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-rw-r--r--src/peripherals/timer.spec.ts97
-rw-r--r--src/peripherals/timer.ts39
2 files changed, 125 insertions, 11 deletions
diff --git a/src/peripherals/timer.spec.ts b/src/peripherals/timer.spec.ts
index 43768d2..11c0264 100644
--- a/src/peripherals/timer.spec.ts
+++ b/src/peripherals/timer.spec.ts
@@ -415,13 +415,13 @@ describe('timer', () => {
describe('Phase-correct PWM mode', () => {
it('should count up to TOP, down to 0, and then set TOV flag', () => {
const { program, instructionCount } = asmProgram(`
+ LDI r16, 0x3 ; OCR0A = 0x3; // <- TOP value
+ OUT 0x27, r16
; Set waveform generation mode (WGM) to PWM, Phase Correct, top OCR0A
LDI r16, 0x1 ; TCCR0A = 1 << WGM00;
OUT 0x24, r16
LDI r16, 0x9 ; TCCR0B = (1 << WGM02) | (1 << CS00);
OUT 0x25, r16
- LDI r16, 0x3 ; OCR0A = 0x3;
- OUT 0x27, r16
LDI r16, 0x2 ; TCNT0 = 0x2;
OUT 0x26, r16
@@ -448,13 +448,13 @@ describe('timer', () => {
it('should clear OC0A when TCNT0=OCR0A and counting up', () => {
const { program, lines, instructionCount } = asmProgram(`
+ LDI r16, 0xfe ; OCR0A = 0xfe; // <- TOP value
+ OUT 0x27, r16
; Set waveform generation mode (WGM) to PWM, Phase Correct
- LDI r16, 0x81 ; TCCR0A = (1 << COM0A1) || (1 << WGM01);
+ LDI r16, 0x81 ; TCCR0A = (1 << COM0A1) | (1 << WGM00);
OUT 0x24, r16
LDI r16, 0x1 ; TCCR0B = (1 << CS00);
OUT 0x25, r16
- LDI r16, 0xfe ; OCR0A = 0xfe;
- OUT 0x27, r16
LDI r16, 0xfd ; TCNT0 = 0xfd;
OUT 0x26, r16
@@ -491,6 +491,46 @@ describe('timer', () => {
expect(cpu.readData(TCNT0)).toEqual(0xfe);
expect(gpioCallback).toHaveBeenCalledWith(6, PinOverrideMode.Set, 0x2b);
});
+
+ it('should only update OCR0A when TCNT0=TOP in PWM Phase Correct mode (issue #76)', () => {
+ const { program, instructionCount } = asmProgram(`
+ LDI r16, 0x4 ; OCR0A = 0x4;
+ OUT 0x27, r16
+ ; Set waveform generation mode (WGM) to PWM, Phase Correct
+ LDI r16, 0x01 ; TCCR0A = (1 << WGM00);
+ OUT 0x24, r16
+ LDI r16, 0x09 ; TCCR0B = (1 << WGM02) | (1 << CS00);
+ OUT 0x25, r16
+ LDI r16, 0x0 ; TCNT0 = 0x0;
+ OUT 0x26, r16
+
+ LDI r16, 0x2 ; OCR0A = 0x2; // TCNT0 should read 0x0
+ OUT 0x27, r16 ; // TCNT0 should read 0x1
+ NOP ; // TCNT0 should read 0x2
+ NOP ; // TCNT0 should read 0x3
+ IN r17, 0x26 ; R17 = TCNT; // TCNT0 should read 0x4 (that's old OCR0A / TOP)
+ NOP ; // TCNT0 should read 0x3
+ NOP ; // TCNT0 should read 0x2
+ NOP ; // TCNT0 should read 0x1
+ NOP ; // TCNT0 should read 0x0
+ NOP ; // TCNT0 should read 0x1
+ NOP ; // TCNT0 should read 0x2
+ IN r18, 0x26 ; R18 = TCNT; // TCNT0 should read 0x1
+ `);
+
+ const cpu = new CPU(program);
+ new AVRTimer(cpu, timer0Config);
+
+ // Listen to Port D's internal callback
+ const gpioCallback = jest.fn();
