1.3
50
µA
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
12. Flash Memory
On-chip, re-programmable Flash memory is included for program code and non-volatile data storage. The
Flash memory can be programmed in-system through the C2 interface or by software using the MOVX
instruction. Once cleared to logic 0, a Flash bit must be erased to set it back to logic 1. Flash bytes would
typically be erased (set to 0xFF) before being reprogrammed. The write and erase operations are automatically timed by hardware for proper execution; data polling to determine the end of the write/erase operation is not required. Code execution is stalled during a Flash write/erase operation. Refer to Table 12.1 for
complete Flash memory electrical characteristics.
12.1. Programming The Flash Memory
The simplest means of programming the Flash memory is through the C2 interface using programming
tools provided by Silicon Labs or a third party vendor. This is the only means for programming a non-initialized device. For details on the C2 commands to program Flash memory, see Section “23. C2 Interface”
on page 271.
To ensure the integrity of Flash contents, it is strongly recommended that the VDD monitor be left
enabled in any system which writes or erases Flash memory from code. It is also crucial to ensure
that the FLRT bit in register FLSCL be set to '1' if a clock speed higher than 25 MHz is being used
for the device.
12.1.1. Flash Lock and Key Functions
Flash writes and erases by user software are protected with a lock and key function. The Flash Lock and
Key Register (FLKEY) must be written with the correct key codes, in sequence, before Flash operations
may be performed. The key codes are: 0xA5, 0xF1. The timing does not matter, but the codes must be
written in order. If the key codes are written out of order, or the wrong codes are written, Flash writes and
erases will be disabled until the next system reset. Flash writes and erases will also be disabled if a Flash
write or erase is attempted before the key codes have been written properly. The Flash lock resets after
each write or erase; the key codes must be written again before a following Flash operation can be performed. The FLKEY register is detailed in SFR Definition 12.2.
12.1.2. Flash Erase Procedure
The Flash memory can be programmed by software using the MOVX write instruction with the address and
data byte to be programmed provided as normal operands. Before writing to Flash memory using MOVX,
Flash write operations must be enabled by: (1) Writing the Flash key codes in sequence to the Flash Lock
register (FLKEY); and (2) Setting the PSWE Program Store Write Enable bit (PSCTL.0) to logic 1 (this
directs the MOVX writes to target Flash memory). The PSWE bit remains set until cleared by software.
A write to Flash memory can clear bits to logic 0 but cannot set them; only an erase operation can set bits
to logic 1 in Flash. A byte location to be programmed must be erased before a new value is written.
The Flash memory is organized in 512-byte pages. The erase operation applies to an entire page (setting
all bytes in the page to 0xFF). To erase an entire 512-byte page, perform the following steps:
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Disable interrupts (recommended).
Write the first key code to FLKEY: 0xA5.
Write the second key code to FLKEY: 0xF1.
Set the PSEE bit (register PSCTL).
Set the PSWE bit (register PSCTL).
Using the MOVX instruction, write a data byte to any location within the 512-byte page to
be erased.
Step 7. Clear the PSWE bit (register PSCTL).
Step 8. Clear the PSEE bit (register PSCTI).
Rev. 1.3
107
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
12.1.3. Flash Write Procedure
Bytes in Flash memory can be written one byte at a time, or in groups of two. The FLBWE bit in register
PFE0CN (SFR Definition 10.1) controls whether a single byte or a block of two bytes is written to Flash
during a write operation. When FLBWE is cleared to ‘0’, the Flash will be written one byte at a time. When
FLBWE is set to ‘1’, the Flash will be written in two-byte blocks. Block writes are performed in the same
amount of time as single-byte writes, which can save time when storing large amounts of data to Flash
memory.During a single-byte write to Flash, bytes are written individually, and a Flash write will be performed after each MOVX write instruction. The recommended procedure for writing Flash in single bytes is:
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Step 7.
Disable interrupts.
Clear the FLBWE bit (register PFE0CN) to select single-byte write mode.
Set the PSWE bit (register PSCTL).
Clear the PSEE bit (register PSCTL).
Write the first key code to FLKEY: 0xA5.
Write the second key code to FLKEY: 0xF1.
Using the MOVX instruction, write a single data byte to the desired location within the
512-byte sector.
Step 8. Clear the PSWE bit.
Step 9. Re-enable interrupts.
Steps 5-7 must be repeated for each byte to be written.
For block Flash writes, the Flash write procedure is only performed after the last byte of each block is written with the MOVX write instruction. A Flash write block is two bytes long, from even addresses to odd
addresses. Writes must be performed sequentially (i.e. addresses ending in 0b and 1b must be written in
order). The Flash write will be performed following the MOVX write that targets the address ending in 1b. If
a byte in the block does not need to be updated in Flash, it should be written to 0xFF. The recommended
procedure for writing Flash in blocks is:
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Step 7.
Disable interrupts.
Set the FLBWE bit (register PFE0CN) to select block write mode.
Set the PSWE bit (register PSCTL).
Clear the PSEE bit (register PSCTL).
Write the first key code to FLKEY: 0xA5.
Write the second key code to FLKEY: 0xF1.
Using the MOVX instruction, write the first data byte to the even block location (ending in
0b).
Step 8. Write the first key code to FLKEY: 0xA5.
Step 9. Write the second key code to FLKEY: 0xF1.
Step 10. Using the MOVX instruction, write the second data byte to the odd block location (ending
in 1b).
Step 11. Clear the PSWE bit.
Step 12. Re-enable interrupts.
Steps 5–10 must be repeated for each block to be written.
108
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 12.1. Flash Electrical Characteristics
Parameter
Flash Size
Endurance
Erase Cycle Time
Write Cycle Time
Conditions
C8051F340/2/4/6/A/C/D*
Min
65536*
C8051F341/3/5/7/8/9/B
32768
20k
10
40
25 MHz System Clock
25 MHz System Clock
Typ
100k
15
55
Max
20
70
Units
Bytes
Bytes
Erase/Write
ms
µs
*Note: 1024 bytes at location 0xFC00 to 0xFFFF are reserved.
12.2. Non-Volatile Data Storage
The Flash memory can be used for non-volatile data storage as well as program code. This allows data
such as calibration coefficients to be calculated and stored at run time. Data is written using the MOVX
write instruction and read using the MOVC instruction. Note: MOVX read instructions always target XRAM.
12.3. Security Options
The CIP-51 provides security options to protect the Flash memory from inadvertent modification by software as well as to prevent the viewing of proprietary program code and constants. The Program Store
Write Enable (bit PSWE in register PSCTL) and the Program Store Erase Enable (bit PSEE in register
PSCTL) bits protect the Flash memory from accidental modification by software. PSWE must be explicitly
set to ‘1’ before software can modify the Flash memory; both PSWE and PSEE must be set to ‘1’ before
software can erase Flash memory. Additional security features prevent proprietary program code and data
constants from being read or altered across the C2 interface.
A Security Lock Byte located at the last byte of Flash user space offers protection of the Flash program
memory from access (reads, writes, or erases) by unprotected code or the C2 interface. The Flash security
mechanism allows the user to lock n 512-byte Flash pages, starting at page 0 (addresses 0x0000 to
0x01FF), where n is the 1’s complement number represented by the Security Lock Byte. Note that the
page containing the Flash Security Lock Byte is also locked when any other Flash pages are locked. See
example below.
Security Lock Byte:
1’s Complement:
Flash pages locked:
11111101b
00000010b
3 (2 + Flash Lock Byte Page)
First two pages of Flash: 0x0000 to 0x03FF
Addresses locked:
Flash Lock Byte Page: (0xFA00 to 0xFBFF for 64k devices; 0x7E00 to
0x7FFF for 32k devices)
Rev. 1.3
109
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
C8051F340/2/4/6/A/C/D
Reserved
0xFC00
Lock Byte
0xFBFF
0xFBFE
0xFA00
FLASH memory
organized in 512-byte
pages
Locked when any
other FLASH pages
are locked
C8051F341/3/5/7/8/9/B
Lock Byte
0x7FFE
0x7E00
Unlocked FLASH Pages
Access limit set
according to the
FLASH security lock
byte
Unlocked FLASH Pages
0x0000
Figure 12.1. Flash Program Memory Map and Security Byte
110
0x7FFF
Rev. 1.3
0x0000
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
The level of FLASH security depends on the FLASH access method. The three FLASH access methods
that can be restricted are reads, writes, and erases from the C2 debug interface, user firmware executing
on unlocked pages, and user firmware executing on locked pages.
Accessing FLASH from the C2 debug interface:
1.
2.
3.
4.
5.
6.
Any unlocked page may be read, written, or erased.
Locked pages cannot be read, written, or erased.
The page containing the Lock Byte may be read, written, or erased if it is unlocked.
Reading the contents of the Lock Byte is always permitted.
Locking additional pages (changing ‘1’s to ‘0’s in the Lock Byte) is not permitted.
Unlocking FLASH pages (changing ‘0’s to ‘1’s in the Lock Byte) requires the C2 Device Erase
command, which erases all FLASH pages including the page containing the Lock Byte and the
Lock Byte itself.
7. The Reserved Area cannot be read, written, or erased.
Accessing FLASH from user firmware executing on an unlocked page:
1. Any unlocked page except the page containing the Lock Byte may be read, written, or erased.
2. Locked pages cannot be read, written, or erased.
3. The page containing the Lock Byte cannot be erased. It may be read or written only if it is
unlocked.
4. Reading the contents of the Lock Byte is always permitted.
5. Locking additional pages (changing ‘1’s to ‘0’s in the Lock Byte) is not permitted.
6. Unlocking FLASH pages (changing ‘0’s to ‘1’s in the Lock Byte) is not permitted.
7. The Reserved Area cannot be read, written, or erased. Any attempt to access the reserved
area, or any other locked page, will result in a FLASH Error device reset.
Accessing FLASH from user firmware executing on a locked page:
1.
2.
3.
4.
5.
6.
7.
Any unlocked page except the page containing the Lock Byte may be read, written, or erased.
Any locked page except the page containing the Lock Byte may be read, written, or erased.
The page containing the Lock Byte cannot be erased. It may only be read or written.
Reading the contents of the Lock Byte is always permitted.
Locking additional pages (changing ‘1’s to ‘0’s in the Lock Byte) is not permitted.
Unlocking FLASH pages (changing ‘0’s to ‘1’s in the Lock Byte) is not permitted.
The Reserved Area cannot be read, written, or erased. Any attempt to access the reserved
area, or any other locked page, will result in a FLASH Error device reset.
Rev. 1.3
111
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 12.1. PSCTL: Program Store R/W Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
-
-
-
-
Reserved
PSEE
PSWE
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x8F
Bits7–3: Unused: Read = 00000b. Write = don’t care.
Bit2:
Reserved. Read = 0b. Must Write = 0b.
Bit1:
PSEE: Program Store Erase Enable
Setting this bit (in combination with PSWE) allows an entire page of Flash program memory
to be erased. If this bit is logic 1 and Flash writes are enabled (PSWE is logic 1), a write to
Flash memory using the MOVX instruction will erase the entire page that contains the location addressed by the MOVX instruction. The value of the data byte written does not matter.
0: Flash program memory erasure disabled.
1: Flash program memory erasure enabled.
Bit0:
PSWE: Program Store Write Enable
Setting this bit allows writing a byte of data to the Flash program memory using the MOVX
write instruction. The Flash location should be erased before writing data.
0: Writes to Flash program memory disabled.
1: Writes to Flash program memory enabled; the MOVX write instruction targets Flash
memory.
SFR Definition 12.2. FLKEY: Flash Lock and Key
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xB7
Bits–0:
112
FLKEY: Flash Lock and Key Register
Write:
This register must be written to before Flash writes or erases can be performed. Flash
remains locked until this register is written to with the following key codes: 0xA5, 0xF1. The
timing of the writes does not matter, as long as the codes are written in order. The key codes
must be written for each Flash write or erase operation. Flash will be locked until the next
system reset if the wrong codes are written or if a Flash operation is attempted before the
codes have been written correctly.
Read:
When read, bits 1-0 indicate the current Flash lock state.
00: Flash is write/erase locked.
01: The first key code has been written (0xA5).
10: Flash is unlocked (writes/erases allowed).
11: Flash writes/erases disabled until the next reset.
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 12.3. FLSCL: Flash Scale
R/W
FOSE
Bit7
R/W
R/W
Reserved Reserved
Bit6
Bit5
R/W
FLRT
Bit4
R/W
R/W
R/W
R/W
Reset Value
Reserved Reserved Reserved Reserved 10000000
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xB6
Bits7:
FOSE: Flash One-shot Enable
This bit enables the Flash read one-shot. When the Flash one-shot disabled, the Flash
sense amps are enabled for a full clock cycle during Flash reads. At system clock frequencies below 10 MHz, disabling the Flash one-shot will increase system power consumption.
0: Flash one-shot disabled.
1: Flash one-shot enabled.
Bits6–5: RESERVED. Read = 00b. Must Write 00b.
Bit 4:
FLRT: FLASH Read Time.
This bit should be programmed to the smallest allowed value, according to the system clock
speed.
0: SYSCLK <= 25 MHz.
1: SYSCLK <= 48 MHz.
Bits3–0: RESERVED. Read = 0000b. Must Write 0000b.
Rev. 1.3
113
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
13. External Data Memory Interface and On-Chip XRAM
4k Bytes (C8051F340/2/4/6/A/C/D) or 2k Bytes (C8051F341/3/5/7/8/9/B) of RAM are included on-chip,
and mapped into the external data memory space (XRAM). The 1k Bytes of USB FIFO space can also be
mapped into XRAM address space for additional general-purpose data storage. Additionally, an External
Memory Interface (EMIF) is available on the C8051F340/1/4/5/8/C devices, which can be used to access
off-chip data memories and memory-mapped devices connected to the GPIO ports. The external memory
space may be accessed using the external move instruction (MOVX) and the data pointer (DPTR), or using
the MOVX indirect addressing mode using R0 or R1. If the MOVX instruction is used with an 8-bit address
operand (such as @R1), then the high byte of the 16-bit address is provided by the External Memory Interface Control Register (EMI0CN, shown in SFR Definition 13.1). Note: the MOVX instruction can also be
used for writing to the FLASH memory. See Section “12. Flash Memory” on page 107 for details. The
MOVX instruction accesses XRAM by default.
13.1. Accessing XRAM
The XRAM memory space is accessed using the MOVX instruction. The MOVX instruction has two forms,
both of which use an indirect addressing method. The first method uses the Data Pointer, DPTR, a 16-bit
register which contains the effective address of the XRAM location to be read from or written to. The second method uses R0 or R1 in combination with the EMI0CN register to generate the effective XRAM
address. Examples of both of these methods are given below.
13.1.1. 16-Bit MOVX Example
The 16-bit form of the MOVX instruction accesses the memory location pointed to by the contents of the
DPTR register. The following series of instructions reads the value of the byte at address 0x1234 into the
accumulator A:
MOV
MOVX
DPTR, #1234h
A, @DPTR
; load DPTR with 16-bit address to read (0x1234)
; load contents of 0x1234 into accumulator A

The above example uses the 16-bit immediate MOV instruction to set the contents of DPTR. Alternately,
the DPTR can be accessed through the SFR registers DPH, which contains the upper 8-bits of DPTR, and
DPL, which contains the lower 8-bits of DPTR.
13.1.2. 8-Bit MOVX Example
The 8-bit form of the MOVX instruction uses the contents of the EMI0CN SFR to determine the upper 8-bits
of the effective address to be accessed and the contents of R0 or R1 to determine the lower 8-bits of the
effective address to be accessed. The following series of instructions read the contents of the byte at
address 0x1234 into the accumulator A.
MOV
MOV
MOVX
114
EMI0CN, #12h
R0, #34h
a, @R0
; load high byte of address into EMI0CN
; load low byte of address into R0 (or R1)
; load contents of 0x1234 into accumulator A
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
13.2. Accessing USB FIFO Space
The C8051F34x devices include 1k of RAM which functions as USB FIFO space. Figure 13.1 shows an
expanded view of the FIFO space and user XRAM. FIFO space is normally accessed via USB FIFO registers; see Section “16.5. FIFO Management” on page 167 for more information on accessing these
FIFOs. The MOVX instruction should not be used to load or modify USB data in the FIFO space.
Unused areas of the USB FIFO space may be used as general purpose XRAM if necessary. The FIFO
block operates on the USB clock domain; thus the USB clock must be active when accessing FIFO space.
Note that the number of SYSCLK cycles required by the MOVX instruction is increased when accessing
USB FIFO space.
To access the FIFO RAM directly using MOVX instructions, the following conditions must be met: (1) the
USBFAE bit in register EMI0CF must be set to '1', and (2) the USB clock must be greater than or equal to
twice the SYSCLK (USBCLK > 2 x SYSCLK). When this bit is set, the USB FIFO space is mapped into
XRAM space at addresses 0x0400 to 0x07FF. The normal XRAM (on-chip or external) at the same
addresses cannot be accessed when the USBFAE bit is set to ‘1’.
Important Note: The USB clock must be active when accessing FIFO space.
0xFFFF
On/Off-Chip XRAM
0x0800
0x07FF
Endpoint0
(64 bytes)
0x07C0
0x07BF
Endpoint1
(128 bytes)
0x0740
0x073F
Endpoint2
(256 bytes)
USB FIFO Space
0x0640
0x063F
(USB Clock Domain)
Endpoint3
(512 bytes)
0x0440
0x043F
Free
(64 bytes)
0x0400
0x03FF
On/Off-Chip XRAM
0x0000
Figure 13.1. USB FIFO Space and XRAM Memory Map with USBFAE set to ‘1’
Rev. 1.3
115
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
13.3. Configuring the External Memory Interface
Configuring the External Memory Interface consists of five steps:
1. Configure the Output Modes of the associated port pins as either push-pull or open-drain
(push-pull is most common), and skip the associated pins in the crossbar.
2. Configure Port latches to “park” the EMIF pins in a dormant state (usually by setting them to
logic ‘1’).
3. Select Multiplexed mode or Non-multiplexed mode.
4. Select the memory mode (on-chip only, split mode without bank select, split mode with bank
select, or off-chip only).
5. Set up timing to interface with off-chip memory or peripherals.
Each of these five steps is explained in detail in the following sections. The Port selection, Multiplexed
mode selection, and Mode bits are located in the EMI0CF register shown in SFR Definition 13.2.
13.4. Port Configuration
The External Memory Interface appears on Ports 4, 3, 2, and 1 when it is used for off-chip memory access.
When the EMIF is used, the Crossbar should be configured to skip over the control lines P1.7 (WR), P1.6
(RD), and if multiplexed mode is selected P1.3 (ALE) using the P1SKIP register. For more information
about configuring the Crossbar, see Section “Figure 15.1. Port I/O Functional Block Diagram (Port 0
through Port 3)” on page 142.
The External Memory Interface claims the associated Port pins for memory operations ONLY during the
execution of an off-chip MOVX instruction. Once the MOVX instruction has completed, control of the Port
pins reverts to the Port latches or to the Crossbar settings for those pins. See Section “15. Port Input/
Output” on page 142 for more information about the Crossbar and Port operation and configuration. The
Port latches should be explicitly configured to ‘park’ the External Memory Interface pins in a dormant state, most commonly by setting them to a logic 1.
During the execution of the MOVX instruction, the External Memory Interface will explicitly disable the drivers on all Port pins that are acting as Inputs (Data[7:0] during a READ operation, for example). The Output
mode of the Port pins (whether the pin is configured as Open-Drain or Push-Pull) is unaffected by the
External Memory Interface operation, and remains controlled by the PnMDOUT registers. In most cases,
the output modes of all EMIF pins should be configured for push-pull mode.
116
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 13.1. EMI0CN: External Memory Interface Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
PGSEL7
PGSEL6
PGSEL5
PGSEL4
PGSEL3
PGSEL2
PGSEL1
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
PGSEL0 00000000
Bit0
SFR Address: 0xAA
Bits7–0: PGSEL[7:0]: XRAM Page Select Bits.
The XRAM Page Select Bits provide the high byte of the 16-bit external data memory
address when using an 8-bit MOVX command, effectively selecting a 256-byte page of
RAM.
0x00: 0x0000 to 0x00FF
0x01: 0x0100 to 0x01FF
...
0xFE: 0xFE00 to 0xFEFF
0xFF: 0xFF00 to 0xFFFF
Rev. 1.3
117
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 13.2. EMI0CF: External Memory Configuration
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
USBFAE
-
EMD2
EMD1
EMD0
EALE1
EALE0
00000011
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x85
Bit7:
Bit6:
Unused. Read = 0b. Write = don’t care.
USBFAE: USB FIFO Access Enable.
0: USB FIFO RAM not available through MOVX instructions.
1: USB FIFO RAM available using MOVX instructions. The 1k of USB RAM will be mapped
in XRAM space at addresses 0x0400 to 0x07FF. The USB clock must be active and
greater than or equal to twice the SYSCLK (USBCLK > 2 x SYSCLK) to access this
area with MOVX instructions.
Bit5:
Unused. Read = 0b. Write = don’t care.
Bit4:
EMD2: EMIF Multiplex Mode Select.
0: EMIF operates in multiplexed address/data mode.
1: EMIF operates in non-multiplexed mode (separate address and data pins).
Bits3–2: EMD1–0: EMIF Operating Mode Select.
These bits control the operating mode of the External Memory Interface.
00: Internal Only: MOVX accesses on-chip XRAM only. All effective addresses alias to
on-chip memory space.
01: Split Mode without Bank Select: Accesses below the on-chip XRAM boundary are
directed on-chip. Accesses above the on-chip XRAM boundary are directed off-chip. 8-bit
off-chip MOVX operations use the current contents of the Address High port latches to
resolve upper address byte. Note that in order to access off-chip space, EMI0CN must be
set to a page that is not contained in the on-chip address space.
10: Split Mode with Bank Select: Accesses below the on-chip XRAM boundary are directed
on-chip. Accesses above the on-chip XRAM boundary are directed off-chip. 8-bit off-chip
MOVX operations use the contents of EMI0CN to determine the high-byte of the address.
11: External Only: MOVX accesses off-chip XRAM only. On-chip XRAM is not visible to the
CPU.
Bits1–0: EALE1–0: ALE Pulse-Width Select Bits (only has effect when EMD2 = 0).
00: ALE high and ALE low pulse width = 1 SYSCLK cycle.
01: ALE high and ALE low pulse width = 2 SYSCLK cycles.
10: ALE high and ALE low pulse width = 3 SYSCLK cycles.
11: ALE high and ALE low pulse width = 4 SYSCLK cycles.
118
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
13.5. Multiplexed and Non-multiplexed Selection
The External Memory Interface is capable of acting in a Multiplexed mode or a Non-multiplexed mode,
depending on the state of the EMD2 (EMI0CF.4) bit.
13.5.1. Multiplexed Configuration
In Multiplexed mode, the Data Bus and the lower 8-bits of the Address Bus share the same Port pins:
AD[7:0]. In this mode, an external latch (74HC373 or equivalent logic gate) is used to hold the lower 8-bits
of the RAM address. The external latch is controlled by the ALE (Address Latch Enable) signal, which is
driven by the External Memory Interface logic. An example of a Multiplexed Configuration is shown in
Figure 13.2.
In Multiplexed mode, the external MOVX operation can be broken into two phases delineated by the state
of the ALE signal. During the first phase, ALE is high and the lower 8-bits of the Address Bus are presented to AD[7:0]. During this phase, the address latch is configured such that the ‘Q’ outputs reflect the
states of the ‘D’ inputs. When ALE falls, signaling the beginning of the second phase, the address latch
outputs remain fixed and are no longer dependent on the latch inputs. Later in the second phase, the Data
Bus controls the state of the AD[7:0] port at the time RD or WR is asserted.
See Section “13.7.2. Multiplexed Mode” on page 127 for more information.
A[15:8]
A[15:8]
ADDRESS BUS
74HC373
E
M
I
F
ALE
AD[7:0]
G
ADDRESS/DATA BUS
D
Q
A[7:0]
VDD
64K X 8
SRAM
(Optional)
8
I/O[7:0]
CE
WE
OE
WR
RD
Figure 13.2. Multiplexed Configuration Example
Rev. 1.3
119
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
13.5.2. Non-multiplexed Configuration
In Non-multiplexed mode, the Data Bus and the Address Bus pins are not shared. An example of a
Non-multiplexed Configuration is shown in Figure 13.3. See Section “13.7.1. Non-multiplexed Mode” on
page 124 for more information about Non-multiplexed operation.
E
M
I
F
A[15:0]
A[15:0]
ADDRESS BUS
VDD
(Optional)
64K X 8
SRAM
I/O[7:0]
8
D[7:0]
DATA BUS
CE
WE
OE
WR
RD
Figure 13.3. Non-multiplexed Configuration Example
13.6. Memory Mode Selection
The external data memory space can be configured in one of four modes, shown in Figure 13.4, based on
the EMIF Mode bits in the EMI0CF register (SFR Definition 13.2). These modes are summarized below.
More information about the different modes can be found in Section “13.7. Timing” on page 122.
EMI0CF[3:2] = 00
EMI0CF[3:2] = 01
0xFFFF
EMI0CF[3:2] = 11
EMI0CF[3:2] = 10
0xFFFF
0xFFFF
0xFFFF
On-Chip XRAM
On-Chip XRAM
Off-Chip
Memory
(No Bank Select)
Off-Chip
Memory
(Bank Select)
On-Chip XRAM
Off-Chip
Memory
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
0x0000
0x0000
0x0000
Figure 13.4. EMIF Operating Modes
120
Rev. 1.3
0x0000
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
13.6.1. Internal XRAM Only
When EMI0CF.[3:2] are set to ‘00’, all MOVX instructions will target the internal XRAM space on the
device. Memory accesses to addresses beyond the populated space will wrap on 2k or 4k boundaries
(depending on the RAM available on the device). As an example, the addresses 0x1000 and 0x2000 both
evaluate to address 0x0000 in on-chip XRAM space.
•
•
8-bit MOVX operations use the contents of EMI0CN to determine the high-byte of the effective address
and R0 or R1 to determine the low-byte of the effective address.
16-bit MOVX operations use the contents of the 16-bit DPTR to determine the effective address.
13.6.2. Split Mode without Bank Select
When EMI0CF.[3:2] are set to ‘01’, the XRAM memory map is split into two areas, on-chip space and
off-chip space.
•
•
•
•
Effective addresses below the internal XRAM size boundary will access on-chip XRAM space.
Effective addresses above the internal XRAM size boundary will access off-chip space.
8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is
on-chip or off-chip. However, in the “No Bank Select” mode, an 8-bit MOVX operation will not drive the
upper 8-bits A[15:8] of the Address Bus during an off-chip access. This allows the user to manipulate
the upper address bits at will by setting the Port state directly via the port latches. This behavior is in
contrast with “Split Mode with Bank Select” described below. The lower 8-bits of the Address Bus
A[7:0] are driven, determined by R0 or R1.
16-bit MOVX operations use the contents of DPTR to determine whether the memory access is
on-chip or off-chip, and unlike 8-bit MOVX operations, the full 16-bits of the Address Bus A[15:0] are
driven during the off-chip transaction.
Rev. 1.3
121
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
13.6.3. Split Mode with Bank Select
When EMI0CF.[3:2] are set to ‘10’, the XRAM memory map is split into two areas, on-chip space and
off-chip space.
•
•
•
•
Effective addresses below the internal XRAM size boundary will access on-chip XRAM space.
Effective addresses above the internal XRAM size boundary will access off-chip space.
8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is
on-chip or off-chip. The upper 8-bits of the Address Bus A[15:8] are determined by EMI0CN, and the
lower 8-bits of the Address Bus A[7:0] are determined by R0 or R1. All 16-bits of the Address Bus
A[15:0] are driven in “Bank Select” mode.
16-bit MOVX operations use the contents of DPTR to determine whether the memory access is
on-chip or off-chip, and the full 16-bits of the Address Bus A[15:0] are driven during the off-chip transaction.
13.6.4. External Only
When EMI0CF[3:2] are set to ‘11’, all MOVX operations are directed to off-chip space. On-chip XRAM is
not visible to the CPU. This mode is useful for accessing off-chip memory located between 0x0000 and the
internal XRAM size boundary.
•
•
8-bit MOVX operations ignore the contents of EMI0CN. The upper Address bits A[15:8] are not driven
(identical behavior to an off-chip access in “Split Mode without Bank Select” described above). This
allows the user to manipulate the upper address bits at will by setting the Port state directly. The lower
8-bits of the effective address A[7:0] are determined by the contents of R0 or R1.
16-bit MOVX operations use the contents of DPTR to determine the effective address A[15:0]. The full
16-bits of the Address Bus A[15:0] are driven during the off-chip transaction.
13.7. Timing
The timing parameters of the External Memory Interface can be configured to enable connection to
devices having different setup and hold time requirements. The Address Setup time, Address Hold time,
RD and WR strobe widths, and in multiplexed mode, the width of the ALE pulse are all programmable in
units of SYSCLK periods through EMI0TC, shown in SFR Definition 13.3, and EMI0CF[1:0].
The timing for an off-chip MOVX instruction can be calculated by adding 4 SYSCLK cycles to the timing
parameters defined by the EMI0TC register. Assuming non-multiplexed operation, the minimum execution
time for an off-chip XRAM operation is 5 SYSCLK cycles (1 SYSCLK for RD or WR pulse + 4 SYSCLKs).
For multiplexed operations, the Address Latch Enable signal will require a minimum of 2 additional SYSCLK cycles. Therefore, the minimum execution time for an off-chip XRAM operation in multiplexed mode is
7 SYSCLK cycles (2 for ALE + 1 for RD or WR + 4). The programmable setup and hold times default to the
maximum delay settings after a reset. Table 13.1 lists the AC parameters for the External Memory Interface, and Figure 13.5 through Figure 13.10 show the timing diagrams for the different External Memory
Interface modes and MOVX operations.
122
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 13.3. EMI0TC: External Memory Timing Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
EAS1
EAS0
EWR3
EWR2
EWR1
EWR0
EAH1
EAH0
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x84
Bits7–6: EAS1–0: EMIF Address Setup Time Bits.
00: Address setup time = 0 SYSCLK cycles.
01: Address setup time = 1 SYSCLK cycle.
10: Address setup time = 2 SYSCLK cycles.
11: Address setup time = 3 SYSCLK cycles.
Bits5–2: EWR3–0: EMIF WR and RD Pulse-Width Control Bits.
0000: WR and RD pulse width = 1 SYSCLK cycle.
0001: WR and RD pulse width = 2 SYSCLK cycles.
0010: WR and RD pulse width = 3 SYSCLK cycles.
0011: WR and RD pulse width = 4 SYSCLK cycles.
0100: WR and RD pulse width = 5 SYSCLK cycles.
0101: WR and RD pulse width = 6 SYSCLK cycles.
0110: WR and RD pulse width = 7 SYSCLK cycles.
0111: WR and RD pulse width = 8 SYSCLK cycles.
1000: WR and RD pulse width = 9 SYSCLK cycles.
1001: WR and RD pulse width = 10 SYSCLK cycles.
1010: WR and RD pulse width = 11 SYSCLK cycles.
1011: WR and RD pulse width = 12 SYSCLK cycles.
1100: WR and RD pulse width = 13 SYSCLK cycles.
1101: WR and RD pulse width = 14 SYSCLK cycles.
1110: WR and RD pulse width = 15 SYSCLK cycles.
1111:WR and RD pulse width = 16 SYSCLK cycles.
Bits1–0: EAH1–0: EMIF Address Hold Time Bits.
00: Address hold time = 0 SYSCLK cycles.
01: Address hold time = 1 SYSCLK cycle.
10: Address hold time = 2 SYSCLK cycles.
11: Address hold time = 3 SYSCLK cycles.
Rev. 1.3
123
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
13.7.1. Non-multiplexed Mode
13.7.1.1.16-bit MOVX: EMI0CF[4:2] = ‘101’, ‘110’, or ‘111’.
Nonmuxed 16-bit WRITE
ADDR[15:8]
P2
EMIF ADDRESS (8 MSBs) from DPH
P2
ADDR[7:0]
P3
EMIF ADDRESS (8 LSBs) from DPL
P3
DATA[7:0]
P4
EMIF WRITE DATA
P4
T
T
WDS
T
ACS
WDH
T
T
ACW
ACH
WR
P1.7
P1.7
RD
P1.6
P1.6
Nonmuxed 16-bit READ
ADDR[15:8]
P2
EMIF ADDRESS (8 MSBs) from DPH
P2
ADDR[7:0]
P3
EMIF ADDRESS (8 LSBs) from DPL
P3
DATA[7:0]
P4
EMIF READ DATA
P4
T
RDS
T
ACS
T
ACW
T
RDH
T
ACH
RD
P1.6
P1.6
WR
P1.7
P1.7
Figure 13.5. Non-multiplexed 16-bit MOVX Timing
124
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
13.7.1.2.8-bit MOVX without Bank Select: EMI0CF[4:2] = ‘101’ or ‘111’.
Nonmuxed 8-bit WRITE without Bank Select
ADDR[15:8]
P2
ADDR[7:0]
P3
EMIF ADDRESS (8 LSBs) from R0 or R1
P3
DATA[7:0]
P4
EMIF WRITE DATA
P4
T
T
WDS
T
WDH
T
ACS
T
ACW
ACH
WR
P1.7
P1.7
RD
P1.6
P1.6
Nonmuxed 8-bit READ without Bank Select
ADDR[15:8]
P2
ADDR[7:0]
P3
DATA[7:0]
P4
EMIF ADDRESS (8 LSBs) from R0 or R1
EMIF READ DATA
T
RDS
T
T
ACS
ACW
P3
P4
T
RDH
T
ACH
RD
P1.6
P1.6
WR
P1.7
P1.7
Figure 13.6. Non-multiplexed 8-bit MOVX without Bank Select Timing
Rev. 1.3
125
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
13.7.1.3.8-bit MOVX with Bank Select: EMI0CF[4:2] = ‘110’.
Muxed 8-bit WRITE with Bank Select
ADDR[15:8]
P3
AD[7:0]
P4
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF ADDRESS (8 LSBs) from
R0 or R1
T
ALEH
ALE
P3
EMIF WRITE DATA
P4
T
ALEL
P1.3
P1.3
T
T
WDS
T
ACS
WDH
T
T
ACW
ACH
WR
P1.7
P1.7
RD
P1.6
P1.6
Muxed 8-bit READ with Bank Select
ADDR[15:8]
P3
AD[7:0]
P4
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF ADDRESS (8 LSBs) from
R0 or R1
T
ALEH
ALE
P3
EMIF READ DATA
T
T
ALEL
RDS
T
RDH
P1.3
P1.3
T
ACS
T
ACW
T
ACH
RD
P1.6
P1.6
WR
P1.7
P1.7
Figure 13.7. Non-multiplexed 8-bit MOVX with Bank Select Timing
126
P4
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
13.7.2. Multiplexed Mode
13.7.2.1.16-bit MOVX: EMI0CF[4:2] = ‘001’, ‘010’, or ‘011’.
Muxed 16-bit WRITE
ADDR[15:8]
P3
AD[7:0]
P4
EMIF ADDRESS (8 MSBs) from DPH
EMIF ADDRESS (8 LSBs) from
DPL
T
ALEH
ALE
P3
EMIF WRITE DATA
P4
T
ALEL
P1.3
P1.3
T
T
WDS
T
ACS
WDH
T
T
ACW
ACH
WR
P1.7
P1.7
RD
P1.6
P1.6
Muxed 16-bit READ
ADDR[15:8]
P3
AD[7:0]
P4
EMIF ADDRESS (8 MSBs) from DPH
EMIF ADDRESS (8 LSBs) from
DPL
T
ALEH
ALE
P3
EMIF READ DATA
T
T
ALEL
RDS
P4
T
RDH
P1.3
P1.3
T
ACS
T
ACW
T
ACH
RD
P1.6
P1.6
WR
P1.7
P1.7
Figure 13.8. Multiplexed 16-bit MOVX Timing
Rev. 1.3
127
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
13.7.2.2.8-bit MOVX without Bank Select: EMI0CF[4:2] = ‘001’ or ‘011’.
Muxed 8-bit WRITE Without Bank Select
ADDR[15:8]
AD[7:0]
P3
P4
EMIF ADDRESS (8 LSBs) from
R0 or R1
T
ALEH
ALE
EMIF WRITE DATA
P4
T
ALEL
P1.3
P1.3
T
T
WDS
T
ACS
WDH
T
T
ACW
ACH
WR
P1.7
P1.7
RD
P1.6
P1.6
Muxed 8-bit READ Without Bank Select
ADDR[15:8]
AD[7:0]
P3
P4
EMIF ADDRESS (8 LSBs) from
R0 or R1
T
ALEH
ALE
EMIF READ DATA
T
T
ALEL
RDS
T
RDH
P1.3
P1.3
T
ACS
T
ACW
T
ACH
RD
P1.6
P1.6
WR
P1.7
P1.7
Figure 13.9. Multiplexed 8-bit MOVX without Bank Select Timing
128
P4
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
13.7.2.3.8-bit MOVX with Bank Select: EMI0CF[4:2] = ‘010’.
