MC68HC05J1A/D Rev. 1.0 HC 5 MC68HC05J1A MC68HCL05J1A MC68HSC05J1A. HCMOS Microcontroller Units TECHNICAL DATA

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1 MC68HC0J1A/D Rev. 1.0 HC MC68HC0J1A MC68HCL0J1A MC68HSC0J1A HCMOS Microcontroller Units TECHNICAL DATA

2 Technical Data Motorola reserves the right to make changes without further notice to any products herein to improve reliability, function or design. Motorola does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others. Motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Motorola product could create a situation where personal injury or death may occur. Should Buyer purchase or use Motorola products for any such unintended or unauthorized application, Buyer shall indemnify and hold Motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that Motorola was negligent regarding the design or manufacture of the part. Motorola, Inc., 1999 Technical Data MC68HC0J1A Rev MOTOROLA

3 Technical Data MC68HC0J1A List of Sections Section 1. General Description Section 2. Memory Section 3. Central Processor Unit (CPU) Section 4. Interrupts Section. Resets Section 6. Low-Power Modes Section 7. Parallel Input/Output (I/O) Section 8. Multifunction Timer Section 9. Instruction Set Section 10. Electrical Specifications Section 11. Mechanical Specifications Section 12. Ordering Information Appendix A. MC68HCL0J1A Appendix B. MC68HSC0J1A MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA List of Sections 3

4 List of Sections Technical Data MC68HC0J1A Rev List of Sections MOTOROLA

5 Technical Data MC68HC0J1A Table of Contents Section 1. General Description 1.1 Contents Introduction Features Mask Options MCU Structure Pin Assignments V DD and V SS OSC1 and OSC Crystal Ceramic Resonator RC Oscillator External Clock RESET IRQ PA7 PA PB PB Section 2. Memory 2.1 Contents Introduction Memory Map Input/Output (I/O) Section Random-Access Memory (RAM) Read-Only Memory (ROM) MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Table of Contents

6 Table of Contents Section 3. Central Processor Unit (CPU) 3.1 Contents Introduction CPU Registers Accumulator Index Register Stack Pointer Program Counter Condition Code Register Arithmetic/Logic Unit (ALU) Section 4. Interrupts 4.1 Contents Introduction Interrupt Sources Software Interrupt External Interrupts IRQ Pin PA3 PA0 Pins IRQ Status and Control Register Timer Interrupts Timer Overflow Interrupt Real-Time Interrupt Interrupt Processing Section. Resets.1 Contents Introduction Reset Types Power-On Reset External Reset Technical Data MC68HC0J1A Rev Table of Contents MOTOROLA

7 Table of Contents.3.3 Computer Operating Properly (COP) Reset Illegal Address Reset Reset States CPU I/O Port Registers Multifunction Timer COP Watchdog Section 6. Low-Power Modes 6.1 Contents Introduction Stop Mode Wait Mode Halt Mode Data-Retention Mode Section 7. Parallel Input/Output (I/O) 7.1 Contents Introduction I/O Port Function Port A Port A Data Register Data Direction Register A Pulldown Register A Port A External Interrupts Port B Port B Data Register Data Direction Register B Pulldown Register B MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Table of Contents 7

8 Table of Contents Section 8. Multifunction Timer 8.1 Contents Introduction Timer Status and Control Register COP Watchdog Section 9. Instruction Set 9.1 Contents Introduction Addressing Modes Inherent Immediate Direct Extended Indexed, No Offset Indexed, 8-Bit Offset Indexed, 16-Bit Offset Relative Instruction Types Register/Memory Instructions Read-Modify-Write Instructions Jump/Branch Instructions Bit Manipulation Instructions Control Instructions Instruction Set Summary Opcode Map Section 10. Electrical Specifications 10.1 Contents Introduction Maximum Ratings Technical Data MC68HC0J1A Rev Table of Contents MOTOROLA

9 Table of Contents 10.4 Operating Temperature Range Thermal Characteristics Power Considerations Volt DC Electrical Characteristics Volt DC Electrical Characteristics Volt Control Timing Volt Control Timing Section 11. Mechanical Specifications 11.1 Contents Introduction Pin Plastic Dual In-Line Package (PDIP) Pin Small Outline Integrated Circuit Package (SOIC) Section 12. Ordering Information 12.1 Contents Introduction MCU Ordering Forms Application Program Media Diskettes EPROMs ROM Program Verification ROM Verification Units (RVUs) MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Table of Contents 9

10 Table of Contents Appendix A. MC68HCL0J1A A.1 Contents A.2 Introduction A.3 DC Electrical Characteristics A.4 MC Ordering Information Appendix B. MC68HSC0J1A B.1 Contents B.2 Introduction B.3 DC Electrical Characteristics B.4 Control Timing B. MC Ordering Information Technical Data MC68HC0J1A Rev Table of Contents MOTOROLA

11 Technical Data MC68HC0J1A List of Figures Figure Title Page 1-1 MC68HC0J1A Block Diagram Pin Assignments Bypassing Layout Recommendation Crystal Connections with Feedback Resistor Mask Option Crystal Connections without Feedback Resistor Mask Option Ceramic Resonator Connections with Feedback Resistor Mask Option Ceramic Resonator Connections without Feedback Resistor Mask Option RC Oscillator Connections External Clock Connections Memory Map I/O Register Summary Programming Model Accumulator (A) Index Register (X) Stack Pointer (SP) Program Counter (PC) Condition Code Register (CCR) External Interrupt Logic IRQ Status and Control Register (ISCR) Stacking Order Interrupt Flowchart MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA List of Figures 11

