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mod02 ex02 ok

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hugogogo
2025-03-07 13:00:13 +01:00
parent 2e47e9dca6
commit c50e5f24aa
1 changed files with 12 additions and 18 deletions
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28
module02/ex02/main.c
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@@ -118,22 +118,20 @@ void uart_init() {
UCSR0C |= ASYNCHRONOUS | PARITY_DISABLED | STOP_ONE_BIT | DATA_EIGHT_BIT; // 20.11.4 : set Frame Format UCSR0C |= ASYNCHRONOUS | PARITY_DISABLED | STOP_ONE_BIT | DATA_EIGHT_BIT; // 20.11.4 : set Frame Format
UCSR0B |= RECEIVER_DISABLED | TRANSMITTER_ENABLED; // 20.11.3 : enable Receiver and/or Transmitter UCSR0B |= RECEIVER_ENABLED | TRANSMITTER_ENABLED; // 20.11.3 : enable Receiver and/or Transmitter
} }
void uart_tx(char c) { void uart_tx(char c) {
while (TEST(UCSR0A, UDRE0) == 0); // 20.11.2 : do nothing until UDR emission buffer is empty, if UDREn flag is 1, UCSRnA register is empty while (TEST(UCSR0A, UDRE0) == 0); // 20.11.2 : do nothing until UDRn buffer is empty, (UDREn flag in UCSRnA register set to 1 when buffer empty)
UDR0 = (unsigned char) c; // 20.11.1 : Put data into buffer, UDRn – USART I/O Data Register (read and write) UDR0 = (unsigned char) c; // 20.11.1 : Put data into buffer, UDRn – USART I/O Data Register (read and write)
} }
void uart_printstr(const char* str) { char uart_rx(void) {
while (*str) { while (TEST(UCSR0A, RXC0) == 0); // 20.11.2 : do nothing until there are unread data in the receive buffer (UDRn), (RXCn flag in UCSRnA register set to 1 when buffer has data)
uart_tx(*str); return UDR0; // 20.11.1 : get data in buffer, UDRn – USART I/O Data Register (read and write)
str++;
}
} }
// print hello world, on serial port, every 2 seconds, with empty infinite loop // send back caracters received on serial port
// `screen /dev/ttyUSB0 115200` // `screen /dev/ttyUSB0 115200`
int main() { int main() {
uart_init(); uart_init();
@@ -141,17 +139,13 @@ int main() {
TCCR1A |= CTC_TOP_OCR1A_IN_TCCR1A; // Table 16-4 : set timer in CTC (Clear Time on Compare) mode TCCR1A |= CTC_TOP_OCR1A_IN_TCCR1A; // Table 16-4 : set timer in CTC (Clear Time on Compare) mode
TCCR1B |= CTC_TOP_OCR1A_IN_TCCR1B; TCCR1B |= CTC_TOP_OCR1A_IN_TCCR1B;
sei(); // enable global interrupts (https://www.nongnu.org/avr-libc/user-manual/group__avr__interrupts.html#gaad5ebd34cb344c26ac87594f79b06b73)
TIMSK1 |= INTERRUPT_ENABLE_CHANNEL_A; // 16.11.8 : enables the Timer1 Compare Match A interrupt, this makes the MCU react when OCR1A == TCNT1 by calling TIMER1_COMPA_vect
OCR1A = TIME_MS(PERIOD); // Table 16-4 : set CTC compare value on channel A, the counter is cleared to zero when the counter value (TCNT1) matches the OCR1A register OCR1A = TIME_MS(PERIOD); // Table 16-4 : set CTC compare value on channel A, the counter is cleared to zero when the counter value (TCNT1) matches the OCR1A register
TCCR1B |= (PRESCALE_SET(PRESCALE_VALUE)); // 16.4 : set timer according to prescale value, in register TCCR1B, table 16-5 : prescale sets TCCR1B |= (PRESCALE_SET(PRESCALE_VALUE)); // 16.4 : set timer according to prescale value, in register TCCR1B, table 16-5 : prescale sets
while(1); char received_char;
} while(1) {
received_char = uart_rx();
// ISR interrupt macro : https://www.nongnu.org/avr-libc/user-manual/group__avr__interrupts.html uart_tx(received_char);
ISR(TIMER1_COMPA_vect) { // Table 12-7 : we select the code for timer 1 on channel A }
uart_printstr("Hello World!");
} }