Muxed 8-bit WRITE with Bank Select
ADDR[15:8]
P3
AD[7:0]
P4
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF ADDRESS (8 LSBs) from
R0 or R1
T
ALEH
ALE
P3
EMIF WRITE DATA
P4
T
ALEL
P1.3
P1.3
T
T
WDS
T
ACS
WDH
T
T
ACW
ACH
WR
P1.7
P1.7
RD
P1.6
P1.6
Muxed 8-bit READ with Bank Select
ADDR[15:8]
P3
AD[7:0]
P4
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF ADDRESS (8 LSBs) from
R0 or R1
T
ALEH
ALE
P3
EMIF READ DATA
T
T
ALEL
RDS
P4
T
RDH
P1.3
P1.3
T
ACS
T
ACW
T
ACH
RD
P1.6
P1.6
WR
P1.7
P1.7
Figure 13.10. Multiplexed 8-bit MOVX with Bank Select Timing
Rev. 1.3
129
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 13.1. AC Parameters for External Memory Interface
Parameter
Description
Min*
Units
TACS
Address / Control Setup Time
0
3 x TSYSCLK
ns
TACW
Address / Control Pulse Width
1 x TSYSCLK
16 x TSYSCLK
ns
TACH
Address / Control Hold Time
0
3 x TSYSCLK
ns
TALEH
Address Latch Enable High Time
1 x TSYSCLK
4 x TSYSCLK
ns
TALEL
Address Latch Enable Low Time
1 x TSYSCLK
4 x TSYSCLK
ns
TWDS
Write Data Setup Time
1 x TSYSCLK
19 x TSYSCLK
ns
TWDH
Write Data Hold Time
0
3 x TSYSCLK
ns
TRDS
Read Data Setup Time
20
ns
TRDH
Read Data Hold Time
0
ns
*Note: TSYSCLK is equal to one period of the device system clock (SYSCLK).
130
Max*
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
14. Oscillators
C8051F34x devices include a programmable internal high-frequency oscillator, a programmable internal
low-frequency oscillator (C8051F340/1/2/3/4/5/8/9/A/B/C/D), an external oscillator drive circuit, and a 4x
Clock Multiplier. The internal high-frequency and low-frequency oscillators can be enabled/disabled and
adjusted using the special function registers, as shown in Figure 14.1. The system clock (SYSCLK) can be
derived from either of the internal oscillators, the external oscillator circuit, or the 4x Clock Multiplier divided
by 2. The USB clock (USBCLK) can be derived from the internal oscillator, external oscillator, or 4x Clock
Multiplier. Oscillator electrical specifications are given in Table 14.1.
CLKSL2
CLKSL1
CLKSL0
IFCN1
IFCN0
CLKSEL
USBCLK2
USBCLK1
USBCLK0
Option 2
VDD
OSCLCN
OSCLEN
OSCLRDY
OSCLF3
OSCLF2
OSCLF1
OSCLF0
OSCLD1
OSCLD0
OSCICN
IOSCEN
IFRDY
SUSPEND
OSCICL
Option 3
XTAL2
EN
Programmable HighFrequency Oscillator
XTAL2
IOSC
n
OSCLF3-0
EN
Programmable LowFrequency Oscillator
(C8051F340/1/2/3/4/5/8/9/
A/B/C/D)
Input
Circuit
XTAL2
Option 4
EXOSC
OSC
IOSC
XTLVLD
10M
SYSCLK
EXOSC
x2
x2
IOSC / 2
XTAL2
EXOSC / 2
Clock Multiplier
EXOSC
XFCN2
XFCN1
XFCN0
XTLVLD
XOSCMD2
XOSCMD1
XOSCMD0
USBCLK
CLKMUL
EXOSC / 2
EXOSC / 3
EXOSC / 4
USBCLK2-0
OSCXCN
MULSEL1
MULSEL0
XTAL1
MULEN
MULINIT
MULRDY
Option 1
n
Figure 14.1. Oscillator Diagram
Rev. 1.3
131
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
14.1. Programmable Internal High-Frequency (H-F) Oscillator
All C8051F34x devices include a programmable internal oscillator that defaults as the system clock after a
system reset. The internal oscillator period can be programmed via the OSCICL register shown in SFR
Definition 14.2. The OSCICL register is factory calibrated to obtain a 12 MHz internal oscillator frequency.
Electrical specifications for the precision internal oscillator are given in Table 14.1 on page 141. Note that
the system clock may be derived from the programmed internal oscillator divided by 1, 2, 4, or 8, as
defined by the IFCN bits in register OSCICN. The divide value defaults to 8 following a reset.
14.1.1. Internal H-F Oscillator Suspend Mode
The internal high-frequency oscillator may be placed in Suspend mode by writing ‘1’ to the SUSPEND bit in
register OSCICN. In Suspend mode, the internal H-F oscillator is stopped until a non-idle USB event is
detected (Section 16) or VBUS matches the polarity selected by the VBPOL bit in register REG0CN (Section 8.2). Note that the USB transceiver can still detect USB events when it is disabled.
SFR Definition 14.1. OSCICN: Internal H-F Oscillator Control
R/W
R
R/W
R
IOSCEN
IFRDY
SUSPEND
-
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
Reset Value
-
-
IFCN1
IFCN0
10000000
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xB2
Bit7:
IOSCEN: Internal H-F Oscillator Enable Bit.
0: Internal H-F Oscillator Disabled.
1: Internal H-F Oscillator Enabled.
Bit6:
IFRDY: Internal H-F Oscillator Frequency Ready Flag.
0: Internal H-F Oscillator is not running at programmed frequency.
1: Internal H-F Oscillator is running at programmed frequency.
Bit5:
SUSPEND: Force Suspend
Writing a ‘1’ to this bit will force the internal H-F oscillator to be stopped. The oscillator will be
re-started on the next non-idle USB event (i.e., RESUME signaling) or VBUS interrupt event
(see SFR Definition 8.1).
Bits4–2: UNUSED. Read = 000b, Write = don't care.
Bits1–0: IFCN1–0: Internal H-F Oscillator Frequency Control.
00: SYSCLK derived from Internal H-F Oscillator divided by 8.
01: SYSCLK derived from Internal H-F Oscillator divided by 4.
10: SYSCLK derived from Internal H-F Oscillator divided by 2.
11: SYSCLK derived from Internal H-F Oscillator divided by 1.
132
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 14.2. OSCICL: Internal H-F Oscillator Calibration
R/W
R/W
R/W
-
-
-
Bit7
Bit6
Bit5
R/W
R/W
Bit4
Bit3
R/W
R/W
R/W
Reset Value
Bit1
Bit0
SFR Address:
OSCCAL
Bit2
Variable
0xB3
Bits4–0: OSCCAL: Oscillator Calibration Value
These bits determine the internal H-F oscillator period. When set to 00000b, the oscillator
operates at its fastest setting. When set to 11111b, the oscillator operates at is slowest setting. The contents of this register are factory calibrated to produce a 12 MHz internal oscillator frequency.
Note: The contents of this register are undefined when Clock Recovery is enabled. See Section
“16.4. USB Clock Configuration” on page 166 for details on Clock Recovery.
14.2. Programmable Internal Low-Frequency (L-F) Oscillator
The C8051F340/1/2/3/4/5/8/9/C/D devices include a programmable internal oscillator which operates at a
nominal frequency of 80 kHz. The low-frequency oscillator circuit includes a divider that can be changed to
divide the clock by 1, 2, 4, or 8, using the OSCLD bits in the OSCLCN register (see SFR Definition 14.3).
Additionally, the OSCLF bits (OSCLCN5:2) can be used to adjust the oscillator’s output frequency.
14.2.1. Calibrating the Internal L-F Oscillator
Timers 2 and 3 include capture functions that can be used to capture the oscillator frequency, when running from a known time base. When either Timer 2 or Timer 3 is configured for L-F Oscillator Capture
Mode, a falling edge (Timer 2) or rising edge (Timer 3) of the low-frequency oscillator’s output will cause a
capture event on the corresponding timer. As a capture event occurs, the current timer value
(TMRnH:TMRnL) is copied into the timer reload registers (TMRnRLH:TMRnRLL). By recording the difference between two successive timer capture values, the low-frequency oscillator’s period can be calculated. The OSCLF bits can then be adjusted to produce the desired oscillator period.
Rev. 1.3
133
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 14.3. OSCLCN: Internal L-F Oscillator Control
R/W
R
R/W
OSCLEN OSCLRDY OSCLF3
Bit7
Bit6
Bit5
R
R/W
R/W
R/W
R/W
Reset Value
OSCLF2
OSCLF1
OSCLF0
OSCLD1
OSCLD0
00vvvv00
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x86
Bit7:
OSCLEN: Internal L-F Oscillator Enable.
0: Internal L-F Oscillator Disabled.
1: Internal L-F Oscillator Enabled.
Bit6:
OSCLRDY: Internal L-F Oscillator Ready Flag.
0: Internal L-F Oscillator frequency not stabilized.
1: Internal L-F Oscillator frequency stabilized.
Bits5–2: OSCLF[3:0]: Internal L-F Oscillator Frequency Control bits.
Fine-tune control bits for the internal L-F Oscillator frequency. When set to 0000b, the L-F
oscillator operates at its fastest setting. When set to 1111b, the L-F oscillator operates at its
slowest setting.
Bits1–0: OSCLD[1:0]: Internal L-F Oscillator Divider Select.
00: Divide by 8 selected.
01: Divide by 4selected.
10: Divide by 2 selected.
11: Divide by 1 selected.
134
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
14.3. External Oscillator Drive Circuit
The external oscillator circuit may drive an external crystal, ceramic resonator, capacitor, or RC network. A
CMOS clock may also provide a clock input. For a crystal or ceramic resonator configuration, the crystal/
resonator must be wired across the XTAL1 and XTAL2 pins as shown in Option 1 of Figure 14.1. A 10 M
resistor also must be wired across the XTAL1 and XTAL2 pins for the crystal/resonator configuration. In
RC, capacitor, or CMOS clock configuration, the clock source should be wired to the XTAL2 pin as shown
in Option 2, 3, or 4 of Figure 14.1. The type of external oscillator must be selected in the OSCXCN register,
and the frequency control bits (XFCN) must be selected appropriately (see SFR Definition 14.4)
Important Note on External Oscillator Usage: Port pins must be configured when using the external
oscillator circuit. When the external oscillator drive circuit is enabled in crystal/resonator mode, Port pins
P0.6 and P0.7 (C8051F340/1/4/5/8) or P0.2 and P0.3 (C8051F342/3/6/7/9/A/B) are used as XTAL1 and
XTAL2 respectively. When the external oscillator drive circuit is enabled in capacitor, RC, or CMOS clock
mode, Port pin P0.7 (C8051F340/1/4/5/8) or P0.3 (C8051F342/3/6/7/9/A/B) is used as XTAL2. The Port I/
O Crossbar should be configured to skip the Port pins used by the oscillator circuit; see Section
“15.1. Priority Crossbar Decoder” on page 144 for Crossbar configuration. Additionally, when using the
external oscillator circuit in crystal/resonator, capacitor, or RC mode, the associated Port pins should be
configured as analog inputs. In CMOS clock mode, the associated pin should be configured as a digital
input. See Section “15.2. Port I/O Initialization” on page 147 for details on Port input mode selection.
14.3.1. Clocking Timers Directly Through the External Oscillator
The external oscillator source divided by eight is a clock option for the timers (Section “21. Timers” on
page 235) and the Programmable Counter Array (PCA) (Section “22. Programmable Counter Array
(PCA0)” on page 255). When the external oscillator is used to clock these peripherals, but is not used as
the system clock, the external oscillator frequency must be less than or equal to the system clock frequency. In this configuration, the clock supplied to the peripheral (external oscillator / 8) is synchronized
with the system clock; the jitter associated with this synchronization is limited to ±0.5 system clock cycles.
14.3.2. External Crystal Example
If a crystal or ceramic resonator is used as an external oscillator source for the MCU, the circuit should be
configured as shown in Figure 14.1, Option 1. The External Oscillator Frequency Control value (XFCN)
should be chosen from the Crystal column of the table in SFR Definition 14.4 (OSCXCN register). For
example, a 12 MHz crystal requires an XFCN setting of 111b.
When the crystal oscillator is first enabled, the oscillator amplitude detection circuit requires a settling time
to achieve proper bias. Introducing a delay of 1 ms between enabling the oscillator and checking the
XTLVLD bit will prevent a premature switch to the external oscillator as the system clock. Switching to the
external oscillator before the crystal oscillator has stabilized can result in unpredictable behavior. The recommended procedure is:
Step 1.
Step 2.
Step 3.
Step 4.
Enable the external oscillator.
Wait at least 1 ms.
Poll for XTLVLD => ‘1’.
Switch the system clock to the external oscillator.
Important Note on External Crystals: Crystal oscillator circuits are quite sensitive to PCB layout. The
crystal should be placed as close as possible to the XTAL pins on the device. The traces should be as
short as possible and shielded with ground plane from any other traces which could introduce noise or
interference.
Rev. 1.3
135
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
14.3.3. External RC Example
If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as
shown in Figure 14.1, Option 2. The capacitor should be no greater than 100 pF; however for very small
capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, first
select the RC network value to produce the desired frequency of oscillation. If the frequency desired is
100 kHz, let R = 246 k and C = 50 pF:
3
3
1.23  10 
1.23  10 
f = ------------------------ = -------------------------- = 0.1 MHz = 100 kHz
RC
 246  50 
Referring to the table in SFR Definition 14.4, the required XFCN setting is 010b. Programming XFCN to a
higher setting in RC mode will improve frequency accuracy at an increased external oscillator supply current.
14.3.4. External Capacitor Example
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in
Figure 14.1, Option 3. The capacitor should be no greater than 100 pF; however for very small capacitors,
the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the
required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the capacitor to be used and find the frequency of oscillation from the equations below. Assume VDD = 3.0 V and C =
50 pF:
KF
KF
f = ------------------------- = ------------------------------- C  VDD 
 50 x 3 MHz
KF
f = ---------------------150 MHz
If a frequency of roughly 150 kHz is desired, select the K Factor from the table in SFR Definition 14.4 as
KF = 22:
22
f = --------- = 0.146 MHz, or 146 kHz
150
Therefore, the XFCN value to use in this example is 011b.
136
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 14.4. OSCXCN: External Oscillator Control
R
R/W
R/W
R/W
XTLVLD XOSCMD2 XOSCMD1 XOSCMD0
Bit7
Bit6
Bit5
Bit4
R
R/W
R/W
R/W
Reset Value
-
XFCN2
XFCN1
XFCN0
00000000
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xB1
Bit7:
XTLVLD: Crystal Oscillator Valid Flag.
(Read only when XOSCMD = 11x.)
0: Crystal Oscillator is unused or not yet stable.
1: Crystal Oscillator is running and stable.
Bits6–4: XOSCMD2–0: External Oscillator Mode Bits.
00x: External Oscillator circuit off.
010: External CMOS Clock Mode.
011: External CMOS Clock Mode with divide by 2 stage.
100: RC Oscillator Mode.
101: Capacitor Oscillator Mode.
110: Crystal Oscillator Mode.
111: Crystal Oscillator Mode with divide by 2 stage.
Bit3:
RESERVED. Read = 0, Write = don't care.
Bits2–0: XFCN2–0: External Oscillator Frequency Control Bits.
000-111: See table below:
XFCN Crystal (XOSCMD = 11x)
000
f  32 kHz
001
32 kHz f 84kHz
010
84 kHz  f 225 kHz
011
225 kHz  f 590 kHz
100
590 kHz  f 1.5 MHz
101
1.5 MHz  f 4 MHz
110
4 MHz  f 10 MHz
111
10 MHz  f 30 MHz
RC (XOSCMD = 10x)
f 25 kHz
25 kHz f 50 kHz
50 kHz f 100 kHz
100 kHz f 200 kHz
200 kHz f 400 kHz
400 kHz f 800 kHz
800 kHz f 1.6 MHz
1.6 MHz f 3.2 MHz
C (XOSCMD = 10x)
K Factor = 0.87
K Factor = 2.6
K Factor = 7.7
K Factor = 22
K Factor = 65
K Factor = 180
K Factor = 664
K Factor = 1590
CRYSTAL MODE (Circuit from Figure 14.1, Option 1; XOSCMD = 11x)
Choose XFCN value to match crystal or resonator frequency.
RC MODE (Circuit from Figure 14.1, Option 2; XOSCMD = 10x)
Choose XFCN value to match frequency range:
f = 1.23(103) / (R x C), where
f = frequency of clock in MHz
C = capacitor value in pF
R = Pull-up resistor value in k
C MODE (Circuit from Figure 14.1, Option 3; XOSCMD = 10x)
Choose K Factor (KF) for the oscillation frequency desired:
f = KF / (C x VDD), where
f = frequency of clock in MHz
C = capacitor value the XTAL2 pin in pF
VDD = Power Supply on MCU in volts
Rev. 1.3
137
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
14.4. 4x Clock Multiplier
The 4x Clock Multiplier allows a 12 MHz oscillator to generate the 48 MHz clock required for Full Speed
USB communication (see Section “16.4. USB Clock Configuration” on page 166). A divided version of
the Multiplier output can also be used as the system clock. C8051F340/1/2/3 devices can use the 48 MHz
Clock Multiplier output as system clock. See Table 3.1, “Global DC Electrical Characteristics,” on page 25
for system clock frequency specifications. See Section 14.5 for details on system clock and USB clock
source selection.
The 4x Clock Multiplier is configured via the CLKMUL register. The procedure for configuring and enabling
the 4x Clock Multiplier is as follows:
1.
2.
3.
4.
5.
6.
Reset the Multiplier by writing 0x00 to register CLKMUL.
Select the Multiplier input source via the MULSEL bits.
Enable the Multiplier with the MULEN bit (CLKMUL | = 0x80).
Delay for >5 µs.
Initialize the Multiplier with the MULINIT bit (CLKMUL | = 0xC0).
Poll for MULRDY => ‘1’.
Important Note: When using an external oscillator as the input to the 4x Clock Multiplier, the external source must be enabled and stable before the Multiplier is initialized. See Section 14.5 for
details on selecting an external oscillator source.
SFR Definition 14.5. CLKMUL: Clock Multiplier Control
R/W
MULEN
Bit7
R/W
R
MULINIT MULRDY
Bit6
Bit5
R/W
R/W
R/W
-
-
-
Bit4
Bit3
Bit2
R/W
R/W
MULSEL
Bit1
Bit0
Reset Value
00000000
SFR Address
0xB9
Bit7:
MULEN: Clock Multiplier Enable
0: Clock Multiplier disabled.
1: Clock Multiplier enabled.
Bit6:
MULINIT: Clock Multiplier Initialize
This bit should be a ‘0’ when the Clock Multiplier is enabled. Once enabled, writing a ‘1’ to
this bit will initialize the Clock Multiplier. The MULRDY bit reads ‘1’ when the Clock Multiplier
is stabilized.
Bit5:
MULRDY: Clock Multiplier Ready
This read-only bit indicates the status of the Clock Multiplier.
0: Clock Multiplier not ready.
1: Clock Multiplier ready (locked).
Bits4–2: Unused. Read = 000b; Write = don’t care.
Bits1–0: MULSEL: Clock Multiplier Input Select
These bits select the clock supplied to the Clock Multiplier.
MULSEL
00
01
10
11
138
Selected Clock
Internal Oscillator
External Oscillator
External Oscillator / 2
RESERVED
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
14.5. System and USB Clock Selection
The internal oscillator requires little start-up time and may be selected as the system or USB clock immediately following the OSCICN write that enables the internal oscillator. External crystals and ceramic resonators typically require a start-up time before they are settled and ready for use. The Crystal Valid Flag
(XTLVLD in register OSCXCN) is set to ‘1’ by hardware when the external oscillator is settled. To avoid
reading a false XTLVLD, in crystal mode software should delay at least 1 ms between enabling the
external oscillator and checking XTLVLD. RC and C modes typically require no startup time.
14.5.1. System Clock Selection
The CLKSL[1:0] bits in register CLKSEL select which oscillator source is used as the system clock.
CLKSL[1:0] must be set to 01b for the system clock to run from the external oscillator; however the external oscillator may still clock certain peripherals (timers, PCA, USB) when the internal oscillator is selected
as the system clock. The system clock may be switched on-the-fly between the internal oscillator, external
oscillator, and 4x Clock Multiplier so long as the selected oscillator is enabled and has settled. C8051F340/
1/2/3 devices can use the 48 MHz Clock Multiplier output as system clock. See Table 3.1, “Global DC Electrical Characteristics,” on page 25 for system clock frequency specifications. When operating with a system clock of greater than 25 MHz (up to 48 MHz), the FLRT bit (FLSCL.4) should be set to ‘1’. See
Section “10. Prefetch Engine” on page 99 for more details.
14.5.2. USB Clock Selection
The USBCLK[2:0] bits in register CLKSEL select which oscillator source is used as the USB clock. The
USB clock may be derived from the 4x Clock Multiplier output, a divided version of the internal oscillator, or
a divided version of the external oscillator. Note that the USB clock must be 48 MHz when operating USB0
as a Full Speed Function; the USB clock must be 6 MHz when operating USB0 as a Low Speed Function.
See SFR Definition 14.6 for USB clock selection options.
Some example USB clock configurations for Full and Low Speed mode are given below:
Clock Signal
USB Clock
Clock Multiplier Input
Internal Oscillator
Clock Signal
USB Clock
Clock Multiplier Input
External Oscillator
Internal Oscillator
Input Source Selection
Clock Multiplier
Internal Oscillator*
Divide by 1
External Oscillator
Input Source Selection
Clock Multiplier
External Oscillator
Crystal Oscillator Mode
12 MHz Crystal
Register Bit Settings
USBCLK = 000b
MULSEL = 00b
IFCN = 11b
Register Bit Settings
USBCLK = 000b
MULSEL = 01b
XOSCMD = 110b
XFCN = 111b
*Note: Clock Recovery must be enabled for this configuration.
Clock Signal
USB Clock
Internal Oscillator
Clock Signal
Internal Oscillator
Input Source Selection
Internal Oscillator / 2
Divide by 1
External Oscillator
Input Source Selection
Register Bit Settings
USBCLK = 001b
IFCN = 11b
Rev. 1.3
Register Bit Settings
139
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Internal Oscillator
Input Source Selection
External Oscillator / 4
Crystal Oscillator Mode
24 MHz Crystal
Clock Signal
USB Clock
External Oscillator
Register Bit Settings
USBCLK = 101b
XOSCMD = 110b
XFCN = 111b
SFR Definition 14.6. CLKSEL: Clock Select
R/W
R/W
Bit7
R/W
R/W
R/W
Bit4
Bit3
USBCLK
Bit6
Bit5
R/W
-
R/W
R/W
Reset Value
Bit0
SFR Address
CLKSL
Bit2
Bit1
00000000
0xA9
Bit 7:
Unused. Read = 0b; Write = don’t care.
Bits6–4: USBCLK2–0: USB Clock Select
These bits select the clock supplied to USB0. When operating USB0 in full-speed mode, the
selected clock should be 48 MHz. When operating USB0 in low-speed mode, the selected
clock should be 6 MHz.
USBCLK
000
001
010
011
100
101
110
111
Selected Clock
4x Clock Multiplier
Internal Oscillator / 2
External Oscillator
External Oscillator / 2
External Oscillator / 3
External Oscillator / 4
RESERVED
RESERVED
Bit3:
Unused. Read = 0b; Write = don’t care.
Bits2–0: CLKSL2–0: System Clock Select
These bits select the system clock source. When operating from a system clock of 25 MHz
or less, the FLRT bit should be set to ‘0’. When operating with a system clock of greater than
25 MHz (up to 48 MHz), the FLRT bit (FLSCL.4) should be set to ‘1’. See Section
“10. Prefetch Engine” on page 99 for more details.
CLKSL
000
001
010
011*
100
101-111
Selected Clock
Internal Oscillator (as determined by the
IFCN bits in register OSCICN)
External Oscillator
4x Clock Multiplier / 2
4x Clock Multiplier*
Low-Frequency Oscillator
RESERVED
*Note: This option is only available on 48 MHz devices.
140
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 14.1. Oscillator Electrical Characteristics
VDD = 2.7 to 3.6 V; –40 to +85 °C unless otherwise specified
Parameter
Conditions
Min
Typ
Max
Units
11.82
12.00
12.18
MHz
—
685
—
µA
72
80
99
kHz
—
7.0
—
µA
Full Speed Mode
47.88
48
48.12
Low Speed Mode
5.91
6
6.09
Internal High-Frequency Oscillator (Using Factory-Calibrated Settings)
Oscillator Frequency
Oscillator Supply Current 
(from VDD)
IFCN = 11b
24 ºC, VDD = 3.0 V,
OSCICN.7 = 1
Internal Low-Frequency Oscillator (Using Factory-Calibrated Settings)
Oscillator Frequency
Oscillator Supply Current 
(from VDD)
OSCLD = 11b
24 ºC, VDD = 3.0 V,
OSCLCN.7 = 1
External USB Clock Requirements
USB Clock Frequency*
MHz
*Note: Applies only to external oscillator sources.
Rev. 1.3
141
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
15. Port Input/Output
Digital and analog resources are available through 40 I/O pins (48-pin packages) or 25 I/O pins (32-pin
packages). Port pins are organized as shown in Figure 15.1. Each of the Port pins can be defined as general-purpose I/O (GPIO) or analog input; Port pins P0.0-P3.7 can be assigned to one of the internal digital
resources as shown in Figure 15.3. The designer has complete control over which functions are assigned,
limited only by the number of physical I/O pins. This resource assignment flexibility is achieved through the
use of a Priority Crossbar Decoder. Note that the state of a Port I/O pin can always be read in the corresponding Port latch, regardless of the Crossbar settings.
The Crossbar assigns the selected internal digital resources to the I/O pins based on the Priority Decoder
(Figure 15.3 and Figure 15.4). The registers XBR0, XBR1, and XBR2 defined in SFR Definition 15.1, SFR
Definition 15.2, and SFR Definition 15.3, are used to select internal digital functions.
All Port I/Os are 5 V tolerant (refer to Figure 15.2 for the Port cell circuit). The Port I/O cells are configured
as either push-pull or open-drain in the Port Output Mode registers (PnMDOUT, where n = 0,1,2,3,4). Complete Electrical Specifications for Port I/O are given in Table 15.1 on page 158.
XBR0, XBR1, XBR2,
PnSKIP Registers
PnMDOUT,
PnMDIN Registers
Priority
Decoder
Highest
Priority
2
UART0
4
SPI
8
2
(Internal Digital Signals)
SMBus
CP0
Outputs
2
CP1
Outputs
2
Digital
Crossbar
8
P0.0
P1
I/O
Cells
P1.0
P2
I/O
Cells
P2.0
P3
I/O
Cells
P3.0
P0.7
P1.7
SYSCLK
8
6
PCA
P2.7
2
T0, T1
8
Lowest
Priority
P0
I/O
Cells
UART1**
2
P3.7*
8
P0
(P0.0-P0.7)
(Port Latches)
8
P1
(P1.0-P1.7)
8
P2
*P3.1-P3.7 only available on 48-pin
packages
**UART1 only available on
C8051F340/1/4/5/8/A/B devices
(P2.0-P2.7)
8
P3
(P3.0-P3.7*)
Figure 15.1. Port I/O Functional Block Diagram (Port 0 through Port 3)
142
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
W E A K -P U LLU P
VDD
P U S H -P U LL
VDD
P O R T -O U T E N A B LE
(W E A K )
PORT
PAD
P O R T -O U T P U T
A nalog S elect
GND
A N A LO G IN P U T
P O R T -IN P U T
Figure 15.2. Port I/O Cell Block Diagram
Rev. 1.3
143
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
15.1. Priority Crossbar Decoder
The Priority Crossbar Decoder (Figure 15.3) assigns a priority to each I/O function, starting at the top with
UART0. When a digital resource is selected, the least-significant unassigned Port pin is assigned to that
resource (excluding UART0, which is always at pins 4 and 5). If a Port pin is assigned, the Crossbar skips
that pin when assigning the next selected resource. Additionally, the Crossbar will skip Port pins whose
associated bits in the PnSKIP registers are set. The PnSKIP registers allow software to skip Port pins that
are to be used for analog input, dedicated functions, or GPIO.
Important Note on Crossbar Configuration: If a Port pin is claimed by a peripheral without use of the
Crossbar, its corresponding PnSKIP bit should be set. This applies to the VREF signal, external oscillator
pins (XTAL1, XTAL2), the ADC’s external conversion start signal (CNVSTR), EMIF control signals, and any
selected ADC or Comparator inputs. The PnSKIP registers may also be used to skip pins to be used as
GPIO. The Crossbar skips selected pins as if they were already assigned, and moves to the next unassigned pin. Figure 15.3 shows all the possible pins available to each peripheral. Figure 15.4 shows the
Crossbar Decoder priority with no Port pins skipped. Figure 15.5 shows a Crossbar example with pins
P0.2, P0.3, and P1.0 skipped.
7
0
1
2
RD
6
WR
5
VREF
4
P3
P3.1-P3.7 unavailable on
the 32-pin packages
ALE
1
P2
CNVSTR
0
VREF
PIN I/O
CNVSTR
3
SF Signals
(48-pin
Package)
XTAL2
2
P1
XTAL1
XTAL2
SF Signals
(32-pin
Package)
XTAL1
P0
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
TX0
RX0
SCK
MISO
MOSI
NSS*
SDA
SCL
CP0
CP0A
CP1
CP1A
SYSCLK
CEX0
CEX1
CEX2
CEX3
CEX4
ECI
T0
T1
TX1**
RX1**
Port pin potentially available to peripheral
**UART1 available only on C8051F340/1/4/5/8/A/B devices
SF Signals Special Function Signals are not assigned by the Crossbar. When these signals are
enabled, the Crossbar must be manually configured to skip their corresponding port pins.
*NSS is only pinned out in 4-wire SPI mode
Figure 15.3. Peripheral Availability on Port I/O Pins
144
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
7
0
1
2
RD
6
WR
5
VREF
4
P3
P3.1-P3.7 unavailable on
the 32-pin packages
ALE
1
P2
CNVSTR
0
VREF
PIN I/O
CNVSTR
3
SF Signals
(48-pin
Package)
XTAL2
2
P1
XTAL1
XTAL2
SF Signals
(32-pin
Package)
XTAL1
P0
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
0
TX0
RX0
SCK
MISO
MOSI
NSS*
*NSS is only pinned out in 4-wire SPI mode
SDA
SCL
CP0
CP0A
CP1
CP1A
SYSCLK
CEX0
CEX1
CEX2
CEX3
CEX4
ECI
T0
T1
TX1**
**UART1 available only on C8051F340/1/4/5/8/A/B devices
RX1**
0
0
0
0
0
0
0
0
0
0
0
P0SKIP[0:7]
0
0
0
0
0
P1SKIP[0:7]
0
0
0
0
0
0
0
0
0
0
P2SKIP[0:7]
Port pin assigned to peripheral by the Crossbar
0
0
0
P3SKIP[0:7]
Example:
SF Signals Special Function Signals are not assigned by the Crossbar. When these signals are
0
XBR0 = 0x07
XBR1 = 0x43
Figure 15.4. Crossbar Priority Decoder in Example Configuration
(No Pins Skipped)
Rev. 1.3
145
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
7
0
1
2
RD
6
WR
5
VREF
4
P3.1-P3.7 una va ila ble on
the 32-pin pa cka ge s
CNVSTR
1
P3
P2
ALE
0
VREF
P IN I/O
CNVSTR
3
S F Signa ls
(48-pin
P a cka ge )
XTAL2
2
P1
XTAL1
XTAL2
S F Signa ls
(32-pin
P a cka ge )
XTAL1
P0
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
0
TX 0
RX0
S CK
M ISO
M OSI
NSS*
*NSS is only pinned out in 4-wire S PI m ode
S DA
S CL
CP0
CP0A
CP1
CP1A
S YSCLK
CEX0
CEX1
CEX2
CEX3
CEX4
ECI
T0
T1
TX 1**
**UA RT1 available only on C8051F340/1/4/5/8/A /B devices
RX1**
0
0
1
1
0
0
0
0
1
0
0
P 0SKIP[0:7]
0
0
0
0
0
P1S KIP[0:7]
0
0
0
0
0
0
0
0
0
0
P2SKIP[0:7]
Port pin assigned to peripheral by the Crossbar
0
0
0
P3SKIP [0:7]
Example:
S F Signa ls Special Function Signals are not assigned by the Crossbar. W hen these signals are
enabled, the Crossbar must be manually configured to skip their corresponding port pins.
0
XBR0 = 0x07
XBR1 = 0x43
P 0SK IP = 0x0C
P 1SK IP = 0x01
Figure 15.5. Crossbar Priority Decoder in Example Configuration (3 Pins Skipped)
Registers XBR0, XBR1, and XBR2 are used to assign the digital I/O resources to the physical I/O Port
pins. Note that when the SMBus is selected, the Crossbar assigns both pins associated with the SMBus
(SDA and SCL); when either UART is selected, the Crossbar assigns both pins associated with the UART
(TX and RX). UART0 pin assignments are fixed for bootloading purposes: UART TX0 is always assigned
to P0.4; UART RX0 is always assigned to P0.5. Standard Port I/Os appear contiguously after the prioritized
functions have been assigned.
Important Note: The SPI can be operated in either 3-wire or 4-wire modes, depending on the state of the
NSSMD1-NSSMD0 bits in register SPI0CN. According to the SPI mode, the NSS signal may or may not be
routed to a Port pin.
146
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
15.2. Port I/O Initialization
Port I/O initialization consists of the following steps:
Step 1. Select the input mode (analog or digital) for all Port pins, using the Port Input Mode
register (PnMDIN).
Step 2. Select the output mode (open-drain or push-pull) for all Port pins, using the Port Output
Mode register (PnMDOUT).
Step 3. Select any pins to be skipped by the I/O Crossbar using the Port Skip registers (PnSKIP).
Step 4. Assign Port pins to desired peripherals (XBR0, XBR1).
Step 5. Enable the Crossbar (XBARE = ‘1’).
All Port pins must be configured as either analog or digital inputs. Any pins to be used as Comparator or
ADC inputs should be configured as an analog inputs. When a pin is configured as an analog input, its
weak pull-up, digital driver, and digital receiver are disabled. This process saves power and reduces noise
on the analog input. Pins configured as digital inputs may still be used by analog peripherals; however this
practice is not recommended. To configure a Port pin for digital input, write ‘0’ to the corresponding bit in
register PnMDOUT, and write ‘1’ to the corresponding Port latch (register Pn).
Additionally, all analog input pins should be configured to be skipped by the Crossbar (accomplished by
setting the associated bits in PnSKIP). Port input mode is set in the PnMDIN register, where a ‘1’ indicates
a digital input, and a ‘0’ indicates an analog input. All pins default to digital inputs on reset.
The output driver characteristics of the I/O pins are defined using the Port Output Mode registers (PnMDOUT). Each Port Output driver can be configured as either open drain or push-pull. This selection is
required even for the digital resources selected in the XBRn registers, and is not automatic. The only
exception to this is the SMBus (SDA, SCL) pins, which are configured as open-drain regardless of the
PnMDOUT settings. When the WEAKPUD bit in XBR1 is ‘0’, a weak pull-up is enabled for all Port I/O configured as open-drain. WEAKPUD does not affect the push-pull Port I/O. Furthermore, the weak pull-up is
turned off on an output that is driving a ‘0’ to avoid unnecessary power dissipation.
Registers XBR0 and XBR1 must be loaded with the appropriate values to select the digital I/O functions
required by the design. Setting the XBARE bit in XBR1 to ‘1’ enables the Crossbar. Until the Crossbar is
enabled, the external pins remain as standard Port I/O (in input mode), regardless of the XBRn Register
settings. For given XBRn Register settings, one can determine the I/O pin-out using the Priority Decode
Table; as an alternative, the Configuration Wizard utility of the Silicon Labs IDE software will determine the
Port I/O pin-assignments based on the XBRn Register settings.
Important Note: The Crossbar must be enabled to use Ports P0, P1, P2, and P3 as standard Port I/O in
output mode. These Port output drivers are disabled while the Crossbar is disabled. Port 4 always functions as standard GPIO.
Rev. 1.3
147
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 15.1. XBR0: Port I/O Crossbar Register 0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
CP1AE
CP1E
CP0AE
CP0E
SYSCKE
SMB0E
SPI0E
URT0E
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xE1
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
148
CP1AE: Comparator1 Asynchronous Output Enable
0: Asynchronous CP1 unavailable at Port pin.
1: Asynchronous CP1 routed to Port pin.
CP1E: Comparator1 Output Enable
0: CP1 unavailable at Port pin.
1: CP1 routed to Port pin.
CP0AE: Comparator0 Asynchronous Output Enable
0: Asynchronous CP0 unavailable at Port pin.
1: Asynchronous CP0 routed to Port pin.
CP0E: Comparator0 Output Enable
0: CP0 unavailable at Port pin.
1: CP0 routed to Port pin.
SYSCKE: /SYSCLK Output Enable
0: /SYSCLK unavailable at Port pin.
1: /SYSCLK output routed to Port pin.
SMB0E: SMBus I/O Enable
0: SMBus I/O unavailable at Port pins.
1: SMBus I/O routed to Port pins.
SPI0E: SPI I/O Enable
0: SPI I/O unavailable at Port pins.
1: SPI I/O routed to Port pins.
URT0E: UART0 I/O Output Enable
0: UART0 I/O unavailable at Port pins.
1: UART0 TX0, RX0 routed to Port pins P0.4 and P0.5.
