From c50e5f24aad4d1c7730ea76880ea5027f9cdb14a Mon Sep 17 00:00:00 2001 From: hugogogo Date: Fri, 7 Mar 2025 13:00:13 +0100 Subject: [PATCH] mod02 ex02 ok --- module02/ex02/main.c | 30 ++++++++++++------------------ 1 file changed, 12 insertions(+), 18 deletions(-) diff --git a/module02/ex02/main.c b/module02/ex02/main.c index fb8bfb9..2c780c4 100644 --- a/module02/ex02/main.c +++ b/module02/ex02/main.c @@ -118,22 +118,20 @@ void uart_init() { 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) { - 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) } -void uart_printstr(const char* str) { - while (*str) { - uart_tx(*str); - str++; - } +char uart_rx(void) { + 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) + return UDR0; // 20.11.1 : get data in buffer, UDRn – USART I/O Data Register (read and write) } -// print hello world, on serial port, every 2 seconds, with empty infinite loop +// send back caracters received on serial port // `screen /dev/ttyUSB0 115200` int main() { 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 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 TCCR1B |= (PRESCALE_SET(PRESCALE_VALUE)); // 16.4 : set timer according to prescale value, in register TCCR1B, table 16-5 : prescale sets - - while(1); -} - -// ISR interrupt macro : https://www.nongnu.org/avr-libc/user-manual/group__avr__interrupts.html -ISR(TIMER1_COMPA_vect) { // Table 12-7 : we select the code for timer 1 on channel A - uart_printstr("Hello World!"); + + char received_char; + while(1) { + received_char = uart_rx(); + uart_tx(received_char); + } }