Timer a, Reload Register Operation | Jameco Electronics 2000, 3000

11.1 Timer A

Timer A consists of ten separate countdown timers A1–A10 as shown in Figure 11-1.

Timers A1 and A2–A10 are 8-bit countdown registers as shown in Figure 11-2.The reload register can contain any number in the range from 0 to 255. The counter divides by (n+1). For example, if the reload register contains 127, then 128 pulses enter on the left before a pulse exits on the right. If the reload register contains zero, then each pulse on the left results in a pulse on the right, that is, there is division by one.

	8-bit reload register
Clock in	8-bit down counter				load
	8-bit down counter						pulse on zero count out
							pulse on zero count out
Input clock
Count value	2	2	1	1	0	0	N	N-1
		Output pulse

Figure 11-2. Reload Register Operation

The timer systems can be driven by the peripheral clock, or peripheral clock divided by two. This clock is always the same as the processor clock, or it is faster than the processor clock by a factor of eight. The output pulses are always one clock long. Clocking of the counters takes place on the negative edge of this pulse. When the counter reaches zero, the reload register is loaded on the next input pulse instead of a count being performed. The reload registers may be reloaded at any time since the peripheral clock is synchronous with the processor clock.

Timers A2, A3, A4, A5, A6 and A7 always provide the baud clock for Serial Ports E, F, A, B, C, and D respectively. Except for very low baud rates, clock A1 does not need to be used to prescale the input clock for timers A2–A7. For example, if the system clock is 11.0592 MHz, and the timer A4 divides by 144, an asynchronous baud rate of 2400 bps can be achieved in one step (assuming that the timer is clocked by peripheral clock divided by two). The clock input to the serial port can be 8 or 16 times the baud rate for asynchronous mode and 8 times the baud rate for synchronous mode. The maximum asynchronous baud rate with a 11.0592 MHz clock would be (11,059,200/(1*8) = 1,382,400.