12 List of Figures Figure Title Page -1 Reset Sources COP Register (COPR) Stop/Wait/Halt Flowchart Port A Data Register (PORTA) Data Direction Register A (DDRA) Pulldown Register A (PDRA) Port A I/O Circuit Port B Data Register (PORTB) Data Direction Register B (DDRB) Pulldown Register B (PDRB) Port B I/O Circuit Multifunction Timer Block Diagram Timer Status and Control Register (TSCR) Timer Counter Register (TCNTR) COP Register (COPR) Typical V OH /I OH (V DD =.0 V) Typical V OH /I OH (V DD = 3.3 V) Typical V OL /I OL (V DD =.0 V) Typical V OL /I OL (V DD = 3.3 V) Typical Operating I DD (2 C) Typical Wait Mode I DD (2 C) Typical Internal Operating Frequency for Various V DD at 2 C RC Option Only External Interrupt Timing Stop Mode Recovery Timing Power-On Reset Timing External Reset Timing A-1 Maximum Run Mode I DD versus Frequency A-2 Maximum Wait Mode I DD versus Frequency Technical Data MC68HC0J1A Rev List of Figures MOTOROLA

13 Technical Data MC68HC0J1A List of Tables Table Title Page 4-1 Reset/Interrupt Vector Addresses Port A Pin Functions Port B Pin Functions Real-Time Interrupt Rate Selection Register/Memory Instructions Read-Modify-Write Instructions Jump and Branch Instructions Bit Manipulation Instructions Control Instructions Instruction Set Summary Opcode Map A-1 Low-Power Output Voltage (V DD = Vdc) A-2 Low-Power Output Voltage (V DD = Vdc) A-3 Low-Power Supply Current A-4 Low-Power Pulldown Current A- MC Order Numbers B-1 High-Speed Supply Current B-2 High-Speed Control Timing (V DD =.0 V ± 10%) B-3 High-Speed Control Timing (V DD = 3.3 V ± 10%) B-4 MC Order Numbers MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA List of Tables 13

14 List of Tables Technical Data MC68HC0J1A Rev List of Tables MOTOROLA

15 Technical Data MC68HC0J1A Section 1. General Description 1.1 Contents 1.2 Introduction Features Mask Options MCU Structure Pin Assignments V DD and V SS OSC1 and OSC Crystal Ceramic Resonator RC Oscillator External Clock RESET IRQ PA7 PA PB PB MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA General Description 1

16 General Description 1.2 Introduction The MC68HC0J1A is a member of the low-cost, high-performance M68HC0 Family of 8-bit microcontroller units (MCU). The M68HC0 Family is based on the customer-specified integrated circuit (CSIC) design strategy. All MCUs in the family use the popular M68HC0 central processor unit (CPU) and are available with a variety of subsystems, memory sizes and types, and package types. On-chip memory of the MC68HC0J1A includes: 1240 bytes of user read-only memory (ROM) 64 bytes of user random-access memory (RAM) Information on the MC68HCL0J1A, a low-power version of the MC68HC0J1A, is introduced in Appendix A. MC68HCL0J1A. Information on the MC68HSC0J1A, a high-speed version of the MC68HC0J1A, is introduced in Appendix B. MC68HSC0J1A. 1.3 Features Features of the MCU include: Popular M68HC0 CPU Memory-mapped input/output (I/O) registers 1240 bytes of user ROM including eight user vector locations 64 bytes of user RAM 14 bidirectional I/O pins with these features: Software programmable pulldown devices Four I/O pins with 8-mA current sinking capability Four I/O pins with maskable external interrupt capability Hardware mask and flag for external interrupts Fully static operation with no minimum clock speed On-chip oscillator with connections for a crystal or ceramic resonator or for a resistor-capacitor (RC) network Technical Data MC68HC0J1A Rev General Description MOTOROLA

17 General Description Mask Options 1-bit multifunction timer Computer operating properly (COP) watchdog Power-saving stop (or halt), wait, and data-retention modes Illegal address reset Internal steering diode between RESET and V DD pins 8 8 unsigned multiply instruction 20-pin plastic dual in-line package (PDIP) 20-pin small outline integrated circuit package (SOIC) 1.4 Mask Options Available MC68HC0J1A mask options are: On-chip oscillator connections: crystal/ceramic resonator connections or resistor-capacitor (RC) network connections Crystal/ceramic resonator feedback resistor: connected or not connected (available only with crystal/ceramic oscillator mask option) STOP instruction: enabled or disabled (converted to WAIT instruction) External interrupt pins: edge-triggered or edge- and level-triggered Port A and port B pulldown resistors: connected or not connected COP watchdog timer: enabled or disabled Port A external interrupt capability: enabled or disabled MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA General Description 17