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 15.2. XBR1: Port I/O Crossbar Register 1
R/W
R/W
R/W
R/W
R/W
WEAKPUD
XBARE
T1E
T0E
ECIE
Bit7
Bit6
Bit5
Bit4
Bit3
R/W
R/W
R/W
Reset Value
Bit0
SFR Address:
PCA0ME
Bit2
Bit1
00000000
0xE2
Bit7:
WEAKPUD: Port I/O Weak Pull-up Disable.
0: Weak Pull-ups enabled (except for Ports whose I/O are configured as analog input or
push-pull output).
1: Weak Pull-ups disabled.
Bit6:
XBARE: Crossbar Enable.
0: Crossbar disabled; all Port drivers disabled.
1: Crossbar enabled.
Bit5:
T1E: T1 Enable
0: T1 unavailable at Port pin.
1: T1 routed to Port pin.
Bit4:
T0E: T0 Enable
0: T0 unavailable at Port pin.
1: T0 routed to Port pin.
Bit3:
ECIE: PCA0 External Counter Input Enable
0: ECI unavailable at Port pin.
1: ECI routed to Port pin.
Bits2–0: PCA0ME: PCA Module I/O Enable Bits.
000: All PCA I/O unavailable at Port pins.
001: CEX0 routed to Port pin.
010: CEX0, CEX1 routed to Port pins.
011: CEX0, CEX1, CEX2 routed to Port pins.
100: CEX0, CEX1, CEX2, CEX3 routed to Port pins.
101: CEX0, CEX1, CEX2, CEX3, CEX4 routed to Port pins.
110: Reserved.
111: Reserved.
SFR Definition 15.3. XBR2: Port I/O Crossbar Register 2
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
URT1E
00000000
Bit0
SFR Address:
0xE3
Bits7–1: RESERVED: Always write to 0000000b
Bit0:
URT1E: UART1 I/O Output Enable (C8051F340/1/4/5/8/A/B Only)
0: UART1 I/O unavailable at Port pins.
1: UART1 TX1, RX1 routed to Port pins.
Rev. 1.3
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C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
15.3. General Purpose Port I/O
Port pins that remain unassigned by the Crossbar and are not used by analog peripherals can be used for
general purpose I/O. Ports 3-0 are accessed through corresponding special function registers (SFRs) that
are both byte addressable and bit addressable. Port 4 (48-pin packages only) uses an SFR which is
byte-addressable. When writing to a Port, the value written to the SFR is latched to maintain the output
data value at each pin. When reading, the logic levels of the Port's input pins are returned regardless of the
XBRn settings (i.e., even when the pin is assigned to another signal by the Crossbar, the Port register can
always read its corresponding Port I/O pin). The exception to this is the execution of the read-modify-write
instructions. The read-modify-write instructions when operating on a Port SFR are the following: ANL,
ORL, XRL, JBC, CPL, INC, DEC, DJNZ and MOV, CLR or SETB, when the destination is an individual bit
in a Port SFR. For these instructions, the value of the register (not the pin) is read, modified, and written
back to the SFR.
SFR Definition 15.4. P0: Port0 Latch
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
P0.7
P0.6
P0.5
P0.4
P0.3
P0.2
P0.1
P0.0
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Reset Value
0x80
Bits7–0: P0.[7:0]
Write - Output appears on I/O pins per Crossbar Registers (when XBARE = ‘1’).
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P0MDOUT.n bit = 0).
Read - Always reads ‘0’ if selected as analog input in register P0MDIN. Directly reads Port
pin when configured as digital input.
0: P0.n pin is logic low.
1: P0.n pin is logic high.
SFR Definition 15.5. P0MDIN: Port0 Input Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
11111111
0xF1
Bits7–0: Analog Input Configuration Bits for P0.7–P0.0 (respectively).
Port pins configured as analog inputs have their weak pull-up, digital driver, and digital
receiver disabled.
0: Corresponding P0.n pin is configured as an analog input.
1: Corresponding P0.n pin is not configured as an analog input.
150
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 15.6. P0MDOUT: Port0 Output Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xA4
Bits7–0: Output Configuration Bits for P0.7–P0.0 (respectively): ignored if corresponding bit in register P0MDIN is logic 0.
0: Corresponding P0.n Output is open-drain.
1: Corresponding P0.n Output is push-pull.
(Note: When SDA and SCL appear on any of the Port I/O, each are open-drain regardless
of the value of P0MDOUT).
SFR Definition 15.7. P0SKIP: Port0 Skip
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xD4
Bits7–0: P0SKIP[7:0]: Port0 Crossbar Skip Enable Bits.
These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar.
0: Corresponding P0.n pin is not skipped by the Crossbar.
1: Corresponding P0.n pin is skipped by the Crossbar.
Rev. 1.3
151
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 15.8. P1: Port1 Latch
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
P1.7
P1.6
P1.5
P1.4
P1.3
P1.2
P1.1
P1.0
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Reset Value
0x90
Bits7–0: P1.[7:0]
Write - Output appears on I/O pins per Crossbar Registers (when XBARE = ‘1’).
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P1MDOUT.n bit = 0).
Read - Always reads ‘0’ if selected as analog input in register P1MDIN. Directly reads Port
pin when configured as digital input.
0: P1.n pin is logic low.
1: P1.n pin is logic high.
SFR Definition 15.9. P1MDIN: Port1 Input Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
11111111
0xF2
Bits7–0: Analog Input Configuration Bits for P1.7–P1.0 (respectively).
Port pins configured as analog inputs have their weak pull-up, digital driver, and digital
receiver disabled.
0: Corresponding P1.n pin is configured as an analog input.
1: Corresponding P1.n pin is not configured as an analog input.
SFR Definition 15.10. P1MDOUT: Port1 Output Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
00000000
0xA5
Bits7–0: Output Configuration Bits for P1.7–P1.0 (respectively): ignored if corresponding bit in register P1MDIN is logic 0.
0: Corresponding P1.n Output is open-drain.
1: Corresponding P1.n Output is push-pull.
152
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 15.11. P1SKIP: Port1 Skip
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xD5
Bits7–0: P1SKIP[7:0]: Port1 Crossbar Skip Enable Bits.
These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar.
0: Corresponding P1.n pin is not skipped by the Crossbar.
1: Corresponding P1.n pin is skipped by the Crossbar.
SFR Definition 15.12. P2: Port2 Latch
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
P2.7
P2.6
P2.5
P2.4
P2.3
P2.2
P2.1
P2.0
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Reset Value
0xA0
Bits7–0: P2.[7:0]
Write - Output appears on I/O pins per Crossbar Registers (when XBARE = ‘1’).
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P2MDOUT.n bit = 0).
Read - Always reads ‘0’ if selected as analog input in register P2MDIN. Directly reads Port
pin when configured as digital input.
0: P2.n pin is logic low.
1: P2.n pin is logic high.
SFR Definition 15.13. P2MDIN: Port2 Input Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
11111111
0xF3
Bits7-0:
Analog Input Configuration Bits for P2.7-P2.0 (respectively).
Port pins configured as analog inputs have their weak pull-up, digital driver, and digital
receiver disabled.
0: Corresponding P2.n pin is configured as an analog input.
1: Corresponding P2.n pin is not configured as an analog input.
Rev. 1.3
153
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 15.14. P2MDOUT: Port2 Output Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xA6
Bits7–0: Output Configuration Bits for P2.7–P2.0 (respectively): ignored if corresponding bit in register P2MDIN is logic 0.
0: Corresponding P2.n Output is open-drain.
1: Corresponding P2.n Output is push-pull.
SFR Definition 15.15. P2SKIP: Port2 Skip
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xD6
Bits7–0: P2SKIP[7:0]: Port2 Crossbar Skip Enable Bits.
These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar.
0: Corresponding P2.n pin is not skipped by the Crossbar.
1: Corresponding P2.n pin is skipped by the Crossbar.
154
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 15.16. P3: Port3 Latch
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
P3.7
P3.6
P3.5
P3.4
P3.3
P3.2
P3.1
P3.0
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Reset Value
0xB0
Bits7–0: P3.[7:0]
Write - Output appears on I/O pins.
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P3MDOUT.n bit = 0).
Read - Always reads ‘0’ if selected as analog input in register P3MDIN. Directly reads Port
pin when configured as digital input.
0: P3.n pin is logic low.
1: P3.n pin is logic high.
Note: P3.1–3.7 are only available on 48-pin devices.
SFR Definition 15.17. P3MDIN: Port3 Input Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
11111111
0xF4
Bits7–0: Analog Input Configuration Bits for P3.7–P3.0 (respectively).
Port pins configured as analog inputs have their weak pull-up, digital driver, and digital
receiver disabled.
0: Corresponding P3.n pin is configured as an analog input.
1: Corresponding P3.n pin is not configured as an analog input.
Note: P3.1–3.7 are only available on 48-pin devices.
SFR Definition 15.18. P3MDOUT: Port3 Output Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xA7
Bits7–0: Output Configuration Bits for P3.7–P3.0 (respectively); ignored if corresponding bit in register P3MDIN is logic 0.
0: Corresponding P3.n Output is open-drain.
1: Corresponding P3.n Output is push-pull.
Note: P3.1–3.7 are only available on 48-pin devices.
Rev. 1.3
155
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 15.19. P3SKIP: Port3 Skip
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xDF
Bits7–0: P3SKIP[3:0]: Port3 Crossbar Skip Enable Bits.
These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar.
0: Corresponding P3.n pin is not skipped by the Crossbar.
1: Corresponding P3.n pin is skipped by the Crossbar.
Note: P3.1–3.7 are only available on 48-pin devices.
SFR Definition 15.20. P4: Port4 Latch
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
P4.7
P4.6
P4.5
P4.4
P4.3
P4.2
P4.1
P4.0
Reset Value
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xC7
Bits7–0: P4.[7:0]
Write - Output appears on I/O pins.
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P4MDOUT.n bit = 0).
Read - Always reads ‘0’ if selected as analog input in register P4MDIN. Directly reads Port
pin when configured as digital input.
0: P4.n pin is logic low.
1: P4.n pin is logic high.
Note: P4 is only available on 48-pin devices.
156
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 15.21. P4MDIN: Port4 Input Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xF5
Bits7–0: Analog Input Configuration Bits for P4.7–P4.0 (respectively).
Port pins configured as analog inputs have their weak pull-up, digital driver, and digital
receiver disabled.
0: Corresponding P4.n pin is configured as an analog input.
1: Corresponding P4.n pin is not configured as an analog input.
Note: P4 is only available on 48-pin devices.
SFR Definition 15.22. P4MDOUT: Port4 Output Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xAE
Bits7–0: Output Configuration Bits for P4.7–P4.0 (respectively); ignored if corresponding bit in register P4MDIN is logic 0.
0: Corresponding P4.n Output is open-drain.
1: Corresponding P4.n Output is push-pull.
Note: P4 is only available on 48-pin devices.
Rev. 1.3
157
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 15.1. Port I/O DC Electrical Characteristics
VDD = 2.7 to 3.6 V, –40 to +85 °C unless otherwise specified
Parameters
Conditions
Min
IOH = –3 mA, Port I/O push-pull
VDD – 0.7
Output High Voltage
IOH = –10 µA, Port I/O push-pull
V
0.6
IOL = 10 µA
0.1
V
1.0
Input High Voltage
Input Low Voltage
158
Units
VDD – 0.8
IOL = 25 mA
Input Leakage Current
Max
VDD – 0.1
IOH = –10 mA, Port I/O push-pull
IOL = 8.5 mA
Output Low Voltage
Typ
2.0
0.8
±1
Weak Pull-up Off
Weak Pull-up On, VIN = 0 V
Rev. 1.3
25
50
V
V
µA
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
16. Universal Serial Bus Controller (USB0)
C8051F34x devices include a complete Full/Low Speed USB function for USB peripheral implementations*. The USB Function Controller (USB0) consists of a Serial Interface Engine (SIE), USB Transceiver
(including matching resistors and configurable pull-up resistors), 1k FIFO block, and clock recovery mechanism for crystal-less operation. No external components are required. The USB Function Controller and
Transceiver is Universal Serial Bus Specification 2.0 compliant.
Transceiver
Serial Interface Engine (SIE)
Endpoint0
VDD
IN/OUT
D+
Data
Transfer
Control
D-
Endpoint1
Endpoint2
Endpoint3
OUT
IN
IN
USB
Control,
Status, and
Interrupt
Registers
CIP-51 Core
OUT
IN
OUT
USB FIFOs
(1k RAM)
Figure 16.1. USB0 Block Diagram
Important Note: This document assumes a comprehensive understanding of the USB
Protocol. Terms and abbreviations used in this document are defined in the USB Specification. We encourage you to review the latest version of the USB Specification before proceeding.
*Note: The C8051F34x cannot be used as a USB Host device.
Rev. 1.3
159
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
16.1. Endpoint Addressing
A total of eight endpoint pipes are available. The control endpoint (Endpoint0) always functions as a
bi-directional IN/OUT endpoint. The other endpoints are implemented as three pairs of IN/OUT endpoint
pipes:
Table 16.1. Endpoint Addressing Scheme
Endpoint
Endpoint0
Endpoint1
Endpoint2
Endpoint3
Associated Pipes
Endpoint0 IN
Endpoint0 OUT
Endpoint1 IN
Endpoint1 OUT
Endpoint2 IN
Endpoint2 OUT
Endpoint3 IN
Endpoint3 OUT
USB Protocol Address
0x00
0x00
0x81
0x01
0x82
0x02
0x83
0x03
16.2. USB Transceiver
The USB Transceiver is configured via the USB0XCN register shown in SFR Definition 16.1. This configuration includes Transceiver enable/disable, pull-up resistor enable/disable, and device speed selection
(Full or Low Speed). When bit SPEED = ‘1’, USB0 operates as a Full Speed USB function, and the on-chip
pull-up resistor (if enabled) appears on the D+ pin. When bit SPEED = ‘0’, USB0 operates as a Low Speed
USB function, and the on-chip pull-up resistor (if enabled) appears on the D- pin. Bits4-0 of register
USB0XCN can be used for Transceiver testing as described in SFR Definition 16.1. The pull-up resistor is
enabled only when VBUS is present (see Section “8.2. VBUS Detection” on page 69 for details on
VBUS detection).
Important Note: The USB clock should be active before the Transceiver is enabled.
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SFR Definition 16.1. USB0XCN: USB0 Transceiver Control
R/W
R/W
R/W
PREN
PHYEN
SPEED
Bit7
Bit6
Bit5
R/W
R/W
PHYTST1 PHYTST0
Bit4
R
R
R
Reset Value
DFREC
Dp
Dn
00000000
Bit2
Bit1
Bit0
SFR Address:
Bit3
0xD7
Bit7:
PREN: Internal Pull-up Resistor Enable
The location of the pull-up resistor (D+ or D–) is determined by the SPEED bit.
0: Internal pull-up resistor disabled (device effectively detached from the USB network).
1: Internal pull-up resistor enabled when VBUS is present (device attached to the USB network).
Bit6:
PHYEN: Physical Layer Enable
This bit enables/disables the USB0 physical layer transceiver.
0: Transceiver disabled (suspend).
1: Transceiver enabled (normal).
Bit5:
SPEED: USB0 Speed Select
This bit selects the USB0 speed.
0: USB0 operates as a Low Speed device. If enabled, the internal pull-up resistor appears
on the D– line.
1: USB0 operates as a Full Speed device. If enabled, the internal pull-up resistor appears on
the D+ line.
Bits4–3: PHYTST1–0: Physical Layer Test
These bits can be used to test the USB0 transceiver.
PHYTST[1:0]
00b
01b
10b
11b
Bit2:
Bit1:
Bit0:
Mode
Mode 0: Normal (non-test mode)
Mode 1: Differential ‘1’ Forced
Mode 2: Differential ‘0’ Forced
Mode 3: Single-Ended ‘0’ Forced
D+
X
1
0
0
D–
X
0
1
0
DFREC: Differential Receiver
The state of this bit indicates the current differential value present on the D+ and D– lines
when PHYEN = ‘1’.
0: Differential ‘0’ signaling on the bus.
1: Differential ‘1’ signaling on the bus.
Dp: D+ Signal Status
This bit indicates the current logic level of the D+ pin.
0: D+ signal currently at logic 0.
1: D+ signal currently at logic 1.
Dn: D- Signal Status
This bit indicates the current logic level of the D– pin.
0: D– signal currently at logic 0.
1: D– signal currently at logic 1.
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16.3. USB Register Access
The USB0 controller registers listed in Table 16.2 are accessed through two SFRs: USB0 Address
(USB0ADR) and USB0 Data (USB0DAT). The USB0ADR register selects which USB register is targeted
by reads/writes of the USB0DAT register. See Figure 16.2.
Endpoint control/status registers are accessed by first writing the USB register INDEX with the target endpoint number. Once the target endpoint number is written to the INDEX register, the control/status registers
associated with the target endpoint may be accessed. See the “Indexed Registers” section of Table 16.2
for a list of endpoint control/status registers.
Important Note: The USB clock must be active when accessing USB registers.
8051
SFRs
USB Controller
Interrupt
Registers
FIFO
Access
Common
Registers
Index
Register
USB0DAT
Endpoint0 Control/
Status Registers
Endpoint1 Control/
Status Registers
Endpoint2 Control/
Status Registers
USB0ADR
Endpoint3 Control/
Status Registers
Figure 16.2. USB0 Register Access Scheme
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SFR Definition 16.2. USB0ADR: USB0 Indirect Address
R/W
R/W
BUSY
AUTORD
Bit7
Bit6
R/W
R/W
R/W
Bit5
Bit4
Bit3
R/W
R/W
R/W
Reset Value
Bit1
Bit0
SFR Address:
USBADDR
Bit2
00000000
0x96
Bits7:
BUSY: USB0 Register Read Busy Flag
This bit is used during indirect USB0 register accesses. Software should write ‘1’ to this bit to
initiate a read of the USB0 register targeted by the USBADDR bits (USB0ADR.[5-0]). The
target address and BUSY bit may be written in the same write to USB0ADR. After BUSY is
set to ‘1’, hardware will clear BUSY when the targeted register data is ready in the
USB0DAT register. Software should check BUSY for ‘0’ before writing to USB0DAT.
Write:
0: No effect.
1: A USB0 indirect register read is initiated at the address specified by the USBADDR bits.
Read:
0: USB0DAT register data is valid.
1: USB0 is busy accessing an indirect register; USB0DAT register data is invalid.
Bit6:
AUTORD: USB0 Register Auto-read Flag
This bit is used for block FIFO reads.
0: BUSY must be written manually for each USB0 indirect register read.
1: The next indirect register read will automatically be initiated when software reads
USB0DAT (USBADDR bits will not be changed).
Bits5–0: USBADDR: USB0 Indirect Register Address
These bits hold a 6-bit address used to indirectly access the USB0 core registers. Table 16.2
lists the USB0 core registers and their indirect addresses. Reads and writes to USB0DAT
will target the register indicated by the USBADDR bits.
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SFR Definition 16.3. USB0DAT: USB0 Data
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
Reset Value
Bit2
Bit1
Bit0
SFR Address:
USB0DAT
Bit3
00000000
0x97
This SFR is used to indirectly read and write USB0 registers.
Write Procedure:
1. Poll for BUSY (USB 0ADR.7) => ‘0’.
2. Load the target USB0 register address into the USBADDR bits in register USB0ADR.
3. Write data to USB0DAT.
4. Repeat (Step 2 may be skipped when writing to the same USB0 register).
Read Procedure:
1. Poll for BUSY (USB 0ADR.7) => ‘0’.
2. Load the target USB0 register address into the USBADDR bits in register USB0ADR.
3. Write ‘1’ to the BUSY bit in register USB0ADR (steps 2 and 3 can be performed in the
same write).
4. Poll for BUSY (USB 0ADR.7) => ‘0’.
5. Read data from USB0DAT.
6. Repeat from Step 2 (Step 2 may be skipped when reading the same USB0 register; Step 3
may be skipped when the AUTORD bit (USB0ADR.6) is logic 1).
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Table 16.2. USB0 Controller Registers
USB Register
Name
USB Register
Address
IN1INT
OUT1INT
CMINT
IN1IE
OUT1IE
CMIE
0x02
0x04
0x06
0x07
0x09
0x0B
FADDR
POWER
FRAMEL
FRAMEH
INDEX
CLKREC
FIFOn
0x00
0x01
0x0C
0x0D
0x0E
0x0F
0x20–0x23
E0CSR
EINCSRL
EINCSRH
EOUTCSRL
EOUTCSRH
E0CNT
EOUTCNTL
EOUTCNTH
0x11
0x12
0x14
0x15
0x16
0x17
Description
Page Number
Interrupt Registers
Endpoint0 and Endpoints1-3 IN Interrupt Flags
Endpoints1-3 OUT Interrupt Flags
Common USB Interrupt Flags
Endpoint0 and Endpoints1-3 IN Interrupt Enables
Endpoints1-3 OUT Interrupt Enables
Common USB Interrupt Enables
Common Registers
Function Address
Power Management
Frame Number Low Byte
Frame Number High Byte
Endpoint Index Selection
Clock Recovery Control
Endpoints0-3 FIFOs
Indexed Registers
Endpoint0 Control / Status
Endpoint IN Control / Status Low Byte
Endpoint IN Control / Status High Byte
Endpoint OUT Control / Status Low Byte
Endpoint OUT Control / Status High Byte
Number of Received Bytes in Endpoint0 FIFO
Endpoint OUT Packet Count Low Byte
Endpoint OUT Packet Count High Byte
173
173
174
175
175
176
169
171
172
172
165
166
168
179
182
183
185
186
180
186
186
USB Register Definition 16.4. INDEX: USB0 Endpoint Index
R
R
R
R
-
-
-
-
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
EPSEL
Bit3
Bit2
Reset Value
00000000
Bit1
Bit0
USB Address:
0x0E
Bits7–4: Unused. Read = 0000b; Write = don’t care.
Bits3–0: EPSEL: Endpoint Select
These bits select which endpoint is targeted when indexed USB0 registers are accessed.
INDEX
0x0
0x1
0x2
0x3
0x4–0xF
Target Endpoint
0
1
2
3
Reserved
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16.4. USB Clock Configuration
USB0 is capable of communication as a Full or Low Speed USB function. Communication speed is
selected via the SPEED bit in SFR USB0XCN. When operating as a Low Speed function, the USB0 clock
must be 6 MHz. When operating as a Full Speed function, the USB0 clock must be 48 MHz. Clock options
are described in Section “14. Oscillators” on page 131. The USB0 clock is selected via SFR CLKSEL
(see SFR Definition 14.6).
Clock Recovery circuitry uses the incoming USB data stream to adjust the internal oscillator; this allows
the internal oscillator (and 4x Clock Multiplier) to meet the requirements for USB clock tolerance. Clock
Recovery should be used in the following configurations:
Communication Speed
Full Speed
Low Speed
USB Clock
4x Clock Multiplier
Internal Oscillator / 2
4x Clock Multiplier Input
Internal Oscillator
N/A
When operating USB0 as a Low Speed function with Clock Recovery, software must write ‘1’ to the
CRLOW bit to enable Low Speed Clock Recovery. Clock Recovery is typically not necessary in Low Speed
mode.
Single Step Mode can be used to help the Clock Recovery circuitry to lock when high noise levels are present on the USB network. This mode is not required (or recommended) in typical USB environments.
USB Register Definition 16.5. CLKREC: Clock Recovery Control
R/W
R/W
R/W
CRE
CRSSEN
CRLOW
Bit7
Bit6
Bit5
R/W
R/W
Bit4
Bit3
R/W
R/W
R/W
Reset Value
Bit1
Bit0
USB Address:
Reserved
Bit2
00001001
0x0F
Bit7:
CRE: Clock Recovery Enable.
This bit enables/disables the USB clock recovery feature.
0: Clock recovery disabled.
1: Clock recovery enabled.
Bit6:
CRSSEN: Clock Recovery Single Step.
This bit forces the oscillator calibration into ‘single-step’ mode during clock recovery.
0: Normal calibration mode.
1: Single step mode.
Bit5:
CRLOW: Low Speed Clock Recovery Mode.
This bit must be set to ‘1’ if clock recovery is used when operating as a Low Speed USB
device.
0: Full Speed Mode.
1: Low Speed Mode.
Bits4–0: Reserved. Read = Variable. Must Write = 01001b.
Note: The USB transceiver must be enabled before enabling Clock Recovery.
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16.5. FIFO Management
1024 bytes of on-chip XRAM are used as FIFO space for USB0. This FIFO space is split between
Endpoints0-3 as shown in Figure 16.3. FIFO space allocated for Endpoints1-3 is configurable as IN, OUT,
or both (Split Mode: half IN, half OUT).
0x07FF
Endpoint0
(64 bytes)
0x07C0
0x07BF
Endpoint1
(128 bytes)
0x0740
0x073F
Configurable as
IN, OUT, or both (Split
Mode)
Endpoint2
(256 bytes)
0x0640
0x063F
Endpoint3
(512 bytes)
0x0440
0x043F
Free
(64 bytes)
0x0400
USB Clock Domain
System Clock Domain
0x03FF
User XRAM
(1024 bytes)
0x0000
Figure 16.3. USB FIFO Allocation
16.5.1. FIFO Split Mode
The FIFO space for Endpoints1-3 can be split such that the upper half of the FIFO space is used by the IN
endpoint, and the lower half is used by the OUT endpoint. For example: if the Endpoint3 FIFO is configured
for Split Mode, the upper 256 bytes (0x0540 to 0x063F) are used by Endpoint3 IN and the lower 256 bytes
(0x0440 to 0x053F) are used by Endpoint3 OUT.
If an endpoint FIFO is not configured for Split Mode, that endpoint IN/OUT pair’s FIFOs are combined to
form a single IN or OUT FIFO. In this case only one direction of the endpoint IN/OUT pair may be used at
a time. The endpoint direction (IN/OUT) is determined by the DIRSEL bit in the corresponding endpoint’s
EINCSRH register (see SFR Definition 16.20).
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16.5.2. FIFO Double Buffering
FIFO slots for Endpoints1-3 can be configured for double-buffered mode. In this mode, the maximum
packet size is halved and the FIFO may contain two packets at a time. This mode is available for
Endpoints1-3. When an endpoint is configured for Split Mode, double buffering may be enabled for the IN
Endpoint and/or the OUT endpoint. When Split Mode is not enabled, double-buffering may be enabled for
the entire endpoint FIFO. See Table 16.3 for a list of maximum packet sizes for each FIFO configuration.
Table 16.3. FIFO Configurations
Endpoint
Number
Split Mode
Enabled?
0
N/A
N
Y
N
Y
N
Y
1
2
3
Maximum IN Packet Size (Double Buffer Disabled / Enabled)
Maximum OUT Packet Size
(Double Buffer Disabled /
Enabled)
64
128 / 64
64 / 32
64 / 32
256 / 128
128 / 64
128 / 64
512 / 256
256 / 128
256 / 128
16.5.1. FIFO Access
Each endpoint FIFO is accessed through a corresponding FIFOn register. A read of an endpoint FIFOn
register unloads one byte from the FIFO; a write of an endpoint FIFOn register loads one byte into the endpoint FIFO. When an endpoint FIFO is configured for Split Mode, a read of the endpoint FIFOn register
unloads one byte from the OUT endpoint FIFO; a write of the endpoint FIFOn register loads one byte into
the IN endpoint FIFO.
USB Register Definition 16.6. FIFOn: USB0 Endpoint FIFO Access
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
FIFODATA
Bit7
Bit6
Bit5
Bit4
Bit3
Reset Value
00000000
Bit2
Bit1
Bit0
USB Address:
0x20 - 0x23
USB Addresses 0x20–0x23 provide access to the 4 pairs of endpoint FIFOs:
IN/OUT Endpoint FIFO
0
1
2
3
USB Address
0x20
0x21
0x22
0x23
Writing to the FIFO address loads data into the IN FIFO for the corresponding endpoint.
Reading from the FIFO address unloads data from the OUT FIFO for the corresponding
endpoint.
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16.6. Function Addressing
The FADDR register holds the current USB0 function address. Software should write the host-assigned
7-bit function address to the FADDR register when received as part of a SET_ADDRESS command. A new
address written to FADDR will not take effect (USB0 will not respond to the new address) until the end of
the current transfer (typically following the status phase of the SET_ADDRESS command transfer). The
UPDATE bit (FADDR.7) is set to ‘1’ by hardware when software writes a new address to the FADDR register. Hardware clears the UPDATE bit when the new address takes effect as described above.
USB Register Definition 16.7. FADDR: USB0 Function Address
R
R/W
R/W
R/W
Bit6
Bit5
Bit4
Update
Bit7
R/W
R/W
R/W
R/W
Reset Value
Bit2
Bit1
Bit0
USB Address:
Function Address
Bit3
00000000
0x00
Bit7:
Update: Function Address Update
Set to ‘1’ when software writes the FADDR register. USB0 clears this bit to ‘0’ when the new
address takes effect.
0: The last address written to FADDR is in effect.
1: The last address written to FADDR is not yet in effect.
Bits6–0: Function Address
Holds the 7-bit function address for USB0. This address should be written by software when
the SET_ADDRESS standard device request is received on Endpoint0. The new address
takes effect when the device request completes.
16.7. Function Configuration and Control
The USB register POWER (SFR Definition 16.8) is used to configure and control USB0 at the device level
(enable/disable, Reset/Suspend/Resume handling, etc.).
USB Reset: The USBRST bit (POWER.3) is set to ‘1’ by hardware when Reset signaling is detected on
the bus. Upon this detection, the following occur:
1. The USB0 Address is reset (FADDR = 0x00).
2. Endpoint FIFOs are flushed.
3. Control/status registers are reset to 0x00 (E0CSR, EINCSRL, EINCSRH, EOUTCSRL,
EOUTCSRH).
4. USB register INDEX is reset to 0x00.
5. All USB interrupts (excluding the Suspend interrupt) are enabled and their corresponding flags
cleared.
6. A USB Reset interrupt is generated if enabled.
Writing a ‘1’ to the USBRST bit will generate an asynchronous USB0 reset. All USB registers are reset to
their default values following this asynchronous reset.
Suspend Mode: With Suspend Detection enabled (SUSEN = ‘1’), USB0 will enter Suspend Mode when
Suspend signaling is detected on the bus. An interrupt will be generated if enabled (SUSINTE = ‘1’). The
Suspend Interrupt Service Routine (ISR) should perform application-specific configuration tasks such as
disabling appropriate peripherals and/or configuring clock sources for low power modes. See Section
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“14. Oscillators” on page 131 for more details on internal oscillator configuration, including the Suspend
mode feature of the internal oscillator.
USB0 exits Suspend mode when any of the following occur: (1) Resume signaling is detected or generated, (2) Reset signaling is detected, or (3) a device or USB reset occurs. If suspended, the internal oscillator will exit Suspend mode upon any of the above listed events.
Resume Signaling: USB0 will exit Suspend mode if Resume signaling is detected on the bus. A Resume
interrupt will be generated upon detection if enabled (RESINTE = ‘1’). Software may force a Remote
Wakeup by writing ‘1’ to the RESUME bit (POWER.2). When forcing a Remote Wakeup, software should
write RESUME = ‘0’ to end Resume signaling 10-15 ms after the Remote Wakeup is initiated (RESUME =
‘1’).
ISO Update: When software writes ‘1’ to the ISOUP bit (POWER.7), the ISO Update function is enabled.
With ISO Update enabled, new packets written to an ISO IN endpoint will not be transmitted until a new
Start-Of-Frame (SOF) is received. If the ISO IN endpoint receives an IN token before a SOF, USB0 will
transmit a zero-length packet. When ISOUP = ‘1’, ISO Update is enabled for all ISO endpoints.
USB Enable: USB0 is disabled following a Power-On-Reset (POR). USB0 is enabled by clearing the
USBINH bit (POWER.4). Once written to ‘0’, the USBINH can only be set to ‘1’ by one of the following: (1)
a Power-On-Reset (POR), or (2) an asynchronous USB0 reset generated by writing ‘1’ to the USBRST bit
(POWER.3).
Software should perform all USB0 configuration before enabling USB0. The configuration sequence
should be performed as follows:
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
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Select and enable the USB clock source.
Reset USB0 by writing USBRST= ‘1’.
Configure and enable the USB Transceiver.
Perform any USB0 function configuration (interrupts, Suspend detect).
Enable USB0 by writing USBINH = ‘0’.
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USB Register Definition 16.8. POWER: USB0 Power
R/W
R/W
R/W
R/W
ISOUD
-
-
USBINH
Bit7
Bit6
Bit5
Bit4
R/W
R/W
USBRST RESUME
Bit3
Bit2
R
R/W
Reset Value
SUSMD
SUSEN
00010000
Bit1
Bit0
USB Address:
0x01
Bit7:
ISOUD: ISO Update
This bit affects all IN Isochronous endpoints.
0: When software writes INPRDY = ‘1’, USB0 will send the packet when the next IN token is
received.
1: When software writes INPRDY = ‘1’, USB0 will wait for a SOF token before sending the
packet. If an IN token is received before a SOF token, USB0 will send a zero-length data
packet.
Bits6–5: Unused. Read = 00b. Write = don’t care.
Bit4:
USBINH: USB0 Inhibit
This bit is set to ‘1’ following a power-on reset (POR) or an asynchronous USB0 reset (see
Bit3: RESET). Software should clear this bit after all USB0 and transceiver initialization is
complete. Software cannot set this bit to ‘1’.
0: USB0 enabled.
1: USB0 inhibited. All USB traffic is ignored.
Bit3:
USBRST: Reset Detect
Writing ‘1’ to this bit forces an asynchronous USB0 reset. Reading this bit provides bus reset
status information.
Read:
0: Reset signaling is not present on the bus.
1: Reset signaling detected on the bus.
Bit2:
RESUME: Force Resume
Software can force resume signaling on the bus to wake USB0 from suspend mode. Writing
a ‘1’ to this bit while in Suspend mode (SUSMD = ‘1’) forces USB0 to generate Resume signaling on the bus (a remote Wakeup event). Software should write RESUME = ‘0’ after
10 ms to15 ms to end the Resume signaling. An interrupt is generated, and hardware clears
SUSMD, when software writes RESUME = ‘0’.
Bit1:
SUSMD: Suspend Mode
Set to ‘1’ by hardware when USB0 enters suspend mode. Cleared by hardware when software writes RESUME = ‘0’ (following a remote wakeup) or reads the CMINT register after
detection of Resume signaling on the bus.
0: USB0 not in suspend mode.
1: USB0 in suspend mode.
Bit0:
SUSEN: Suspend Detection Enable
0: Suspend detection disabled. USB0 will ignore suspend signaling on the bus.
1: Suspend detection enabled. USB0 will enter suspend mode if it detects suspend signaling
on the bus.
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USB Register Definition 16.9. FRAMEL: USB0 Frame Number Low
R
R
R
R
R
R
R
R
Frame Number Low
Bit7
Bit6
Bit5
Bit4
Bit3
Reset Value
00000000
Bit2
Bit1
Bit0
USB Address:
0x0C
Bits7-0:
Frame Number Low
This register contains bits7-0 of the last received frame number.
USB Register Definition 16.10. FRAMEH: USB0 Frame Number High
R
R
R
R
R
-
-
-
-
-
Bit7
Bit6
Bit5
Bit4
Bit3
R
R
R
Frame Number High
Bit2
Bit1
Bit0
Reset Value
00000000
USB Address:
0x0D
Bits7-3:
Bits2-0:
Unused. Read = 0. Write = don’t care.
Frame Number High Byte
This register contains bits10-8 of the last received frame number.
16.8. Interrupts
The read-only USB0 interrupt flags are located in the USB registers shown in USB Register
Definition 16.11 through USB Register Definition 16.13. The associated interrupt enable bits are located in
the USB registers shown in USB Register Definition 16.14 through USB Register Definition 16.16. A USB0
interrupt is generated when any of the USB interrupt flags is set to ‘1’. The USB0 interrupt is enabled via
the EIE1 SFR (see Section “9.3. Interrupt Handler” on page 88).
Important Note: Reading a USB interrupt flag register resets all flags in that register to ‘0’.
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USB Register Definition 16.11. IN1INT: USB0 IN Endpoint Interrupt
R
R
R
R
R
R
R
R
Reset Value
-
-
-
-
IN3
IN2
IN1
EP0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
USB Address:
0x02
Bits7–4: Unused. Read = 0000b. Write = don’t care.
Bit3:
IN3: IN Endpoint 3 Interrupt-pending Flag
This bit is cleared when software reads the IN1INT register.
0: IN Endpoint 3 interrupt inactive.
1: IN Endpoint 3 interrupt active.
Bit2:
IN2: IN Endpoint 2 Interrupt-pending Flag
This bit is cleared when software reads the IN1INT register.
0: IN Endpoint 2 interrupt inactive.
1: IN Endpoint 2 interrupt active.
Bit1:
IN1: IN Endpoint 1 Interrupt-pending Flag
This bit is cleared when software reads the IN1INT register.
0: IN Endpoint 1 interrupt inactive.
1: IN Endpoint 1 interrupt active.
Bit0:
EP0: Endpoint 0 Interrupt-pending Flag
This bit is cleared when software reads the IN1INT register.
0: Endpoint 0 interrupt inactive.
1: Endpoint 0 interrupt active.
