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first version of ex01

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hugogogo
2025-03-05 17:57:36 +01:00
parent e919c5f7a5
commit 670e5f1f5e
2 changed files with 32 additions and 10 deletions
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4
module01/ex00/main.c
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@@ -54,10 +54,10 @@ int main() {
TCCR1B |= (PRESCALE_SET); // set timer with prescale
// -> set timer with bits CS10-12, in register TCCR1B : 16.4 Timer/Counter Clock Sources
// -> prescale values : 16.11.2 TCCR1B – Timer/Counter1 Control Register B, table 16-5. Clock Select Bit Description
// -> prescale values : table 16-5. Clock Select Bit Description
while(1) {
if ( TCNT1 >= TIME_MS(500)) { // read timer with register TCNT1 (read/write allowed), that combines two 8 bits registers : 16.11.4 TCNT1H and TCNT1L – Timer/Counter1
if (TCNT1 >= TIME_MS(500)) { // read timer with register TCNT1 (read/write allowed), that combines two 8 bits registers : 16.11.4 TCNT1H and TCNT1L – Timer/Counter1
TOGGLE_LED(D2);
TCNT1 = 0; // reset timer value, also in register TCNT1
}

38
module01/ex01/main.c
View File

@@ -1,5 +1,4 @@
#include <avr/io.h>
#include <util/delay.h>
// #define FIRST_LETTER_IMPL(x) #x[0]
// #define FIRST_LETTER(x) FIRST_LETTER_IMPL(x)
@@ -26,7 +25,7 @@
#define TURN_OFF_LED(bit) CLEAR(PORTB, bit)
#define TOGGLE_LED(led) TOGGLE_PIN(B, led)
// ELEMENTS
#define D1 0
#define D2 1
#define D3 2
@@ -34,19 +33,42 @@
#define SW1 2
#define SW2 4
// TIME
#define PRESCALE_VALUE 1024
#define TIME(ms) (((F_CPU / PRESCALE_VALUE) * ms) / 1000)
#if (PRESCALE_VALUE == 1)
#define PRESCALE_SET (1 << CS10)
#elif (PRESCALE_VALUE == 8)
#define PRESCALE_SET (1 << CS11)
#elif (PRESCALE_VALUE == 64)
#define PRESCALE_SET (1 << CS10) | (1 << CS11)
#elif (PRESCALE_VALUE == 256)
#define PRESCALE_SET (1 << CS12)
#elif (PRESCALE_VALUE == 1024)
#define PRESCALE_SET (1 << CS10) | (1 << CS12)
#endif
#define TIME_MS(ms) (((F_CPU / PRESCALE_VALUE) * ms) / 1000)
int main() {
MODE_OUTPUT(B, D2);
TURN_OFF_LED(D2);
TCCR1B |= ((1 << CS10 ) | (1 << CS12 ) ); // set timer with prescale
TCCR1B |= (1 << WGM12); // set timer in CTC (Clear Time on Compare) mode
// -> use bit WGM12 to set mode ctc : Table 16-4. Waveform Generation Mode Bit Description
// -> bit WGM12 is located in register TCCR1B : 16.11.2 TCCR1B Timer/Counter1 Control Register B
OCR1A = TIME_MS(500); // set CTC compare value
// -> the value to reset the timer is the Output Compare Registers OCR1A : Table 16-4. Waveform Generation Mode Bit Description
TCCR1B |= (PRESCALE_SET);
while(1) {
if ( TCNT1 >= TIME(500)) {
TOGGLE_LED(D2);
TCNT1 = 0; // reset timer value
if (TIFR1 & (1 << OCF1A)) { // when comparison has occured, bit OCF1A is set
// -> "The compare match event will also set the Compare Match Flag (OCF1A/B) which can be used to generate an Output Compare interrupt request" : 16.2.1 Register
// -> bit OCF1A is in register TIFR1 : 16.11.9 TIFR1 – Timer/Counter1 Interrupt Flag Register
TOGGLE_LED(D2); // toggle using PINx register
TIFR1 = (1 << OCF1A); // clear the CTC flag
// -> "OCF1A can be cleared by writing a logic one to its bit location" : 16.11.9 TIFR1 – Timer/Counter1 Interrupt Flag Register
}
}
}