18 General Description 1. MCU Structure Figure 1-1 shows the structure of the MC68HC0J1A MCU. IRQ RESET RESET CPU CONTROL STACK POINTER USER ROM 1240 BYTES USER RAM 64 BYTES M68HC0 MCU PROGRAM COUNTER 0 0 ARITHMETIC/LOGIC UNIT ACCUMULATOR INDEX REGISTER CONDITION CODE REGISTER H I N C Z * ** DATA DIRECTION REGISTER A PORT A DATA DIRECTION REGISTER B PORT B PA7 PA6 PA PA4 PA3 PA2 PA1 PA0 PB PB4 PB3 PB2 PB1 PB0 * * * * ** ** ** ** 8-mA sink capability External interrupt capability COP WATCHDOG AND ILLEGAL ADDRESS DETECT MULTIFUNCTION TIMER V DD V SS POWER CPU CLOCK OSC1 OSC2 INTERNAL OSCILLATOR DIVIDE BY TWO INTERNAL CLOCK Figure 1-1. MC68HC0J1A Block Diagram Technical Data MC68HC0J1A Rev General Description MOTOROLA

19 General Description Pin Assignments 1.6 Pin Assignments Figure 1-2 shows the MC68HC0J1A pin assignments. OSC RESET OSC IRQ PB 3 18 PA0 PB PA1 PB3 16 PA2 PB2 6 1 PA3 PB PA4 PB PA V DD 9 12 PA6 V SS PA7 Figure 1-2. Pin Assignments V DD and V SS V DD and V SS are the power supply and ground pins. The MCU operates from a single -V power supply. Very fast signal transitions occur on the MCU pins, placing high short-duration current demands on the power supply. To prevent noise problems, take special care to provide good power supply bypassing at the MCU. Place bypass capacitors as close to the MCU as possible, as Figure 1-3 shows. C2 is an optional bulk current bypass capacitor for use in applications that require the port pins to source high current levels. MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA General Description 19

20 General Description V+ V DD V DD MCU C1 0.1 F + C2 C2 C1 V SS V SS Figure 1-3. Bypassing Layout Recommendation OSC1 and OSC2 The OSC1 and OSC2 pins are the control connections for the on-chip oscillator. Depending on the mask option selected, the oscillator can be driven by any one of these: Crystal Ceramic resonator Resistor-capacitor (RC) network External clock signal The frequency of the internal oscillator is f OSC. The MCU divides the internal oscillator output by two to produce the internal clock with a frequency of f OP. An internal feedback resistor between the OSC1 and OSC2 pins is available as a mask option. The feedback resistor mask option is available only when the crystal/ceramic resonator mask option is also selected Crystal With the crystal/ceramic resonator mask option, a crystal connected to the OSC1 and OSC2 pins can drive the on-chip oscillator. Figure 1-4 and Figure 1- show a typical crystal oscillator circuit for an AT-cut, parallel resonant crystal. Follow the crystal supplier s recommendations, as the crystal parameters determine the external component values Technical Data MC68HC0J1A Rev General Description MOTOROLA

21 General Description Pin Assignments required to provide reliable startup and maximum stability. The load capacitance values used in the oscillator circuit design should include all stray layout capacitances. To minimize output distortion, mount the crystal and capacitors as close as possible to the pins. NOTE: Use an AT-cut crystal and not an AT-strip crystal. The MCU may overdrive an AT-strip crystal. V SS MCU C3 OSC1 OSC1 OSC2 XTAL OSC2 C3 27 pf XTAL C4 27 pf C4 C2 C1 V DD V SS Figure 1-4. Crystal Connections with Feedback Resistor Mask Option V SS MCU C3 OSC1 OSC1 R 10 M OSC2 XTAL R OSC2 C4 C3 27 pf XTAL C4 27 pf C2 C1 V DD V SS Figure 1-. Crystal Connections without Feedback Resistor Mask Option MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA General Description 21

22 General Description Ceramic Resonator To reduce cost, use a ceramic resonator in place of the crystal. Use the circuit in Figure 1-6 or Figure 1-7 for a ceramic resonator and follow the resonator manufacturer s recommendations. The load capacitance values used in the oscillator circuit design should include all stray layout capacitances. To minimize output distortion, mount the resonator as close as possible to the pins. MCU V SS C3 OSC1 OSC2 CERAMIC RESONATOR OSC1 OSC2 C3 27 pf CERAMIC RESONATOR C4 27 pf C4 V DD C2 C1 V SS Figure 1-6. Ceramic Resonator Connections with Feedback Resistor Mask Option V SS MCU C3 OSC1 R 10 M OSC2 CERAMIC RESONATOR R OSC1 OSC2 C4 C3 27 pf CERAMIC RESONATOR C4 27 pf C2 C1 V DD V SS Figure 1-7. Ceramic Resonator Connections without Feedback Resistor Mask Option Technical Data MC68HC0J1A Rev General Description MOTOROLA

23 General Description Pin Assignments RC Oscillator For maximum cost reduction, the RC oscillator mask option allows the configuration shown in Figure 1-8 to drive the on-chip oscillator. The OSC2 signal is a square wave, and the signal on OSC1 is a triangular wave. The optimum frequency for the RC oscillator configuration is 2 MHz. Mount the RC components as close as possible to the pins for startup stabilization and to minimize output distortion. OSC1 R MCU OSC2 OSC1 R OSC2 V DD C2 C1 V SS Figure 1-8. RC Oscillator Connections External Clock With the RC oscillator mask option, an external clock from another CMOS-compatible device can drive the OSC1 input. Leave the OSC2 pin unconnected, as Figure 1-9 shows. MCU OSC1 OSC2 EXTERNAL CMOS CLOCK Figure 1-9. External Clock Connections MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA General Description 23

