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mod04 ex01 ok but not accurate

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hugo LAMY
2025-03-12 10:01:52 +01:00
parent b487d8f353
commit fc77fb1749
1 changed files with 20 additions and 10 deletions
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30
module04/ex01/main.c
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@@ -25,7 +25,13 @@
// - 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"
// - 1024 : (16000000 / 1024) * 0.01 = 15625 * 0.01 = 156.25 "ticks"
// - after how many "ticks" do i need to reset my clock, for a duration of 0.005s (*200/s), for every prescalers :
// - 1 : (16000000 / 1) * 0.005 = 16000000 * 0.005 = 80000 "ticks"
// - 8 : (16000000 / 8) * 0.005 = 2000000 * 0.005 = 10000 "ticks"
// - 64 : (16000000 / 64) * 0.005 = 250000 * 0.005 = 1250 "ticks"
// - 256 : (16000000 / 256) * 0.005 = 62500 * 0.005 = 312.5 "ticks"
// - 1024 : (16000000 / 1024) * 0.005 = 15625 * 0.005 = 78.125 "ticks"
// alternatively, can use the default values :
// - Fast PWM, 8-bit, TOP 0x00FF (255)
@@ -50,13 +56,13 @@
// 16.9.3 : timer1 fast PWM
// TIMER 1
#define T1_PWM_PRESCALER 256 // can be 1, 8, 64, 256, 1024
#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
#define T0_PWM_PRESCALER 1024 // can be 1, 8, 64, 256, 1024
#define T0_FREQUENCY_MS 5
typedef enum {
DOWN,
@@ -66,6 +72,7 @@ typedef enum {
volatile uint8_t duty_cycle = T1_DUTY_CYCLE_PERCENT;
volatile Slope slope = UP;
// using TIMER 1
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
TCCR1B = (1 << WGM13) | (1 << WGM12); // mode 15 with OCR1A TOP prevent using duty cycle trigger on OC1A (OCR1B is free but triggers OC1B -> PB2)
@@ -80,14 +87,15 @@ void blink_led_1() {
OCR1A = PERCENT(duty_cycle, ICR1); // 16.9.3 : duty cycle
}
// using TIMER 0
void vary_duty() {
TCCR0A = (1 << WGM11); // Table 15-8 : set timer0 in CTC mode, with TOP OCRA (15.9.1 : WGM11 in register TCCR0A)
TCCR0A = (1 << WGM01); // Table 15-8 : set timer0 in CTC mode, with TOP OCRA (15.9.1 : WGM01 in register TCCR0A)
OCR0A = TIME_MS(T0_FREQUENCY_MS, T0_PWM_PRESCALER); // 15.9.4 : compare value to trigger an Output Compare interrupt on register A
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
TIMSK0 = (1 << OCIE0A); // 15.9.6 : enable interrupt in timer 0
}
// use timers interruptions to varie led1 intensity using duty cycle, from 0% to 100% to 0% in 1 second
@@ -113,16 +121,18 @@ int main() {
ISR(TIMER0_COMPA_vect) {
if (slope == UP) {
if (duty_cycle >= 100) {
duty_cycle = 100;
slope = DOWN;
} else {
duty_cycle += 2;
duty_cycle += 1;
}
}
if (slope == DOWN) {
} else if (slope == DOWN) {
if (duty_cycle <= 0) {
duty_cycle = 0;
slope = UP;
} else {
duty_cycle -= 2;
duty_cycle -= 1;
}
}
OCR1A = PERCENT(duty_cycle, ICR1);
}