150	Rabbit 3000 Microprocessor

Image 159

Jameco Electronics 2000, 3000 manual Timer a, Reload Register Operation

Contents

Page Rabbit 3000 Microprocessor Rabbit Semiconductor Trademarks Table of Contents Rabbit Internal I/O Registers Parallel Ports 129 Rabbit 3000 Clocks 209 Appendix B. Rabbit 3000 Revisions 273 Rabbit 3000 Microprocessor Introduction Features and Specifications Rabbit User’s Manual 1shows a block diagram of the Rabbit CPU Summary of Rabbit 3000 Advantages Differences Rabbit 3000 vs. Rabbit Feature Rabbit Serial ports with support for SDLC/HDLC IrDA Rabbit 3000 Design Features Rabbit 8-bit Processor vs. Other Processors Overview of On-Chip Peripherals and Features 1 5 V Tolerant InputsSerial Ports 4 32.768 kHz Oscillator Input System Clock Cascaded Output Registers for Parallel Ports D and E Parallel I/O Rabbit Slave Port Auxiliary I/O Bus Timers PWM Input Capture Channels Pulse Width Modulation Outputs Quadrature Encoder Inputs Programming Port Separate Core and I/O Power PinsDesign Standards Spread Spectrum Clock Dynamic C Support for the Rabbit Standard Bios Rabbit 3000 Microprocessor Processor Registers Details on Rabbit Microprocessor Features Rabbit 3000 Microprocessor Addressing Memory Components Memory Mapping Example of Memory Mapping Operation 4shows a memory interface unit Extended Code Space Use of XPC Segment Separate I and D Space Extending Data Memory Xpc window stack Using the Stack Segment for Data Storage Data RAM Root Code Practical Memory Considerations User’s Manual Instruction Set Outline Load or Store Data from or to a Constant Address Load Immediate Data to a Register Other 8-bit loads and stores are the following Load or Store Data Using an Index Register Register Exchanges Register-to-Register Move 7 16-bit Arithmetic and Logical Ops Push and Pop Instructions Bool SBC instruction can also be used to perform a sign extension Input/Output Instructions Manipulation of Boolean Variables How to Do It in Assembly Language-Tips and TricksZero HL in 4 Clocks Exchanges Not Directly Implemented Comparisons of Integers HLB Atomic Moves from Memory to I/O Space Interrupt Priority Interrupt Structure Processor Priority Effect on Interrupts Effect of Processor Priorities on Interrupts Privileged Instructions, Critical Sections and Semaphores Multiple External Interrupting Devices Critical Sections Semaphores Using Bit B,HL Computed Long Calls and Jumps Precisely Timed Output Pulses Rabbit Capabilities Pulse Width Modulation to Reduce Relay Power Open-Drain Outputs Used for Key Scan Using Open-Drain Outputs for Key Scan Cold Boot Slave Port Slave Rabbit As a Protocol Uart PIN Assignments and Functions Pinout Lqfp Package Same pin dimensions apply along the x axis and the y axis Mechanical Dimensions and Land Pattern PC Board Land Pattern for Rabbit 3000 128-pin Lqfp Ball Grid Array Package C D E F G H J K L M Nominal Ball Tolerance Ball Pitch Nominal Land Ball and Land Size DimensionsDesign Considerations All dimensions in mm Key Feature Recommendation BGA Package Outline Lqfp Tfbga Rabbit Pin DescriptionsRabbit Pin Descriptions Pin Pin Group Pin Name Direction Function Numbers Vddcore Bus Timing Read and Write Bus Timing Pins With Alternate Functions Description of Pins with Alternate Functions PF7 PWM3 AQD2A Parallel Port x Alternate Functions Control Bits Parallel Port x Alternate Functions Symbol Parameter Test Conditions Min Typ Max Units DC Characteristics3 Volt DC Characteristics Symbol Parameter Maximum Rating I/O Buffer Sourcing and Sinking Limit Rabbit 3000 Microprocessor Rabbit Internal I/O Registers On-Chip Peripheral ISR Starting Address Rabbit 3000 Peripherals and Interrupt Service Vectors Default Values for all the Peripheral Control Registers Register Name Mnemonic Address ResetRabbit Internal I/O Registers Grev PEB7R PWM0R Tbcsr Sdar Processor Identification Global ROM Configuration RegisterGlobal RAM Configuration Register Miscellaneous Functions Gcpu Rabbit Oscillators and ClocksGlobal CPU Register Global Revision Register Rabbit Gcsr Global Control/Status RegisterClock Select Field of Gcsr Global Control/Status Register Gcdr Recommended Delays Set In Gcdr for Clock DoublerClock Doubler Global Clock Double Register Effect of Clock Doubler User’s Manual Reduction in Peak Spectral Strength from Spectrum Spreader Clock Spectrum Spreader Chip Select Options for Low Power Address = 0x0D Global Power Save Control Register Short Chip Select Memory Read Global Output Control Register Gocr = 0x0E Output Pins CLK, STATUS, /WDTOUT, /BUFEN Time/Date Clock Real-Time Clock 11. Real-Time Clock Control Register Rtccr adr = 10. Real-Time Clock RTCxR Data