24 General Description RESET A logic 0 on the RESET pin forces the MCU to a known startup state. See.3.2 External Reset for more information IRQ The IRQ pin is an asynchronous external interrupt pin. See IRQ Pin PA7 PA0 PA7 PA0 are the pins of port A, a general-purpose, bidirectional I/O port. See 7.4 Port A PB PB0 PB PB0 are the pins of port B, a general-purpose, bidirectional I/O port. See 7. Port B. Technical Data MC68HC0J1A Rev General Description MOTOROLA

25 Technical Data MC68HC0J1A Section 2. Memory 2.1 Contents 2.2 Introduction Memory Map Input/Output Section RAM ROM Introduction This section describes the organization of the on-chip memory. 2.3 Memory Map The central processor unit (CPU) can address 2 Kbytes of memory space as shown in Figure 2-1. The read-only memory (ROM) portion of memory holds the program instructions, fixed data, user-defined vectors, and interrupt service routines. The random-access memory (RAM) portion of memory holds variable data. Input/output (I/O) registers are memory-mapped so that the CPU can access their locations in the same way that it accesses all other memory locations. MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Memory 2

26 Memory 2.4 Input/Output (I/O) Section The first 32 addresses of the memory space, $0001 $001F, are the I/O section. These are the addresses of the I/O control registers, status registers, and data registers. See Figure 2-2. One I/O register shown in Figure 2-2 is located outside the 32-byte I/O section: the computer operating properly (COP) register is mapped at $07F0. 2. Random-Access Memory (RAM) The 64 addresses from $00C0 to $00FF serve as both the user RAM and the stack RAM. The CPU uses five stack RAM bytes to save all CPU register contents before processing an interrupt. During a subroutine call, the CPU uses two bytes to store the return address. The stack pointer decrements during pushes and increments during pulls. NOTE: Be careful when using nested subroutines or multiple interrupt levels. The CPU may overwrite data in the RAM during a subroutine or during the interrupt stacking operation. 2.6 Read-Only Memory (ROM) The ROM is located in two areas of the memory map: 1. Addresses $0300 $07CF contain 1232 bytes of user ROM. 2. Addresses $07F8 $07FF contain 16 bytes of ROM reserved for user vectors. Technical Data MC68HC0J1A Rev Memory MOTOROLA

27 Memory Read-Only Memory (ROM) $0000 $001F $0020 $00BF $00C0 $00FF $0100 $02FF $0300 I/O REGISTERS 32 BYTES USER RAM 64 BYTES UNUSED 160 BYTES UNUSED 12 BYTES STACK RAM 64 BYTES PORT A DATA REGISTER PORT B DATA REGISTER UNUSED UNUSED PORT A DATA DIRECTION REGISTER PORT B DATA DIRECTION REGISTER UNUSED UNUSED TIMER STATUS AND CONTROL REGISTER TIMER COUNTER REGISTER IRQ STATUS AND CONTROL REGISTER UNUSED UNUSED UNUSED UNUSED UNUSED PORT A PULLDOWN REGISTER PORT B PULLDOWN REGISTER UNUSED UNUSED UNUSED RESERVED $0000 $0001 $0002 $0003 $0004 $000 $0006 $0007 $0008 $0009 $000A $000B $000C $000D $000E $000F $0010 $0011 $0012 $0013 $0014 $001F $07CF $07D0 $07EF $07F0 $07F7 $07F8 $07FF USER ROM 1232 BYTES TEST ROM 32 BYTES RESERVED FOR TEST (ROM) 8 BYTES USER VECTORS (ROM) 8 BYTES Figure 2-1. Memory Map * $07F0 $07F1 $07F2 $07F3 $07F4 $07F $07F6 COP REGISTER RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED TIMER VECTOR (HIGH BYTE) TIMER VECTOR (LOW BYTE) EXTERNAL INTERRUPT VECTOR (HIGH BYTE) EXTERNAL INTERRUPT VECTOR (LOW BYTE) SOFTWARE INTERRUPT VECTOR (HIGH BYTE) SOFTWARE INTERRUPT VECTOR (LOW BYTE) RESET VECTOR (LOW BYTE) RESET VECTOR (LOW BYTE) * Writing to bit 0 of $07F0 clears the COP watchdog. Reading $07F0 returns ROM data. $07F7 $07F8 $07F9 $07FA $07FB $07FC $07FD $07FE $07FF MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Memory 27