USB Register Definition 16.12. OUT1INT: USB0 Out Endpoint Interrupt
R
R
R
R
R
R
R
R
Reset Value
-
-
-
-
OUT3
OUT2
OUT1
-
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
USB Address:
0x04
Bits7–4: Unused. Read = 0000b. Write = don’t care.
Bit3:
OUT3: OUT Endpoint 3 Interrupt-pending Flag
This bit is cleared when software reads the OUT1INT register.
0: OUT Endpoint 3 interrupt inactive.
1: OUT Endpoint 3 interrupt active.
Bit2:
OUT2: OUT Endpoint 2 Interrupt-pending Flag
This bit is cleared when software reads the OUT1INT register.
0: OUT Endpoint 2 interrupt inactive.
1: OUT Endpoint 2 interrupt active.
Bit1:
OUT1: OUT Endpoint 1 Interrupt-pending Flag
This bit is cleared when software reads the OUT1INT register.
0: OUT Endpoint 1 interrupt inactive.
1: OUT Endpoint 1 interrupt active.
Bit0:
Unused. Read = 0; Write = don’t care.
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USB Register Definition 16.13. CMINT: USB0 Common Interrupt
R
R
R
R
R
R
R
R
Reset Value
-
-
-
-
SOF
RSTINT
RSUINT
SUSINT
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
USB Address:
0x06
Bits7–4: Unused. Read = 0000b; Write = don’t care.
Bit3:
SOF: Start of Frame Interrupt
Set by hardware when a SOF token is received. This interrupt event is synthesized by hardware: an interrupt will be generated when hardware expects to receive a SOF event, even if
the actual SOF signal is missed or corrupted.
This bit is cleared when software reads the CMINT register.
0: SOF interrupt inactive.
1: SOF interrupt active.
Bit2:
RSTINT: Reset Interrupt-pending Flag
Set by hardware when Reset signaling is detected on the bus.
This bit is cleared when software reads the CMINT register.
0: Reset interrupt inactive.
1: Reset interrupt active.
Bit1:
RSUINT: Resume Interrupt-pending Flag
Set by hardware when Resume signaling is detected on the bus while USB0 is in suspend
mode.
This bit is cleared when software reads the CMINT register.
0: Resume interrupt inactive.
1: Resume interrupt active.
Bit0:
SUSINT: Suspend Interrupt-pending Flag
When Suspend detection is enabled (bit SUSEN in register POWER), this bit is set by hardware when Suspend signaling is detected on the bus. This bit is cleared when software
reads the CMINT register.
0: Suspend interrupt inactive.
1: Suspend interrupt active.
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USB Register Definition 16.14. IN1IE: USB0 IN Endpoint Interrupt Enable
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
-
-
-
IN3E
IN2E
IN1E
EP0E
00001111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
USB Address:
0x07
Bits7–4: Unused. Read = 0000b. Write = don’t care.
Bit3:
IN3E: IN Endpoint 3 Interrupt Enable
0: IN Endpoint 3 interrupt disabled.
1: IN Endpoint 3 interrupt enabled.
Bit2:
IN2E: IN Endpoint 2 Interrupt Enable
0: IN Endpoint 2 interrupt disabled.
1: IN Endpoint 2 interrupt enabled.
Bit1:
IN1E: IN Endpoint 1 Interrupt Enable
0: IN Endpoint 1 interrupt disabled.
1: IN Endpoint 1 interrupt enabled.
Bit0:
EP0E: Endpoint 0 Interrupt Enable
0: Endpoint 0 interrupt disabled.
1: Endpoint 0 interrupt enabled.
USB Register Definition 16.15. OUT1IE: USB0 Out Endpoint Interrupt Enable
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
-
-
-
OUT3E
OUT2E
OUT1E
-
00001110
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
USB Address:
0x09
Bits7–4: Unused. Read = 0000b. Write = don’t care.
Bit3:
OUT3E: OUT Endpoint 3 Interrupt Enable
0: OUT Endpoint 3 interrupt disabled.
1: OUT Endpoint 3 interrupt enabled.
Bit2:
OUT2E: OUT Endpoint 2 Interrupt Enable
0: OUT Endpoint 2 interrupt disabled.
1: OUT Endpoint 2 interrupt enabled.
Bit1:
OUT1E: OUT Endpoint 1 Interrupt Enable
0: OUT Endpoint 1 interrupt disabled.
1: OUT Endpoint 1 interrupt enabled.
Bit0:
Unused. Read = 0; Write = don’t’ care.
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USB Register Definition 16.16. CMIE: USB0 Common Interrupt Enable
R/W
R/W
R/W
R/W
R/W
-
-
-
-
SOFE
Bit7
Bit6
Bit5
Bit4
Bit3
R/W
R/W
R/W
Reset Value
RSTINTE RSUINTE SUSINTE 00000110
Bit2
Bit1
Bit0
USB Address:
0x0B
Bits7–4: Unused. Read = 0000b; Write = don’t care.
Bit3:
SOFE: Start of Frame Interrupt Enable
0: SOF interrupt disabled.
1: SOF interrupt enabled.
Bit2:
RSTINTE: Reset Interrupt Enable
0: Reset interrupt disabled.
1: Reset interrupt enabled.
Bit1:
RSUINTE: Resume Interrupt Enable
0: Resume interrupt disabled.
1: Resume interrupt enabled.
Bit0:
SUSINTE: Suspend Interrupt Enable
0: Suspend interrupt disabled.
1: Suspend interrupt enabled.
16.9. The Serial Interface Engine
The Serial Interface Engine (SIE) performs all low level USB protocol tasks, interrupting the processor
when data has successfully been transmitted or received. When receiving data, the SIE will interrupt the
processor when a complete data packet has been received; appropriate handshaking signals are automatically generated by the SIE. When transmitting data, the SIE will interrupt the processor when a complete
data packet has been transmitted and the appropriate handshake signal has been received.
The SIE will not interrupt the processor when corrupted/erroneous packets are received.
16.10. Endpoint0
Endpoint0 is managed through the USB register E0CSR (USB Register Definition 16.17). The INDEX register must be loaded with 0x00 to access the E0CSR register.
An Endpoint0 interrupt is generated when:
1. A data packet (OUT or SETUP) has been received and loaded into the Endpoint0 FIFO. The
OPRDY bit (E0CSR.0) is set to ‘1’ by hardware.
2. An IN data packet has successfully been unloaded from the Endpoint0 FIFO and transmitted
to the host; INPRDY is reset to ‘0’ by hardware.
3. An IN transaction is completed (this interrupt generated during the status stage of the transaction).
4. Hardware sets the STSTL bit (E0CSR.2) after a control transaction ended due to a protocol
violation.
5. Hardware sets the SUEND bit (E0CSR.4) because a control transfer ended before firmware
sets the DATAEND bit (E0CSR.3).
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The E0CNT register (USB Register Definition 16.18) holds the number of received data bytes in the
Endpoint0 FIFO.
Hardware will automatically detect protocol errors and send a STALL condition in response. Firmware may
force a STALL condition to abort the current transfer. When a STALL condition is generated, the STSTL bit
will be set to ‘1’ and an interrupt generated. The following conditions will cause hardware to generate a
STALL condition:
1. The host sends an OUT token during a OUT data phase after the DATAEND bit has been set
to ‘1’.
2. The host sends an IN token during an IN data phase after the DATAEND bit has been set to
‘1’.
3. The host sends a packet that exceeds the maximum packet size for Endpoint0.
4. The host sends a non-zero length DATA1 packet during the status phase of an IN transaction.
5. Firmware sets the SDSTL bit (E0CSR.5) to ‘1’.
16.10.1.Endpoint0 SETUP Transactions
All control transfers must begin with a SETUP packet. SETUP packets are similar to OUT packets, containing an 8-byte data field sent by the host. Any SETUP packet containing a command field of anything other
than 8 bytes will be automatically rejected by USB0. An Endpoint0 interrupt is generated when the data
from a SETUP packet is loaded into the Endpoint0 FIFO. Software should unload the command from the
Endpoint0 FIFO, decode the command, perform any necessary tasks, and set the SOPRDY bit to indicate
that it has serviced the OUT packet.
16.10.2.Endpoint0 IN Transactions
When a SETUP request is received that requires USB0 to transmit data to the host, one or more IN
requests will be sent by the host. For the first IN transaction, firmware should load an IN packet into the
Endpoint0 FIFO, and set the INPRDY bit (E0CSR.1). An interrupt will be generated when an IN packet is
transmitted successfully. Note that no interrupt will be generated if an IN request is received before firmware has loaded a packet into the Endpoint0 FIFO. If the requested data exceeds the maximum packet
size for Endpoint0 (as reported to the host), the data should be split into multiple packets; each packet
should be of the maximum packet size excluding the last (residual) packet. If the requested data is an integer multiple of the maximum packet size for Endpoint0, the last data packet should be a zero-length packet
signaling the end of the transfer. Firmware should set the DATAEND bit to ‘1’ after loading into the
Endpoint0 FIFO the last data packet for a transfer.
Upon reception of the first IN token for a particular control transfer, Endpoint0 is said to be in Transmit
Mode. In this mode, only IN tokens should be sent by the host to Endpoint0. The SUEND bit (E0CSR.4) is
set to ‘1’ if a SETUP or OUT token is received while Endpoint0 is in Transmit Mode.
Endpoint0 will remain in Transmit Mode until any of the following occur:
1. USB0 receives an Endpoint0 SETUP or OUT token.
2. Firmware sends a packet less than the maximum Endpoint0 packet size.
3. Firmware sends a zero-length packet.
Firmware should set the DATAEND bit (E0CSR.3) to ‘1’ when performing (2) and (3) above.
The SIE will transmit a NAK in response to an IN token if there is no packet ready in the IN FIFO (INPRDY
= ‘0’).
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16.10.3.Endpoint0 OUT Transactions
When a SETUP request is received that requires the host to transmit data to USB0, one or more OUT
requests will be sent by the host. When an OUT packet is successfully received by USB0, hardware will set
the OPRDY bit (E0CSR.0) to ‘1’ and generate an Endpoint0 interrupt. Following this interrupt, firmware
should unload the OUT packet from the Endpoint0 FIFO and set the SOPRDY bit (E0CSR.6) to ‘1’.
If the amount of data required for the transfer exceeds the maximum packet size for Endpoint0, the data
will be split into multiple packets. If the requested data is an integer multiple of the maximum packet size
for Endpoint0 (as reported to the host), the host will send a zero-length data packet signaling the end of the
transfer.
Upon reception of the first OUT token for a particular control transfer, Endpoint0 is said to be in Receive
Mode. In this mode, only OUT tokens should be sent by the host to Endpoint0. The SUEND bit (E0CSR.4)
is set to ‘1’ if a SETUP or IN token is received while Endpoint0 is in Receive Mode.
Endpoint0 will remain in Receive mode until:
1. The SIE receives a SETUP or IN token.
2. The host sends a packet less than the maximum Endpoint0 packet size.
3. The host sends a zero-length packet.
Firmware should set the DATAEND bit (E0CSR.3) to ‘1’ when the expected amount of data has been
received. The SIE will transmit a STALL condition if the host sends an OUT packet after the DATAEND bit
has been set by firmware. An interrupt will be generated with the STSTL bit (E0CSR.2) set to ‘1’ after the
STALL is transmitted.
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USB Register Definition 16.17. E0CSR: USB0 Endpoint0 Control
R/W
R/W
SSUEND SOPRDY
Bit7
Bit6
R/W
SDSTL
Bit5
R
R/W
SUEND DATAEND
Bit4
Bit3
R/W
R/W
R
Reset Value
STSTL
INPRDY
OPRDY
00000000
Bit2
Bit1
Bit0
USB Address:
0x11
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
SSUEND: Serviced Setup End
Write: Software should set this bit to ‘1’ after servicing a Setup End (bit SUEND) event.
Hardware clears the SUEND bit when software writes ‘1’ to SSUEND.
Read: This bit always reads ‘0’.
SOPRDY: Serviced OPRDY
Write: Software should write ‘1’ to this bit after servicing a received Endpoint0 packet. The
OPRDY bit will be cleared by a write of ‘1’ to SOPRDY.
Read: This bit always reads ‘0’.
SDSTL: Send Stall
Software can write ‘1’ to this bit to terminate the current transfer (due to an error condition,
unexpected transfer request, etc.). Hardware will clear this bit to ‘0’ when the STALL handshake is transmitted.
SUEND: Setup End
Hardware sets this read-only bit to ‘1’ when a control transaction ends before software has
written ‘1’ to the DATAEND bit. Hardware clears this bit when software writes ‘1’ to SSUEND.
DATAEND: Data End
Software should write ‘1’ to this bit:
1. When writing ‘1’ to INPRDY for the last outgoing data packet.
2. When writing ‘1’ to INPRDY for a zero-length data packet.
3. When writing ‘1’ to SOPRDY after servicing the last incoming data packet.
This bit is automatically cleared by hardware.
STSTL: Sent Stall
Hardware sets this bit to ‘1’ after transmitting a STALL handshake signal. This flag must be
cleared by software.
INPRDY: IN Packet Ready
Software should write ‘1’ to this bit after loading a data packet into the Endpoint0 FIFO for
transmit. Hardware clears this bit and generates an interrupt under either of the following
conditions:
1. The packet is transmitted.
2. The packet is overwritten by an incoming SETUP packet.
3. The packet is overwritten by an incoming OUT packet.
OPRDY: OUT Packet Ready
Hardware sets this read-only bit and generates an interrupt when a data packet has been
received. This bit is cleared only when software writes ‘1’ to the SOPRDY bit.
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USB Register Definition 16.18. E0CNT: USB0 Endpoint 0 Data Count
R
R
R
R
-
R
R
R
R
E0CNT
Bit7
Bit6
Bit5
Bit4
Bit3
Reset Value
00000000
Bit2
Bit1
Bit0
USB Address:
0x16
Bit7:
Unused. Read = 0; Write = don’t care.
Bits6–0: E0CNT: Endpoint 0 Data Count
This 7-bit number indicates the number of received data bytes in the Endpoint 0 FIFO. This
number is only valid while bit OPRDY is a ‘1’.
16.11. Configuring Endpoints1-3
Endpoints1-3 are configured and controlled through their own sets of the following control/status registers:
IN registers EINCSRL and EINCSRH, and OUT registers EOUTCSRL and EOUTCSRH. Only one set of
endpoint control/status registers is mapped into the USB register address space at a time, defined by the
contents of the INDEX register (USB Register Definition 16.4).
Endpoints1-3 can be configured as IN, OUT, or both IN/OUT (Split Mode) as described in Section 16.5.1.
The endpoint mode (Split/Normal) is selected via the SPLIT bit in register EINCSRH.
When SPLIT = ‘1’, the corresponding endpoint FIFO is split, and both IN and OUT pipes are available.
When SPLIT = ‘0’, the corresponding endpoint functions as either IN or OUT; the endpoint direction is
selected by the DIRSEL bit in register EINCSRH.
16.12. Controlling Endpoints1-3 IN
Endpoints1-3 IN are managed via USB registers EINCSRL and EINCSRH. All IN endpoints can be used
for Interrupt, Bulk, or Isochronous transfers. Isochronous (ISO) mode is enabled by writing ‘1’ to the ISO bit
in register EINCSRH. Bulk and Interrupt transfers are handled identically by hardware.
An Endpoint1-3 IN interrupt is generated by any of the following conditions:
1. An IN packet is successfully transferred to the host.
2. Software writes ‘1’ to the FLUSH bit (EINCSRL.3) when the target FIFO is not empty.
3. Hardware generates a STALL condition.
16.12.1.Endpoints1-3 IN Interrupt or Bulk Mode
When the ISO bit (EINCSRH.6) = ‘0’ the target endpoint operates in Bulk or Interrupt Mode. Once an endpoint has been configured to operate in Bulk/Interrupt IN mode (typically following an Endpoint0
SET_INTERFACE command), firmware should load an IN packet into the endpoint IN FIFO and set the
INPRDY bit (EINCSRL.0). Upon reception of an IN token, hardware will transmit the data, clear the
INPRDY bit, and generate an interrupt.
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Writing ‘1’ to INPRDY without writing any data to the endpoint FIFO will cause a zero-length packet to be
transmitted upon reception of the next IN token.
A Bulk or Interrupt pipe can be shut down (or Halted) by writing ‘1’ to the SDSTL bit (EINCSRL.4). While
SDSTL = ‘1’, hardware will respond to all IN requests with a STALL condition. Each time hardware generates a STALL condition, an interrupt will be generated and the STSTL bit (EINCSRL.5) set to ‘1’. The
STSTL bit must be reset to ‘0’ by firmware.
Hardware will automatically reset INPRDY to ‘0’ when a packet slot is open in the endpoint FIFO. Note that
if double buffering is enabled for the target endpoint, it is possible for firmware to load two packets into the
IN FIFO at a time. In this case, hardware will reset INPRDY to ‘0’ immediately after firmware loads the first
packet into the FIFO and sets INPRDY to ‘1’. An interrupt will not be generated in this case; an interrupt will
only be generated when a data packet is transmitted.
When firmware writes ‘1’ to the FCDT bit (EINCSRH.3), the data toggle for each IN packet will be toggled
continuously, regardless of the handshake received from the host. This feature is typically used by Interrupt endpoints functioning as rate feedback communication for Isochronous endpoints. When FCDT = ‘0’,
the data toggle bit will only be toggled when an ACK is sent from the host in response to an IN packet.
16.12.2.Endpoints1-3 IN Isochronous Mode
When the ISO bit (EINCSRH.6) is set to ‘1’, the target endpoint operates in Isochronous (ISO) mode. Once
an endpoint has been configured for ISO IN mode, the host will send one IN token (data request) per
frame; the location of data within each frame may vary. Because of this, it is recommended that double
buffering be enabled for ISO IN endpoints.
Hardware will automatically reset INPRDY (EINCSRL.0) to ‘0’ when a packet slot is open in the endpoint
FIFO. Note that if double buffering is enabled for the target endpoint, it is possible for firmware to load two
packets into the IN FIFO at a time. In this case, hardware will reset INPRDY to ‘0’ immediately after firmware loads the first packet into the FIFO and sets INPRDY to ‘1’. An interrupt will not be generated in this
case; an interrupt will only be generated when a data packet is transmitted.
If there is not a data packet ready in the endpoint FIFO when USB0 receives an IN token from the host,
USB0 will transmit a zero-length data packet and set the UNDRUN bit (EINCSRL.2) to ‘1’.
The ISO Update feature (see Section 16.7) can be useful in starting a double buffered ISO IN endpoint. If
the host has already set up the ISO IN pipe (has begun transmitting IN tokens) when firmware writes the
first data packet to the endpoint FIFO, the next IN token may arrive and the first data packet sent before
firmware has written the second (double buffered) data packet to the FIFO. The ISO Update feature
ensures that any data packet written to the endpoint FIFO will not be transmitted during the current frame;
the packet will only be sent after a SOF signal has been received.
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USB Register Definition 16.19. EINCSRL: USB0 IN Endpoint Control Low Byte
R
W
R/W
R/W
R/W
-
CLRDT
STSTL
SDSTL
FLUSH
Bit7
Bit6
Bit5
Bit4
Bit3
R/W
R/W
UNDRUN FIFONE
Bit2
Bit1
R/W
Reset Value
INPRDY
00000000
Bit0
USB Address:
0x11
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
182
Unused. Read = 0; Write = don’t care.
CLRDT: Clear Data Toggle.
Write: Software should write ‘1’ to this bit to reset the IN Endpoint data toggle to ‘0’.
Read: This bit always reads ‘0’.
STSTL: Sent Stall
Hardware sets this bit to ‘1’ when a STALL handshake signal is transmitted. The FIFO is
flushed, and the INPRDY bit cleared. This flag must be cleared by software.
SDSTL: Send Stall.
Software should write ‘1’ to this bit to generate a STALL handshake in response to an IN
token. Software should write ‘0’ to this bit to terminate the STALL signal. This bit has no
effect in ISO mode.
FLUSH: FIFO Flush.
Writing a ‘1’ to this bit flushes the next packet to be transmitted from the IN Endpoint FIFO.
The FIFO pointer is reset and the INPRDY bit is cleared. If the FIFO contains multiple packets, software must write ‘1’ to FLUSH for each packet. Hardware resets the FLUSH bit to ‘0’
when the FIFO flush is complete.
UNDRUN: Data Underrun.
The function of this bit depends on the IN Endpoint mode:
Isochronous: Set when a zero-length packet is sent after an IN token is received while bit
INPRDY = ‘0’.
Interrupt/Bulk: This bit is not used in these modes and will always read a '0'.
This bit must be cleared by software.
FIFONE: FIFO Not Empty.
0: The IN Endpoint FIFO is empty.
1. The IN Endpoint FIFO contains one or more packets.
INPRDY: In Packet Ready.
Software should write ‘1’ to this bit after loading a data packet into the IN Endpoint FIFO.
Hardware clears INPRDY due to any of the following:
1. A data packet is transmitted.
2. Double buffering is enabled (DBIEN = ‘1’) and there is an open FIFO packet slot.
3. If the endpoint is in Isochronous Mode (ISO = ‘1’) and ISOUD = ‘1’, INPRDY will read ‘0’
until the next SOF is received.
An interrupt (if enabled) will be generated when hardware clears INPRDY as a result
of a packet being transmitted.
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USB Register Definition 16.20. EINCSRH: USB0 IN Endpoint Control High Byte
R/W
R/W
R/W
R
R/W
R/W
R
R
Reset Value
DBIEN
ISO
DIRSEL
-
FCDT
SPLIT
-
-
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
USB Address:
0x12
Bit7:
DBIEN: IN Endpoint Double-buffer Enable.
0: Double-buffering disabled for the selected IN endpoint.
1: Double-buffering enabled for the selected IN endpoint.
Bit6:
ISO: Isochronous Transfer Enable.
This bit enables/disables isochronous transfers on the current endpoint.
0: Endpoint configured for bulk/interrupt transfers.
1: Endpoint configured for isochronous transfers.
Bit5:
DIRSEL: Endpoint Direction Select.
This bit is valid only when the selected FIFO is not split (SPLIT = ‘0’).
0: Endpoint direction selected as OUT.
1: Endpoint direction selected as IN.
Bit4:
Unused. Read = ‘0’. Write = don’t care.
Bit3:
FCDT: Force Data Toggle.
0: Endpoint data toggle switches only when an ACK is received following a data packet
transmission.
1: Endpoint data toggle forced to switch after every data packet is transmitted, regardless of
ACK reception.
Bit2:
SPLIT: FIFO Split Enable.
When SPLIT = ‘1’, the selected endpoint FIFO is split. The upper half of the selected FIFO is
used by the IN endpoint; the lower half of the selected FIFO is used by the OUT endpoint.
Bits1–0: Unused. Read = 00b; Write = don’t care.
16.13. Controlling Endpoints1-3 OUT
Endpoints1-3 OUT are managed via USB registers EOUTCSRL and EOUTCSRH. All OUT endpoints can
be used for Interrupt, Bulk, or Isochronous transfers. Isochronous (ISO) mode is enabled by writing ‘1’ to
the ISO bit in register EOUTCSRH. Bulk and Interrupt transfers are handled identically by hardware.
An Endpoint1-3 OUT interrupt may be generated by the following:
1. Hardware sets the OPRDY bit (EINCSRL.0) to ‘1’.
2. Hardware generates a STALL condition.
16.13.1.Endpoints1-3 OUT Interrupt or Bulk Mode
When the ISO bit (EOUTCSRH.6) = ‘0’ the target endpoint operates in Bulk or Interrupt mode. Once an
endpoint has been configured to operate in Bulk/Interrupt OUT mode (typically following an Endpoint0
SET_INTERFACE command), hardware will set the OPRDY bit (EOUTCSRL.0) to ‘1’ and generate an
interrupt upon reception of an OUT token and data packet. The number of bytes in the current OUT data
packet (the packet ready to be unloaded from the FIFO) is given in the EOUTCNTH and EOUTCNTL registers. In response to this interrupt, firmware should unload the data packet from the OUT FIFO and reset
the OPRDY bit to ‘0’.
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A Bulk or Interrupt pipe can be shut down (or Halted) by writing ‘1’ to the SDSTL bit (EOUTCSRL.5). While
SDSTL = ‘1’, hardware will respond to all OUT requests with a STALL condition. Each time hardware generates a STALL condition, an interrupt will be generated and the STSTL bit (EOUTCSRL.6) set to ‘1’. The
STSTL bit must be reset to ‘0’ by firmware.
Hardware will automatically set OPRDY when a packet is ready in the OUT FIFO. Note that if double buffering is enabled for the target endpoint, it is possible for two packets to be ready in the OUT FIFO at a time.
In this case, hardware will set OPRDY to ‘1’ immediately after firmware unloads the first packet and resets
OPRDY to ‘0’. A second interrupt will be generated in this case.
16.13.2.Endpoints1-3 OUT Isochronous Mode
When the ISO bit (EOUTCSRH.6) is set to ‘1’, the target endpoint operates in Isochronous (ISO) mode.
Once an endpoint has been configured for ISO OUT mode, the host will send exactly one data per USB
frame; the location of the data packet within each frame may vary, however. Because of this, it is recommended that double buffering be enabled for ISO OUT endpoints.
Each time a data packet is received, hardware will load the received data packet into the endpoint FIFO,
set the OPRDY bit (EOUTCSRL.0) to ‘1’, and generate an interrupt (if enabled). Firmware would typically
use this interrupt to unload the data packet from the endpoint FIFO and reset the OPRDY bit to ‘0’.
If a data packet is received when there is no room in the endpoint FIFO, an interrupt will be generated and
the OVRUN bit (EOUTCSRL.2) set to ‘1’. If USB0 receives an ISO data packet with a CRC error, the data
packet will be loaded into the endpoint FIFO, OPRDY will be set to ‘1’, an interrupt (if enabled) will be generated, and the DATAERR bit (EOUTCSRL.3) will be set to ‘1’. Software should check the DATAERR bit
each time a data packet is unloaded from an ISO OUT endpoint FIFO.
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USB Register Definition 16.21. EOUTCSRL: USB0 OUT Endpoint Control Low Byte
W
R/W
R/W
R/W
R
R/W
R
R/W
Reset Value
CLRDT
STSTL
SDSTL
FLUSH
DATERR
OVRUN
FIFOFUL
OPRDY
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
USB Address:
0x14
Bit7:
Bit6:
Bit5:
Bit4:
CLRDT: Clear Data Toggle
Write: Software should write ‘1’ to this bit to reset the OUT endpoint data toggle to ‘0’.
Read: This bit always reads ‘0’.
STSTL: Sent Stall
Hardware sets this bit to ‘1’ when a STALL handshake signal is transmitted. This flag must
be cleared by software.
SDSTL: Send Stall
Software should write ‘1’ to this bit to generate a STALL handshake. Software should write
‘0’ to this bit to terminate the STALL signal. This bit has no effect in ISO mode.
FLUSH: FIFO Flush
Writing a ‘1’ to this bit flushes the next packet to be read from the OUT endpoint FIFO. The
FIFO pointer is reset and the OPRDY bit is cleared. If the FIFO contains multiple packets,
software must write ‘1’ to FLUSH for each packet. Hardware resets the FLUSH bit to ‘0’
when the FIFO flush is complete.
Note: If data for the current packet has already been read from the FIFO, the FLUSH bit should
not be used to flush the packet. Instead, the entire data packet should be read from the
FIFO manually.
Bit3:
Bit2:
Bit1:
Bit0:
DATERR: Data Error
In ISO mode, this bit is set by hardware if a received packet has a CRC or bit-stuffing error.
It is cleared when software clears OPRDY. This bit is only valid in ISO mode.
OVRUN: Data Overrun
This bit is set by hardware when an incoming data packet cannot be loaded into the OUT
endpoint FIFO. This bit is only valid in ISO mode, and must be cleared by software.
0: No data overrun.
1: A data packet was lost because of a full FIFO since this flag was last cleared.
FIFOFUL: OUT FIFO Full
This bit indicates the contents of the OUT FIFO. If double buffering is enabled for the endpoint (DBIEN = ‘1’), the FIFO is full when the FIFO contains two packets. If DBIEN = ‘0’, the
FIFO is full when the FIFO contains one packet.
0: OUT endpoint FIFO is not full.
1: OUT endpoint FIFO is full.
OPRDY: OUT Packet Ready
Hardware sets this bit to ‘1’ and generates an interrupt when a data packet is available. Software should clear this bit after each data packet is unloaded from the OUT endpoint FIFO.
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USB Register Definition 16.22. EOUTCSRH: USB0 OUT Endpoint Control High Byte
R/W
R/W
R/W
R/W
R
R
R
R
Reset Value
DBOEN
ISO
-
-
-
-
-
-
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
USB Address:
0x15
Bit7:
DBOEN: Double-buffer Enable
0: Double-buffering disabled for the selected OUT endpoint.
1: Double-buffering enabled for the selected OUT endpoint.
Bit6:
ISO: Isochronous Transfer Enable
This bit enables/disables isochronous transfers on the current endpoint.
0: Endpoint configured for bulk/interrupt transfers.
1: Endpoint configured for isochronous transfers.
Bits5–0: Unused. Read = 000000b; Write = don’t care.
USB Register Definition 16.23. EOUTCNTL: USB0 OUT Endpoint Count Low
R
R
R
R
R
R
R
R
EOCL
Bit7
Bit6
Bit5
Bit4
Reset Value
00000000
Bit3
Bit2
Bit1
Bit0
USB Address:
0x16
Bits7–0: EOCL: OUT Endpoint Count Low Byte
EOCL holds the lower 8-bits of the 10-bit number of data bytes in the last received packet in
the current OUT endpoint FIFO. This number is only valid while OPRDY = ‘1’.
USB Register Definition 16.24. EOUTCNTH: USB0 OUT Endpoint Count High
R
R
R
R
R
R
-
-
-
-
-
-
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
R
R
E0CH
Bit1
Reset Value
00000000
Bit0
USB Address:
0x17
Bits7–2: Unused. Read = 00000. Write = don’t care.
Bits1–0: EOCH: OUT Endpoint Count High Byte
EOCH holds the upper 2-bits of the 10-bit number of data bytes in the last received packet in
the current OUT endpoint FIFO. This number is only valid while OPRDY = ‘1’.
186
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Table 16.4. USB Transceiver Electrical Characteristics
VDD = 3.0 to 3.6 V, –40 to +85 °C unless otherwise specified
Parameters
Symbol
Conditions
Transmitter
VOH
Output High Voltage
VOL
Output Low Voltage
VCRS
Output Crossover Point
Driving High
ZDRV
Output Impedance
Driving Low
Full Speed (D+ Pull-up)
RPU
Pull-up Resistance
Low Speed (D– Pull-up)
Low Speed
TR
Output Rise Time
Full Speed
Low Speed
TF
Output Fall Time
Full Speed
Receiver
Differential Input
VDI
| (D+) – (D–) |
Sensitivity
Differential Input Common
VCM
Mode Range
IL
Pullups Disabled
Input Leakage Current
Min
Typ
Max
Units
0.8
2.0
V
V
V
2.8
1.3
38

38
1.425
1.5
1.575
75
300
4
75
20
300
4
20
0.2
k
ns
ns
V
0.8
2.5
<1.0
V
µA
Note: Refer to the USB Specification for timing diagrams and symbol definitions.
Rev. 1.3
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C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
17. SMBus
The SMBus I/O interface is a two-wire, bi-directional serial bus. The SMBus is compliant with the System
Management Bus Specification, version 1.1, and compatible with the I2C serial bus. Reads and writes to
the interface by the system controller are byte oriented with the SMBus interface autonomously controlling
the serial transfer of the data. Data can be transferred at up to 1/20th of the system clock as a master or
slave (this can be faster than allowed by the SMBus specification, depending on the system clock used). A
method of extending the clock-low duration is available to accommodate devices with different speed
capabilities on the same bus.
The SMBus interface may operate as a master and/or slave, and may function on a bus with multiple masters. The SMBus provides control of SDA (serial data), SCL (serial clock) generation and synchronization,
arbitration logic, and START/STOP control and generation. Three SFRs are associated with the SMBus:
SMB0CF configures the SMBus; SMB0CN controls the status of the SMBus; and SMB0DAT is the data
register, used for both transmitting and receiving SMBus data and slave addresses.
SMB0CN
MT S S A A A S
A X T T CRC I
SMAOK B K
T O
R L
E D
QO
R E
S
T
SMB0CF
E I B E S S S S
N N U XMMMM
S HS T B B B B
M Y H T F CC
B
OO T S S
L E E 1 0
D
00
T0 Overflow
01
T1 Overflow
10
TMR2H Overflow
11
TMR2L Overflow
SMBUS CONTROL LOGIC
Interrupt
Request
SCL
FILTER
Arbitration
SCL Synchronization
SCL Generation (Master Mode)
SDA Control
Data Path
IRQ Generation
Control
SCL
Control
C
R
O
S
S
B
A
R
N
SDA
Control
SMB0DAT
7 6 5 4 3 2 1 0
SDA
FILTER
N
Figure 17.1. SMBus Block Diagram
188
Rev. 1.3
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17.1. Supporting Documents
It is assumed the reader is familiar with or has access to the following supporting documents:
1. The I2C-Bus and How to Use It (including specifications), Philips Semiconductor.
2. The I2C-Bus Specification -- Version 2.0, Philips Semiconductor.
3. System Management Bus Specification -- Version 1.1, SBS Implementers Forum.
17.2. SMBus Configuration
Figure 17.2 shows a typical SMBus configuration. The SMBus specification allows any recessive voltage
between 3.0 V and 5.0 V; different devices on the bus may operate at different voltage levels. The bi-directional SCL (serial clock) and SDA (serial data) lines must be connected to a positive power supply voltage
through a pull-up resistor or similar circuit. Every device connected to the bus must have an open-drain or
open-collector output for both the SCL and SDA lines, so that both are pulled high (recessive state) when
the bus is free. The maximum number of devices on the bus is limited only by the requirement that the rise
and fall times on the bus not exceed 300 ns and 1000 ns, respectively.
VDD = 5V
VDD = 3V
VDD = 5V
VDD = 3V
Master
Device
Slave
Device 1
Slave
Device 2
SDA
SCL
Figure 17.2. Typical SMBus Configuration
17.3. SMBus Operation
Two types of data transfers are possible: data transfers from a master transmitter to an addressed slave
receiver (WRITE), and data transfers from an addressed slave transmitter to a master receiver (READ).
The master device initiates both types of data transfers and provides the serial clock pulses on SCL. The
SMBus interface may operate as a master or a slave, and multiple master devices on the same bus are
supported. If two or more masters attempt to initiate a data transfer simultaneously, an arbitration scheme
is employed with a single master always winning the arbitration. Note that it is not necessary to specify one
device as the Master in a system; any device who transmits a START and a slave address becomes the
master for the duration of that transfer.
A typical SMBus transaction consists of a START condition followed by an address byte (Bits7-1: 7-bit
slave address; Bit0: R/W direction bit), one or more bytes of data, and a STOP condition. Each byte that is
received (by a master or slave) must be acknowledged (ACK) with a low SDA during a high SCL (see
Figure 17.3). If the receiving device does not ACK, the transmitting device will read a NACK (not acknowledge), which is a high SDA during a high SCL.
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The direction bit (R/W) occupies the least-significant bit position of the address byte. The direction bit is set
to logic 1 to indicate a "READ" operation and cleared to logic 0 to indicate a "WRITE" operation.
All transactions are initiated by a master, with one or more addressed slave devices as the target. The
master generates the START condition and then transmits the slave address and direction bit. If the transaction is a WRITE operation from the master to the slave, the master transmits the data a byte at a time
waiting for an ACK from the slave at the end of each byte. For READ operations, the slave transmits the
data waiting for an ACK from the master at the end of each byte. At the end of the data transfer, the master
generates a STOP condition to terminate the transaction and free the bus. Figure 17.3 illustrates a typical
SMBus transaction.
SCL
SDA
SLA6
START
SLA5-0
Slave Address + R/W
R/W
D7
ACK
D6-0
Data Byte
NACK
STOP
Figure 17.3. SMBus Transaction
17.3.1. Arbitration
A master may start a transfer only if the bus is free. The bus is free after a STOP condition or after the SCL
and SDA lines remain high for a specified time (see Section “17.3.4. SCL High (SMBus Free) Timeout”
on page 191). In the event that two or more devices attempt to begin a transfer at the same time, an arbitration scheme is employed to force one master to give up the bus. The master devices continue transmitting until one attempts a HIGH while the other transmits a LOW. Since the bus is open-drain, the bus will
be pulled LOW. The master attempting the HIGH will detect a LOW SDA and lose the arbitration. The winning master continues its transmission without interruption; the losing master becomes a slave and
receives the rest of the transfer if addressed. This arbitration scheme is non-destructive: one device
always wins, and no data is lost.
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17.3.2. Clock Low Extension
SMBus provides a clock synchronization mechanism, similar to I2C, which allows devices with different
speed capabilities to coexist on the bus. A clock-low extension is used during a transfer in order to allow
slower slave devices to communicate with faster masters. The slave may temporarily hold the SCL line
LOW to extend the clock low period, effectively decreasing the serial clock frequency.
17.3.3. SCL Low Timeout
If the SCL line is held low by a slave device on the bus, no further communication is possible. Furthermore,
the master cannot force the SCL line high to correct the error condition. To solve this problem, the SMBus
protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than
25 ms as a “timeout” condition. Devices that have detected the timeout condition must reset the communication no later than 10 ms after detecting the timeout condition.