Registers 12. Watchdog Timer Control Register Wdtcr adr = Watchdog Timer 13. Watchdog Timer Test Register Wdttr adr = System Reset Pin Name Direction Reset Low Post-Reset† Recognized by CPU 14. Rabbit 3000 Reset Sequence and State of I/O Pins Rabbit Interrupt Structure 15. Interrupts-Priority and Action to Clear Requests External Interrupt Line Logic External Interrupts Interrupt Vectors INT0 EIR,0x00/INT1 EIR,0x08 16. Control Registers for External InterruptsReg Name Reg Address Bits 7,6 Bits 5,4 Bits 3,2 Bits 1,0 Bootstrap Operation 102 Rabbit 3000 Microprocessor Pulse Width LSBs 1st 2nd 3rd 4th Pulse Width Modulator 18. PWM MSB x Register 17. PWM LSB x Register Input Capture 106 Rabbit 3000 Microprocessor 19. Input Capture Control/Status Register Input Capture Control/Status RegisterIccsr ICT1R 20. Input Capture Control Register21. Input Capture Trigger x Register Iccr 22. Input Capture Source x Register 23. Input Capture LSB x Register24. Input Capture MSB x Register Quadrature Decoder Rejected 25. Quadrature Decoder Control/Status Register Quad Decode Control/Status RegisterQdcsr QDC1R 26. Quadrature Decoder Control Register27. Quadrature Decoder Count Register Qdcr 114 Rabbit 3000 Microprocessor Interface for Static Memory Chips Memory Interface and Mapping Rabbit Data Lines Static Address Lines Memory FlashRAM Memory Mapping Overview Memory-Mapping UnitProcessor Memory Mapping Unit Interface Memory Chips Segment Register Function 64KSegment Registers Segment Size Register Memory Interface Unit Memory Bank Control Register x MBxCR = 0x014 + Memory Bank Control Registers Mmidr Optional A16, A19 Inversions by Segment /CS1 EnableMMU Instruction/Data Register Mmidr = MMU Instruction/Data Register Memory Timing Control Register Memory Timing Control Register MTCR, adr =MMU Expanded Code Register Mecr Bdcr Allocation of Extended Code and DataBreakpoint/Debug Control Register BDCR, adr = 0x01C Breakpoint/Debug Control Register Instruction and Data Space Support RAM Use of Physical Memory Separate I & D Space Model How the Compiler Compiles to Memory 128 Rabbit 3000 Microprocessor Parallel Ports Parallel Port a Parallel Port a RegistersParallel Port a Data Register Bit Functions Parallel Port B Parallel Port B RegistersParallel Port B Register Bit Functions Parallel Port C Parallel Port C RegistersParallel Port C Register Bit Functions Parallel Port D Registers Parallel Port D PD7 Parallel Port D Register functions Parallel Port D Control Register adr =Bits 7 Bits 5 Bits 3 Bits 1 136 Rabbit 3000 Microprocessor PE0 Parallel Port E 10. Parallel Port E Registers 12. Parallel Port E Control Register adr = 11. Parallel Port E Register functions Parallel Port F 13. Parallel Port F Registers14. Parallel Port F Register Functions 15. Parallel Port F Control Register adr = 0x03C Using Parallel Port a and Parallel Port F Summary Parallel Port a Parallel Port F Parallel Port G 16. Parallel Port G Registers17. Parallel Port G Data Register Functions Parallel Port G Control Register adr= 0x04C External I/O Timing with 1 wait state 10. I/O Bank Control RegistersWrite data Write strobe T1 Tw T2 Read data Read strobe Chip select strobe I/O Bank x Control Register Control Register Port E Address Pin A1513 Range External I/O Register Address Range and Pin Mapping 148 Rabbit 3000 Microprocessor Timers Reload Register Operation Timer a Timer a I/O Registers Timer a I/O Registers Timer a Capabilities Timer a Control and Status RegisterTacsr User’s Manual 153 Tapr Timer a Control RegisterTimer a Prescale Register Tacr Practical Use of Timer a Timer B Timer B RegistersRegister Name Mnemonic Reset Address Tbcr Timer B Control and Status RegisterTimer B Control Register Tbcsr 12. Timer B Count LSB Register Timer B Count MSB x Registers10. Timer B Count LSB x Registers 11. Timer B Count MSB Register Using Timer B 160 Rabbit 3000 Microprocessor Serial Port Signals Serial Port Signal Name FunctionRabbit Serial Ports Clka User’s Manual 163 Serial Port Register Layout Signals Shown at Microprocessor Tx Pin User’s Manual 165 Serial Port C Registers Serial Port RegistersSerial Port a Registers Serial Port B Registers Serial Port D Registers Serial Port E RegistersSerial Port F Registers Address Register All Ports Data Register All Ports 10. Long Stop Register All Ports 11. Status Register Asynchronous Mode Only All Ports 12. Status Register Clocked Serial Ports A-D only Bits Value Description Clocked serial mode only Bits Value Description Hdlc mode only 13. Status Register Hdlc Mode Ports E and F only 14. Serial Port Control Register Ports a and B SacrSbcr Sdcr 15. Serial Port Control Register Ports C and DSccr Address = 0xE4 