28 Memory Addr. Register Name Bit Bit 0 $0000 Port A Data Register (PORTA) See page 60. Read: Write: Reset: PA7 PA6 PA PA4 PA3 PA2 PA1 PA0 Unaffected by reset $0001 Port B Data Register (PORTB) See page 6. Read: 0 0 Write: Reset: PB PB4 PB3 PB2 PB1 PB0 Unaffected by reset $0002 Unimplemented $0003 Unimplemented $0004 $000 Data Direction Register A (DDRA) See page 61. Data Direction Register B (DDRB) See page 66. Read: DDRA7 DDRA6 DDRA DDRA4 DDRA3 DDRA2 DDRA1 DDRA0 Write: Reset: Read: 0 0 DDRB DDRB4 DDRB3 DDRB2 DDRB1 DDRB0 Write: Reset: $0006 Unimplemented $0007 Unimplemented $0008 $0009 $000A Timer Status and Control Register (TSCR) See page 71. Timer Counter Register (TCNTR) See page 73. IRQ Status and Control Register (ISCR) See page 43. Read: TOF RTIF 0 0 TOIE RTIE RT1 RT0 Write: TOFR RTIFR Reset: Read: Bit 7 Bit 6 Bit Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Write: Reset: Read: IRQF IRQE Write: IRQR Reset: = Unimplemented R = Reserved U = Unaffected Figure 2-2. I/O Register Summary (Sheet 1 of 2) Technical Data MC68HC0J1A Rev Memory MOTOROLA

29 Memory Read-Only Memory (ROM) Addr. Register Name Bit Bit 0 $000B Unimplemented $000F Unimplemented $0010 $0011 Pulldown Register A (PDRA) See page 62. Pulldown Register B (PDRB) See page 67. Read: Write: PDIA7 PDIA6 PDIA PDIA4 PDIA3 PDIA2 PDIA1 PDIA0 Reset: Read: Write: PDIB PDIB4 PDIB3 PDIB2 PDIB1 PDIB0 Reset: U U $0012 Unimplemented $001E Unimplemented $001F Reserved Read: Write: R R R R R R R R Reset: Unaffected by reset $07F0 COP Register (COPR) See page 49. Read: Write: COPC Reset: U U U U U U U 0 = Unimplemented R = Reserved U = Unaffected Figure 2-2. I/O Register Summary (Sheet 2 of 2) MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Memory 29

30 Memory Technical Data MC68HC0J1A Rev Memory MOTOROLA

31 Technical Data MC68HC0J1A Section 3. Central Processor Unit (CPU) 3.1 Contents 3.2 Introduction CPU Registers Accumulator Index Register Stack Pointer Program Counter Condition Code Register Arithmetic/Logic Unit (ALU) Introduction This section describes the central processor unit (CPU) registers. MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Central Processor Unit (CPU) 31

32 Central Processor Unit (CPU) 3.3 CPU Registers Figure 3-1 shows the five CPU registers. CPU registers and are not part of the memory map ACCUMULATOR (A) INDEX REGISTER (X) SP STACK POINTER (SP) PCL PCH PROGRAM COUNTER (PC) H I N Z 0 C CONDITION CODE REGISTER (CCR) HALF-CARRY FLAG INTERRUPT MASK NEGATIVE FLAG ZERO FLAG CARRY/BORROW FLAG Figure 3-1. Programming Model Technical Data MC68HC0J1A Rev Central Processor Unit (CPU) MOTOROLA

33 Central Processor Unit (CPU) CPU Registers Accumulator The accumulator (A) shown in Figure 3-2 is a general-purpose 8-bit register. The CPU uses the accumulator to hold operands and results of arithmetic and non-arithmetic operations. Read: Write: Bit Bit 0 Reset: Unaffected by reset Figure 3-2. Accumulator (A) Index Register In the indexed addressing modes, the CPU uses the byte in the index register (X) shown in Figure 3-3 to determine the conditional address of the operand. See 9.3. Indexed, No Offset, Indexed, 8-Bit Offset, and Indexed, 16-Bit Offset for more information on indexed addressing. The 8-bit index register also can serve as a temporary data storage location. Read: Write: Bit Bit 0 Reset: Unaffected by reset Figure 3-3. Index Register (X) MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Central Processor Unit (CPU) 33

34 Central Processor Unit (CPU) Stack Pointer The stack pointer (SP) shown in Figure 3-4 is a 16-bit register that contains the address of the next free location on the stack. During a reset or after the reset stack pointer (RSP) instruction, the stack pointer initializes to $00FF. The address in the stack pointer decrements as data is pushed onto the stack and increments as data is pulled from the stack. The 10 most significant bits of the stack pointer are fixed permanently at , so the stack pointer produces addresses from $00C0 to $00FF. If subroutines and interrupts use more than 64 stack locations, the stack pointer wraps around to address $00FF and begins writing over the previously stored data. A subroutine uses two stack locations. An interrupt uses five locations. Bit Read: Write: Reset: = Unimplemented Figure 3-4. Stack Pointer (SP) Bit 0 Technical Data MC68HC0J1A Rev Central Processor Unit (CPU) MOTOROLA

35 Central Processor Unit (CPU) CPU Registers Program Counter The program counter (PC) shown in Figure 3- is a 16-bit register that contains the address of the next instruction or operand to be fetched. The five most significant bits of the program counter are ignored internally and appear as Normally, the address in the program counter automatically increments to the next sequential memory location every time an instruction or operand is fetched. Jump, branch, and interrupt operations load the program counter with an address other than that of the next sequential location. Bit Read: Write: Reset: Loaded with vector from $07FE and $07FF Bit 0 Figure 3-. Program Counter (PC) MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Central Processor Unit (CPU) 3

