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mod04 ex01 trigger timer0 set but not working

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hugo LAMY
2025-03-11 22:40:13 +01:00
parent d0427ce83d
commit b487d8f353
2 changed files with 58 additions and 25 deletions
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69
module04/ex01/main.c
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@@ -20,12 +20,12 @@
// - if i want my cycle to be 0.01 second, which prescaler ?
// - 8 * 0,004096 = 0.032768 -> it is enough
// - 64 * 0,004096 = 0.262144 -> it is largely enough
// - if i choose prescaler 1 for a duration of 0.001 seconds, i need to restart the clock after how many cycles :
// - (16000000 / 1) * 0.001 = 16000 ticks -> set ICR1 = 16000
// - if i choose prescaler 8 for a duration of 0.01 seconds, i need to restart the clock after how many cycles :
// - (16000000 / 8) * 0.01 = 20000 ticks -> set ICR1 = 20000
// - if i choose prescaler 64 for a duration of 0.01 seconds, i need to restart the clock after how many cycles :
// - (16000000 / 64) * 0.01 = 2500 ticks -> set ICR1 = 2500
// - after how many "ticks" do i need to reset my clock, for a duration of 0.01s, for every prescalers :
// - 1 : (16000000 / 1) * 0.01 = 16000000 * 0.01 = 160000 "ticks"
// - 8 : (16000000 / 8) * 0.01 = 2000000 * 0.01 = 20000 "ticks"
// - 64 : (16000000 / 64) * 0.01 = 250000 * 0.01 = 2500 "ticks"
// - 256 : (16000000 / 256) * 0.01 = 62500 * 0.01 = 625 "ticks"
// - 1024 : (16000000 / 1024) * 0.01 = 15625 * 0.01 = 156,25 "ticks"
// alternatively, can use the default values :
// - Fast PWM, 8-bit, TOP 0x00FF (255)
@@ -49,12 +49,22 @@
// 16.9.3 : timer1 fast PWM
#define LED1_PWM_PRESCALER 256 // can be 1, 8, 64, 256, 1024
#define DUTY_CYCLE_PERCENT 9
#define FREQUENCY_MS 1
#define TOP_VALUE 1000
// TIMER 1
#define T1_PWM_PRESCALER 256 // can be 1, 8, 64, 256, 1024
#define T1_DUTY_CYCLE_PERCENT 9
// #define FREQUENCY_MS 1
#define T1_TOP_VALUE 1000
// TIMER 0
#define T0_PWM_PRESCALER 256 // can be 1, 8, 64, 256, 1024
#define T0_FREQUENCY_MS 20
volatile uint8_t duty_cycle = DUTY_CYCLE_PERCENT;
typedef enum {
DOWN,
UP
} Slope;
volatile uint8_t duty_cycle = T1_DUTY_CYCLE_PERCENT;
volatile Slope slope = UP;
void blink_led_1() {
TCCR1A = (1 << WGM11); // Table 16-4 : set timer1 in fast PWM mode 14, with TOP ICR1, so we can use OCR1A for duty cycle and keep ICR1 for frequency
@@ -63,25 +73,21 @@ void blink_led_1() {
TCCR1A |= (1 << COM1A1); // Table 16-2 : set non-inverting mode to trigger OC1A on fast PWM (14.3.1 : OC1A is alternate function of PB1)
TCCR1B |= PRESCALE_SET(LED1_PWM_PRESCALER); // Table 16-5 : set the appropriate prescale values
TCCR1B |= T1_PRESCALE_SET(T1_PWM_PRESCALER); // Table 16-5 : set the appropriate prescale values for timer 1
// ICR1 = TIME_MS(FREQUENCY_MS, LED1_PWM_PRESCALER); // top value for Xms
ICR1 = TOP_VALUE;
// ICR1 = TIME_MS(FREQUENCY_MS, T1_PWM_PRESCALER); // top value for Xms
ICR1 = T1_TOP_VALUE;
OCR1A = PERCENT(duty_cycle, ICR1); // 16.9.3 : duty cycle
}
vary_duty() {
// TCCR0A = (1 << WGM11); // Table 15-8 : set timer0 in CTC mode, with TOP OCRA
// TCCR1B = (1 << WGM13) | (1 << WGM12);
void vary_duty() {
TCCR0A = (1 << WGM11); // Table 15-8 : set timer0 in CTC mode, with TOP OCRA (15.9.1 : WGM11 in register TCCR0A)
// TCCR1A |= (1 << COM1A1); // Table 16-2 : set non-inverting mode to trigger OC1A on fast PWM (14.3.1 : OC1A is alternate function of PB1)
OCR0A = TIME_MS(T0_FREQUENCY_MS, T0_PWM_PRESCALER); // 15.9.4 : compare value to trigger an Output Compare interrupt on register A
// TCCR1B |= PRESCALE_SET(LED1_PWM_PRESCALER); // Table 16-5 : set the appropriate prescale values
// // ICR1 = TIME_MS(FREQUENCY_MS, LED1_PWM_PRESCALER); // top value for Xms
// ICR1 = TOP_VALUE;
// OCR1A = PERCENT(duty_cycle, ICR1); // 16.9.3 : duty cycle
TCCR0B |= T0_PRESCALE_SET(T0_PWM_PRESCALER); // 15.9.2 : set the appropriate prescale values for timer 0
TIMSK0 = (1 << OCIE0A); // 15.9.6 : set OCIE0A in TIMSK0 to enable Compare Match A interrupt in Timer0
}
// use timers interruptions to varie led1 intensity using duty cycle, from 0% to 100% to 0% in 1 second
@@ -103,3 +109,20 @@ int main() {
while (1);
}
ISR(TIMER0_COMPA_vect) {
if (slope == UP) {
if (duty_cycle >= 100) {
slope = DOWN;
} else {
duty_cycle += 2;
}
}
if (slope == DOWN) {
if (duty_cycle <= 0) {
slope = UP;
} else {
duty_cycle -= 2;
}
}
}

14
module04/ex01/timer.h
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@@ -1,8 +1,18 @@
#ifndef TIMER_H
#define TIMER_H
// table 16-5 : prescale sets
#define PRESCALE_SET(value) \
// table 15-9 : timer 0 prescale sets
#define T0_PRESCALE_SET(value) \
((value) == 1 ? (0<<CS02 | 0<<CS01 | 1<<CS00) : \
(value) == 8 ? (0<<CS02 | 1<<CS01 | 0<<CS00) : \
(value) == 64 ? (0<<CS02 | 1<<CS01 | 1<<CS00) : \
(value) == 256 ? (1<<CS02 | 0<<CS01 | 0<<CS00) : \
(value) == 1024? (1<<CS02 | 0<<CS01 | 1<<CS00) : \
(0<<CS02 | 0<<CS01 | 0<<CS00))
#define TIME_MS(ms, prescale_value) (((F_CPU / prescale_value) * ms) / 1000)
// table 16-5 : timer 1 prescale sets
#define T1_PRESCALE_SET(value) \
((value) == 1 ? (0<<CS12 | 0<<CS11 | 1<<CS10) : \
(value) == 8 ? (0<<CS12 | 1<<CS11 | 0<<CS10) : \
(value) == 64 ? (0<<CS12 | 1<<CS11 | 1<<CS10) : \