Sfcr 16. Serial Port Control Register Ports E and FSecr Address = 0xCC 17. Extended Register Asynchronous Mode All Ports 18. Extended Register Clocked Serial Mode Ports A-D only 19. Extended Register Hdlc Mode Ports E and F only Transmitter IRQ Serial Port Interrupt Transmit Serial Data Timing Serial Port Synchronization Receive Serial Data Timing Clocked Serial Ports Clock Polarities Supported in Clocked Serial Mode User’s Manual 183 184 Rabbit 3000 Microprocessor Clocked Serial Timing Clocked Serial Timing With Internal ClockClocked Serial Timing with External Clock Valid Synchronous Communications on Ports E and F Last Byte Bit Pattern Valid Data Hits User’s Manual 189 190 Rabbit 3000 Microprocessor User’s Manual 191 Push AF IOI LD A,SCSR Serial Port Software Suggestions Transmitting Dummy Characters Controlling an RS-485 Driver and Receiver Transmitting and Detecting a Break Using a Serial Port to Generate a Periodic Interrupt Stop bit Parity, Extra Stop Bits with 7-Data-Bit CharactersParity, Extra Stop Bits with 8-Data-Bit Characters Stop bit Start bit Data bits 9th bit low Supporting 9th Bit Communication Protocols Rabbit-Only Master/Slave ProtocolData Framing/Modbus User’s Manual 197 198 Rabbit 3000 Microprocessor SRD SCS Rabbit Slave Port Slave Port Read Cycle Following table explains the parameters used in Figure Symbol Parameter Minimum Maximum Slaveattn PB7 Typical Connection Slave Rabbit to Master Rabbit Register Mnemonic Internal Address External Address Hardware Design of Slave Port InterconnectionSlave Port Registers Slave Port Registers Bit Bits 6,5 Bit 3,2 Bits 1,0 Write Only Read Only Slave Port Control Register Spcr adr = Applications and Communications Protocols for Slaves Slave ApplicationsSlave Port Status Register Spsr adr = Master-Slave Messaging Protocol 208 Rabbit 3000 Microprocessor Rabbit 3000 Main Oscillator Circuit Rabbit 3000 Clocks Low-Power Design EMI Control Using the Clock Spectrum Spreader Power Supply Connections and Board Layout GCM1R Spread Spectrum Enable/Disable RegisterSpread Spectrum Mode Select GCM0R 214 Rabbit 3000 Microprocessor Memory Requirements at 3.3 V, -40C to +85C, Adr Bus 60 pF AC Timing SpecificationsMemory Access Time Access Enable Access MHz Data and Clock Delays VDD ±10%, Temp, -40C-+85C maximum VDDNormal Strong 30 pF 60 pF 90 pF No dbl/dbl CSx Memory Read Time Delays Memory Write Time DelaysTime Delay Output Capacitance 30 pF 60 pF 90 pF CLK A190 CSx WEx D70 Example Clock Doubler Max-Min Clock Low Times 222 Rabbit 3000 Microprocessor Bufen 16.2 I/O Access Time I/O Write Time Delays I/O Read Time Delays Further Discussion of Bus and Clock Timing Clock Doubler and Memory Timing Period Frequency Maximum Clock SpeedsMaximum Clock Speeds at 3.3 V Preliminary Conditions Commercial Ratings Industrial Ratings External Oscillator Buffer User’s Manual 229 Power and Current Consumption Rabbit 3000 System Current vs. Frequency at 3.3 11. Sleepy Mode Current Consumption Current Consumption Mechanisms Sleepy Mode Current Consumption Memory Current Consumption Current is negligible for V 1.14 Battery-Backed Clock Current Consumption Voltage Current incl built-in buffer Reduced-Power External Main Oscillator Rabbit Bios and Virtual Driver BiosBios Services Periodic Interrupt Bios AssumptionsWatchdog Timer Support Virtual Driver User’s Manual 239 240 Rabbit 3000 Microprocessor Other Rabbit Software Power Management Support Using Assembly Language Using Library FunctionsReading and Writing I/O Registers Atomic Instruction Shadow RegistersUpdating Shadow Registers Interrupt While Updating Registers Timer and Clock Usage Write-only Registers Without Shadow RegistersNon-atomic Instructions Format of the structure used is the following 246 Rabbit 3000 Microprocessor Summary Rabbit Instructions Flag Description Spreadsheet Conventions Rabbit Z180 Meaning Symbols 19.4 16-bit Indexed Loads and Stores Load Immediate DataLoad & Store to Immediate Address 19.3 8-bit Indexed Load and Store Register to Register Moves 19.5 16-bit Load and Store 20-bit Address Exchange Instructions Stack Manipulation Instructions19.9 16-bit Arithmetic and Logical Ops ADD A,HL 19.10 8-bit Arithmetic and Logical Ops 19.12 8-bit Increment and Decrement 19.11 8-bit Bit Set, Reset and Test 19.14 8-bit Shifts and Rotates 19.13 8-bit Fast a Register Operations Block Move Instructions Instruction Prefixes Miscellaneous Instructions Control Instructions Jumps and Calls Following instructions are privileged Privileged Instructions Differences Rabbit VS. Z80/Z180 Instructions Z80/Z180 Instructions Dropped Rabbit Instructions to Use Flag Register Key IOI and IOE I Column Symbol Key Rabbit Z180 