+ cpu.gpioTimerHooks[PORTD] = gpioCallback;
+
+ const runner = new TestProgramRunner(cpu);
+ runner.runInstructions(instructionCount);
+
+ expect(cpu.readData(R17)).toEqual(0x4);
+ expect(cpu.readData(R18)).toEqual(0x1);
+ });
});
describe('16 bit timers', () => {
@@ -638,5 +678,52 @@ describe('timer', () => {
expect(cpu.readData(TCNT1)).toEqual(0x4a);
expect(gpioCallback).toHaveBeenCalledWith(2, PinOverrideMode.Toggle, 0x25);
});
+
+ it('should only update OCR0A when TCNT0=BOTTOM in PWM Phase/Frequency Correct mode (issue #76)', () => {
+ const { program, instructionCount } = asmProgram(`
+ LDI r16, 0x0 ; OCR1AH = 0x0;
+ STS 0x89, r16
+ LDI r16, 0x4 ; OCR1AL = 0x4;
+ STS 0x88, r16
+ ; Set waveform generation mode (WGM) to PWM Phase/Frequency Correct mode (9)
+ LDI r16, 0x01 ; TCCR1A = (1 << WGM10);
+ STS 0x80, r16
+ LDI r16, 0x11 ; TCCR1B = (1 << WGM13) | (1 << CS00);
+ STS 0x81, r16
+ LDI r16, 0x0 ; TCNT1H = 0x0;
+ STS 0x85, r16
+ LDI r16, 0x0 ; TCNT1L = 0x0;
+ STS 0x84, r16
+
+ LDI r16, 0x8 ; OCR1AL = 0x8; // TCNT1 should read 0x0
+ STS 0x88, r16 ; // TCNT1 should read 0x2 (going up)
+ LDS r17, 0x84 ; // TCNT1 should read 0x4 (going down)
+ LDS r18, 0x84 ; // TCNT1 should read 0x2 (going down)
+ NOP ; // TCNT1 should read 0x0 (going up)
+ NOP ; // TCNT1 should read 0x1 (going up)
+ NOP ; // TCNT1 should read 0x2 (going up)
+ NOP ; // TCNT1 should read 0x3 (going up)
+ NOP ; // TCNT1 should read 0x4 (going up)
+ NOP ; // TCNT1 should read 0x5 (going up)
+ LDS r19, 0x84 ; // TCNT1 should read 0x6 (going up)
+ NOP ; // TCNT1 should read 0x8 (going up)
+ LDS r20, 0x84 ; // TCNT1 should read 0x7 (going up)
+ `);
+
+ const cpu = new CPU(program);
+ new AVRTimer(cpu, timer1Config);
+
+ // Listen to Port D's internal callback
+ const gpioCallback = jest.fn();
+ cpu.gpioTimerHooks[PORTD] = gpioCallback;
+
+ const runner = new TestProgramRunner(cpu);
+ runner.runInstructions(instructionCount);
+
+ expect(cpu.readData(R17)).toEqual(0x4);
+ expect(cpu.readData(R18)).toEqual(0x2);
+ expect(cpu.readData(R19)).toEqual(0x6);
+ expect(cpu.readData(R20)).toEqual(0x7);
+ });
});
});
diff --git a/src/peripherals/timer.ts b/src/peripherals/timer.ts
index 188832d..0f4d837 100644
--- a/src/peripherals/timer.ts
+++ b/src/peripherals/timer.ts
@@ -240,7 +240,10 @@ function compToOverride(comp: CompBitsValue) {
export class AVRTimer {
private lastCycle = 0;
private ocrA: u16 = 0;
+ private nextOcrA: u16 = 0;
private ocrB: u16 = 0;
+ private nextOcrB: u16 = 0;
+ private ocrUpdateMode = OCRUpdateMode.Immediate;
private icr: u16 = 0; // only for 16-bit timers
private timerMode: TimerMode;
private topValue: TimerTopValue;
@@ -297,12 +300,16 @@ export class AVRTimer {
this.timerUpdated();
};
this.cpu.writeHooks[config.OCRA] = (value: u8) => {
