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fix(timer): keeps counting even when stopped #41
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@urish
urish committed Aug 1, 2020
1 parent b0bfe88 commit 78377f7
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Showing 2 changed files with 51 additions and 36 deletions.
85 changes: 49 additions & 36 deletions src/peripherals/timer.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,11 @@ import { AVRTimer, timer0Config, timer1Config, timer2Config } from './timer';
// CPU registers
const R1 = 1;
const R17 = 17;
const R18 = 18;
const R19 = 19;
const R20 = 20;
const R21 = 21;
const R22 = 22;
const SREG = 95;

// Port Registers
Expand Down Expand Up @@ -168,10 +173,10 @@ describe('timer', () => {
const cpu = new CPU(new Uint16Array(0x1000));
const timer = new AVRTimer(cpu, timer0Config);
cpu.writeData(TCNT0, 0x10);
timer.tick();
cpu.writeData(OCR0A, 0x11);
cpu.writeData(TCCR0A, 0x0); // WGM: Normal
cpu.writeData(TCCR0B, CS00); // Set prescaler to 1
timer.tick();
cpu.cycles = 1;
timer.tick();
expect(cpu.data[TIFR0]).toEqual(OCF0A);
Expand All @@ -183,10 +188,10 @@ describe('timer', () => {
const cpu = new CPU(new Uint16Array(0x1000));
const timer = new AVRTimer(cpu, timer0Config);
cpu.writeData(TCNT0, 0x10);
timer.tick();
cpu.writeData(OCR0A, 0x11);
cpu.writeData(TCCR0A, WGM01); // WGM: CTC
cpu.writeData(TCCR0B, CS00); // Set prescaler to 1
timer.tick();
cpu.cycles = 1;
timer.tick();
const tcnt = cpu.readData(TCNT0);
Expand All @@ -199,10 +204,10 @@ describe('timer', () => {
const cpu = new CPU(new Uint16Array(0x1000));
const timer = new AVRTimer(cpu, timer0Config);
cpu.writeData(TCNT0, 0x10);
timer.tick();
cpu.writeData(OCR0B, 0x11);
cpu.writeData(TCCR0A, 0x0); // WGM: (Normal)
cpu.writeData(TCCR0B, CS00); // Set prescaler to 1
timer.tick();
cpu.cycles = 1;
timer.tick();
expect(cpu.data[TIFR0]).toEqual(OCF0B);
Expand All @@ -214,11 +219,11 @@ describe('timer', () => {
const cpu = new CPU(new Uint16Array(0x1000));
const timer = new AVRTimer(cpu, timer0Config);
cpu.writeData(TCNT0, 0x20);
timer.tick();
cpu.writeData(OCR0A, 0x21);
cpu.writeData(TCCR0B, CS00); // Set prescaler to 1
cpu.writeData(TIMSK0, OCIE0A);
cpu.writeData(95, 0x80); // SREG: I-------
timer.tick();
cpu.cycles = 1;
timer.tick();
const tcnt = cpu.readData(TCNT0);
Expand All @@ -232,11 +237,11 @@ describe('timer', () => {
const cpu = new CPU(new Uint16Array(0x1000));
const timer = new AVRTimer(cpu, timer0Config);
cpu.writeData(TCNT0, 0x20);
timer.tick();
cpu.writeData(OCR0A, 0x21);
cpu.writeData(TCCR0B, CS00); // Set prescaler to 1
cpu.writeData(TIMSK0, 0);
cpu.writeData(95, 0x80); // SREG: I-------
timer.tick();
cpu.cycles = 1;
timer.tick();
const tcnt = cpu.readData(TCNT0);
Expand All @@ -249,11 +254,11 @@ describe('timer', () => {
const cpu = new CPU(new Uint16Array(0x1000));
const timer = new AVRTimer(cpu, timer0Config);
cpu.writeData(TCNT0, 0x20);
timer.tick();
cpu.writeData(OCR0B, 0x21);
cpu.writeData(TCCR0B, CS00); // Set prescaler to 1
cpu.writeData(TIMSK0, OCIE0B);
cpu.writeData(95, 0x80); // SREG: I-------
timer.tick();
cpu.cycles = 1;
timer.tick();
const tcnt = cpu.readData(TCNT0);
Expand Down Expand Up @@ -311,9 +316,27 @@ describe('timer', () => {
expect(cpu.data[R1]).toEqual(2);
});

it('should not start counting before the prescaler is first set (issue #41)', () => {
const { program, instructionCount } = asmProgram(`
NOP
NOP
NOP
NOP
LDI r16, 0x1 ; TCCR2B = 1 << CS20;
STS 0xb1, r16 ; Should start counting after this line
NOP
LDS r17, 0xb2 ; TCNT should equal 2 at this point
`);
const cpu = new CPU(program);
const timer = new AVRTimer(cpu, timer2Config);
const runner = new TestProgramRunner(cpu, timer);
runner.runInstructions(instructionCount);
expect(cpu.readData(R17)).toEqual(2);
});