36 Central Processor Unit (CPU) 3.3. Condition Code Register The condition code register (CCR) shown in Figure 3-6 is an 8-bit register whose three most significant bits are permanently fixed at 111. The condition code register contains the interrupt mask and four flags that indicate the results of prior instructions. Bit Bit 0 Read: Write: H I N Z C Reset: U 1 U U U = Unimplemented U = Unaffected Figure 3-6. Condition Code Register (CCR) H Half-Carry Flag The CPU sets the half-carry flag when a carry occurs between bits 3 and 4 of the accumulator during an add without carry (ADD) or add with carry (ADC) operation. The half-carry bit is required for binary-coded decimal (BCD) arithmetic operations. Reset has no effect on the half-carry flag. I Interrupt Mask Flag Setting the interrupt mask (I) disables interrupts. If an interrupt request occurs while the interrupt mask is a logic 0, the CPU saves the CPU registers on the stack, sets the interrupt mask, and then fetches the interrupt vector. If an interrupt request occurs while the interrupt mask is set, the interrupt request is latched. The CPU processes the latched interrupt as soon as the interrupt mask is cleared again. A return-from-interrupt (RTI) instruction pulls the CPU registers from the stack, restoring the interrupt mask to its cleared state. After a reset, the interrupt mask is set and can be cleared only by a clear interrupt mask bit (CLI), STOP, or WAIT instruction. Technical Data MC68HC0J1A Rev Central Processor Unit (CPU) MOTOROLA

37 Central Processor Unit (CPU) Arithmetic/Logic Unit (ALU) N Negative Flag The CPU sets the negative flag when an arithmetic operation, logical operation, or data manipulation produces a negative result (bit 7 in the results is a logic 1). Reset has no effect on the negative flag. Z Zero Flag The CPU sets the zero flag when an arithmetic operation, logical operation, or data manipulation produces a result of $00. Reset has no effect on the zero flag. C Carry/Borrow Flag The CPU sets the carry/borrow flag when an addition operation produces a carry out of bit 7 of the accumulator or when a subtraction operation requires a borrow. Some logical operations and data manipulation instructions also clear or set the carry/borrow bit. Reset has no effect on the carry/borrow flag. 3.4 Arithmetic/Logic Unit (ALU) The arithmetic/logic unit (ALU) performs the arithmetic and logical operations defined by the instruction set. The binary arithmetic circuits decode instructions and set up the ALU for the selected operation. Most binary arithmetic is based on the addition algorithm, carrying out subtraction as negative addition. Multiplication is not performed as a discrete operation but as a chain of addition and shift operations within the ALU. The multiply instruction requires 11 internal clock cycles to complete this chain of operations. MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Central Processor Unit (CPU) 37

38 Central Processor Unit (CPU) Technical Data MC68HC0J1A Rev Central Processor Unit (CPU) MOTOROLA

39 Technical Data MC68HC0J1A Section 4. Interrupts 4.1 Contents 4.2 Introduction Interrupt Sources Software Interrupt External Interrupts IRQ Pin PA3 PA0 Pins IRQ Status and Control Register Timer Interrupts Timer Overflow Interrupt Real-Time Interrupt Interrupt Processing Introduction This section describes how interrupts temporarily change the normal processing sequence. 4.3 Interrupt Sources These sources can generate interrupt requests: SWI (software interrupt) instruction IRQ pin PA3 PA0 pins (mask option) Multifunction timer MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Interrupts 39

40 Interrupts An interrupt temporarily stops normal program execution to process a particular event. An interrupt does not stop the execution of the instruction in progress, but takes effect when the current instruction completes its execution. Interrupt processing automatically saves the central processor unit (CPU) registers on the stack and loads the program counter with a user-defined vector address Software Interrupt The software interrupt (SWI) instruction causes a non-maskable interrupt External Interrupts These sources can generate external interrupts: IRQ pin PA3 PA0 pins (mask option) Setting the I bit in the condition code register or clearing the IRQE bit in the interrupt status and control register disables external interrupts IRQ Pin An interrupt signal on the IRQ pin latches an external interrupt request. When the CPU completes its current instruction, it tests the IRQ latch. If the IRQ latch is set, the CPU then tests the I bit in the condition code register and the IRQE bit in the interrupt status and control register. If the I bit is clear and the IRQE bit is set, the CPU then begins the interrupt sequence. The CPU clears the IRQ latch while it fetches the interrupt vector, so that another external interrupt request can be latched during the interrupt service routine. As soon as the I bit is cleared during the return from interrupt, the CPU can recognize the new interrupt request. Figure 4-1 shows the external interrupt logic. Technical Data MC68HC0J1A Rev Interrupts MOTOROLA