- // TODO implement buffering when timer running in PWM mode
- this.ocrA = (this.highByteTemp << 8) | value;
+ this.nextOcrA = (this.highByteTemp << 8) | value;
+ if (this.ocrUpdateMode === OCRUpdateMode.Immediate) {
+ this.ocrA = this.nextOcrA;
+ }
};
this.cpu.writeHooks[config.OCRB] = (value: u8) => {
- // TODO implement buffering when timer running in PWM mode
- this.ocrB = (this.highByteTemp << 8) | value;
+ this.nextOcrB = (this.highByteTemp << 8) | value;
+ if (this.ocrUpdateMode === OCRUpdateMode.Immediate) {
+ this.ocrB = this.nextOcrB;
+ }
};
this.cpu.writeHooks[config.ICR] = (value: u8) => {
this.icr = (this.highByteTemp << 8) | value;
@@ -351,7 +358,9 @@ export class AVRTimer {
this.divider = 0;
this.lastCycle = 0;
this.ocrA = 0;
+ this.nextOcrA = 0;
this.ocrB = 0;
+ this.nextOcrB = 0;
this.icr = 0;
this.tcnt = 0;
this.tcntNext = 0;
@@ -394,9 +403,10 @@ export class AVRTimer {
private updateWGMConfig() {
const wgmModes = this.config.bits === 16 ? wgmModes16Bit : wgmModes8Bit;
- const [timerMode, topValue] = wgmModes[this.WGM];
+ const [timerMode, topValue, ocrUpdateMode] = wgmModes[this.WGM];
this.timerMode = timerMode;
this.topValue = topValue;
+ this.ocrUpdateMode = ocrUpdateMode;
}
count = (reschedule = true) => {
@@ -410,14 +420,23 @@ export class AVRTimer {
const { timerMode } = this;
const phasePwm =
timerMode === TimerMode.PWMPhaseCorrect || timerMode === TimerMode.PWMPhaseFrequencyCorrect;
+ const limit = this.TOP + 1;
const newVal = phasePwm
? this.phasePwmCount(val, counterDelta)
- : (val + counterDelta) % (this.TOP + 1);
+ : (val + counterDelta) % limit;
+ const overflow = val + counterDelta >= limit;
// A CPU write overrides (has priority over) all counter clear or count operations.
if (!this.tcntUpdated) {
this.tcnt = newVal;
this.timerUpdated();
}
+
+ if (!phasePwm && this.ocrUpdateMode == OCRUpdateMode.Bottom && overflow) {
+ // OCRUpdateMode.Top only occurs in Phase Correct modes, handled by phasePwmCount()
+ this.ocrA = this.nextOcrA;
+ this.ocrB = this.nextOcrB;
+ }
+
if ((timerMode === TimerMode.Normal || timerMode === TimerMode.FastPWM) && val > newVal) {
cpu.setInterruptFlag(this.OVF);
}
@@ -447,12 +466,20 @@ export class AVRTimer {
value++;
if (value === this.TOP && !this.tcntUpdated) {
this.countingUp = false;
+ if (this.ocrUpdateMode === OCRUpdateMode.Top) {
+ this.ocrA = this.nextOcrA;
+ this.ocrB = this.nextOcrB;
+ }
}
} else {
value--;
if (!value && !this.tcntUpdated) {
this.countingUp = true;
this.cpu.setInterruptFlag(this.OVF);
+ if (this.ocrUpdateMode === OCRUpdateMode.Bottom) {
+ this.ocrA = this.nextOcrA;
+ this.ocrB = this.nextOcrB;
+ }
}
}
delta--;
generated by cgit v1.2.3 (git 2.25.1) at 2026-03-31 15:04:09 +0000