When the SMBTOE bit in SMB0CF is set, Timer 3 is used to detect SCL low timeouts. Timer 3 is forced to
reload when SCL is high, and allowed to count when SCL is low. With Timer 3 enabled and configured to
overflow after 25 ms (and SMBTOE set), the Timer 3 interrupt service routine can be used to reset (disable
and re-enable) the SMBus in the event of an SCL low timeout.
17.3.4. SCL High (SMBus Free) Timeout
The SMBus specification stipulates that if the SCL and SDA lines remain high for more that 50 µs, the bus
is designated as free. When the SMBFTE bit in SMB0CF is set, the bus will be considered free if SCL and
SDA remain high for more than 10 SMBus clock source periods. If the SMBus is waiting to generate a
Master START, the START will be generated following this timeout. Note that a clock source is required for
free timeout detection, even in a slave-only implementation.
17.4. Using the SMBus
The SMBus can operate in both Master and Slave modes. The interface provides timing and shifting control for serial transfers; higher level protocol is determined by user software. The SMBus interface provides
the following application-independent features:
•
•
•
•
•
•
•
Byte-wise serial data transfers
Clock signal generation on SCL (Master Mode only) and SDA data synchronization
Timeout/bus error recognition, as defined by the SMB0CF configuration register
START/STOP timing, detection, and generation
Bus arbitration
Interrupt generation
Status information
SMBus interrupts are generated for each data byte or slave address that is transferred. When transmitting,
this interrupt is generated after the ACK cycle so that software may read the received ACK value; when
receiving data, this interrupt is generated before the ACK cycle so that software may define the outgoing
ACK value. See Section “17.5. SMBus Transfer Modes” on page 198 for more details on transmission
sequences.
Interrupts are also generated to indicate the beginning of a transfer when a master (START generated), or
the end of a transfer when a slave (STOP detected). Software should read the SMB0CN (SMBus Control
register) to find the cause of the SMBus interrupt. The SMB0CN register is described in Section
“17.4.2. SMB0CN Control Register” on page 195; Table 17.4 provides a quick SMB0CN decoding reference.
Rev. 1.3
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SMBus configuration options include:
•
•
•
•
Timeout detection (SCL Low Timeout and/or Bus Free Timeout)
SDA setup and hold time extensions
Slave event enable/disable
Clock source selection
These options are selected in the SMB0CF register, as described in Section “17.4.1. SMBus Configuration Register” on page 192.
17.4.1. SMBus Configuration Register
The SMBus Configuration register (SMB0CF) is used to enable the SMBus Master and/or Slave modes,
select the SMBus clock source, and select the SMBus timing and timeout options. When the ENSMB bit is
set, the SMBus is enabled for all master and slave events. Slave events may be disabled by setting the
INH bit. With slave events inhibited, the SMBus interface will still monitor the SCL and SDA pins; however,
the interface will NACK all received addresses and will not generate any slave interrupts. When the INH bit
is set, all slave events will be inhibited following the next START (interrupts will continue for the duration of
the current transfer).
Table 17.1. SMBus Clock Source Selection
SMBCS1
0
0
1
1
SMBCS0
0
1
0
1
SMBus Clock Source
Timer 0 Overflow
Timer 1 Overflow
Timer 2 High Byte Overflow
Timer 2 Low Byte Overflow
The SMBCS1-0 bits select the SMBus clock source, which is used only when operating as a master or
when the Free Timeout detection is enabled. When operating as a master, overflows from the selected
source determine the absolute minimum SCL low and high times as defined in Equation 17.1. Note that the
selected clock source may be shared by other peripherals so long as the timer is left running at all times.
For example, Timer 1 overflows may generate the SMBus and UART baud rates simultaneously. Timer
configuration is covered in Section “21. Timers” on page 235.
1
T HighMin = T LowMin = ---------------------------------------------f ClockSourceOverflow
Equation 17.1. Minimum SCL High and Low Times
The selected clock source should be configured to establish the minimum SCL High and Low times as per
Equation 17.1. When the interface is operating as a master (and SCL is not driven or extended by any
other devices on the bus), the typical SMBus bit rate is approximated by Equation 17.2.
f ClockSourceOverflow
BitRate = ---------------------------------------------3
Equation 17.2. Typical SMBus Bit Rate
192
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Figure 17.4 shows the typical SCL generation described by Equation 17.2. Notice that THIGH is typically
twice as large as TLOW. The actual SCL output may vary due to other devices on the bus (SCL may be
extended low by slower slave devices, or driven low by contending master devices). The bit rate when
operating as a master will never exceed the limits defined by equation Equation 17.1.
Timer Source
Overflows
SCL
TLow
SCL High Timeout
THigh
Figure 17.4. Typical SMBus SCL Generation
Setting the EXTHOLD bit extends the minimum setup and hold times for the SDA line. The minimum SDA
setup time defines the absolute minimum time that SDA is stable before SCL transitions from low-to-high.
The minimum SDA hold time defines the absolute minimum time that the current SDA value remains stable
after SCL transitions from high-to-low. EXTHOLD should be set so that the minimum setup and hold times
meet the SMBus Specification requirements of 250 ns and 300 ns, respectively. Table 17.2 shows the minimum setup and hold times for the two EXTHOLD settings. Setup and hold time extensions are typically
necessary when SYSCLK is above 10 MHz.
Table 17.2. Minimum SDA Setup and Hold Times
EXTHOLD
Minimum SDA Setup Time
Tlow - 4 system clocks
Minimum SDA Hold Time
0
OR
3 system clocks
1
1 system clock + s/w delay*
11 system clocks
12 system clocks
*Note: Setup Time for ACK bit transmissions and the MSB of all data transfers. The s/w delay
occurs between the time SMB0DAT or ACK is written and when SI is cleared. Note that if SI
is cleared in the same write that defines the outgoing ACK value, s/w delay is zero.
With the SMBTOE bit set, Timer 3 should be configured to overflow after 25 ms in order to detect SCL low
timeouts (see Section “17.3.3. SCL Low Timeout” on page 191). The SMBus interface will force Timer 3
to reload while SCL is high, and allow Timer 3 to count when SCL is low. The Timer 3 interrupt service routine should be used to reset SMBus communication by disabling and re-enabling the SMBus.
SMBus Free Timeout detection can be enabled by setting the SMBFTE bit. When this bit is set, the bus will
be considered free if SDA and SCL remain high for more than 10 SMBus clock source periods (see
Figure 17.4). When a Free Timeout is detected, the interface will respond as if a STOP was detected (an
interrupt will be generated, and STO will be set).
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SFR Definition 17.1. SMB0CF: SMBus Clock/Configuration
R/W
R/W
R
ENSMB
INH
BUSY
Bit7
Bit6
Bit5
R/W
R/W
R/W
R/W
R/W
Reset Value
EXTHOLD SMBTOE SMBFTE SMBCS1 SMBCS0 00000000
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xC1
Bit7:
ENSMB: SMBus Enable.
This bit enables/disables the SMBus interface. When enabled, the interface constantly monitors the SDA and SCL pins.
0: SMBus interface disabled.
1: SMBus interface enabled.
Bit6:
INH: SMBus Slave Inhibit.
When this bit is set to logic 1, the SMBus does not generate an interrupt when slave events
occur. This effectively removes the SMBus slave from the bus. Master Mode interrupts are
not affected.
0: SMBus Slave Mode enabled.
1: SMBus Slave Mode inhibited.
Bit5:
BUSY: SMBus Busy Indicator.
This bit is set to logic 1 by hardware when a transfer is in progress. It is cleared to logic 0
when a STOP or free-timeout is sensed.
Bit4:
EXTHOLD: SMBus Setup and Hold Time Extension Enable.
This bit controls the SDA setup and hold times according to.
0: SDA Extended Setup and Hold Times disabled.
1: SDA Extended Setup and Hold Times enabled.
Bit3:
SMBTOE: SMBus SCL Timeout Detection Enable.
This bit enables SCL low timeout detection. If set to logic 1, the SMBus forces Timer 3 to
reload while SCL is high and allows Timer 3 to count when SCL goes low. Timer 3 should be
programmed to generate interrupts at 25 ms, and the Timer 3 interrupt service routine
should reset SMBus communication.
Bit2:
SMBFTE: SMBus Free Timeout Detection Enable.
When this bit is set to logic 1, the bus will be considered free if SCL and SDA remain high for
more than 10 SMBus clock source periods.
Bits1–0: SMBCS1-SMBCS0: SMBus Clock Source Selection.
These two bits select the SMBus clock source, which is used to generate the SMBus bit
rate. The selected device should be configured according to Equation 17.1.
SMBCS1
0
0
1
1
194
SMBCS0
0
1
0
1
SMBus Clock Source
Timer 0 Overflow
Timer 1 Overflow
Timer 2 High Byte Overflow
Timer 2 Low Byte Overflow
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
17.4.2. SMB0CN Control Register
SMB0CN is used to control the interface and to provide status information (see SFR Definition 17.2). The
higher four bits of SMB0CN (MASTER, TXMODE, STA, and STO) form a status vector that can be used to
jump to service routines. MASTER and TXMODE indicate the master/slave state and transmit/receive
modes, respectively.
STA and STO indicate that a START and/or STOP has been detected or generated since the last SMBus
interrupt. STA and STO are also used to generate START and STOP conditions when operating as a master. Writing a ‘1’ to STA will cause the SMBus interface to enter Master Mode and generate a START when
the bus becomes free (STA is not cleared by hardware after the START is generated). Writing a ‘1’ to STO
while in Master Mode will cause the interface to generate a STOP and end the current transfer after the
next ACK cycle. If STO and STA are both set (while in Master Mode), a STOP followed by a START will be
generated.
As a receiver, writing the ACK bit defines the outgoing ACK value; as a transmitter, reading the ACK bit
indicates the value received on the last ACK cycle. ACKRQ is set each time a byte is received, indicating
that an outgoing ACK value is needed. When ACKRQ is set, software should write the desired outgoing
value to the ACK bit before clearing SI. A NACK will be generated if software does not write the ACK bit
before clearing SI. SDA will reflect the defined ACK value immediately following a write to the ACK bit;
however SCL will remain low until SI is cleared. If a received slave address is not acknowledged, further
slave events will be ignored until the next START is detected.
The ARBLOST bit indicates that the interface has lost an arbitration. This may occur anytime the interface
is transmitting (master or slave). A lost arbitration while operating as a slave indicates a bus error condition. ARBLOST is cleared by hardware each time SI is cleared.
The SI bit (SMBus Interrupt Flag) is set at the beginning and end of each transfer, after each byte frame, or
when an arbitration is lost; see Table 17.3 for more details.
Important Note About the SI Bit: The SMBus interface is stalled while SI is set; thus SCL is held low, and
the bus is stalled until software clears SI.
Table 17.3 lists all sources for hardware changes to the SMB0CN bits. Refer to Table 17.4 for SMBus status decoding using the SMB0CN register.
Rev. 1.3
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SFR Definition 17.2. SMB0CN: SMBus Control
R
R
MASTER TXMODE
Bit7
Bit6
R/W
R/W
STA
STO
Bit5
Bit4
R
R
ACKRQ ARBLOST
Bit3
Bit2
R/W
R/W
Reset Value
ACK
SI
00000000
Bit1
Bit0
Bit
Addressable
SFR Address: 0xC0
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
196
MASTER: SMBus Master/Slave Indicator.
This read-only bit indicates when the SMBus is operating as a master.
0: SMBus operating in Slave Mode.
1: SMBus operating in Master Mode.
TXMODE: SMBus Transmit Mode Indicator.
This read-only bit indicates when the SMBus is operating as a transmitter.
0: SMBus in Receiver Mode.
1: SMBus in Transmitter Mode.
STA: SMBus Start Flag.
Write:
0: No Start generated.
1: When operating as a master, a START condition is transmitted if the bus is free (If the bus
is not free, the START is transmitted after a STOP is received or a timeout is detected). If
STA is set by software as an active Master, a repeated START will be generated after the
next ACK cycle.
Read:
0: No Start or repeated Start detected.
1: Start or repeated Start detected.
STO: SMBus Stop Flag.
Write:
0: No STOP condition is transmitted.
1: Setting STO to logic 1 causes a STOP condition to be transmitted after the next ACK
cycle. When the STOP condition is generated, hardware clears STO to logic 0. If both STA
and STO are set, a STOP condition is transmitted followed by a START condition.
Read:
0: No Stop condition detected.
1: Stop condition detected (if in Slave Mode) or pending (if in Master Mode).
ACKRQ: SMBus Acknowledge Request
This read-only bit is set to logic 1 when the SMBus has received a byte and needs the ACK
bit to be written with the correct ACK response value.
ARBLOST: SMBus Arbitration Lost Indicator.
This read-only bit is set to logic 1 when the SMBus loses arbitration while operating as a
transmitter. A lost arbitration while a slave indicates a bus error condition.
ACK: SMBus Acknowledge Flag.
This bit defines the out-going ACK level and records incoming ACK levels. It should be written each time a byte is received (when ACKRQ=1), or read after each byte is transmitted.
0: A "not acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if
in Receiver Mode).
1: An "acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if in
Receiver Mode).
SI: SMBus Interrupt Flag.
This bit is set by hardware under the conditions listed in Table 17.3. SI must be cleared by
software. While SI is set, SCL is held low and the SMBus is stalled.
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Table 17.3. Sources for Hardware Changes to SMB0CN
Bit
MASTER
TXMODE
STA
STO
ACKRQ
ARBLOST
ACK
SI
Set by Hardware When:
• A START is generated.
• START is generated.
• SMB0DAT is written before the start of an
SMBus frame.
• A START followed by an address byte is
received.
• A STOP is detected while addressed as a
slave.
• Arbitration is lost due to a detected STOP.
• A byte has been received and an ACK
response value is needed.
• A repeated START is detected as a MASTER
when STA is low (unwanted repeated START).
• SCL is sensed low while attempting to generate a STOP or repeated START condition.
• SDA is sensed low while transmitting a ‘1’
(excluding ACK bits).
• The incoming ACK value is low (ACKNOWLEDGE).
• A START has been generated.
• Lost arbitration.
• A byte has been transmitted and an ACK/
NACK received.
• A byte has been received.
• A START or repeated START followed by a
slave address + R/W has been received.
• A STOP has been received.
Rev. 1.3
Cleared by Hardware When:
• A STOP is generated.
• Arbitration is lost.
• A START is detected.
• Arbitration is lost.
• SMB0DAT is not written before the
start of an SMBus frame.
• Must be cleared by software.
• A pending STOP is generated.
• After each ACK cycle.
• Each time SI is cleared.
• The incoming ACK value is high (NOT
ACKNOWLEDGE).
• Must be cleared by software.
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17.4.3. Data Register
The SMBus Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been
received. Software may safely read or write to the data register when the SI flag is set. Software should not
attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag is cleared to logic 0,
as the interface may be in the process of shifting a byte of data into or out of the register.
Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received
data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously
being shifted in. SMB0DAT always contains the last data byte present on the bus. In the event of lost arbitration, the transition from master transmitter to slave receiver is made with the correct data or address in
SMB0DAT.
SFR Definition 17.3. SMB0DAT: SMBus Data
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xC2
Bits7-0:
SMB0DAT: SMBus Data.
The SMB0DAT register contains a byte of data to be transmitted on the SMBus serial interface or a byte that has just been received on the SMBus serial interface. The CPU can read
from or write to this register whenever the SI serial interrupt flag (SMB0CN.0) is set to
logic 1. The serial data in the register remains stable as long as the SI flag is set. When the
SI flag is not set, the system may be in the process of shifting data in/out and the CPU
should not attempt to access this register.
17.5. SMBus Transfer Modes
The SMBus interface may be configured to operate as master and/or slave. At any particular time, it will be
operating in one of the following four modes: Master Transmitter, Master Receiver, Slave Transmitter, or
Slave Receiver. The SMBus interface enters Master Mode any time a START is generated, and remains in
Master Mode until it loses an arbitration or generates a STOP. An SMBus interrupt is generated at the end
of all SMBus byte frames; however, note that the interrupt is generated before the ACK cycle when operating as a receiver, and after the ACK cycle when operating as a transmitter.
17.5.1. Master Transmitter Mode
Serial data is transmitted on SDA while the serial clock is output on SCL. The SMBus interface generates
the START condition and transmits the first byte containing the address of the target slave and the data
direction bit. In this case the data direction bit (R/W) will be logic 0 (WRITE). The master then transmits
one or more bytes of serial data. After each byte is transmitted, an acknowledge bit is generated by the
slave. The transfer is ended when the STO bit is set and a STOP is generated. Note that the interface will
switch to Master Receiver Mode if SMB0DAT is not written following a Master Transmitter interrupt.
Figure 17.5 shows a typical Master Transmitter sequence. Two transmit data bytes are shown, though any
number of bytes may be transmitted. Notice that the ‘data byte transferred’ interrupts occur after the ACK
cycle in this mode.
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S
SLA
W
Interrupt
A
Data Byte
Interrupt
A
Data Byte
Interrupt
A
P
Interrupt
S = START
P = STOP
A = ACK
W = WRITE
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Figure 17.5. Typical Master Transmitter Sequence
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17.5.2. Master Receiver Mode
Serial data is received on SDA while the serial clock is output on SCL. The SMBus interface generates the
START condition and transmits the first byte containing the address of the target slave and the data direction bit. In this case the data direction bit (R/W) will be logic 1 (READ). Serial data is then received from the
slave on SDA while the SMBus outputs the serial clock. The slave transmits one or more bytes of serial
data. After each byte is received, ACKRQ is set to ‘1’ and an interrupt is generated. Software must write
the ACK bit (SMB0CN.1) to define the outgoing acknowledge value (Note: writing a ‘1’ to the ACK bit generates an ACK; writing a ‘0’ generates a NACK). Software should write a ‘0’ to the ACK bit after the last
byte is received, to transmit a NACK. The interface exits Master Receiver Mode after the STO bit is set and
a STOP is generated. Note that the interface will switch to Master Transmitter Mode if SMB0DAT is written
while an active Master Receiver. Figure 17.6 shows a typical Master Receiver sequence. Two received
data bytes are shown, though any number of bytes may be received. Notice that the ‘data byte transferred’
interrupts occur before the ACK cycle in this mode.
S
SLA
R
Interrupt
A
Interrupt
Data Byte
A
Interrupt
Data Byte
N
Interrupt
S = START
P = STOP
A = ACK
N = NACK
R = READ
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Figure 17.6. Typical Master Receiver Sequence
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17.5.3. Slave Receiver Mode
Serial data is received on SDA and the clock is received on SCL. When slave events are enabled (INH =
0), the interface enters Slave Receiver Mode when a START followed by a slave address and direction bit
(WRITE in this case) is received. Upon entering Slave Receiver Mode, an interrupt is generated and the
ACKRQ bit is set. Software responds to the received slave address with an ACK, or ignores the received
slave address with a NACK. If the received slave address is ignored, slave interrupts will be inhibited until
the next START is detected. If the received slave address is acknowledged, zero or more data bytes are
received. Software must write the ACK bit after each received byte to ACK or NACK the received byte. The
interface exits Slave Receiver Mode after receiving a STOP. Note that the interface will switch to Slave
Transmitter Mode if SMB0DAT is written while an active Slave Receiver. Figure 17.7 shows a typical Slave
Receiver sequence. Two received data bytes are shown, though any number of bytes may be received.
Notice that the ‘data byte transferred’ interrupts occur before the ACK cycle in this mode.
Interrupt
S
SLA
W
A
Interrupt
Data Byte
A
Interrupt
Data Byte
A
P
Interrupt
S = START
P = STOP
A = ACK
W = WRITE
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Figure 17.7. Typical Slave Receiver Sequence
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17.5.4. Slave Transmitter Mode
Serial data is transmitted on SDA and the clock is received on SCL. When slave events are enabled (INH
= 0), the interface enters Slave Receiver Mode (to receive the slave address) when a START followed by a
slave address and direction bit (READ in this case) is received. Upon entering Slave Transmitter Mode, an
interrupt is generated and the ACKRQ bit is set. Software responds to the received slave address with an
ACK, or ignores the received slave address with a NACK. If the received slave address is ignored, slave
interrupts will be inhibited until a START is detected. If the received slave address is acknowledged, data
should be written to SMB0DAT to be transmitted. The interface enters Slave Transmitter Mode, and transmits one or more bytes of data. After each byte is transmitted, the master sends an acknowledge bit; if the
acknowledge bit is an ACK, SMB0DAT should be written with the next data byte. If the acknowledge bit is
a NACK, SMB0DAT should not be written to before SI is cleared (Note: an error condition may be generated if SMB0DAT is written following a received NACK while in Slave Transmitter Mode). The interface
exits Slave Transmitter Mode after receiving a STOP. Note that the interface will switch to Slave Receiver
Mode if SMB0DAT is not written following a Slave Transmitter interrupt. Figure 17.8 shows a typical Slave
Transmitter sequence. Two transmitted data bytes are shown, though any number of bytes may be transmitted. Notice that the ‘data byte transferred’ interrupts occur after the ACK cycle in this mode.
Interrupt
S
SLA
R
A
Interrupt
Data Byte
A
Data Byte
Interrupt
N
P
Interrupt
S = START
P = STOP
N = NACK
R = READ
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Figure 17.8. Typical Slave Transmitter Sequence
17.6. SMBus Status Decoding
The current SMBus status can be easily decoded using the SMB0CN register. In the table below, STATUS
VECTOR refers to the four upper bits of SMB0CN: MASTER, TXMODE, STA, and STO. Note that the
shown response options are only the typical responses; application-specific procedures are allowed as
long as they conform to the SMBus specification. Highlighted responses are allowed but do not conform to
the SMBus specification.
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Table 17.4. SMBus Status Decoding
Values
Written
ARBLOST
ACK
0
X A master START was generated.
0
0
0
1000
1
0
0
1
X
0
0
X
1
0
X
0
1
X
Load next data byte into
SMB0DAT.
0
0
X
End transfer with STOP.
0
1
X
End transfer with STOP and
start another transfer.
1
1
X
Send repeated START.
1
0
X
Switch to Master Receiver
Mode (clear SI without writing new data to SMB0DAT).
0
0
X
Acknowledge received byte;
Read SMB0DAT.
0
0
1
Send NACK to indicate last
byte, and send STOP.
0
1
0
Send NACK to indicate last
byte, and send STOP followed by START.
1
1
0
Send ACK followed by
repeated START.
1
0
1
1
0
0
Send ACK and switch to
Master Transmitter Mode
(write to SMB0DAT before
clearing SI).
0
0
1
Send NACK and switch to
Master Transmitter Mode
(write to SMB0DAT before
clearing SI).
0
0
0
Load slave address + R/W
into SMB0DAT.
Set STA to restart transfer.
A master data or address byte
was transmitted; NACK received. Abort transfer.
1100
0
ACK
ACKRQ
0
Typical Response Options
STo
Status
Vector
1110
Current SMbus State
STA
Master Receiver
Master Transmitter
Mode
Values Read
A master data or address byte
was transmitted; ACK received.
A master data byte was received; Send NACK to indicate last
ACK requested.
byte, and send repeated
START.
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Table 17.4. SMBus Status Decoding (Continued)
Values
Written
ACK
STA
STo
ACK
0101
ARBLOST
Status
Vector
0100
ACKRQ
Slave Transmitter
Mode
Values Read
0
0
0
A slave byte was transmitted;
NACK received.
No action required (expecting STOP condition).
0
0
X
0
0
1
A slave byte was transmitted;
ACK received.
Load SMB0DAT with next
data byte to transmit.
0
0
X
0
1
X
A Slave byte was transmitted;
error detected.
No action required (expecting Master to end transfer).
0
0
X
0
X
An illegal STOP or bus error was
X detected while a Slave Transmis- Clear STO.
sion was in progress.
0
0
X
Acknowledge received
address.
0
0
1
Do not acknowledge
received address.
0
0
0
Acknowledge received
address.
0
0
1
Do not acknowledge
received address.
0
0
0
Reschedule failed transfer;
do not acknowledge received
address.
1
0
0
0
0
X
1
0
X
0
0
0
0
0
X
0
0
X
1
0
X
Acknowledge received byte;
Read SMB0DAT.
0
0
1
Do not acknowledge
received byte.
0
0
0
0
0
0
1
0
0
1
0
X
Current SMbus State
A slave address was received;
ACK requested.
0010
Slave Receiver
1
0010
0001
1
Lost arbitration as master; slave
X address received; ACK
requested.
0
1
X
Lost arbitration while attempting a Abort failed transfer.
repeated START.
Reschedule failed transfer.
1
1
X
Lost arbitration while attempting a No action required (transfer
STOP.
complete/aborted).
0
0
A STOP was detected while
X addressed as a Slave Transmitter Clear STO.
or Slave Receiver.
0
1
X
1
0
X
Lost arbitration due to a detected Abort transfer.
STOP.
Reschedule failed transfer.
A slave byte was received; ACK
requested.
0000
1
204
Typical Response Options
1
X
Lost arbitration while transmitting Abort failed transfer.
a data byte as master.
Reschedule failed transfer.
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
18. UART0
UART0 is an asynchronous, full duplex serial port offering modes 1 and 3 of the standard 8051 UART.
Enhanced baud rate support allows a wide range of clock sources to generate standard baud rates (details
in Section “18.1. Enhanced Baud Rate Generation” on page 206). Received data buffering allows
UART0 to start reception of a second incoming data byte before software has finished reading the previous
data byte.
UART0 has two associated SFRs: Serial Control Register 0 (SCON0) and Serial Data Buffer 0 (SBUF0).
The single SBUF0 location provides access to both transmit and receive registers. Writes to SBUF0
always access the Transmit register. Reads of SBUF0 always access the buffered Receive register;
it is not possible to read data from the Transmit register.
With UART0 interrupts enabled, an interrupt is generated each time a transmit is completed (TI0 is set in
SCON0), or a data byte has been received (RI0 is set in SCON0). The UART0 interrupt flags are not
cleared by hardware when the CPU vectors to the interrupt service routine. They must be cleared manually
by software, allowing software to determine the cause of the UART0 interrupt (transmit complete or receive
complete).
SFR Bus
Write to
SBUF0
TB80
SBUF0
(TX Shift)
SET
D
Q
TX0
CLR
Crossbar
Zero Detector
Stop Bit
Shift
Start
Data
Tx Control
Tx Clock
Tx IRQ
Send
SCON
TI0
Serial
Port
Interrupt
MCE0
REN0
TB80
RB80
TI0
RI0
S0MODE
UART0 Baud
Rate Generator
Port I/O
RI0
Rx IRQ
Rx Clock
Rx Control
Start
Shift
0x1FF
RB80
Load
SBUF0
Input Shift Register
(9 bits)
Load SBUF0
SBUF0
(RX Latch)
Read
SBUF0
SFR Bus
RX0
Crossbar
Figure 18.1. UART0 Block Diagram
Rev. 1.3
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18.1. Enhanced Baud Rate Generation
The UART0 baud rate is generated by Timer 1 in 8-bit auto-reload mode. The TX clock is generated by
TL1; the RX clock is generated by a copy of TL1 (shown as RX Timer in Figure 18.2), which is not
user-accessible. Both TX and RX Timer overflows are divided by two to generate the TX and RX baud
rates. The RX Timer runs when Timer 1 is enabled, and uses the same reload value (TH1). However, an
RX Timer reload is forced when a START condition is detected on the RX pin. This allows a receive to
begin any time a START is detected, independent of the TX Timer state.
Timer 1
TL1
UART
Overflow
2
TX Clock
Overflow
2
RX Clock
TH1
Start
Detected
RX Timer
Figure 18.2. UART0 Baud Rate Logic
Timer 1 should be configured for Mode 2, 8-bit auto-reload (see Section “21.1.3. Mode 2: 8-bit Counter/
Timer with Auto-Reload” on page 237). The Timer 1 reload value should be set so that overflows will
occur at two times the desired UART baud rate frequency. Note that Timer 1 may be clocked by one of six
sources: SYSCLK, SYSCLK / 4, SYSCLK / 12, SYSCLK / 48, the external oscillator clock / 8, or an external input T1. For any given Timer 1 clock source, the UART0 baud rate is determined by Equation 18.1.
T1 CLK
1
UartBaudRate = -------------------------------  -- 256 – T1H  2
Equation 18.1. UART0 Baud Rate
Where T1CLK is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (reload
value). Timer 1 clock frequency is selected as described in Section “21. Timers” on page 235. A quick
reference for typical baud rates using the internal oscillator is given in Table 18.1. Note that the internal
oscillator may still generate the system clock if an external oscillator is driving Timer 1.
18.2. Operational Modes
UART0 provides standard asynchronous, full duplex communication. The UART mode (8-bit or 9-bit) is
selected by the S0MODE bit (SCON0.7). Typical UART connection options are shown below.
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TX
RS-232
LEVEL
XLTR
RS-232
RX
C8051Fxxx
OR
TX
TX
RX
RX
MCU
C8051Fxxx
Figure 18.3. UART Interconnect Diagram
18.2.1. 8-Bit UART
8-Bit UART mode uses a total of 10 bits per data byte: one start bit, eight data bits (LSB first), and one stop
bit. Data are transmitted LSB first from the TX0 pin and received at the RX0 pin. On receive, the eight data
bits are stored in SBUF0 and the stop bit goes into RB80 (SCON0.2).
Data transmission begins when software writes a data byte to the SBUF0 register. The TI0 Transmit Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to logic 1. After the stop bit is
received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met:
RI0 must be logic 0, and if MCE0 is logic 1, the stop bit must be logic 1. In the event of a receive data overrun, the first received 8 bits are latched into the SBUF0 receive register and the following overrun data bits
are lost.
If these conditions are met, the eight bits of data is stored in SBUF0, the stop bit is stored in RB80 and the
RI0 flag is set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not
be set. An interrupt will occur if enabled when either TI0 or RI0 is set.
MARK
SPACE
START
BIT
D0
D1
D2
D3
D4
D5
D6
D7
STOP
BIT
BIT TIMES
BIT SAMPLING
Figure 18.4. 8-Bit UART Timing Diagram
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18.2.2. 9-Bit UART
9-bit UART mode uses a total of eleven bits per data byte: a start bit, 8 data bits (LSB first), a programmable ninth data bit, and a stop bit. The state of the ninth transmit data bit is determined by the value in TB80
(SCON0.3), which is assigned by user software. It can be assigned the value of the parity flag (bit P in register PSW) for error detection, or used in multiprocessor communications. On receive, the ninth data bit
goes into RB80 (SCON0.2) and the stop bit is ignored.
Data transmission begins when an instruction writes a data byte to the SBUF0 register. The TI0 Transmit
Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data
reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to ‘1’. After the stop bit
is received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met:
(1) RI0 must be logic 0, and (2) if MCE0 is logic 1, the 9th bit must be logic 1 (when MCE0 is logic 0, the
state of the ninth data bit is unimportant). If these conditions are met, the eight bits of data are stored in
SBUF0, the ninth bit is stored in RB80, and the RI0 flag is set to ‘1’. If the above conditions are not met,
SBUF0 and RB80 will not be loaded and the RI0 flag will not be set to ‘1’. A UART0 interrupt will occur if
enabled when either TI0 or RI0 is set to ‘1’.
MARK
SPACE
START
BIT
D0
D1
D2
D3
D4
D5
D6
D7
D8
STOP
BIT
BIT TIMES
BIT SAMPLING
Figure 18.5. 9-Bit UART Timing Diagram
18.3. Multiprocessor Communications
9-Bit UART mode supports multiprocessor communication between a master processor and one or more
slave processors by special use of the ninth data bit. When a master processor wants to transmit to one or
more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte
in that its ninth bit is logic 1; in a data byte, the ninth bit is always set to logic 0.
Setting the MCE0 bit (SCON0.5) of a slave processor configures its UART such that when a stop bit is
received, the UART will generate an interrupt only if the ninth bit is logic 1 (RB80 = 1) signifying an address
byte has been received. In the UART interrupt handler, software will compare the received address with
the slave's own assigned 8-bit address. If the addresses match, the slave will clear its MCE0 bit to enable
interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave their MCE0
bits set and do not generate interrupts on the reception of the following data bytes, thereby ignoring the
data. Once the entire message is received, the addressed slave resets its MCE0 bit to ignore all transmissions until it receives the next address byte.
Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple
slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master
processor can be configured to receive all transmissions or a protocol can be implemented such that the
master/slave role is temporarily reversed to enable half-duplex transmission between the original master
and slave(s).
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Master
Device
Slave
Device
Slave
Device
Slave
Device
V+
RX
TX
RX
TX
RX
TX
RX
TX
Figure 18.6. UART Multi-Processor Mode Interconnect Diagram
Rev. 1.3
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SFR Definition 18.1. SCON0: Serial Port 0 Control
R/W
R
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
S0MODE
-
MCE0
REN0
TB80
RB80
TI0
RI0
01000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0x98
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
210
S0MODE: Serial Port 0 Operation Mode.
This bit selects the UART0 Operation Mode.
0: 8-bit UART with Variable Baud Rate.
1: 9-bit UART with Variable Baud Rate.
UNUSED. Read = 1b. Write = don’t care.
MCE0: Multiprocessor Communication Enable.
The function of this bit is dependent on the Serial Port 0 Operation Mode.
S0MODE = 0: Checks for valid stop bit.
0: Logic level of stop bit is ignored.
1: RI0 will only be activated if stop bit is logic level 1.
S0MODE = 1: Multiprocessor Communications Enable.
0: Logic level of ninth bit is ignored.
1: RI0 is set and an interrupt is generated only when the ninth bit is logic 1.
REN0: Receive Enable.
This bit enables/disables the UART receiver.
0: UART0 reception disabled.
1: UART0 reception enabled.
TB80: Ninth Transmission Bit.
The logic level of this bit will be assigned to the ninth transmission bit in 9-bit UART Mode. It
is not used in 8-bit UART Mode. Set or cleared by software as required.
RB80: Ninth Receive Bit.
RB80 is assigned the value of the STOP bit in Mode 0; it is assigned the value of the 9th
data bit in Mode 1.
TI0: Transmit Interrupt Flag.
Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit in
8-bit UART Mode, or at the beginning of the STOP bit in 9-bit UART Mode). When the
UART0 interrupt is enabled, setting this bit causes the CPU to vector to the UART0 interrupt
service routine. This bit must be cleared manually by software.
RI0: Receive Interrupt Flag.
Set to ‘1’ by hardware when a byte of data has been received by UART0 (set at the STOP bit
sampling time). When the UART0 interrupt is enabled, setting this bit to ‘1’ causes the CPU
to vector to the UART0 interrupt service routine. This bit must be cleared manually by software.
Rev. 1.3
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SFR Definition 18.2. SBUF0: Serial (UART0) Port Data Buffer
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0x99
Bits7–0: SBUF0[7:0]: Serial Data Buffer Bits 7–0 (MSB-LSB)
This SFR accesses two registers; a transmit shift register and a receive latch register. When
data is written to SBUF0, it goes to the transmit shift register and is held for serial transmission. Writing a byte to SBUF0 initiates the transmission. A read of SBUF0 returns the contents of the receive latch.
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Table 18.1. Timer Settings for Standard Baud Rates Using the Internal Oscillator
SYSCLK = 48 MHz SYSCLK = 24 MHz
SYSCLK = 12 MHz
Target
Actual
Baud
Baud
Baud
Rate Error
Rate (bps) Rate (bps)
230400
230769
0.16%
115200
115385
0.16%
57600
57692
0.16%
28800
28846
0.16%
14400
14423
0.16%
9600
9615
0.16%
2400
2404
0.16%
1200
1202
0.16%
230400
230769
0.16%
115200
115385
0.16%
57600
57692
0.16%
28800
28846
0.16%
14400
14423
0.16%
9600
9615
0.16%
2400
2404
0.16%
1200
1202
0.16%
230400
230769
0.16%
115200
115385
0.16%
57600
57692
0.16%
28800
28846
0.16%
14400
14388
0.08%
9600
9615
0.16%
2400
2404
0.16%
X = Don’t care
Oscillator
Divide
Factor
52
104
208
416
832
1248
4992
9984
104
208
416
832
1664
2496
9984
19968
208
416
832
1664
3336
4992
19968
Timer Clock SCA1-SCA0 T1M*
Timer 1
Source
(pre-scale
Reload
select*
Value (hex)
SYSCLK
XX
1
0xE6
SYSCLK
XX
1
0xCC
SYSCLK
XX
1
0x98
SYSCLK
XX
1
0x30
SYSCLK / 4
01
0
0x98
SYSCLK / 4
01
0
0x64
SYSCLK / 12
00
0
0x30
SYSCLK / 48
10
0
0x98
SYSCLK
XX
1
0xCC
SYSCLK
XX
1
0x98
SYSCLK
XX
1
0x30
SYSCLK / 4
01
0
0x98
SYSCLK / 4
01
0
0x30
SYSCLK / 12
00
0
0x98
SYSCLK / 48
10
0
0x98
SYSCLK / 48
10
0
0x30
SYSCLK
XX
1
0x98
SYSCLK
XX
1
0x30
SYSCLK / 4
01
0
0x98
SYSCLK / 4
01
0
0x30
SYSCLK / 12
00
0
0x75
SYSCLK / 12
00
0
0x30
SYSCLK / 48
10
0
0x30
*Note: SCA1-SCA0 and T1M define the Timer Clock Source. Bit definitions for these values can be found in
Section 21.1.