41 Interrupts Interrupt Sources IRQ TO BIH & BIL INSTRUCTION PROCESSING PA3 LEVEL-SENSITIVE TRIGGER (MASK OPTION) V DD PA2 PA1 IRQ LATCH R EXTERNAL INTERRUPT REQUEST PA0 PORT A EXTERNAL INTERRUPTS ENABLED (MASK OPTION) RST IRQ VECTOR FETCH INTERNAL DATA BUS IRQE IRQF IRQR IRQ STATUS AND CONTROL REGISTER Figure 4-1. External Interrupt Logic External interrupt triggering sensitivity is a mask option. The IRQ pin can be negative edge-triggered only or negative edge- and low level-triggered. With the mask option for an edge- and level-sensitive external interrupt trigger, a falling edge or a low level on the IRQ pin latches an external interrupt request. Edge- and level-sensitive triggering allows the use of multiple wired-or external interrupt sources. An external interrupt request is latched as long as any source is holding the IRQ pin low. With the mask option for an edge-sensitive only external interrupt trigger, a falling edge on the IRQ pin latches an external interrupt request. A subsequent external interrupt request can be latched only after the voltage level on the IRQ pin returns to logic 1 and then falls again to logic 0. MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Interrupts 41

42 Interrupts PA3 PA0 Pins The mask option for port A external interrupts enables pins PA3 PA0 to serve as additional external interrupt sources. An interrupt signal on a PA3 PA0 pin latches an external interrupt request. After completing the current instruction, the CPU tests the IRQ latch. If the IRQ latch is set, the CPU then tests the I bit in the condition code register and the IRQE bit in the interrupt status and control register. If the I bit is clear and the IRQE bit is set, the CPU then begins the interrupt sequence. The CPU clears the IRQ latch while it fetches the interrupt vector, so that another external interrupt request can be latched during the interrupt service routine. As soon as the I bit is cleared during the return from interrupt, the CPU can recognize the new interrupt request. External interrupt triggering sensitivity is a mask option. The PA3 PA0 pins can be positive edge-triggered only or positive edge- and high level-triggered. With the mask option for an edge- and level-sensitive external interrupt trigger, a rising edge or a high level on a PA3 PA0 pin latches an external interrupt request. Edge- and level-sensitive triggering allows the use of multiple wired-or external interrupt sources. As long as any source is holding a PA3 PA0 pin high, an external interrupt request is latched, and the CPU continues to execute the interrupt service routine. With the mask option for an edge-sensitive only external interrupt trigger, a rising edge on a PA3 PA0 pin latches an external interrupt request. A subsequent external interrupt request can be latched only after the voltage level of the previous interrupt signal returns to logic 0 and then rises again to logic 1. Technical Data MC68HC0J1A Rev Interrupts MOTOROLA

43 Interrupts Interrupt Sources IRQ Status and Control Register The IRQ status and control register (ISCR), shown in Figure 4-2, contains an external interrupt mask, an external interrupt flag, and a flag reset bit. Address: $000A Read: Write: Bit Bit 0 IRQE IRQF IRQE External Interrupt Request Enable Bit This read/write bit enables external interrupts. Resets set the IRQE bit. 1 = External interrupt processing enabled 0 = External interrupt processing disabled IRQF External Interrupt Request Flag The IRQ flag is a clearable, read-only bit that is set when an external interrupt request is pending. Resets clear the IRQF bit. 1 = Interrupt request pending 0 = No interrupt request pending These conditions set the IRQ flag: a. An external interrupt signal on the IRQ pin b. An external interrupt signal on pin PA3, PA2, PA1, or PA0 when PA3 PA0 are enabled to serve as external interrupt sources The CPU clears the IRQ flag when fetching the interrupt vector. Writing to the IRQ flag has no effect. Clear the IRQ flag by writing a logic 1 to the IRQR bit. IRQR Interrupt Request Reset Bit This write-only bit clears the IRQ flag. 1 = IRQF bit cleared 0 = No effect IRQR Reset: = Unimplemented Figure 4-2. IRQ Status and Control Register (ISCR) MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Interrupts 43

44 Interrupts Timer Interrupts The multifunction timer can generate these interrupts: Timer overflow interrupt Real-time interrupt Setting the I bit in the condition code register disables timer interrupts Timer Overflow Interrupt A timer overflow interrupt request occurs if the timer overflow flag, TOF, becomes set while the timer overflow interrupt enable bit, TOIE, is also set. See 8.3 Timer Status and Control Register Real-Time Interrupt A real-time interrupt request occurs if the real-time interrupt flag, RTIF, becomes set while the real-time interrupt enable bit, RTIE, is also set. See 8.3 Timer Status and Control Register. 4.4 Interrupt Processing The CPU takes these actions to begin servicing an interrupt: Stores the CPU registers on the stack in the order shown in Figure 4-3 Sets the I bit in the condition code register to prevent further interrupts Loads the program counter with the contents of the appropriate interrupt vector locations: $07FC and $07FD (software interrupt vector) $07FA and $07FB (external interrupt vector) $07F8 and $07F9 (timer interrupt vector) The return-from-interrupt (RTI) instruction causes the CPU to recover the CPU registers from the stack as shown in Figure 4-3. Technical Data MC68HC0J1A Rev Interrupts MOTOROLA