describe('Phase-correct PWM mode', () => {
it('should count up to TOP, down to 0, and then set TOV flag', () => {
const { program, lines, instructionCount } = asmProgram(`
const { program, instructionCount } = asmProgram(`
; Set waveform generation mode (WGM) to PWM, Phase Correct, top OCR0A
LDI r16, 0x1 ; TCCR0A = 1 << WGM00;
OUT 0x24, r16
Expand All @@ -323,36 +346,26 @@ describe('timer', () => {
OUT 0x27, r16
LDI r16, 0x2 ; TCNT0 = 0x2;
OUT 0x26, r16
NOP ; TCNT0 will be 3
NOP ; TCNT0 will be 2
NOP ; TCNT0 will be 1
NOP ; TCNT0 will be 0
NOP ; TCNT0 will be 1 (end of test)
IN r17, 0x26 ; TCNT0 will be 2
IN r18, 0x26 ; TCNT0 will be 3
IN r19, 0x26 ; TCNT0 will be 2
IN r20, 0x26 ; TCNT0 will be 1
IN r21, 0x26 ; TCNT0 will be 0
IN r22, 0x26 ; TCNT0 will be 1 (end of test)
`);
const nopCount = lines.filter((line) => line.bytes == nopOpCode).length;
const cpu = new CPU(program);
const timer = new AVRTimer(cpu, timer0Config);
const runner = new TestProgramRunner(cpu, timer);
runner.runInstructions(instructionCount - nopCount);
expect(cpu.readData(TCNT0)).toEqual(2);

runner.runInstructions(1);
expect(cpu.readData(TCNT0)).toEqual(3);

runner.runInstructions(1);
expect(cpu.readData(TCNT0)).toEqual(2);

runner.runInstructions(1);
expect(cpu.readData(TCNT0)).toEqual(1);
expect(cpu.data[TIFR0] & TOV0).toEqual(0);

runner.runInstructions(1);
expect(cpu.readData(TCNT0)).toEqual(0);
runner.runInstructions(instructionCount);

expect(cpu.readData(R17)).toEqual(2);
expect(cpu.readData(R18)).toEqual(3);
expect(cpu.readData(R19)).toEqual(2);
expect(cpu.readData(R20)).toEqual(1);
expect(cpu.readData(R21)).toEqual(0);
expect(cpu.readData(R22)).toEqual(1);
expect(cpu.data[TIFR0] & TOV0).toEqual(TOV0);

runner.runInstructions(1);
expect(cpu.readData(TCNT0)).toEqual(1);
});

it('should clear OC0A when TCNT0=OCR0A and counting up', () => {
Expand Down Expand Up @@ -408,12 +421,12 @@ describe('timer', () => {
const timer = new AVRTimer(cpu, timer1Config);
cpu.writeData(TCNT1H, 0x22); // TCNT1 <- 0x2233
cpu.writeData(TCNT1, 0x33); // ...
timer.tick();
const timerLow = cpu.readData(TCNT1);
const timerHigh = cpu.readData(TCNT1H);
expect((timerHigh << 8) | timerLow).toEqual(0x2233);
cpu.writeData(TCCR1A, 0x0); // WGM: Normal
cpu.writeData(TCCR1B, CS10); // Set prescaler to 1
timer.tick();
cpu.cycles = 1;
timer.tick();
cpu.readData(TCNT1);
Expand All @@ -425,11 +438,11 @@ describe('timer', () => {
const timer = new AVRTimer(cpu, timer1Config);
cpu.writeData(TCNT1H, 0x10); // TCNT1 <- 0x10ee
cpu.writeData(TCNT1, 0xee); // ...
timer.tick();
cpu.writeData(OCR1AH, 0x10); // OCR1 <- 0x10ef
cpu.writeData(OCR1A, 0xef); // ...
cpu.writeData(TCCR1A, 0x0); // WGM: Normal
cpu.writeData(TCCR1B, CS10); // Set prescaler to 1
timer.tick();
cpu.cycles = 1;
timer.tick();
expect(cpu.data[TIFR1]).toEqual(OCF1A); // TIFR1 should have OCF1A bit on
Expand All @@ -442,11 +455,11 @@ describe('timer', () => {
const timer = new AVRTimer(cpu, timer1Config);
cpu.writeData(TCNT1H, 0x3); // TCNT1 <- 0x3ff
cpu.writeData(TCNT1, 0xff); // ...
timer.tick();
cpu.writeData(TCCR1A, 0x3); // TCCR1A <- WGM10 | WGM11 (Fast PWM, 10-bit)
cpu.writeData(TCCR1B, 0x9); // TCCR1B <- WGM12 | CS10
cpu.data[0x6f] = 0x1; // TIMSK1: TOIE1
cpu.data[SREG] = 0x80; // SREG: I-------
timer.tick();
cpu.cycles = 1;
timer.tick();
cpu.readData(TCNT1); // Refresh TCNT1
Expand All @@ -461,10 +474,10 @@ describe('timer', () => {
const timer = new AVRTimer(cpu, timer1Config);
cpu.writeData(TCNT1H, 0x50); // TCNT1 <- 0x500f
cpu.writeData(TCNT1, 0x0f); // ...
timer.tick();
cpu.writeData(ICR1H, 0x50); // ICR1 <- 0x5010
cpu.writeData(ICR1, 0x10); // ...
cpu.writeData(TCCR1B, WGM13 | WGM12 | CS10); // Set prescaler to 1, WGM: CTC
timer.tick();
cpu.cycles = 2; // 2 cycles should increment timer twice, beyond ICR1
timer.tick();
cpu.readData(TCNT1); // Refresh TCNT1
Expand Down
2 changes: 2 additions & 0 deletions src/peripherals/timer.ts
View file
Original file line number Diff line number Diff line change
Expand Up @@ -247,6 +247,7 @@ export class AVRTimer {

this.cpu.writeHooks[config.TCNT] = (value: u8) => {
this.tcnt = (this.highByteTemp << 8) | value;
this.countingUp = true;
this.tcntUpdated = true;
this.timerUpdated();
};
Expand Down Expand Up @@ -281,6 +282,7 @@ export class AVRTimer {
};
cpu.writeHooks[config.TCCRB] = (value) => {
this.cpu.data[config.TCCRB] = value;
this.tcntUpdated = true;
this.updateWGMConfig();
return true;
};
Expand Down

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