212
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
19. UART1 (C8051F340/1/4/5/8/A/B/C Only)
UART1 is an asynchronous, full duplex serial port offering a variety of data formatting options. A dedicated
baud rate generator with a 16-bit timer and selectable prescaler is included, which can generate a wide
range of baud rates (details in Section “19.1. Baud Rate Generator” on page 214). A received data
FIFO allows UART1 to receive up to three data bytes before data is lost and an overflow occurs.
UART1 has six associated SFRs. Three are used for the Baud Rate Generator (SBCON1, SBRLH1, and
SBRLL1), two are used for data formatting, control, and status functions (SCON1, SMOD1), and one is
used to send and receive data (SBUF1). The single SBUF1 location provides access to both the transmit
holding register and the receive FIFO. Writes to SBUF1 always access the Transmit Holding Register.
Reads of SBUF1 always access the first byte of the Receive FIFO; it is not possible to read data
from the Transmit Holding Register.
With UART1 interrupts enabled, an interrupt is generated each time a transmit is completed (TI1 is set in
SCON1), or a data byte has been received (RI1 is set in SCON1). The UART1 interrupt flags are not
cleared by hardware when the CPU vectors to the interrupt service routine. They must be cleared manually
by software, allowing software to determine the cause of the UART1 interrupt (transmit complete or receive
complete). Note that if additional bytes are available in the Receive FIFO, the RI1 bit cannot be cleared by
software.
Timer (16-bit)
EN
Overflow
Pre-Scaler
(1, 4, 12, 48)
SMOD1
TX
Logic
TX1
TX Holding
Register
Write to SBUF1
SBUF1
SBCON1
Control / Status
SCON1
OVR1
PERR1
THRE1
REN1
TBX1
RBX1
TI1
RI1
SB1RUN
SYSCLK
SBRLL1
SB1PS1
SB1PS0
SBRLH1
Data Formatting
MCE1
S1PT1
S1PT0
PE1
S1DL1
S1DL0
XBE1
SBL1
Baud Rate Generator
Read of SBUF1
RX FIFO
(3 Deep)
RX
Logic
RX1
UART1
Interrupt
Figure 19.1. UART1 Block Diagram
Rev. 1.3
213
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
19.1. Baud Rate Generator
The UART1 baud rate is generated by a dedicated 16-bit timer which runs from the controller’s core clock
(SYSCLK), and has prescaler options of 1, 4, 12, or 48. The timer and prescaler options combined allow
for a wide selection of baud rates over many SYSCLK frequencies.
The baud rate generator is configured using three registers: SBCON1, SBRLH1, and SBRLL1. The
UART1 Baud Rate Generator Control Register (SBCON1, SFR Definition 19.4) enables or disables the
baud rate generator, and selects the prescaler value for the timer. The baud rate generator must be
enabled for UART1 to function. Registers SBRLH1 and SBRLL1 contain a 16-bit reload value for the dedicated 16-bit timer. The internal timer counts up from the reload value on every clock tick. On timer overflows (0xFFFF to 0x0000), the timer is reloaded. For reliable UART operation, it is recommended that the
UART baud rate is not configured for baud rates faster than SYSCLK/16. The baud rate for UART1 is
defined in Equation 19.1.
SYSCLK
1
1
Baud Rate = ---------------------------------------------------------------------------  ---  --------------------- 65536 – (SBRLH1:SBRLL1)  2 Prescaler
Equation 19.1. UART1 Baud Rate
A quick reference for typical baud rates and system clock frequencies is given in Table 19.1.
SYSCLK = 48 MHz
SYSCLK = 24 MHz
SYSCLK = 12 MHz
Table 19.1. Baud Rate Generator Settings for Standard Baud Rates
214
Target Baud
Rate (bps)
Actual Baud
Rate (bps)
Baud Rate
Error
230400
115200
57600
28800
14400
9600
2400
1200
230400
115200
57600
28800
14400
9600
2400
1200
230400
115200
57600
28800
14400
9600
2400
1200
230769
115385
57692
28846
14388
9600
2400
1200
230769
115385
57692
28777
14406
9600
2400
1200
230769
115385
57554
28812
14397
9600
2400
1200
0.16%
0.16%
0.16%
0.16%
0.08%
0.0%
0.0%
0.0%
0.16%
0.16%
0.16%
0.08%
0.04%
0.0%
0.0%
0.0%
0.16%
0.16%
0.08%
0.04%
0.02%
0.0%
0.0%
0.0%
Oscillator
Divide
Factor
52
104
208
416
834
1250
5000
10000
104
208
416
834
1666
2500
10000
20000
208
416
834
1666
3334
5000
20000
40000
Rev. 1.3
SB1PS[1:0]
(Prescaler Bits)
Reload Value in
SBRLH1:SBRLL1
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
11
0xFFE6
0xFFCC
0xFF98
0xFF30
0xFE5F
0xFD8F
0xF63C
0xEC78
0xFFCC
0xFF98
0xFF30
0xFE5F
0xFCBF
0xFB1E
0xEC78
0xD8F0
0xFF98
0xFF30
0xFE5F
0xFCBF
0xF97D
0xF63C
0xD8F0
0xB1E0
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
19.2. Data Format
UART1 has a number of available options for data formatting. Data transfers begin with a start bit (logic
low), followed by the data bits (sent LSB-first), a parity or extra bit (if selected), and end with one or two
stop bits (logic high). The data length is variable between 5 and 8 bits. A parity bit can be appended to the
data, and automatically generated and detected by hardware for even, odd, mark, or space parity. The stop
bit length is selectable between short (1 bit time) and long (1.5 or 2 bit times), and a multi-processor communication mode is available for implementing networked UART buses. All of the data formatting options
can be configured using the SMOD1 register, shown in SFR Definition 19.2. Figure 19.2 shows the timing
for a UART1 transaction without parity or an extra bit enabled. Figure 19.3 shows the timing for a UART1
transaction with parity enabled (PE1 = 1). Figure 19.4 is an example of a UART1 transaction when the
extra bit is enabled (XBE1 = 1). Note that the extra bit feature is not available when parity is enabled, and
the second stop bit is only an option for data lengths of 6, 7, or 8 bits.
MARK
START
BIT
SPACE
D0
D1
DN-2
STOP
BIT 1
DN-1
STOP
BIT 2
BIT TIMES
Optional
N bits; N = 5, 6, 7, or 8
Figure 19.2. UART1 Timing Without Parity or Extra Bit
MARK
SPACE
START
BIT
D0
D1
DN-2
DN-1
PARITY
STOP
BIT 1
STOP
BIT 2
BIT TIMES
Optional
N bits; N = 5, 6, 7, or 8
Figure 19.3. UART1 Timing With Parity
MARK
SPACE
START
BIT
D0
D1
DN-2
DN-1
EXTRA
STOP
BIT 1
STOP
BIT 2
BIT TIMES
Optional
N bits; N = 5, 6, 7, or 8
Figure 19.4. UART1 Timing With Extra Bit
Rev. 1.3
215
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
19.3. Configuration and Operation
UART1 provides standard asynchronous, full duplex communication. It can operate in a point-to-point
serial communications application, or as a node on a multi-processor serial interface. To operate in a
point-to-point application, where there are only two devices on the serial bus, the MCE1 bit in SMOD1
should be cleared to ‘0’. For operation as part of a multi-processor communications bus, the MCE1 and
XBE1 bits should both be set to ‘1’. In both types of applications, data is transmitted from the microcontroller on the TX1 pin, and received on the RX1 pin. The TX1 and RX1 pins are configured using the crossbar and the Port I/O registers, as detailed in Section “15. Port Input/Output” on page 142.
In typical UART communications, The transmit (TX) output of one device is connected to the receive (RX)
input of the other device, either directly or through a bus transceiver, as shown in Figure 19.5.
PC
COM Port
RS-232
RS-232
LEVEL
TRANSLATOR
TX
RX
C8051Fxxx
OR
TX
TX
RX
RX
MCU
C8051Fxxx
Figure 19.5. Typical UART Interconnect Diagram
19.3.1. Data Transmission
Data transmission is double-buffered, and begins when software writes a data byte to the SBUF1 register.
Writing to SBUF1 places data in the Transmit Holding Register, and the Transmit Holding Register Empty
flag (THRE1) will be cleared to ‘0’. If the UARTs shift register is empty (i.e., no transmission is in progress)
the data will be placed in the shift register, and the THRE1 bit will be set to ‘1’. If a transmission is in progress, the data will remain in the Transmit Holding Register until the current transmission is complete. The
TI1 Transmit Interrupt Flag (SCON1.1) will be set at the end of any transmission (the beginning of the
stop-bit time). If enabled, an interrupt will occur when TI1 is set.
If the extra bit function is enabled (XBE1 = ‘1’) and the parity function is disabled (PE1 = ‘0’), the value of
the TBX1 (SCON1.3) bit will be sent in the extra bit position. When the parity function is enabled (PE1 =
‘1’), hardware will generate the parity bit according to the selected parity type (selected with S1PT[1:0]),
and append it to the data field. Note: when parity is enabled, the extra bit function is not available.
19.3.2. Data Reception
Data reception can begin any time after the REN1 Receive Enable bit (SCON1.4) is set to logic 1. After the
stop bit is received, the data byte will be stored in the receive FIFO if the following conditions are met: the
receive FIFO (3 bytes deep) must not be full, and the stop bit(s) must be logic 1. In the event that the
receive FIFO is full, the incoming byte will be lost, and a Receive FIFO Overrun Error will be generated
(OVR1 in register SCON1 will be set to logic 1). If the stop bit(s) were logic 0, the incoming data will not be
stored in the receive FIFO. If the reception conditions are met, the data is stored in the receive FIFO, and
the RI1 flag will be set. Note: when MCE1 = ‘1’, RI1 will only be set if the extra bit was equal to ‘1’. Data can
be read from the receive FIFO by reading the SBUF1 register. The SBUF1 register represents the oldest
byte in the FIFO. After SBUF1 is read, the next byte in the FIFO is immediately loaded into SBUF1, and
216
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
space is made available in the FIFO for another incoming byte. If enabled, an interrupt will occur when RI1
is set. RI1 can only be cleared to '0' by software when there is no more information in the FIFO. The recommended procedure to empty the FIFO contents is as follows:
1. Clear RI1 to '0'.
2. Read SBUF1.
3. Check RI1, and repeat at step 1 if RI1 is set to '1'.
If the extra bit function is enabled (XBE1 = ‘1’) and the parity function is disabled (PE1 = ‘0’), the extra bit
for the oldest byte in the FIFO can be read from the RBX1 bit (SCON1.2). If the extra bit function is not
enabled, the value of the stop bit for the oldest FIFO byte will be presented in RBX1. When the parity function is enabled (PE1 = ‘1’), hardware will check the received parity bit against the selected parity type
(selected with S1PT[1:0]) when receiving data. If a byte with parity error is received, the PERR1 flag will be
set to ‘1’. This flag must be cleared by software. Note: when parity is enabled, the extra bit function is not
available.
19.3.3. Multiprocessor Communications
UART1 supports multiprocessor communication between a master processor and one or more slave processors by special use of the extra data bit. When a master processor wants to transmit to one or more
slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte in that
its extra bit is logic 1; in a data byte, the extra bit is always set to logic 0.
Setting the MCE1 bit (SMOD1.7) of a slave processor configures its UART such that when a stop bit is
received, the UART will generate an interrupt only if the extra bit is logic 1 (RBX1 = 1) signifying an
address byte has been received. In the UART interrupt handler, software will compare the received
address with the slave's own assigned address. If the addresses match, the slave will clear its MCE1 bit to
enable interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave their
MCE1 bits set and do not generate interrupts on the reception of the following data bytes, thereby ignoring
the data. Once the entire message is received, the addressed slave resets its MCE1 bit to ignore all transmissions until it receives the next address byte.
Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple
slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master
processor can be configured to receive all transmissions or a protocol can be implemented such that the
master/slave role is temporarily reversed to enable half-duplex transmission between the original master
and slave(s).
Master
Device
Slave
Device
Slave
Device
Slave
Device
V+
RX
TX
RX
TX
RX
Rev. 1.3
TX
RX
TX
217
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Figure 19.6. UART Multi-Processor Mode Interconnect Diagram
SFR Definition 19.1. SCON1: UART1 Control
R/W
R/W
R
R/W
R/W
R/W
R/W
R/W
Reset Value
OVR1
PERR1
THRE1
REN1
TBX1
RBX1
TI1
RI1
00100000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xD2
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
218
OVR1: Receive FIFO Overrun Flag.
This bit is used to indicate a receive FIFO overrun condition.
0: Receive FIFO Overrun has not occurred.
1: Receive FIFO Overrun has occurred (an incoming character was discarded due to a full
FIFO).
This bit must be cleared to ‘0’ by software.
PERR1: Parity Error Flag.
When parity is enabled, this bit is used to indicate that a parity error has occurred. It is set to
‘1’ when the parity of the oldest byte in the FIFO does not match the selected Parity Type.
0: Parity Error has not occurred.
1: Parity Error has occurred.
This bit must be cleared to ‘0’ by software.
THRE1: Transmit Holding Register Empty Flag.
0: Transmit Holding Register not Empty - do not write to SBUF1.
1: Transmit Holding Register Empty - it is safe to write to SBUF1.
REN1: Receive Enable.
This bit enables/disables the UART receiver. When disabled, bytes can still be read from the
receive FIFO.
0: UART1 reception disabled.
1: UART1 reception enabled.
TBX1: Extra Transmission Bit.
The logic level of this bit will be assigned to the extra transmission bit when XBE1 is set to
‘1’. This bit is not used when Parity is enabled.
RBX1: Extra Receive Bit.
RBX1 is assigned the value of the extra bit when XBE1 is set to ‘1’. If XBE1 is cleared to ‘0’,
RBX1 will be assigned the logic level of the first stop bit. This bit is not valid when Parity is
enabled.
TI1: Transmit Interrupt Flag.
Set to a ‘1’ by hardware after data has been transmitted, at the beginning of the STOP bit.
When the UART1 interrupt is enabled, setting this bit causes the CPU to vector to the
UART1 interrupt service routine. This bit must be cleared manually by software.
RI1: Receive Interrupt Flag.
Set to ‘1’ by hardware when a byte of data has been received by UART1 (set at the STOP bit
sampling time). When the UART1 interrupt is enabled, setting this bit to ‘1’ causes the CPU
to vector to the UART1 interrupt service routine. This bit must be cleared manually by software. Note that RI1 will remain set to '1' as long as there is still data in the UART FIFO. After
the last byte has been shifted from the FIFO to SBUF1, RI1 can be cleared.
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 19.2. SMOD1: UART1 Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
MCE1
S1PT1
S1PT0
PE1
S1DL1
S1DL0
XBE1
SBL1
00001100
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xE5
Bit7:
MCE1: Multiprocessor Communication Enable.
0: RI will be activated if stop bit(s) are ‘1’.
1: RI will be activated if stop bit(s) and extra bit are ‘1’ (extra bit must be enabled using
XBE1).
Note: This function is not available when hardware parity is enabled.
Bits6–5: S1PT[1:0]: Parity Type.
00: Odd
01: Even
10: Mark
11: Space
Bit4:
PE1: Parity Enable.
This bit activates hardware parity generation and checking. The parity type is selected by
bits S1PT1-0 when parity is enabled.
0: Hardware parity is disabled.
1: Hardware parity is enabled.
Bits3–2: S1DL[1:0]: Data Length.
00: 5-bit data
01: 6-bit data
10: 7-bit data
11: 8-bit data
Bit1:
XBE1: Extra Bit Enable
When enabled, the value of TBX1 will be appended to the data field.
0: Extra Bit Disabled.
1: Extra Bit Enabled.
Bit0:
SBL1: Stop Bit Length
0: Short - Stop bit is active for one bit time.
1: Long - Stop bit is active for two bit times (data length = 6, 7, or 8 bits), or 1.5 bit times
(data length = 5 bits).
Rev. 1.3
219
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 19.3. SBUF1: UART1 Data Buffer
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0xD3
Bits7–0: SBUF1[7:0]: Serial Data Buffer Bits 7–0 (MSB-LSB)
This SFR is used to both send data from the UART and to read received data from the
UART1 receive FIFO.
Write: Writing a byte to SBUF1 initiates the transmission. When data is written to SBUF1, it
first goes to the Transmit Holding Register, where it is held for serial transmission. When the
transmit shift register is available, data is transferred into the shift register, and SBUF1 may
be written again.
Read: Reading SBUF1 retrieves data from the receive FIFO. When read, the oldest byte in
the receive FIFO is returned, and removed from the FIFO. Up to three bytes may be held in
the FIFO. If there are additional bytes available in the FIFO, the RI1 bit will remain at logic
‘1’, even after being cleared by software.
SFR Definition 19.4. SBCON1: UART1 Baud Rate Generator Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reserved SB1RUN Reserved Reserved Reserved Reserved SB1PS1
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
SB1PS0
00000000
Bit0
SFR Address: 0xAC
Bit7:
Bit6:
RESERVED: Read = 0b; Must write 0b.
SB1RUN: Baud Rate Generator Enable.
0: Baud Rate Generator is disabled. UART1 will not function.
1: Baud Rate Generator is enabled.
Bits5–2: RESERVED: Read = 0000b; Must write 0000b.
Bits1–0: SB1PS[1:0]: Baud Rate Prescaler Select.
00: Prescaler = 12
01: Prescaler = 4
10: Prescaler = 48
11: Prescaler = 1
220
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 19.5. SBRLH1: UART1 Baud Rate Generator High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0xB5
Bits7–0: SBRLH1[7:0]: High Byte of reload value for UART1 Baud Rate Generator.
SFR Definition 19.6. SBRLL1: UART1 Baud Rate Generator Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0xB4
Bits7–0: SBRLL1[7:0]: Low Byte of reload value for UART1 Baud Rate Generator.
Rev. 1.3
221
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
20. Enhanced Serial Peripheral Interface (SPI0)
The Enhanced Serial Peripheral Interface (SPI0) provides access to a flexible, full-duplex synchronous
serial bus. SPI0 can operate as a master or slave device in both 3-wire or 4-wire modes, and supports multiple masters and slaves on a single SPI bus. The slave-select (NSS) signal can be configured as an input
to select SPI0 in slave mode, or to disable Master Mode operation in a multi-master environment, avoiding
contention on the SPI bus when more than one master attempts simultaneous data transfers. NSS can
also be configured as a chip-select output in master mode, or disabled for 3-wire operation. Additional general purpose port I/O pins can be used to select multiple slave devices in master mode.
SFR Bus
SYSCLK
SPI0CN
SPIF
WCOL
MODF
RXOVRN
NSSMD1
NSSMD0
TXBMT
SPIEN
SPI0CFG
SPIBSY
MSTEN
CKPHA
CKPOL
SLVSEL
NSSIN
SRMT
RXBMT
SCR7
SCR6
SCR5
SCR4
SCR3
SCR2
SCR1
SCR0
SPI0CKR
Clock Divide
Logic
SPI CONTROL LOGIC
Data Path
Control
SPI IRQ
Pin Interface
Control
MOSI
Tx Data
SPI0DAT
SCK
Transmit Data Buffer
Shift Register
Rx Data
7 6 5 4 3 2 1 0
Receive Data Buffer
Pin
Control
Logic
MISO
NSS
Read
SPI0DAT
Write
SPI0DAT
SFR Bus
Figure 20.1. SPI Block Diagram
222
Rev. 1.3
C
R
O
S
S
B
A
R
Port I/O
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
20.1. Signal Descriptions
The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below.
20.1.1. Master Out, Slave In (MOSI)
The master-out, slave-in (MOSI) signal is an output from a master device and an input to slave devices. It
is used to serially transfer data from the master to the slave. This signal is an output when SPI0 is operating as a master and an input when SPI0 is operating as a slave. Data is transferred most-significant bit
first. When configured as a master, MOSI is driven by the MSB of the shift register in both 3- and 4-wire
mode.
20.1.2. Master In, Slave Out (MISO)
The master-in, slave-out (MISO) signal is an output from a slave device and an input to the master device.
It is used to serially transfer data from the slave to the master. This signal is an input when SPI0 is operating as a master and an output when SPI0 is operating as a slave. Data is transferred most-significant bit
first. The MISO pin is placed in a high-impedance state when the SPI module is disabled and when the SPI
operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is
always driven by the MSB of the shift register.
20.1.3. Serial Clock (SCK)
The serial clock (SCK) signal is an output from the master device and an input to slave devices. It is used
to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPI0 generates this signal when operating as a master. The SCK signal is ignored by a SPI slave when the slave is
not selected (NSS = 1) in 4-wire slave mode.
20.1.4. Slave Select (NSS)
The function of the slave-select (NSS) signal is dependent on the setting of the NSSMD1 and NSSMD0
bits in the SPI0CN register. There are three possible modes that can be selected with these bits:
1. NSSMD[1:0] = 00: 3-Wire Master or 3-Wire Slave Mode: SPI0 operates in 3-wire mode, and
NSS is disabled. When operating as a slave device, SPI0 is always selected in 3-wire mode.
Since no select signal is present, SPI0 must be the only slave on the bus in 3-wire mode. This
is intended for point-to-point communication between a master and one slave.
2. NSSMD[1:0] = 01: 4-Wire Slave or Multi-Master Mode: SPI0 operates in 4-wire mode, and
NSS is enabled as an input. When operating as a slave, NSS selects the SPI0 device. When
operating as a master, a 1-to-0 transition of the NSS signal disables the master function of
SPI0 so that multiple master devices can be used on the same SPI bus.
3. NSSMD[1:0] = 1x: 4-Wire Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as
an output. The setting of NSSMD0 determines what logic level the NSS pin will output. This
configuration should only be used when operating SPI0 as a master device.
See Figure 20.2, Figure 20.3, and Figure 20.4 for typical connection diagrams of the various operational
modes. Note that the setting of NSSMD bits affects the pinout of the device. When in 3-wire master or
3-wire slave mode, the NSS pin will not be mapped by the crossbar. In all other modes, the NSS signal will
be mapped to a pin on the device. See Section “15. Port Input/Output” on page 142 for general purpose
port I/O and crossbar information.
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20.2. SPI0 Master Mode Operation
A SPI master device initiates all data transfers on a SPI bus. SPI0 is placed in master mode by setting the
Master Enable flag (MSTEN, SPI0CFG.6). Writing a byte of data to the SPI0 data register (SPI0DAT) when
in master mode writes to the transmit buffer. If the SPI shift register is empty, the byte in the transmit buffer
is moved to the shift register, and a data transfer begins. The SPI0 master immediately shifts out the data
serially on the MOSI line while providing the serial clock on SCK. The SPIF (SPI0CN.7) flag is set to logic
1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag
is set. While the SPI0 master transfers data to a slave on the MOSI line, the addressed SPI slave device
simultaneously transfers the contents of its shift register to the SPI master on the MISO line in a full-duplex
operation. Therefore, the SPIF flag serves as both a transmit-complete and receive-data-ready flag. The
data byte received from the slave is transferred MSB-first into the master's shift register. When a byte is
fully shifted into the register, it is moved to the receive buffer where it can be read by the processor by
reading SPI0DAT.
When configured as a master, SPI0 can operate in one of three different modes: multi-master mode, 3-wire
single-master mode, and 4-wire single-master mode. The default, multi-master mode is active when
NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In this mode, NSS is an input to the device, and
is used to disable the master SPI0 when another master is accessing the bus. When NSS is pulled low in
this mode, MSTEN (SPI0CFG.6) and SPIEN (SPI0CN.0) are set to 0 to disable the SPI master device, and
a Mode Fault is generated (MODF, SPI0CN.5 = 1). Mode Fault will generate an interrupt if enabled. SPI0
must be manually re-enabled in software under these circumstances. In multi-master systems, devices will
typically default to being slave devices while they are not acting as the system master device. In multi-master mode, slave devices can be addressed individually (if needed) using general-purpose I/O pins.
Figure 20.2 shows a connection diagram between two master devices in multiple-master mode.
3-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. In this
mode, NSS is not used, and is not mapped to an external port pin through the crossbar. Any slave devices
that must be addressed in this mode should be selected using general-purpose I/O pins. Figure 20.3
shows a connection diagram between a master device in 3-wire master mode and a slave device.
4-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 1. In this mode, NSS is configured as an
output pin, and can be used as a slave-select signal for a single SPI device. In this mode, the output value
of NSS is controlled (in software) with the bit NSSMD0 (SPI0CN.2). Additional slave devices can be
addressed using general-purpose I/O pins. Figure 20.4 shows a connection diagram for a master device in
4-wire master mode and two slave devices.
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Master
Device 1
NSS
GPIO
MISO
MISO
MOSI
MOSI
SCK
SCK
GPIO
NSS
Master
Device 2
Figure 20.2. Multiple-Master Mode Connection Diagram
Master
Device
MISO
MISO
MOSI
MOSI
SCK
SCK
Slave
Device
Figure 20.3. 3-Wire Single Master and Slave Mode Connection Diagram
Master
Device
GPIO
MISO
MISO
MOSI
MOSI
SCK
SCK
NSS
NSS
MISO
MOSI
Slave
Device
Slave
Device
SCK
NSS
Figure 20.4. 4-Wire Single Master Mode and Slave Mode Connection Diagram
Rev. 1.3
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20.3. SPI0 Slave Mode Operation
When SPI0 is enabled and not configured as a master, it will operate as a SPI slave. As a slave, bytes are
shifted in through the MOSI pin and out through the MISO pin by a master device controlling the SCK signal. A bit counter in the SPI0 logic counts SCK edges. When 8 bits have been shifted through the shift register, the SPIF flag is set to logic 1, and the byte is copied into the receive buffer. Data is read from the
receive buffer by reading SPI0DAT. A slave device cannot initiate transfers. Data to be transferred to the
master device is pre-loaded into the shift register by writing to SPI0DAT. Writes to SPI0DAT are double-buffered, and are placed in the transmit buffer first. If the shift register is empty, the contents of the
transmit buffer will immediately be transferred into the shift register. When the shift register already contains data, the SPI will load the shift register with the transmit buffer’s contents after the last SCK edge of
the next (or current) SPI transfer.
When configured as a slave, SPI0 can be configured for 4-wire or 3-wire operation. The default, 4-wire
slave mode, is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In 4-wire mode, the
NSS signal is routed to a port pin and configured as a digital input. SPI0 is enabled when NSS is logic 0,
and disabled when NSS is logic 1. The bit counter is reset on a falling edge of NSS. Note that the NSS signal must be driven low at least 2 system clocks before the first active edge of SCK for each byte transfer.
Figure 20.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master
device.
3-wire slave mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. NSS is not
used in this mode, and is not mapped to an external port pin through the crossbar. Since there is no way of
uniquely addressing the device in 3-wire slave mode, SPI0 must be the only slave device present on the
bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter
that determines when a full byte has been received. The bit counter can only be reset by disabling and
re-enabling SPI0 with the SPIEN bit. Figure 20.3 shows a connection diagram between a slave device in
3-wire slave mode and a master device.
20.4. SPI0 Interrupt Sources
When SPI0 interrupts are enabled, the following four flags will generate an interrupt when they are set to
logic 1:
Note that all of the following bits must be cleared by software.
1. The SPI Interrupt Flag, SPIF (SPI0CN.7) is set to logic 1 at the end of each byte transfer. This
flag can occur in all SPI0 modes.
2. The Write Collision Flag, WCOL (SPI0CN.6) is set to logic 1 if a write to SPI0DAT is attempted
when the transmit buffer has not been emptied to the SPI shift register. When this occurs, the
write to SPI0DAT will be ignored, and the transmit buffer will not be written.This flag can occur
in all SPI0 modes.
3. The Mode Fault Flag MODF (SPI0CN.5) is set to logic 1 when SPI0 is configured as a master,
and for multi-master mode and the NSS pin is pulled low. When a Mode Fault occurs, the
MSTEN and SPIEN bits in SPI0CN are set to logic 0 to disable SPI0 and allow another master
device to access the bus.
4. The Receive Overrun Flag RXOVRN (SPI0CN.4) is set to logic 1 when configured as a slave,
and a transfer is completed and the receive buffer still holds an unread byte from a previous
transfer. The new byte is not transferred to the receive buffer, allowing the previously received
data byte to be read. The data byte which caused the overrun is lost.
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20.5. Serial Clock Timing
Four combinations of serial clock phase and polarity can be selected using the clock control bits in the
SPI0 Configuration Register (SPI0CFG). The CKPHA bit (SPI0CFG.5) selects one of two clock phases
(edge used to latch the data). The CKPOL bit (SPI0CFG.4) selects between an active-high or active-low
clock. Both master and slave devices must be configured to use the same clock phase and polarity. SPI0
should be disabled (by clearing the SPIEN bit, SPI0CN.0) when changing the clock phase or polarity. The
clock and data line relationships for master mode are shown in Figure 20.5. For slave mode, the clock and
data relationships are shown in Figure 20.6 and Figure 20.7.
The SPI0 Clock Rate Register (SPI0CKR) as shown in SFR Definition 20.3 controls the master mode
serial clock frequency. This register is ignored when operating in slave mode. When the SPI is configured
as a master, the maximum data transfer rate (bits/sec) is one-half the system clock frequency or 12.5 MHz,
whichever is slower. When the SPI is configured as a slave, the maximum data transfer rate (bits/sec) for
full-duplex operation is 1/10 the system clock frequency, provided that the master issues SCK, NSS (in
4-wire slave mode), and the serial input data synchronously with the slave’s system clock. If the master
issues SCK, NSS, and the serial input data asynchronously, the maximum data transfer rate (bits/sec)
must be less than 1/10 the system clock frequency. In the special case where the master only wants to
transmit data to the slave and does not need to receive data from the slave (i.e. half-duplex operation), the
SPI slave can receive data at a maximum data transfer rate (bits/sec) of 1/4 the system clock frequency.
This is provided that the master issues SCK, NSS, and the serial input data synchronously with the slave’s
system clock.
SCK
(CKPOL=0, CKPHA=0)
SCK
(CKPOL=0, CKPHA=1)
SCK
(CKPOL=1, CKPHA=0)
SCK
(CKPOL=1, CKPHA=1)
MISO/MOSI
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
NSS (Must Remain High
in Multi-Master Mode)
Figure 20.5. Master Mode Data/Clock Timing
Rev. 1.3
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SCK
(CKPOL=0, CKPHA=0)
SCK
(CKPOL=1, CKPHA=0)
MOSI
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
MISO
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
NSS (4-Wire Mode)
Figure 20.6. Slave Mode Data/Clock Timing (CKPHA = 0)
SCK
(CKPOL=0, CKPHA=1)
SCK
(CKPOL=1, CKPHA=1)
MOSI
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
MISO
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
NSS (4-Wire Mode)
Figure 20.7. Slave Mode Data/Clock Timing (CKPHA = 1)
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Bit 0
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20.6. SPI Special Function Registers
SPI0 is accessed and controlled through four special function registers in the system controller: SPI0CN
Control Register, SPI0DAT Data Register, SPI0CFG Configuration Register, and SPI0CKR Clock Rate
Register. The four special function registers related to the operation of the SPI0 Bus are described in the
following figures.
SFR Definition 20.1. SPI0CFG: SPI0 Configuration
R
R/W
R/W
R/W
R
R
R
R
Reset Value
SPIBSY
MSTEN
CKPHA
CKPOL
SLVSEL
NSSIN
SRMT
RXBMT
00000111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit 7:
Bit 6:
Bit 5:
Bit 4:
Bit 3:
Bit 2:
Bit 1:
Bit 0:
Bit0
SFR Address: 0xA1
SPIBSY: SPI Busy (read only).
This bit is set to logic 1 when a SPI transfer is in progress (Master or slave Mode).
MSTEN: Master Mode Enable.
0: Disable master mode. Operate in slave mode.
1: Enable master mode. Operate as a master.
CKPHA: SPI0 Clock Phase.
This bit controls the SPI0 clock phase.
0: Data centered on first edge of SCK period.*
1: Data centered on second edge of SCK period.*
CKPOL: SPI0 Clock Polarity.
This bit controls the SPI0 clock polarity.
0: SCK line low in idle state.
1: SCK line high in idle state.
SLVSEL: Slave Selected Flag (read only).
This bit is set to logic 1 whenever the NSS pin is low indicating SPI0 is the selected slave. It
is cleared to logic 0 when NSS is high (slave not selected). This bit does not indicate the
instantaneous value at the NSS pin, but rather a de-glitched version of the pin input.
NSSIN: NSS Instantaneous Pin Input (read only).
This bit mimics the instantaneous value that is present on the NSS port pin at the time that
the register is read. This input is not de-glitched.
SRMT: Shift Register Empty (Valid in Slave Mode, read only).
This bit will be set to logic 1 when all data has been transferred in/out of the shift register,
and there is no new information available to read from the transmit buffer or write to the
receive buffer. It returns to logic 0 when a data byte is transferred to the shift register from
the transmit buffer or by a transition on SCK.
NOTE: SRMT = 1 when in Master Mode.
RXBMT: Receive Buffer Empty (Valid in Slave Mode, read only).
This bit will be set to logic 1 when the receive buffer has been read and contains no new
information. If there is new information available in the receive buffer that has not been read,
this bit will return to logic 0.
NOTE: RXBMT = 1 when in Master Mode.
*Note: In slave mode, data on MOSI is sampled in the center of each data bit. In master mode, data on MISO is
sampled one SYSCLK before the end of each data bit, to provide maximum settling time for the slave device.
See Table 20.1 for timing parameters.
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SFR Definition 20.2. SPI0CN: SPI0 Control
R/W
R/W
R/W
SPIF
WCOL
MODF
Bit7
Bit6
Bit5
R/W
R/W
R/W
RXOVRN NSSMD1 NSSMD0
Bit4
Bit3
Bit 7:
Bit2
R
R/W
Reset Value
TXBMT
SPIEN
00000110
Bit1
Bit
Addressable
SFR Address: 0xF8
Bit0
SPIF: SPI0 Interrupt Flag.
This bit is set to logic 1 by hardware at the end of a data transfer. If interrupts are enabled,
setting this bit causes the CPU to vector to the SPI0 interrupt service routine. This bit is not
automatically cleared by hardware. It must be cleared by software.
Bit 6:
WCOL: Write Collision Flag.
This bit is set to logic 1 if a write to SPI0DAT is attempted when the transmit buffer has not
been emptied to the SPI shift register. When this occurs, the write to SPI0DAT will be
ignored, and the transmit buffer will not be written. This flag can occur in all SPI0 modes. It
must be cleared by software.
Bit 5:
MODF: Mode Fault Flag.
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when a master mode
collision is detected (NSS is low, MSTEN = 1, and NSSMD[1:0] = 01). This bit is not automatically cleared by hardware. It must be cleared by software.
Bit 4:
RXOVRN: Receive Overrun Flag (Slave Mode only).
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when the receive buffer still holds unread data from a previous transfer and the last bit of the current transfer is
shifted into the SPI0 shift register. This bit is not automatically cleared by hardware. It must
be cleared by software.
Bits 3–2: NSSMD1–NSSMD0: Slave Select Mode.
Selects between the following NSS operation modes:
(See Section “20.2. SPI0 Master Mode Operation” on page 224 and Section “20.3. SPI0
Slave Mode Operation” on page 226).
00: 3-Wire Slave or 3-wire Master Mode. NSS signal is not routed to a port pin.
01: 4-Wire Slave or Multi-Master Mode (Default). NSS is always an input to the device.
1x: 4-Wire Single-Master Mode. NSS signal is mapped as an output from the device and will
assume the value of NSSMD0.
Bit 1:
TXBMT: Transmit Buffer Empty.
This bit will be set to logic 0 when new data has been written to the transmit buffer. When
data in the transmit buffer is transferred to the SPI shift register, this bit will be set to logic 1,
indicating that it is safe to write a new byte to the transmit buffer.
Bit 0:
SPIEN: SPI0 Enable.
This bit enables/disables the SPI.
0: SPI disabled.
1: SPI enabled.
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SFR Definition 20.3. SPI0CKR: SPI0 Clock Rate
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
SCR7
SCR6
SCR5
SCR4
SCR3
SCR2
SCR1
SCR0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xA2
Bits 7–0: SCR7–SCR0: SPI0 Clock Rate.
These bits determine the frequency of the SCK output when the SPI0 module is configured
for master mode operation. The SCK clock frequency is a divided version of the system
clock, and is given in the following equation, where SYSCLK is the system clock frequency
and SPI0CKR is the 8-bit value held in the SPI0CKR register.
SYSCLK
f SCK = ------------------------------------------------2   SPI0CKR + 1 
for 0 <= SPI0CKR <= 255
Example: If SYSCLK = 2 MHz and SPI0CKR = 0x04,
2000000
f SCK = -------------------------2  4 + 1
f SCK = 200kHz
SFR Definition 20.4. SPI0DAT: SPI0 Data
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
00000000
Bit0
SFR Address: 0xA3
Bits 7–0: SPI0DAT: SPI0 Transmit and Receive Data.
The SPI0DAT register is used to transmit and receive SPI0 data. Writing data to SPI0DAT
places the data into the transmit buffer and initiates a transfer when in Master Mode. A read
of SPI0DAT returns the contents of the receive buffer.