45 Interrupts Interrupt Processing UNSTACKING ORDER $00C0 (BOTTOM OF STACK) $00C1 $00C CONDITION CODE REGISTER ACCUMULATOR INDEX REGISTER PROGRAM COUNTER (HIGH BYTE) PROGRAM COUNTER (LOW BYTE) STACKING ORDER $00FD $00FE $00FF (TOP OF STACK) Figure 4-3. Stacking Order Table 4-1 summarizes the reset and interrupt sources and vector assignments. Function Reset Software interrupt (SWI) External interrupt Timer interrupts Table 4-1. Reset/Interrupt Vector Addresses Source Power-on RESET pin COP watchdog (1) illegal address Local Mask None Global Mask None None None None User code None None IRQ pin PA3 pin (2) PA2 pin (2) PA1 pin (2) PA0 pin (2) TOF bit RTIF bit 1. The COP watchdog is a mask option. 2. Port A external interrupt capability is a mask option. Priority (1 = Highest) Same priority as instruction Vector Address $07FE $07FF $07FC $07FD IRQE bit I bit 2 $07FA $07FB TOFE bit RTIE bit I bit 3 $07F8 $07F9 MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Interrupts 4

46 Interrupts Figure 4-4 shows the sequence of events caused by an interrupt. FROM RESET YES I BIT SET? NO EXTERNAL INTERRUPT? YES CLEAR IRQ LATCH NO TIMER INTERRUPT? YES NO STACK PCL, PCH, X, A, CCR SET I BIT LOAD PC WITH INTERRUPT VECTOR FETCH NEXT INSTRUCTION SWI INSTRUCTION? YES NO RTI INSTRUCTION? YES UNSTACK CCR, A, X, PCH, PCL NO EXECUTE INSTRUCTION Figure 4-4. Interrupt Flowchart Technical Data MC68HC0J1A Rev Interrupts MOTOROLA

47 Technical Data MC68HC0J1A Section. Resets.1 Contents.2 Introduction Reset Types Power-On Reset External Reset Computer Operating Properly (COP) Reset Illegal Address Reset Reset States CPU I/O Port Registers Multifunction Timer COP Watchdog Introduction This section describes the four reset sources and how they initialize the microcontroller unit (MCU). MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Resets 47

48 Resets.3 Reset Types A reset immediately stops the operation of the instruction being executed, initializes certain control bits, and loads the program counter with a user-defined reset vector address. These conditions produce a reset: Initial power-up (power-on reset) A logic 0 applied to the RESET pin (external reset) Timeout of the mask-optional computer operating properly (COP) watchdog (COP reset) An opcode fetch from an address not in the memory map (illegal address reset) Figure -1 is a block diagram of the reset sources. COP WATCHDOG (MASK OPTION) V DD POWER-ON RESET ILLEGAL ADDRESS RESET INTERNAL ADDRESS BUS RESET INTERNAL CLOCK R RESET LATCH RST TO CPU AND SUBSYSTEMS Figure -1. Reset Sources.3.1 Power-On Reset A positive transition on the V DD pin generates a power-on reset. The power-on reset is strictly for power-up conditions and cannot be used to detect drops in power supply voltage. Technical Data MC68HC0J1A Rev Resets MOTOROLA

49 Resets Reset Types A 4064 t CYC (internal clock cycle) delay after the oscillator becomes active allows the clock generator to stabilize. If the RESET pin is at logic 0 at the end of 4064 t CYC, the MCU remains in the reset condition until the signal on the RESET pin goes to logic External Reset A logic 0 applied to the RESET pin for one and one-half t CYC generates an external reset. A Schmitt trigger senses the logic level at the RESET pin..3.3 Computer Operating Properly (COP) Reset A timeout of the COP watchdog generates a COP reset. The COP watchdog is part of a software error detection system and must be cleared periodically to start a new timeout period. See 8.4 COP Watchdog. To clear the COP watchdog and prevent a COP reset, write a logic 0 to bit 0 (COPC) of the COP register at location $07F0. The COP register, shown in Figure -2, is a write-only register that returns the contents of a ROM location when read. The COP watchdog function is a mask option. Address: $07F0 Read: Bit Bit 0 Write: COPC Reset: U U U U U U U 0 = Unimplemented U = Unaffected by reset Figure -2. COP Register (COPR) COPC COP Clear Bit COPC is a write-only bit. Periodically writing a logic 0 to COPC prevents the COP watchdog from resetting the MCU. MC68HC0J1A Rev. 1.0 Technical Data MOTOROLA Resets 49

50 Resets.3.4 Illegal Address Reset An opcode fetch from an address that is not in the ROM (locations $0300 $07FF) or the RAM (locations $00C0 $00FF) generates an illegal address reset..4 Reset States This subsection describes how resets initialize the MCU..4.1 CPU A reset has the following effects on the CPU: Loads the stack pointer with $FF Sets the I bit in the condition code register, inhibiting interrupts Sets the IRQE bit in the interrupt status and control register Loads the program counter with the user-defined reset vector from locations $07FE and $07FF Clears the stop latch, enabling the CPU clock Clears the wait latch, waking the CPU from the wait mode.4.2 I/O Port Registers A reset has these effects on I/O port registers: Clears bits DDRA7 DDRA0 in data direction register A so that port A pins are inputs Clears bits PDIA7 PDIA0 in pulldown register A so that port A pulldown devices are enabled Clears bits DDRB DDRB0 in data direction register B so that port B pins are inputs Clears bits PDIB PDIB0 in pulldown register B so that port B pulldown devices are enabled Has no effect on port A or port B data registers Technical Data MC68HC0J1A Rev Resets MOTOROLA