Meaning Z V C EX AF,AF LD A,BC LDP HL,IX RRA 268 Rabbit 3000 Microprocessor Programming Port PIN Assignments Appendix A. the Rabbit Programming Port Alternate Programming Port Use of the Programming Port as a Diagnostic/Setup Port Suggested Rabbit Crystal Frequencies Non-Stock Crystals Appendix B. Rabbit 3000 Revisions 274 Rabbit 3000 Microprocessor User’s Manual 275 IL1T/IZ1T IL2T/IZ2T Discussion of Fixes and ImprovementsTable B-1. Summary of Rabbit 3000 Improvements and Fixes Rabbit Description 3000 3000A Rabbit Internal I/O Registers Table B-2. Reset State of New Rabbit 3000A I/O Registers Iuer Rabbit Register Name Mnemonic 3000 3000A Address Reset On-Chip Peripheral Address Range ISR Starting Address Peripheral and ISR Address User’s Manual 281 Gcpu Grev Revision-Level ID RegisterTable B-5. Rabbit 3000 Revision Identification Information Processor Revision Package System/User Mode Wpcr Memory ProtectionTable B-6. Write Protect Control Register Write Protect Control Register Table B-7. Write Protect Low Register Write Protect Low RegisterWplr Wpsar Table B-8. Write Protect High RegisterTable B-9. Write Protect Segment x Register Wphr Wpsblr Table B-10. Write Protect Segment x Low RegisterWrite Protect Segment x Low Register Wpsalr Wpsbhr Table B-11. Write Protect Segment x High RegisterWrite Protect Segment x High Register Wpsahr Figure B-2. Simple Stack Protection Layout Stack Protection Table B-12. Stack Limit Control Register Table B-13. Stack Low Limit RegisterTable B-14. Stack High Limit Register Ramsr RAM Segment RelocationTable B-15. RAM Segment Register RAM Segment Register Wdtcr Secondary Watchdog TimerTable B-16. Watchdog Timer Control Register-Updated Table B-17. Secondary Watchdog Timer Register New UMA/UMS Opcodes New OpcodesTable B-18. New Rabbit 3000 Opcodes Instruction Bytes Clks Operation IOI/IOE Table B-19. Rabbit 3000 Revision Block Copy Opcode EffectsNew Block Copy Opcodes Source Destination Table B-20. MMU Instruction/Data Register Expanded I/O Memory Addressing Table B-21 Bank x Control Register External I/O Improvements Table B-22. Global Power Save Control Register Short Chip Select Timing for WritesAddress = 0x000D Clock Select and Power Save Modes Table B-23. Global Control/Status RegisterTable B-24. Clock Select Field of Gcsr Figure B-3. Short Chip Select Timing CLK/8, Read Operation Short Chip Select Timing Figure B-4. Short Chip Select Timing CLK/6, Read Operation Figure B-6. Short Chip Select Timing CLK/2, Read Operation Figure B-7. Short Chip Select Timing 2 kHz, Read Operation Figure B-9. Short Chip Select Timing 8 kHz, Read Operation Figure B-11. Short Chip Select Timing 32 kHz, Read Operation Figure B-12. Short Chip Select Timing CLK/8, Write Operation Figure B-13. Short Chip Select Timing CLK/6, Write Operation Figure B-15. Short Chip Select Timing CLK/2, Write Operation Figure B-16. Short Chip Select Timing 2 kHz, Write Operation Figure B-18. Short Chip Select Timing 8 kHz, Write Operation 310 Rabbit 3000 Microprocessor Figure B-21. PWM Interrupt and Output Timing Pulse Width Modulator Improvements PWM LSB 1 Register Table B-25. PWM LSB 0 RegisterTable B-26. PWM LSB 1 Register PWM LSB 0 Register Table B-27. PWM LSB 2 and 3 Registers Address = 0x008CAddress = 0x008E QDC1HR Quadrature Decoder ImprovementsTable B-28. Quadrature Decoder Control Register Table B-29. Quadrature Decoder Count High Register User’s Manual 315 Serial Ports E/F Pins with Alternate Functions Appendix C. SYSTEM/USER Mode System Mode User ModeTable C-1. Differences Between System and User Modes System/User Mode Opcodes Table C-2. New System/User Mode OpcodesInstruction Bytes Clk Operation Priv Table C-3. System/User Mode I/O Registers System/User Mode Registers Register Name Mnemonic Address Table C-4. I/O Addresses Inaccessible in User Mode Interrupts Figure C-1. Interrupt Handing in System/User Mode Peripheral Interrupt Prioritization Table C-5. Interrupts-Priority and Action to Clear Requests Memory Protection Only Using the System/User Mode Figure C-3. System/User Mode Setup for Mixed Operation Mixed System/User Mode Operation Complete Operating System Figure C-4. System/User Mode Setup for Operating System Table D-1 Rabbit 3000A Internal I/O Registers Appendix D. Rabbit 3000A Internal I/O Registers Table D-1. Rabbit 3000A Internal I/O Registers 0x03C0 00000000 Serial Port E User Enable Register 0x006A Xxxxxxxx Port D Bit 3 Register 0x0082 00000000 Bank 3 Control Register 0x0098 Xx000000 Interrupt 1 Control Register 0x00D1 Xxxxxxxx Serial Port B Long Stop Register 334 Rabbit 3000 Microprocessor User’s Manual 335 Page Numerics Index Memory A16, A19 inversions /CS1 PWL2R, PWL3R 200