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SCK*
T
T
MCKH
MCKL
T
T
MIS
MIH
MISO
MOSI
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 20.8. SPI Master Timing (CKPHA = 0)
SCK*
T
T
MCKH
MCKL
T
T
MIS
MIH
MISO
MOSI
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 20.9. SPI Master Timing (CKPHA = 1)
232
Rev. 1.3
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NSS
T
T
SE
T
CKL
SD
SCK*
T
CKH
T
SIS
T
SIH
MOSI
T
T
SEZ
T
SOH
SDZ
MISO
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 20.10. SPI Slave Timing (CKPHA = 0)
NSS
T
T
SE
T
CKL
SD
SCK*
T
CKH
T
SIS
T
SIH
MOSI
T
SEZ
T
T
SOH
SLH
T
SDZ
MISO
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 20.11. SPI Slave Timing (CKPHA = 1)
Rev. 1.3
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Table 20.1. SPI Slave Timing Parameters
Parameter
Description
Min
Max
Units
Master Mode Timing* (See Figure 20.8 and Figure 20.9)
TMCKH
SCK High Time
1 x TSYSCLK
ns
TMCKL
SCK Low Time
1 x TSYSCLK
ns
1 x TSYSCLK + 20
ns
0
ns
TMIS
MISO Valid to SCK Shift Edge
TMIH
SCK Shift Edge to MISO Change
Slave Mode Timing* (See Figure 20.10 and Figure 20.11)
TSE
NSS Falling to First SCK Edge
2 x TSYSCLK
ns
TSD
Last SCK Edge to NSS Rising
2 x TSYSCLK
ns
TSEZ
NSS Falling to MISO Valid
4 x TSYSCLK
ns
TSDZ
NSS Rising to MISO High-Z
4 x TSYSCLK
ns
TCKH
SCK High Time
5 x TSYSCLK
ns
TCKL
SCK Low Time
5 x TSYSCLK
ns
TSIS
MOSI Valid to SCK Sample Edge
2 x TSYSCLK
ns
TSIH
SCK Sample Edge to MOSI Change
2 x TSYSCLK
ns
TSOH
SCK Shift Edge to MISO Change
TSLH
Last SCK Edge to MISO Change (CKPHA = 1
ONLY)
6 x TSYSCLK
*Note: TSYSCLK is equal to one period of the device system clock (SYSCLK).
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4 x TSYSCLK
ns
8 x TSYSCLK
ns
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21. Timers
Each MCU includes four counter/timers: two are 16-bit counter/timers compatible with those found in the
standard 8051, and two are 16-bit auto-reload timer for use with the ADC, SMBus, USB (frame measurements), Low-Frequency Oscillator (period measurements), or for general purpose use. These timers can
be used to measure time intervals, count external events and generate periodic interrupt requests. Timer 0
and Timer 1 are nearly identical and have four primary modes of operation. Timer 2 and Timer 3 offer
16-bit and split 8-bit timer functionality with auto-reload.
Timer 0 and Timer 1 Modes:
13-bit counter/timer
16-bit counter/timer
8-bit counter/timer with auto-reload
Two 8-bit counter/timers (Timer 0 only)
Timer 2 Modes:
Timer 3 Modes:
16-bit timer with auto-reload
16-bit timer with auto-reload
Two 8-bit timers with
auto-reload
Two 8-bit timers with
auto-reload
Timers 0 and 1 may be clocked by one of five sources, determined by the Timer Mode Select bits
(T1M-T0M) and the Clock Scale bits (SCA1-SCA0). The Clock Scale bits define a pre-scaled clock from
which Timer 0 and/or Timer 1 may be clocked (See SFR Definition 21.3 for pre-scaled clock selection).
Timer 0/1 may then be configured to use this pre-scaled clock signal or the system clock. Timer 2 and
Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
clock source divided by 8.
Timer 0 and Timer 1 may also be operated as counters. When functioning as a counter, a counter/timer
register is incremented on each high-to-low transition at the selected input pin (T0 or T1). Events with a frequency of up to one-fourth the system clock's frequency can be counted. The input signal need not be periodic, but it should be held at a given level for at least two full system clock cycles to ensure the level is
properly sampled.
21.1. Timer 0 and Timer 1
Each timer is implemented as a 16-bit register accessed as two separate bytes: a low byte (TL0 or TL1)
and a high byte (TH0 or TH1). The Counter/Timer Control register (TCON) is used to enable Timer 0 and
Timer 1 as well as indicate status. Timer 0 interrupts can be enabled by setting the ET0 bit in the IE register
(Section “9.3.5. Interrupt Register Descriptions” on page 90); Timer 1 interrupts can be enabled by
setting the ET1 bit in the IE register (Section 9.3.5). Both counter/timers operate in one of four primary
modes selected by setting the Mode Select bits T1M1-T0M0 in the Counter/Timer Mode register (TMOD).
Each timer can be configured independently. Each operating mode is described below.
21.1.1. Mode 0: 13-bit Counter/Timer
Timer 0 and Timer 1 operate as 13-bit counter/timers in Mode 0. The following describes the configuration
and operation of Timer 0. However, both timers operate identically, and Timer 1 is configured in the same
manner as described for Timer 0.
The TH0 register holds the eight MSBs of the 13-bit counter/timer. TL0 holds the five LSBs in bit positions
TL0.4-TL0.0. The three upper bits of TL0 (TL0.7-TL0.5) are indeterminate and should be masked out or
ignored when reading. As the 13-bit timer register increments and overflows from 0x1FFF (all ones) to
0x0000, the timer overflow flag TF0 (TCON.5) is set and an interrupt will occur if Timer 0 interrupts are
enabled.
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C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
The C/T0 bit (TMOD.2) selects the counter/timer's clock source. When C/T0 is set to logic 1, high-to-low
transitions at the selected Timer 0 input pin (T0) increment the timer register (Refer to Section
“15.1. Priority Crossbar Decoder” on page 144 for information on selecting and configuring external I/O
pins). Clearing C/T selects the clock defined by the T0M bit (CKCON.3). When T0M is set, Timer 0 is
clocked by the system clock. When T0M is cleared, Timer 0 is clocked by the source selected by the Clock
Scale bits in CKCON (see SFR Definition 21.3).
Setting the TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or the input signal
INT0 is active as defined by bit IN0PL in register INT01CF (see SFR Definition 9.13). Setting GATE0 to ‘1’
allows the timer to be controlled by the external input signal INT0 (see Section “9.3.5. Interrupt Register
Descriptions” on page 90), facilitating pulse width measurements.
TR0
GATE0
0
X
1
0
1
1
1
1
X = Don't Care
INT0
X
X
0
1
Counter/Timer
Disabled
Enabled
Disabled
Enabled
Setting TR0 does not force the timer to reset. The timer registers should be loaded with the desired initial
value before the timer is enabled.
TL1 and TH1 form the 13-bit register for Timer 1 in the same manner as described above for TL0 and TH0.
Timer 1 is configured and controlled using the relevant TCON and TMOD bits just as with Timer 0. The
input signal INT1 is used with Timer 1; the INT1 polarity is defined by bit IN1PL in register INT01CF (see
SFR Definition 9.13).
CKCON
TMOD
TTTTTTSS
3 3 2 2 1 0 CC
MMMMMM A A
HLHL
1 0
Pre-scaled Clock
G
A
T
E
1
C
/
T
1
T TG
1 1 A
MM T
1 0 E
0
C
/
T
0
INT01CF
T T
0 0
MM
1 0
I
N
1
P
L
I
N
1
S
L
2
I
N
1
S
L
1
I
N
1
S
L
0
I
N
0
P
L
I
N
0
S
L
2
I
N
0
S
L
1
I
N
0
S
L
0
0
0
SYSCLK
1
1
TR0
TCLK
TL0
(5 bits)
TH0
(8 bits)
GATE0
Crossbar
INT0
IN0PL
TCON
T0
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
Interrupt
XOR
Figure 21.1. T0 Mode 0 Block Diagram
21.1.2. Mode 1: 16-bit Counter/Timer
Mode 1 operation is the same as Mode 0, except that the counter/timer registers use all 16 bits. The counter/timers are enabled and configured in Mode 1 in the same manner as for Mode 0.
236
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
21.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload
Mode 2 configures Timer 0 and Timer 1 to operate as 8-bit counter/timers with automatic reload of the start
value. TL0 holds the count and TH0 holds the reload value. When the counter in TL0 overflows from all
ones to 0x00, the timer overflow flag TF0 (TCON.5) is set and the counter in TL0 is reloaded from TH0. If
Timer 0 interrupts are enabled, an interrupt will occur when the TF0 flag is set. The reload value in TH0 is
not changed. TL0 must be initialized to the desired value before enabling the timer for the first count to be
correct. When in Mode 2, Timer 1 operates identically to Timer 0.
Both counter/timers are enabled and configured in Mode 2 in the same manner as Mode 0. Setting the
TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or when the input signal INT0
is active as defined by bit IN0PL in register INT01CF (see Section “9.3.2. External Interrupts” on
page 88 for details on the external input signals INT0 and INT1).
Pre-scaled Clock
CKCON
TMOD
TTTTTTSS
3 3 2 2 1 0 CC
MMMMMM A A
HLHL
10
GC T TGC T T
A / 1 1 A / 0 0
T T MM T T MM
E 1 1 0 E 0 1 0
1
0
INT01CF
I
N
1
P
L
I
N
1
S
L
2
I
N
1
S
L
1
I
N
1
S
L
0
I
N
0
P
L
I
N
0
S
L
2
I
N
0
S
L
1
I
N
0
S
L
0
0
0
SYSCLK
1
1
T0
TL0
(8 bits)
TCON
TCLK
TR0
Crossbar
GATE0
TH0
(8 bits)
INT0
IN0PL
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
Interrupt
Reload
XOR
Figure 21.2. T0 Mode 2 Block Diagram
Rev. 1.3
237
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
21.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)
In Mode 3, Timer 0 is configured as two separate 8-bit counter/timers held in TL0 and TH0. The counter/
timer in TL0 is controlled using the Timer 0 control/status bits in TCON and TMOD: TR0, C/T0, GATE0 and
TF0. TL0 can use either the system clock or an external input signal as its timebase. The TH0 register is
restricted to a timer function sourced by the system clock or prescaled clock. TH0 is enabled using the
Timer 1 run control bit TR1. TH0 sets the Timer 1 overflow flag TF1 on overflow and thus controls the
Timer 1 interrupt.
Timer 1 is inactive in Mode 3. When Timer 0 is operating in Mode 3, Timer 1 can be operated in Modes 0,
1 or 2, but cannot be clocked by external signals nor set the TF1 flag and generate an interrupt. However,
the Timer 1 overflow can be used to generate baud rates for the SMBus and/or UART, and/or initiate ADC
conversions. While Timer 0 is operating in Mode 3, Timer 1 run control is handled through its mode settings. To run Timer 1 while Timer 0 is in Mode 3, set the Timer 1 Mode as 0, 1, or 2. To disable Timer 1,
configure it for Mode 3.
CKCON
T T T T T T S
3 3 2 2 1 0 C
MMMMMMA
H L H L
1
Pre-scaled Clock
TMOD
S
C
A
0
G
A
T
E
1
C
/
T
1
T
1
M
1
T
1
M
0
G
A
T
E
0
C
/
T
0
T
0
M
1
T
0
M
0
0
TR1
SYSCLK
TH0
(8 bits)
1
TCON
0
1
T0
TL0
(8 bits)
TR0
Crossbar
INT0
GATE0
IN0PL
XOR
Figure 21.3. T0 Mode 3 Block Diagram
238
Rev. 1.3
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
Interrupt
Interrupt
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 21.1. TCON: Timer Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
Reset Value
0x88
TF1: Timer 1 Overflow Flag.
Set by hardware when Timer 1 overflows. This flag can be cleared by software but is automatically cleared when the CPU vectors to the Timer 1 interrupt service routine.
0: No Timer 1 overflow detected.
1: Timer 1 has overflowed.
TR1: Timer 1 Run Control.
0: Timer 1 disabled.
1: Timer 1 enabled.
TF0: Timer 0 Overflow Flag.
Set by hardware when Timer 0 overflows. This flag can be cleared by software but is automatically cleared when the CPU vectors to the Timer 0 interrupt service routine.
0: No Timer 0 overflow detected.
1: Timer 0 has overflowed.
TR0: Timer 0 Run Control.
0: Timer 0 disabled.
1: Timer 0 enabled.
IE1: External Interrupt 1.
This flag is set by hardware when an edge/level of type defined by IT1 is detected. It can be
cleared by software but is automatically cleared when the CPU vectors to the External Interrupt 1 service routine if IT1 = 1. When IT1 = 0, this flag is set to ‘1’ when INT1 is active as
defined by bit IN1PL in register INT01CF (see SFR Definition 9.13).
IT1: Interrupt 1 Type Select.
This bit selects whether the configured INT1 interrupt will be edge or level sensitive. INT1 is
configured active low or high by the IN1PL bit in the IT01CF register (see SFR Definition
9.13).
0: INT1 is level triggered.
1: INT1 is edge triggered.
IE0: External Interrupt 0.
This flag is set by hardware when an edge/level of type defined by IT0 is detected. It can be
cleared by software but is automatically cleared when the CPU vectors to the External Interrupt 0 service routine if IT0 = 1. When IT0 = 0, this flag is set to ‘1’ when INT0 is active as
defined by bit IN0PL in register INT01CF (see SFR Definition 9.13).
IT0: Interrupt 0 Type Select.
This bit selects whether the configured INT0 interrupt will be edge or level sensitive. INT0 is
configured active low or high by the IN0PL bit in register IT01CF (see SFR Definition 9.13).
0: INT0 is level triggered.
1: INT0 is edge triggered.
Rev. 1.3
239
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 21.2. TMOD: Timer Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
GATE1
C/T1
T1M1
T1M0
GATE0
C/T0
T0M1
T0M0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x89
Bit7:
GATE1: Timer 1 Gate Control.
0: Timer 1 enabled when TR1 = 1 irrespective of INT1 logic level.
1: Timer 1 enabled only when TR1 = 1 AND INT1 is active as defined by bit IN1PL in register
INT01CF (see SFR Definition 9.13).
Bit6:
C/T1: Counter/Timer 1 Select.
0: Timer Function: Timer 1 incremented by clock defined by T1M bit (CKCON.3).
1: Counter Function: Timer 1 incremented by high-to-low transitions on external input pin
(T1).
Bits5–4: T1M1–T1M0: Timer 1 Mode Select.
These bits select the Timer 1 operation mode.
T1M1
0
0
T1M0
0
1
1
0
1
1
Mode
Mode 0: 13-bit counter/timer
Mode 1: 16-bit counter/timer
Mode 2: 8-bit counter/timer with
auto-reload
Mode 3: Timer 1 inactive
Bit3:
GATE0: Timer 0 Gate Control.
0: Timer 0 enabled when TR0 = 1 irrespective of INT0 logic level.
1: Timer 0 enabled only when TR0 = 1 AND INT0 is active as defined by bit IN0PL in register
INT01CF (see SFR Definition 9.13).
Bit2:
C/T0: Counter/Timer Select.
0: Timer Function: Timer 0 incremented by clock defined by T0M bit (CKCON.2).
1: Counter Function: Timer 0 incremented by high-to-low transitions on external input pin
(T0).
Bits1–0: T0M1–T0M0: Timer 0 Mode Select.
These bits select the Timer 0 operation mode.
240
T0M1
0
0
T0M0
0
1
1
0
1
1
Mode
Mode 0: 13-bit counter/timer
Mode 1: 16-bit counter/timer
Mode 2: 8-bit counter/timer with
auto-reload
Mode 3: Two 8-bit counter/timers
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 21.3. CKCON: Clock Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
T3MH
T3ML
T2MH
T2ML
T1M
T0M
SCA1
SCA0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x8E
Bit7:
T3MH: Timer 3 High Byte Clock Select.
This bit selects the clock supplied to the Timer 3 high byte if Timer 3 is configured in split
8-bit timer mode. T3MH is ignored if Timer 3 is in any other mode.
0: Timer 3 high byte uses the clock defined by the T3XCLK bit in TMR3CN.
1: Timer 3 high byte uses the system clock.
Bit6:
T3ML: Timer 3 Low Byte Clock Select.
This bit selects the clock supplied to Timer 3. If Timer 3 is configured in split 8-bit timer
mode, this bit selects the clock supplied to the lower 8-bit timer.
0: Timer 3 low byte uses the clock defined by the T3XCLK bit in TMR3CN.
1: Timer 3 low byte uses the system clock.
Bit5:
T2MH: Timer 2 High Byte Clock Select.
This bit selects the clock supplied to the Timer 2 high byte if Timer 2 is configured in split
8-bit timer mode. T2MH is ignored if Timer 2 is in any other mode.
0: Timer 2 high byte uses the clock defined by the T2XCLK bit in TMR2CN.
1: Timer 2 high byte uses the system clock.
Bit4:
T2ML: Timer 2 Low Byte Clock Select.
This bit selects the clock supplied to Timer 2. If Timer 2 is configured in split 8-bit timer
mode, this bit selects the clock supplied to the lower 8-bit timer.
0: Timer 2 low byte uses the clock defined by the T2XCLK bit in TMR2CN.
1: Timer 2 low byte uses the system clock.
Bit3:
T1M: Timer 1 Clock Select.
This select the clock source supplied to Timer 1. T1M is ignored when C/T1 is set to logic 1.
0: Timer 1 uses the clock defined by the prescale bits, SCA1-SCA0.
1: Timer 1 uses the system clock.
Bit2:
T0M: Timer 0 Clock Select.
This bit selects the clock source supplied to Timer 0. T0M is ignored when C/T0 is set to
logic 1.
0: Counter/Timer 0 uses the clock defined by the prescale bits, SCA1-SCA0.
1: Counter/Timer 0 uses the system clock.
Bits1–0: SCA1-SCA0: Timer 0/1 Prescale Bits.
These bits control the division of the clock supplied to Timer 0 and/or Timer 1 if configured
to use prescaled clock inputs.
SCA1
0
0
1
1
SCA0
0
1
0
1
Prescaled Clock
System clock divided by 12
System clock divided by 4
System clock divided by 48
External clock divided by 8
Note: External clock divided by 8 is synchronized with the
system clock.
Rev. 1.3
241
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 21.4. TL0: Timer 0 Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x8A
Bits 7–0: TL0: Timer 0 Low Byte.
The TL0 register is the low byte of the 16-bit Timer 0.
SFR Definition 21.5. TL1: Timer 1 Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
00000000
0x8B
Bits 7–0: TL1: Timer 1 Low Byte.
The TL1 register is the low byte of the 16-bit Timer 1.
SFR Definition 21.6. TH0: Timer 0 High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x8C
Bits 7–0: TH0: Timer 0 High Byte.
The TH0 register is the high byte of the 16-bit Timer 0.
SFR Definition 21.7. TH1: Timer 1 High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x8D
Bits 7–0: TH1: Timer 1 High Byte.
The TH1 register is the high byte of the 16-bit Timer 1.
242
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
21.2. Timer 2
Timer 2 is a 16-bit timer formed by two 8-bit SFRs: TMR2L (low byte) and TMR2H (high byte). Timer 2 may
operate in 16-bit auto-reload mode, (split) 8-bit auto-reload mode, USB Start-of-Frame (SOF) capture
mode, or Low-Frequency Oscillator (LFO) Falling Edge capture mode. The Timer 2 operation mode is
defined by the T2SPLIT (TMR2CN.3), T2CE (TMR2CN.4) bits, and T2CSS (TMR2CN.1) bits.
Timer 2 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
source divided by 8. The external clock mode is ideal for real-time clock (RTC) functionality, where the
internal oscillator drives the system clock while Timer 2 (and/or the PCA) is clocked by an external precision oscillator. Note that the external oscillator source divided by 8 is synchronized with the system clock.
21.2.1. 16-bit Timer with Auto-Reload
When T2SPLIT = ‘0’ and T2CE = ‘0’, Timer 2 operates as a 16-bit timer with auto-reload. Timer 2 can be
clocked by SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. As the
16-bit timer register increments and overflows from 0xFFFF to 0x0000, the 16-bit value in the Timer 2
reload registers (TMR2RLH and TMR2RLL) is loaded into the Timer 2 register as shown in Figure 21.4,
and the Timer 2 High Byte Overflow Flag (TMR2CN.7) is set. If Timer 2 interrupts are enabled, an interrupt
will be generated on each Timer 2 overflow. Additionally, if Timer 2 interrupts are enabled and the TF2LEN
bit is set (TMR2CN.5), an interrupt will be generated each time the lower 8 bits (TMR2L) overflow from
0xFF to 0x00.
CKCON
T2XCLK
SYSCLK / 12
TTTTTTSS
3 3 2 2 1 0 CC
MMMMMM A A
HLHL
1 0
TL2
Overflow
0
SYSCLK
1
TCLK
TMR2L
TMR2H
TMR2CN
TR2
External Clock / 8
To ADC,
SMBus
To SMBus
0
1
TF2H
TF2L
TF2LEN
T2CE
T2SPLIT
TR2
T2CSS
T2XCLK
Interrupt
TMR2RLL TMR2RLH
Reload
Figure 21.4. Timer 2 16-Bit Mode Block Diagram
Rev. 1.3
243
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
21.2.2. 8-bit Timers with Auto-Reload
When T2SPLIT = ‘1’ and T2CE = ‘0’, Timer 2 operates as two 8-bit timers (TMR2H and TMR2L). Both 8-bit
timers operate in auto-reload mode as shown in Figure 21.5. TMR2RLL holds the reload value for TMR2L;
TMR2RLH holds the reload value for TMR2H. The TR2 bit in TMR2CN handles the run control for TMR2H.
TMR2L is always running when configured for 8-bit Mode.
Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the external oscillator clock
source divided by 8. The Timer 2 Clock Select bits (T2MH and T2ML in CKCON) select either SYSCLK or
the clock defined by the Timer 2 External Clock Select bit (T2XCLK in TMR2CN), as follows:
T2MH
0
0
1
T2XCLK
0
1
X
TMR2H Clock Source
SYSCLK / 12
External Clock / 8
SYSCLK
T2ML
0
0
1
T2XCLK
0
1
X
TMR2L Clock Source
SYSCLK / 12
External Clock / 8
SYSCLK
The TF2H bit is set when TMR2H overflows from 0xFF to 0x00; the TF2L bit is set when TMR2L overflows
from 0xFF to 0x00. When Timer 2 interrupts are enabled, an interrupt is generated each time TMR2H overflows. If Timer 2 interrupts are enabled and TF2LEN (TMR2CN.5) is set, an interrupt is generated each
time either TMR2L or TMR2H overflows. When TF2LEN is enabled, software must check the TF2H and
TF2L flags to determine the source of the Timer 2 interrupt. The TF2H and TF2L interrupt flags are not
cleared by hardware and must be manually cleared by software.
CKCON
TTTTTTSS
3 3 2 2 1 0 CC
MMMMMM A A
HLHL
1 0
T2XCLK
SYSCLK / 12
0
External Clock / 8
1
TMR2RLH
Reload
To SMBus
0
TCLK
TR2
TMR2H
TMR2RLL
SYSCLK
Reload
TMR2CN
1
TF2H
TF2L
TF2LEN
T2CE
T2SPLIT
TR2
T2CSS
T2XCLK
1
TCLK
TMR2L
To ADC,
SMBus
0
Figure 21.5. Timer 2 8-Bit Mode Block Diagram
244
Rev. 1.3
Interrupt
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
21.2.3. Timer 2 Capture Modes: USB Start-of-Frame or LFO Falling Edge
When T2CE = ‘1’, Timer 2 will operate in one of two special capture modes. The capture event can be
selected between a USB Start-of-Frame (SOF) capture, and a Low-Frequency Oscillator (LFO) Falling
Edge capture, using the T2CSS bit. The USB SOF capture mode can be used to calibrate the system clock
or external oscillator against the known USB host SOF clock. The LFO falling-edge capture mode can be
used to calibrate the internal Low-Frequency Oscillator against the internal High-Frequency Oscillator or
an external clock source. When T2SPLIT = ‘0’, Timer 2 counts up and overflows from 0xFFFF to 0x0000.
Each time a capture event is received, the contents of the Timer 2 registers (TMR2H:TMR2L) are latched
into the Timer 2 Reload registers (TMR2RLH:TMR2RLL). A Timer 2 interrupt is generated if enabled.
TMR2CN
T
F
2
H
T
F
2
L
TT
F 2
2C
LE
E
N
SYSCLK / 12
TTTT
2R2 2
S2CX
P SC
L SL
I
K
T
CKCON
TTTTTTSS
3 3 2 2 1 0 CC
MMMMMM A A
HLHL
1 0
0
TL2
Overflow
To SMBus
0
TCLK
TR2
External Clock / 8
SYSCLK
1
TMR2L
TMR2H
To ADC,
SMBus
1
USB Start-of-Frame (SOF)
0
Capture
Low-Frequency Oscillator
Falling Edge
TMR2RLL TMR2RLH
1
T2CSS
Enable
Interrupt
Figure 21.6. Timer 2 Capture Mode (T2SPLIT = ‘0’)
Rev. 1.3
245
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
When T2SPLIT = ‘1’, the Timer 2 registers (TMR2H and TMR2L) act as two 8-bit counters. Each counter
counts up independently and overflows from 0xFF to 0x00. Each time a capture event is received, the contents of the Timer 2 registers are latched into the Timer 2 Reload registers (TMR2RLH and TMR2RLL). A
Timer 2 interrupt is generated if enabled.
TMR2CN
T
F
2
H
T
F
2
L
TT
F 2
2C
LE
E
N
SYSCLK / 12
TTTT
2R2 2
S2CX
P SC
L SL
I
K
T
CKCON
TTTTTTSS
3 3 2 2 1 0CC
MMMMMM A A
HLHL
1 0
TMR2RLH
Enable
Capture
0
0
External Clock / 8
1
TCLK
TR2
TMR2H
To SMBus
1
TMR2RLL
Capture
SYSCLK
1
TCLK
TMR2L
To ADC,
SMBus
0
USB Start-of-Frame (SOF)
0
Low-Frequency Oscillator
Falling Edge
1
T2CSS
Figure 21.7. Timer 2 Capture Mode (T2SPLIT = ‘1’)
246
Rev. 1.3
Interrupt
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 21.8. TMR2CN: Timer 2 Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
TF2H
TF2L
TF2LEN
T2CE
T2SPLIT
TR2
T2CSS
T2XCLK
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
0xC8
TF2H: Timer 2 High Byte Overflow Flag.
Set by hardware when the Timer 2 high byte overflows from 0xFF to 0x00. In 16 bit mode,
this will occur when Timer 2 overflows from 0xFFFF to 0x0000. When the Timer 2 interrupt is
enabled, setting this bit causes the CPU to vector to the Timer 2 interrupt service routine.
TF2H is not automatically cleared by hardware and must be cleared by software.
TF2L: Timer 2 Low Byte Overflow Flag.
Set by hardware when the Timer 2 low byte overflows from 0xFF to 0x00. When this bit is
set, an interrupt will be generated if TF2LEN is set and Timer 2 interrupts are enabled. TF2L
will set when the low byte overflows regardless of the Timer 2 mode. This bit is not automatically cleared by hardware.
TF2LEN: Timer 2 Low Byte Interrupt Enable.
This bit enables/disables Timer 2 Low Byte interrupts. If TF2LEN is set and Timer 2 interrupts are enabled, an interrupt will be generated when the low byte of Timer 2 overflows.
0: Timer 2 Low Byte interrupts disabled.
1: Timer 2 Low Byte interrupts enabled.
T2CE: Timer 2 Capture Enable
0: Capture function disabled.
1: Capture function enabled. The timer is in capture mode, with the capture event selected
by bit T2CSS. Each time a capture event is received, the contents of the Timer 2 registers
(TMR2H and TMR2L) are latched into the Timer 2 reload registers (TMR2RLH and
TMR2RLH), and a Timer 2 interrupt is generated (if enabled).
T2SPLIT: Timer 2 Split Mode Enable.
When this bit is set, Timer 2 operates as two 8-bit timers with auto-reload.
0: Timer 2 operates in 16-bit auto-reload mode.
1: Timer 2 operates as two 8-bit auto-reload timers.
TR2: Timer 2 Run Control.
This bit enables/disables Timer 2. In 8-bit mode, this bit enables/disables TMR2H only;
TMR2L is always enabled in this mode.
0: Timer 2 disabled.
1: Timer 2 enabled.
T2CSS: Timer 2 Capture Source Select.
This bit selects the source of a capture event when bit T2CE is set to ‘1’.
0: Capture source is USB SOF event.
1: Capture source is falling edge of Low-Frequency Oscillator.
T2XCLK: Timer 2 External Clock Select.
This bit selects the external clock source for Timer 2. If Timer 2 is in 8-bit mode, this bit
selects the external oscillator clock source for both timer bytes. However, the Timer 2 Clock
Select bits (T2MH and T2ML in register CKCON) may still be used to select between the
external clock and the system clock for either timer.
0: Timer 2 external clock selection is the system clock divided by 12.
1: Timer 2 external clock selection is the external clock divided by 8. Note that the external
oscillator source divided by 8 is synchronized with the system clock.
Rev. 1.3
247
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 21.9. TMR2RLL: Timer 2 Reload Register Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xCA
Bits 7–0: TMR2RLL: Timer 2 Reload Register Low Byte.
TMR2RLL holds the low byte of the reload value for Timer 2 when operating in auto-reload
mode, or the captured value of the TMR2L register in capture mode.
SFR Definition 21.10. TMR2RLH: Timer 2 Reload Register High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xCB
Bits 7–0: TMR2RLH: Timer 2 Reload Register High Byte.
The TMR2RLH holds the high byte of the reload value for Timer 2 when operating in
auto-reload mode, or the captured value of the TMR2H register in capture mode.
SFR Definition 21.11. TMR2L: Timer 2 Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xCC
Bits 7–0: TMR2L: Timer 2 Low Byte.
In 16-bit mode, the TMR2L register contains the low byte of the 16-bit Timer 2. In 8-bit mode,
TMR2L contains the 8-bit low byte timer value.
SFR Definition 21.12. TMR2H Timer 2 High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
00000000
0xCD
Bits 7–0: TMR2H: Timer 2 High Byte.
In 16-bit mode, the TMR2H register contains the high byte of the 16-bit Timer 2. In 8-bit
mode, TMR2H contains the 8-bit high byte timer value.
248
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
21.3. Timer 3
Timer 3 is a 16-bit timer formed by two 8-bit SFRs: TMR3L (low byte) and TMR3H (high byte). Timer 3 may
operate in 16-bit auto-reload mode, (split) 8-bit auto-reload mode, USB Start-of-Frame (SOF) capture
mode, or Low-Frequency Oscillator (LFO) Rising Edge capture mode. The Timer 3 operation mode is
defined by the T3SPLIT (TMR3CN.3), T3CE (TMR3CN.4) bits, and T3CSS (TMR3CN.1) bits.
Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
source divided by 8. The external clock mode is ideal for real-time clock (RTC) functionality, where the
internal oscillator drives the system clock while Timer 3 (and/or the PCA) is clocked by an external precision oscillator. Note that the external oscillator source divided by 8 is synchronized with the system clock.
21.3.1. 16-bit Timer with Auto-Reload
When T3SPLIT (TMR3CN.3) is ‘0’ and T3CE = ‘0’, Timer 3 operates as a 16-bit timer with auto-reload.
Timer 3 can be clocked by SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided
by 8. As the 16-bit timer register increments and overflows from 0xFFFF to 0x0000, the 16-bit value in the
Timer 3 reload registers (TMR3RLH and TM3RLL) is loaded into the Timer 3 register as shown in
Figure 21.4, and the Timer 3 High Byte Overflow Flag (TMR3CN.7) is set. If Timer 3 interrupts are enabled,
an interrupt will be generated on each Timer 3 overflow. Additionally, if Timer 3 interrupts are enabled and
the TF3LEN bit is set (TMR3CN.5), an interrupt will be generated each time the lower 8 bits (TMR3L) overflow from 0xFF to 0x00.
CKCON
T3XCLK
SYSCLK / 12
TTTTTTSS
3 3 2 2 1 0CC
MMMMMM A A
HLHL
1 0
To ADC
0
0
SYSCLK
1
TCLK
TMR3L
TMR3H
TMR3CN
TR3
External Clock / 8
1
TF3H
TF3L
TF3LEN
T3CE
T3SPLIT
TR3
T3CSS
T3XCLK
Interrupt
TMR3RLL TMR3RLH
Reload
Figure 21.8. Timer 3 16-Bit Mode Block Diagram
Rev. 1.3
249
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
21.3.2. 8-bit Timers with Auto-Reload
When T3SPLIT is ‘1’ and T3CE = ‘0’, Timer 3 operates as two 8-bit timers (TMR3H and TMR3L). Both 8-bit
timers operate in auto-reload mode as shown in Figure 21.5. TMR3RLL holds the reload value for TMR3L;
TMR3RLH holds the reload value for TMR3H. The TR3 bit in TMR3CN handles the run control for TMR3H.
TMR3L is always running when configured for 8-bit Mode.
Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the external oscillator clock
source divided by 8. The Timer 3 Clock Select bits (T3MH and T3ML in CKCON) select either SYSCLK or
the clock defined by the Timer 3 External Clock Select bit (T3XCLK in TMR3CN), as follows:
T3MH
0
0
1
T3XCLK
0
1
X
TMR3H Clock Source
SYSCLK / 12
External Clock / 8
SYSCLK
T3ML
0
0
1
T3XCLK
0
1
X
TMR3L Clock Source
SYSCLK / 12
External Clock / 8
SYSCLK
The TF3H bit is set when TMR3H overflows from 0xFF to 0x00; the TF3L bit is set when TMR3L overflows
from 0xFF to 0x00. When Timer 3 interrupts are enabled, an interrupt is generated each time TMR3H overflows. If Timer 3 interrupts are enabled and TF3LEN (TMR3CN.5) is set, an interrupt is generated each
time either TMR3L or TMR3H overflows. When TF3LEN is enabled, software must check the TF3H and
TF3L flags to determine the source of the Timer 3 interrupt. The TF3H and TF3L interrupt flags are not
cleared by hardware and must be manually cleared by software.
CKCON
TTTTTTSS
3 3 2 2 1 0 CC
MMMMMM A A
HLHL
1 0
T3XCLK
SYSCLK / 12
TMR3RLH
Reload
0
To ADC
0
External Clock / 8
1
TCLK
TR3
TMR3H
TMR3RLL
SYSCLK
Reload
TMR3CN
1
TF3H
TF3L
TF3LEN
T3CE
T3SPLIT
TR3
T3CSS
T3XCLK
1
TCLK
TMR3L
0
Figure 21.9. Timer 3 8-Bit Mode Block Diagram
250
Rev. 1.3
Interrupt
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
21.3.3. USB Start-of-Frame Capture
When T3CE = ‘1’, Timer 3 will operate in one of two special capture modes. The capture event can be
selected between a USB Start-of-Frame (SOF) capture, and a Low-Frequency Oscillator (LFO) Rising
Edge capture, using the T3CSS bit. The USB SOF capture mode can be used to calibrate the system clock
or external oscillator against the known USB host SOF clock. The LFO rising-edge capture mode can be
used to calibrate the internal Low-Frequency Oscillator against the internal High-Frequency Oscillator or
an external clock source. When T3SPLIT = ‘0’, Timer 3 counts up and overflows from 0xFFFF to 0x0000.
Each time a capture event is received, the contents of the Timer 3 registers (TMR3H:TMR3L) are latched
into the Timer 3 Reload registers (TMR3RLH:TMR3RLL). A Timer 3 interrupt is generated if enabled.
TMR3CN
T
F
3
H
T
F
3
L
TT
F 3
3C
LE
E
N
SYSCLK / 12
TTTT
3R3 3
S 3CX
P SC
L SL
I
K
T
CKCON
TTTTTTSS
3 3 2 2 1 0 CC
MMMMMM A A
HLHL
1 0
0
0
TCLK
TR3
External Clock / 8
SYSCLK
1
TMR3L
TMR3H
To ADC
1
USB Start-of-Frame (SOF)
0
Capture
Low-Frequency Oscillator
Falling Edge
TMR3RLL TMR3RLH
1
T3CSS
Enable
Interrupt
Figure 21.10. Timer 3 Capture Mode (T3SPLIT = ‘0’)
Rev. 1.3
251
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
When T3SPLIT = ‘1’, the Timer 3 registers (TMR3H and TMR3L) act as two 8-bit counters. Each counter
counts up independently and overflows from 0xFF to 0x00. Each time a capture event is received, the contents of the Timer 3 registers are latched into the Timer 3 Reload registers (TMR3RLH and TMR3RLL). A
Timer 3 interrupt is generated if enabled.
TMR3CN
T
F
3
H
T
F
3
L
TT
F 3
3C
LE
E
N
TTTT
3R3 3
S 3CX
P SC
L SL
I
K
T
SYSCLK / 12
0
External Clock / 8
1
CKCON
TTTTTTSS
3 3 2 2 1 0CC
MMMMMM A A
HLHL
1 0
TMR3RLH
Enable
Capture
0
TCLK
TR3
TMR3H
To ADC
1
TMR3RLL
Capture
SYSCLK
1
TCLK
TMR3L
0
USB Start-of-Frame (SOF)
0
Low-Frequency Oscillator
Falling Edge
1
T3CSS
Figure 21.11. Timer 3 Capture Mode (T3SPLIT = ‘1’)
252
Rev. 1.3
Interrupt
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 21.13. TMR3CN: Timer 3 Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
TF3H
TF3L
TF3LEN
T3CE
T3SPLIT
TR3
T3CSS
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
T3XCLK 00000000
Bit0
SFR Address:
0x91
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
TF3H: Timer 3 High Byte Overflow Flag.
Set by hardware when the Timer 3 high byte overflows from 0xFF to 0x00. In 16 bit mode,
this will occur when Timer 3 overflows from 0xFFFF to 0x0000. When the Timer 3 interrupt is
enabled, setting this bit causes the CPU to vector to the Timer 3 interrupt service routine.
TF3H is not automatically cleared by hardware and must be cleared by software.
TF3L: Timer 3 Low Byte Overflow Flag.
Set by hardware when the Timer 3 low byte overflows from 0xFF to 0x00. When this bit is
set, an interrupt will be generated if TF3LEN is set and Timer 3 interrupts are enabled. TF3L
will set when the low byte overflows regardless of the Timer 3 mode. This bit is not automatically cleared by hardware.
TF3LEN: Timer 3 Low Byte Interrupt Enable.
This bit enables/disables Timer 3 Low Byte interrupts. If TF3LEN is set and Timer 3 interrupts are enabled, an interrupt will be generated when the low byte of Timer 3 overflows.
This bit should be cleared when operating Timer 3 in 16-bit mode.
0: Timer 3 Low Byte interrupts disabled.
1: Timer 3 Low Byte interrupts enabled.
T3CE: Timer 3 Capture Enable
0: Capture function disabled.
1: Capture function enabled. The timer is in capture mode, with the capture event selected
by bit T3CSS. Each time a capture event is received, the contents of the Timer 3 registers
(TMR3H and TMR3L) are latched into the Timer 3 reload registers (TMR3RLH and
TMR3RLH), and a Timer 3 interrupt is generated (if enabled).
T3SPLIT: Timer 3 Split Mode Enable.
When this bit is set, Timer 3 operates as two 8-bit timers with auto-reload.
0: Timer 3 operates in 16-bit auto-reload mode.
1: Timer 3 operates as two 8-bit auto-reload timers.
TR3: Timer 3 Run Control.
This bit enables/disables Timer 3. In 8-bit mode, this bit enables/disables TMR3H only;
TMR3L is always enabled in this mode.
0: Timer 3 disabled.
1: Timer 3 enabled.
T3CSS: Timer 3 Capture Source Select.
This bit selects the source of a capture event when bit T3CE is set to ‘1’.
0: Capture source is USB SOF event.
1: Capture source is rising edge of Low-Frequency Oscillator.
T3XCLK: Timer 3 External Clock Select.
This bit selects the external clock source for Timer 3. If Timer 3 is in 8-bit mode, this bit
selects the external oscillator clock source for both timer bytes. However, the Timer 3 Clock
Select bits (T3MH and T3ML in register CKCON) may still be used to select between the
external clock and the system clock for either timer.
0: Timer 3 external clock selection is the system clock divided by 12.
1: Timer 3 external clock selection is the external clock divided by 8. Note that the external
oscillator source divided by 8 is synchronized with the system clock.
Rev. 1.3
253
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 21.14. TMR3RLL: Timer 3 Reload Register Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x92
Bits 7–0: TMR3RLL: Timer 3 Reload Register Low Byte.
TMR3RLL holds the low byte of the reload value for Timer 3 when operating in auto-reload
mode, or the captured value of the TMR3L register when operating in capture mode.
SFR Definition 21.15. TMR3RLH: Timer 3 Reload Register High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x93
Bits 7–0: TMR3RLH: Timer 3 Reload Register High Byte.
The TMR3RLH holds the high byte of the reload value for Timer 3 when operating in
auto-reload mode, or the captured value of the TMR3H register when operating in capture
mode.
SFR Definition 21.16. TMR3L: Timer 3 Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x94
Bits 7–0: TMR3L: Timer 3 Low Byte.
In 16-bit mode, the TMR3L register contains the low byte of the 16-bit Timer 3. In 8-bit mode,
TMR3L contains the 8-bit low byte timer value.
SFR Definition 21.17. TMR3H Timer 3 High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0x95
Bits 7–0: TMR3H: Timer 3 High Byte.
In 16-bit mode, the TMR3H register contains the high byte of the 16-bit Timer 3. In 8-bit
mode, TMR3H contains the 8-bit high byte timer value.
254
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
22. Programmable Counter Array (PCA0)
The Programmable Counter Array (PCA0) provides enhanced timer functionality while requiring less CPU
intervention than the standard 8051 counter/timers. The PCA consists of a dedicated 16-bit counter/timer
and five 16-bit capture/compare modules. Each capture/compare module has its own associated I/O line
(CEXn) which is routed through the Crossbar to Port I/O when enabled (See Section “15.1. Priority
Crossbar Decoder” on page 144 for details on configuring the Crossbar). The counter/timer is driven by
a programmable timebase that can select between six sources: system clock, system clock divided by four,
system clock divided by twelve, the external oscillator clock source divided by 8, Timer 0 overflow, or an
external clock signal on the ECI input pin. Each capture/compare module may be configured to operate
independently in one of six modes: Edge-Triggered Capture, Software Timer, High-Speed Output, Frequency Output, 8-Bit PWM, or 16-Bit PWM (each mode is described in Section “22.2. Capture/Compare
Modules” on page 257). The external oscillator clock option is ideal for real-time clock (RTC) functionality,
allowing the PCA to be clocked by a precision external oscillator while the internal oscillator drives the system clock. The PCA is configured and controlled through the system controller's Special Function Registers. The PCA block diagram is shown in Figure 22.1
Important Note: The PCA Module 4 may be used as a watchdog timer (WDT), and is enabled in this mode
following a system reset. Access to certain PCA registers is restricted while WDT mode is enabled. See
Section 22.3 for details.
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
PCA
CLOCK
MUX
16-Bit Counter/Timer
SYSCLK
External Clock/8
Capture/Compare
Module 0
Capture/Compare
Module 1
Capture/Compare
Module 2
Capture/Compare
Module 3
Capture/Compare
Module 4 / WDT
CEX4
CEX3
CEX2
CEX1
CEX0
ECI
Crossbar
Port I/O
Figure 22.1. PCA Block Diagram
Rev. 1.3
255
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
22.1. PCA Counter/Timer
The 16-bit PCA counter/timer consists of two 8-bit SFRs: PCA0L and PCA0H. PCA0H is the high byte
(MSB) of the 16-bit counter/timer and PCA0L is the low byte (LSB). Reading PCA0L automatically latches
the value of PCA0H into a “snapshot” register; the following PCA0H read accesses this “snapshot” register.
Reading the PCA0L Register first guarantees an accurate reading of the entire 16-bit PCA0 counter.
Reading PCA0H or PCA0L does not disturb the counter operation. The CPS2-CPS0 bits in the PCA0MD
register select the timebase for the counter/timer as shown in Table 22.1.
When the counter/timer overflows from 0xFFFF to 0x0000, the Counter Overflow Flag (CF) in PCA0MD is
set to logic 1 and an interrupt request is generated if CF interrupts are enabled. Setting the ECF bit in
PCA0MD to logic 1 enables the CF flag to generate an interrupt request. The CF bit is not automatically
cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by software (Note: PCA0 interrupts must be globally enabled before CF interrupts are recognized. PCA0 interrupts are globally enabled by setting the EA bit (IE.7) and the EPCA0 bit in EIE1 to logic 1). Clearing the
CIDL bit in the PCA0MD register allows the PCA to continue normal operation while the CPU is in Idle
mode.
Table 22.1. PCA Timebase Input Options
CPS2
0
0
0
CPS1
0
0
1
CPS0
0
1
0
0
1
1
1
1
0
0
0
1
Timebase
System clock divided by 12
System clock divided by 4
Timer 0 overflow
High-to-low transitions on ECI (max rate = system clock divided
by 4)
System clock
External oscillator source divided by 8*
*Note: External oscillator source divided by 8 is synchronized with the system clock.
IDLE
PCA0MD
CWW
I D D
D T L
L E C
K
C
P
S
2
C
P
S
1
PCA0CN
CE
PC
SF
0
CC
FR
C
C
F
4
C
C
F
3
C
C
F
2
C
C
F
1
C
C
F
0
To SFR Bus
PCA0L
read
Snapshot
Register
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
SYSCLK
External Clock/8
000
001
010
0
011
1
PCA0H
PCA0L
Overflow
100
101
To PCA Modules
Figure 22.2. PCA Counter/Timer Block Diagram
256
To PCA Interrupt System
CF
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
22.2. Capture/Compare Modules
Each module can be configured to operate independently in one of six operation modes: Edge-triggered
Capture, Software Timer, High Speed Output, Frequency Output, 8-Bit Pulse Width Modulator, or 16-Bit
Pulse Width Modulator. Each module has Special Function Registers (SFRs) associated with it in the
CIP-51 system controller. These registers are used to exchange data with a module and configure the
module's mode of operation.
Table 22.2 summarizes the bit settings in the PCA0CPMn registers used to select the PCA capture/compare module’s operating modes. Setting the ECCFn bit in a PCA0CPMn register enables the module's
CCFn interrupt. Note: PCA0 interrupts must be globally enabled before individual CCFn interrupts are recognized. PCA0 interrupts are globally enabled by setting the EA bit and the EPCA0 bit to logic 1. See
Figure 22.3 for details on the PCA interrupt configuration.
Table 22.2. PCA0CPM Register Settings for PCA Capture/Compare Modules
PWM16 ECOM CAPP CAPN MAT
TOG
PWM ECCF
X
X
1
0
0
0
0
X
X
X
0
1
0
0
0
X
1
0
0
0
0
0
0
1
1
X
X
X
0
0
1
1
0
0
0
0
0
1
1
1
X
X
X
X
X
X
X
X
X
X
0
1
X
1
1
0
1
0
1
0
1
0
1
0
X = Don’t Care
Operation Mode
Capture triggered by positive edge on
CEXn
Capture triggered by negative edge on
CEXn
Capture triggered by transition on CEXn
Software Timer
High Speed Output
Frequency Output
8-Bit Pulse Width Modulator
16-Bit Pulse Width Modulator
(for n = 0 to 4)
PCA0CPMn
P ECCMT P E
WCA A AOWC
MOP P TGMC
1 MP N n n n F
6 n n n
n
n
PCA0CN
CC
FR
CCCCC
CCCCC
FFFFF
4 3 2 1 0
PCA0MD
C WW
I DD
DT L
LEC
K
CCCE
PPPC
SSSF
2 1 0
0
PCA Counter/
Timer Overflow
1
ECCF0
EPCA0
0
PCA Module 0
(CCF0)
1
ECCF1
EA
0
0
1
1
Interrupt
Priority
Decoder
0
PCA Module 1
(CCF1)
1
ECCF2
0
PCA Module 2
(CCF2)
1
ECCF3
0
PCA Module 3
(CCF3)
1
ECCF4
PCA Module 4
(CCF4)
0
1
Figure 22.3. PCA Interrupt Block Diagram
Rev. 1.3
257
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
22.2.1. Edge-triggered Capture Mode
In this mode, a valid transition on the CEXn pin causes the PCA to capture the value of the PCA counter/
timer and load it into the corresponding module's 16-bit capture/compare register (PCA0CPLn and
PCA0CPHn). The CAPPn and CAPNn bits in the PCA0CPMn register are used to select the type of transition that triggers the capture: low-to-high transition (positive edge), high-to-low transition (negative edge),
or either transition (positive or negative edge). When a capture occurs, the Capture/Compare Flag (CCFn)
in PCA0CN is set to logic 1 and an interrupt request is generated if CCF interrupts are enabled. The CCFn
bit is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and
must be cleared by software. If both CAPPn and CAPNn bits are set to logic 1, then the state of the Port
pin associated with CEXn can be read directly to determine whether a rising-edge or falling-edge caused
the capture.
PCA Interrupt
PCA0CPMn
P E CCMT P E
WC A A AOWC
MOPP TGMC
1 MPN n n n F
6 n n n
n
n
0 0 0 x
0
Port I/O
Crossbar
CEXn
CCCCC
CCCCC
FFFFF
4 3 2 1 0
(to CCFn)
x 0
PCA0CN
CC
FR
1
PCA0CPLn
PCA0CPHn
Capture
0
1
PCA
Timebase
PCA0L
PCA0H
Figure 22.4. PCA Capture Mode Diagram
Note: The CEXn input signal must remain high or low for at least 2 system clock cycles to be recognized by
the hardware.
258
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
22.2.2. Software Timer (Compare) Mode
In Software Timer mode, the PCA counter/timer value is compared to the module's 16-bit capture/compare
register (PCA0CPHn and PCA0CPLn). When a match occurs, the Capture/Compare Flag (CCFn) in
PCA0CN is set to logic 1 and an interrupt request is generated if CCF interrupts are enabled. The CCFn bit
is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must
be cleared by software. Setting the ECOMn and MATn bits in the PCA0CPMn register enables Software
Timer mode.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Write to
PCA0CPLn
0
ENB
Reset
Write to
PCA0CPHn
PCA Interrupt
ENB
1
PCA0CPMn
P ECCMT P E
WC A A AOWC
MOP P TGMC
1 MP N n n n F
6 n n n
n
n
x
0 0
PCA0CN
PCA0CPLn
CC
FR
PCA0CPHn
CCCCC
CCCCC
FFFFF
4 3 2 1 0
0 0 x
Enable
16-bit Comparator
PCA
Timebase
PCA0L
Match
0
1
PCA0H
Figure 22.5. PCA Software Timer Mode Diagram
Rev. 1.3
259
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
22.2.3. High Speed Output Mode
In High Speed Output mode, a module’s associated CEXn pin is toggled each time a match occurs
between the PCA Counter and the module's 16-bit capture/compare register (PCA0CPHn and
PCA0CPLn) Setting the TOGn, MATn, and ECOMn bits in the PCA0CPMn register enables the
High-Speed Output mode.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Write to
PCA0CPLn
0
ENB
Reset
Write to
PCA0CPHn
PCA0CPMn
P ECCMT P E
WC A A A OWC
MOPP TGMC
1 MP N n n n F
6 n n n
n
n
ENB
1
x
0 0
0 x
PCA Interrupt
PCA0CN
PCA0CPLn
Enable
CC
FR
PCA0CPHn
Match
16-bit Comparator
CCCCC
CCCCC
FFFFF
4 3 2 1 0
0
1
TOGn
Toggle
PCA
Timebase
0 CEXn
1
PCA0L
Crossbar
PCA0H
Figure 22.6. PCA High Speed Output Mode Diagram
260
Rev. 1.3
Port I/O
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
22.2.4. Frequency Output Mode
Frequency Output Mode produces a programmable-frequency square wave on the module’s associated
CEXn pin. The capture/compare module high byte holds the number of PCA clocks to count before the output is toggled. The frequency of the square wave is then defined by Equation 22.1.
F PCA
F CEXn = ----------------------------------------2  PCA0CPHn
Note: A value of 0x00 in the PCA0CPHn register is equal to 256 for this equation.
Equation 22.1. Square Wave Frequency Output
Where FPCA is the frequency of the clock selected by the CPS2-0 bits in the PCA mode register, PCA0MD.
The lower byte of the capture/compare module is compared to the PCA counter low byte; on a match,
CEXn is toggled and the offset held in the high byte is added to the matched value in PCA0CPLn. Frequency Output Mode is enabled by setting the ECOMn, TOGn, and PWMn bits in the PCA0CPMn register.
Write to
PCA0CPLn
0
ENB
Reset
PCA0CPMn
Write to
PCA0CPHn
ENB
1
P ECCMT P E
WC A A AOWC
MOPP TGMC
1 MP N n n n F
6 nnn
n
n
x
0 0 0
PCA0CPLn
8-bit Adder
PCA0CPHn
Adder
Enable
TOGn
Toggle
x
Enable
PCA Timebase
8-bit
Comparator
match
0 CEXn
1
Crossbar
Port I/O
PCA0L
Figure 22.7. PCA Frequency Output Mode
Rev. 1.3
261
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
22.2.5. 8-Bit Pulse Width Modulator Mode
Each module can be used independently to generate a pulse width modulated (PWM) output on its associated CEXn pin. The frequency of the output is dependent on the timebase for the PCA counter/timer. The
duty cycle of the PWM output signal is varied using the module's PCA0CPLn capture/compare register.
When the value in the low byte of the PCA counter/timer (PCA0L) is equal to the value in PCA0CPLn, the
output on the CEXn pin will be set. When the count value in PCA0L overflows, the CEXn output will be
reset (see Figure 22.8). Also, when the counter/timer low byte (PCA0L) overflows from 0xFF to 0x00,
PCA0CPLn is reloaded automatically with the value stored in the module’s capture/compare high byte
(PCA0CPHn) without software intervention. Setting the ECOMn and PWMn bits in the PCA0CPMn register
enables 8-Bit Pulse Width Modulator mode. The duty cycle for 8-Bit PWM Mode is given by Equation 22.2.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
 256 – PCA0CPHn 
DutyCycle = --------------------------------------------------256
Equation 22.2. 8-Bit PWM Duty Cycle
Using Equation 22.2, the largest duty cycle is 100% (PCA0CPHn = 0), and the smallest duty cycle is
0.39% (PCA0CPHn = 0xFF). A 0% duty cycle may be generated by clearing the ECOMn bit to ‘0’.
Write to
PCA0CPLn
0
PCA0CPHn
ENB
Reset
Write to
PCA0CPHn
ENB
1
PCA0CPMn
P ECCMT P E
WC A A AOWC
MOPP TGMC
1 MP N n n n F
6 n n n
n
n
0
0 0 x 0
PCA0CPLn
x
Enable
8-bit
Comparator
match
S
R
PCA Timebase
SET
CLR
Q
CEXn
Q
PCA0L
Overflow
Figure 22.8. PCA 8-Bit PWM Mode Diagram
262
Rev. 1.3
Crossbar
Port I/O
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
22.2.6. 16-Bit Pulse Width Modulator Mode
A PCA module may also be operated in 16-Bit PWM mode. In this mode, the 16-bit capture/compare module defines the number of PCA clocks for the low time of the PWM signal. When the PCA counter matches
the module contents, the output on CEXn is asserted high; when the counter overflows, CEXn is asserted
low. To output a varying duty cycle, new value writes should be synchronized with PCA CCFn match interrupts. 16-Bit PWM Mode is enabled by setting the ECOMn, PWMn, and PWM16n bits in the PCA0CPMn
register. For a varying duty cycle, match interrupts should be enabled (ECCFn = 1 AND MATn = 1) to help
synchronize the capture/compare register writes. The duty cycle for 16-Bit PWM Mode is given by
Equation 22.3.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
 65536 – PCA0CPn 
DutyCycle = ----------------------------------------------------65536
Equation 22.3. 16-Bit PWM Duty Cycle
Using Equation 22.3, the largest duty cycle is 100% (PCA0CPn = 0), and the smallest duty cycle is
0.0015% (PCA0CPn = 0xFFFF). A 0% duty cycle may be generated by clearing the ECOMn bit to ‘0’.
Write to
PCA0CPLn
0
ENB
Reset
Write to
PCA0CPHn
ENB
1
PCA0CPMn
P ECCMT P E
WC A A AOWC
MOPP TGMC
1 MP N n n n F
6 n n n
n
n
1
0 0 x 0
PCA0CPHn
PCA0CPLn
x
Enable
16-bit Comparator
match
S
R
PCA Timebase
PCA0H
SET
CLR
Q
CEXn
Crossbar
Port I/O
Q
PCA0L
Overflow
Figure 22.9. PCA 16-Bit PWM Mode
Rev. 1.3
263
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
22.3. Watchdog Timer Mode
A programmable watchdog timer (WDT) function is available through the PCA Module 4. The WDT is used
to generate a reset if the time between writes to the WDT update register (PCA0CPH4) exceed a specified
limit. The WDT can be configured and enabled/disabled as needed by software.
With the WDTE and/or WDLCK bits set to ‘1’ in the PCA0MD register, Module 4 operates as a watchdog
timer (WDT). The Module 4 high byte is compared to the PCA counter high byte; the Module 4 low byte
holds the offset to be used when WDT updates are performed. The Watchdog Timer is enabled on
reset. Writes to some PCA registers are restricted while the Watchdog Timer is enabled.
22.3.1. Watchdog Timer Operation
While the WDT is enabled:
•
•
•
•
•
•
PCA counter is forced on.
Writes to PCA0L and PCA0H are not allowed.
PCA clock source bits (CPS2-CPS0) are frozen.
PCA Idle control bit (CIDL) is frozen.
Module 4 is forced into Watchdog Timer mode.
Writes to the Module 4 mode register (PCA0CPM4) are disabled.
While the WDT is enabled, writes to the CR bit will not change the PCA counter state; the counter will run
until the WDT is disabled. The PCA counter run control (CR) will read zero if the WDT is enabled but user
software has not enabled the PCA counter. If a match occurs between PCA0CPH4 and PCA0H while the
WDT is enabled, a reset will be generated. To prevent a WDT reset, the WDT may be updated with a write
of any value to PCA0CPH4. Upon a PCA0CPH4 write, PCA0H plus the offset held in PCA0CPL4 is loaded
into PCA0CPH4 (See Figure 22.10).
PCA0MD
CWW
I DD
DT L
L E C
K
CCCE
PPPC
SSSF
2 1 0
PCA0CPH4
Enable
PCA0CPL4
Write to
PCA0CPH4
8-bit Adder
8-bit
Comparator
PCA0H
Match
Reset
PCA0L Overflow
Adder
Enable
Figure 22.10. PCA Module 4 with Watchdog Timer Enabled
Note that the 8-bit offset held in PCA0CPH4 is compared to the upper byte of the 16-bit PCA counter. This
offset value is the number of PCA0L overflows before a reset. Up to 256 PCA clocks may pass before the
first PCA0L overflow occurs, depending on the value of the PCA0L when the update is performed. The
total offset is then given (in PCA clocks) by Equation 22.4, where PCA0L is the value of the PCA0L register
at the time of the update.
264
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Offset =  256  PCA0CPL4  +  256 – PCA0L 
Equation 22.4. Watchdog Timer Offset in PCA Clocks
The WDT reset is generated when PCA0L overflows while there is a match between PCA0CPH4 and
PCA0H. Software may force a WDT reset by writing a ‘1’ to the CCF4 flag (PCA0CN.4) while the WDT is
enabled.
22.3.2. Watchdog Timer Usage
To configure the WDT, perform the following tasks:
1. Disable the WDT by writing a ‘0’ to the WDTE bit.
2. Select the desired PCA clock source (with the CPS2-CPS0 bits).
3. Load PCA0CPL4 with the desired WDT update offset value.
4. Configure the PCA Idle mode (set CIDL if the WDT should be suspended while the CPU is in
Idle mode).
5. Enable the WDT by setting the WDTE bit to ‘1’.
6. (optional) Lock the WDT (prevent WDT disable until the next system reset) by setting the
WDLCK bit to ‘1’.
7. Write a value to PCA0CPH4 to reload the WDT.
The PCA clock source and Idle mode select cannot be changed while the WDT is enabled. The watchdog
timer is enabled by setting the WDTE or WDLCK bits in the PCA0MD register. When WDLCK is set, the
WDT cannot be disabled until the next system reset. If WDLCK is not set, the WDT is disabled by clearing
the WDTE bit.
The WDT is enabled following any reset. The PCA0 counter clock defaults to the system clock divided by
12, PCA0L defaults to 0x00, and PCA0CPL4 defaults to 0x00. Using Equation 22.4, this results in a WDT
timeout interval of 256 PCA clocks. Table 22.3 lists some example timeout intervals for typical system
clocks.
Table 22.3. Watchdog Timer Timeout Intervals1
System Clock (Hz)
12,000,000
12,000,000
12,000,000
24,000,000
24,000,000
24,000,000
1,500,0002
PCA0CPL4
255
128
32
255
128
32
255
Timeout Interval (ms)
65.5
33.0
8.4
32.8
16.5
4.2
524.3
1,500,0002
128
264.2
1,500,0002
32,768
32,768
32,768
32
67.6
255
128
32
24,000
12,093.75
3,093.75
Notes:
1. Assumes SYSCLK / 12 as the PCA clock source, and a PCA0L
value of 0x00 at the update time.
2. System Clock reset frequency.
Rev. 1.3
265
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
22.4. Register Descriptions for PCA
Following are detailed descriptions of the special function registers related to the operation of the PCA.
SFR Definition 22.1. PCA0CN: PCA Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
CF
Bit7
CR
-
CCF4
CCF3
CCF2
CCF1
CCF0
00000000
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
(bit addressable)
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
266
Reset Value
0xD8
CF: PCA Counter/Timer Overflow Flag.
Set by hardware when the PCA Counter/Timer overflows from 0xFFFF to 0x0000. When the
Counter/Timer Overflow (CF) interrupt is enabled, setting this bit causes the CPU to vector
to the PCA interrupt service routine. This bit is not automatically cleared by hardware and
must be cleared by software.
CR: PCA Counter/Timer Run Control.
This bit enables/disables the PCA Counter/Timer.
0: PCA Counter/Timer disabled.
1: PCA Counter/Timer enabled.
UNUSED. Read = 0b, Write = don't care.
CCF4: PCA Module 4 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF4 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
CCF3: PCA Module 3 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF3 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
CCF2: PCA Module 2 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF2 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
CCF1: PCA Module 1 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF1 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
CCF0: PCA Module 0 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF0 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 22.2. PCA0MD: PCA Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
CIDL
WDTE
Bit7
Bit6
Reset Value
WDLCK
-
CPS2
CPS1
CPS0
ECF
01000000
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xD9
Bit7:
CIDL: PCA Counter/Timer Idle Control.
Specifies PCA behavior when CPU is in Idle Mode.
0: PCA continues to function normally while the system controller is in Idle Mode.
1: PCA operation is suspended while the system controller is in Idle Mode.
Bit6:
WDTE: Watchdog Timer Enable
If this bit is set, PCA Module 4 is used as the watchdog timer.
0: Watchdog Timer disabled.
1: PCA Module 4 enabled as Watchdog Timer.
Bit5:
WDLCK: Watchdog Timer Lock
This bit enables and locks the Watchdog Timer. When WDLCK is set to ‘1’, the Watchdog
Timer may not be disabled until the next system reset.
0: Watchdog Timer unlocked.
1: Watchdog Timer enabled and locked.
Bit4:
UNUSED. Read = 0b, Write = don't care.
Bits3–1: CPS2–CPS0: PCA Counter/Timer Pulse Select.
These bits select the timebase source for the PCA counter.
CPS2
0
0
0
CPS1
0
0
1
CPS0
0
1
0
0
1
1
1
1
1
1
0
0
1
1
0
1
0
1
Timebase
System clock divided by 12
System clock divided by 4
Timer 0 overflow
High-to-low transitions on ECI (max rate = system clock
divided by 4)
System clock
External clock divided by 8*
Reserved
Reserved
*Note: External oscillator source divided by 8 is synchronized with the system clock.
Bit0:
ECF: PCA Counter/Timer Overflow Interrupt Enable.
This bit sets the masking of the PCA Counter/Timer Overflow (CF) interrupt.
0: Disable the CF interrupt.
1: Enable a PCA Counter/Timer Overflow interrupt request when CF (PCA0CN.7) is set.
Note: When the WDTE bit is set to ‘1’, the PCA0MD register cannot be modified. To change the
contents of the PCA0MD register, the Watchdog Timer must first be disabled.
Rev. 1.3
267
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 22.3. PCA0CPMn: PCA Capture/Compare Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
PWM16n
ECOMn
CAPPn
CAPNn
MATn
TOGn
PWMn
ECCFn
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xDA, 0xDB,
0xDC, 0xDD,
0xDE
PCA0CPMn Address:
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
268
PCA0CPM0 = 0xDA (n = 0), PCA0CPM1 = 0xDB (n = 1),
PCA0CPM2 = 0xDC (n = 2), PCA0CPM3 = 0xDD (n = 3),
PCA0CPM4 = 0xDE (n = 4)
PWM16n: 16-bit Pulse Width Modulation Enable.
This bit selects 16-bit mode when Pulse Width Modulation mode is enabled (PWMn = 1).
0: 8-bit PWM selected.
1: 16-bit PWM selected.
ECOMn: Comparator Function Enable.
This bit enables/disables the comparator function for PCA module n.
0: Disabled.
1: Enabled.
CAPPn: Capture Positive Function Enable.
This bit enables/disables the positive edge capture for PCA module n.
0: Disabled.
1: Enabled.
CAPNn: Capture Negative Function Enable.
This bit enables/disables the negative edge capture for PCA module n.
0: Disabled.
1: Enabled.
MATn: Match Function Enable.
This bit enables/disables the match function for PCA module n. When enabled, matches of
the PCA counter with a module's capture/compare register cause the CCFn bit in PCA0MD
register to be set to logic 1.
0: Disabled.
1: Enabled.
TOGn: Toggle Function Enable.
This bit enables/disables the toggle function for PCA module n. When enabled, matches of
the PCA counter with a module's capture/compare register cause the logic level on the
CEXn pin to toggle. If the PWMn bit is also set to logic 1, the module operates in Frequency
Output Mode.
0: Disabled.
1: Enabled.
PWMn: Pulse Width Modulation Mode Enable.
This bit enables/disables the PWM function for PCA module n. When enabled, a pulse width
modulated signal is output on the CEXn pin. 8-bit PWM is used if PWM16n is cleared; 16-bit
mode is used if PWM16n is set to logic 1. If the TOGn bit is also set, the module operates in
Frequency Output Mode.
0: Disabled.
1: Enabled.
ECCFn: Capture/Compare Flag Interrupt Enable.
This bit sets the masking of the Capture/Compare Flag (CCFn) interrupt.
0: Disable CCFn interrupts.
1: Enable a Capture/Compare Flag interrupt request when CCFn is set.
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 22.4. PCA0L: PCA Counter/Timer Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
00000000
0xF9
Bits 7–0: PCA0L: PCA Counter/Timer Low Byte.
The PCA0L register holds the low byte (LSB) of the 16-bit PCA Counter/Timer.
SFR Definition 22.5. PCA0H: PCA Counter/Timer High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xFA
Bits 7–0: PCA0H: PCA Counter/Timer High Byte.
The PCA0H register holds the high byte (MSB) of the 16-bit PCA Counter/Timer.
SFR Definition 22.6. PCA0CPLn: PCA Capture Module Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xFB, 0xE9,
0xEB, 0xED,
0xFD
PCA0CPLn Address:
PCA0CPL0 = 0xFB (n = 0), PCA0CPL1 = 0xE9 (n = 1),
PCA0CPL2 = 0xEB (n = 2), PCA0CPL3 = 0xED (n = 3),
PCA0CPL4 = 0xFD (n = 4)
Bits7–0: PCA0CPLn: PCA Capture Module Low Byte.
The PCA0CPLn register holds the low byte (LSB) of the 16-bit capture module n.
Rev. 1.3
269
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
SFR Definition 22.7. PCA0CPHn: PCA Capture Module High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address:
0xFC, 0xEA,
0xEC,0xEE,
0xFE
PCA0CPHn Address:
PCA0CPH0 = 0xFC (n = 0), PCA0CPH1 = 0xEA (n = 1),
PCA0CPH2 = 0xEC (n = 2), PCA0CPH3 = 0xEE (n = 3),
PCA0CPH4 = 0xFE (n = 4)
Bits7–0: PCA0CPHn: PCA Capture Module High Byte.
The PCA0CPHn register holds the high byte (MSB) of the 16-bit capture module n.
270
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
23. C2 Interface
C8051F34x devices include an on-chip Silicon Labs 2-Wire (C2) debug interface to allow Flash programming and in-system debugging with the production part installed in the end application. The C2 interface
uses a clock signal (C2CK) and a bi-directional C2 data signal (C2D) to transfer information between the
device and a host system. See the C2 Interface Specification for details on the C2 protocol.
23.1. C2 Interface Registers
The following describes the C2 registers necessary to perform Flash programming functions through the
C2 interface. All C2 registers are accessed through the C2 interface as described in the C2 Interface Specification.
C2 Register Definition 23.1. C2ADD: C2 Address
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–0: The C2ADD register is accessed via the C2 interface to select the target Data register for
C2 Data Read and Data Write commands.
Address
0x00
0x01
0x02
0xAD
Description
Selects the Device ID register for Data Read instructions
Selects the Revision ID register for Data Read instructions
Selects the C2 Flash Programming Control register for Data Read/Write instructions
Selects the C2 Flash Programming Data register for Data Read/Write instructions
C2 Register Definition 23.2. DEVICEID: C2 Device ID
Reset Value
00001111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
This read-only register returns the 8-bit device ID: 0x0F (C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D).
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C2 Register Definition 23.3. REVID: C2 Revision ID
Reset Value
Variable
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
This read-only register returns the 8-bit revision ID.
C2 Register Definition 23.4. FPCTL: C2 Flash Programming Control
Reset Value
00000000
Bit7
Bits7–0
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
FPCTL: Flash Programming Control Register.
This register is used to enable Flash programming via the C2 interface. To enable C2 Flash
programming, the following codes must be written in order: 0x02, 0x01. Note that once C2
Flash programming is enabled, a system reset must be issued to resume normal operation.
C2 Register Definition 23.5. FPDAT: C2 Flash Programming Data
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–0: FPDAT: C2 Flash Programming Data Register.
This register is used to pass Flash commands, addresses, and data during C2 Flash
accesses. Valid commands are listed below.
Code
0x06
0x07
0x08
0x03
272
Command
Flash Block Read
Flash Block Write
Flash Page Erase
Device Erase
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23.2. C2 Pin Sharing
The C2 protocol allows the C2 pins to be shared with user functions so that in-system debugging and
Flash programming functions may be performed. This is possible because C2 communication is typically
performed when the device is in the halt state, where all on-chip peripherals and user software are stalled.
In this halted state, the C2 interface can safely ‘borrow’ the C2CK (RST) and C2D (P3.0) pins. Note that
the C2D pin is shared on the 32-pin packages only (C8051F342/3/6/7/9/A/B). In most applications, external resistors are required to isolate C2 interface traffic from the user application. A typical isolation configuration is shown in Figure 23.1.
C8051Fxxx
RST (a)
C2CK
Input (b)
C2D
Output (c)
C2 Interface Master
Figure 23.1. Typical C2 Pin Sharing
The configuration in Figure 23.1 assumes the following:
1. The user input (b) cannot change state while the target device is halted.
2. The RST pin on the target device is used as an input only.
Additional resistors may be necessary depending on the specific application.
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DOCUMENT CHANGE LIST
Revision 0.5 to Revision 1.0
•
•
•
•
•
Updated Table 3.1, “Global DC Electrical Characteristics,” on page 25.
Updated Table 5.1, “ADC0 Electrical Characteristics,” on page 56.
Various small text changes.
Updated Table 8.1, “Voltage Regulator Electrical Specifications,” on page 69.
Updated Flash security behavior.
Revision 1.0 to Revision 1.1
•
•
•
•
•
•
•
•
•
•
•
•
Added two new part numbers C8051F348/9 and made associated changes.
Corrected the entries "24 kHz" and "48 kHz" to "24 MHz" and "48 MHz" in the "Conditions" column of
Table 3.1, "Global DC Electrical Characteristics," on page 38.
Added note to configure external interrupt pin as open-drain with a “1” in the port latch in Section 9.3.2.
"External Interrupts" on page 96.
Various small text changes.
Updated the figures in Section 15.1. "Priority Crossbar Decoder" and added a new figure to clarify
crossbar capabilities.
Corrected the description of the UNDRUN bit in USB Register Definition 16.19. "EINCSRL: USB0 IN
Endpoint Control Low Byte" on page 198 to clarify that this bit works only in Isochronous Mode.
Corrected the maximum SMBus speed from 1/10th to 1/20th of the system clock in Section 17.
"SMBus" on page 205.
Corrected the descriptions for the following states and the corresponding typical response options in
Table 17.4. "SMBus Status Decoding" on page 221:
- Slave Transmitter (Status Vector: 0101)
- Slave Receiver (Status Vector: 0001)
Corrected the bit location of MSTEN from SPI0CN.6 to SPI0CFG.6 in Section 20.2. "SPI0 Master
Operation" on page 243.
Corrected the description of the WCOL bit in SFR Definition 20.2. "SPI0CN: SPI0 Control" on page
249 to match the description in Section 20.4. "SPI0 Interrupt Sources" on page 245.
Clarified the following parameters in Table 8.1, “Voltage Regulator Electrical Specifications,” on
page 69:
- VBUS Detection Input High and Low Voltages
- Dropout Voltage
Updated the package drawings with additional dimensions in Figure 4.2 and Table 4.2, “TQFP-48
Package Dimensions,” on page 32, and Figure 4.4 and Table 4.4, “LQFP-32 Package Dimensions,”
on page 35.
Revision 1.1 to Revision 1.2
•
•
•
Added two new part numbers C8051F34A/B and made associated changes.
Corrected references to locations of T0M and T1M in the SFR definition of TMOD on page 240.
Corrected instances of "8k" to "4k" in the SFR definition of EMI0CF on page 118.
Revision 1.2 to Revision 1.3
•
Added QFN-32 package.
Revision 1.3 to Revision 1.4
•
274
Added C8051F34C and C8051F34D devices.
Rev. 1.3
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
NOTES:
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