44 lines
1.4 KiB
C
44 lines
1.4 KiB
C
#include <avr/io.h>
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#include <util/delay.h>
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#include <avr/interrupt.h>
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#include "utils.h"
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#include "bitmanip.h"
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#include "usart.h"
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// USART
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#define USART_BAUDRATE 115200
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// END MACROS
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void uart_init() {
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UBRR0H = (unsigned char) (BAUD_PRESCALER(USART_BAUDRATE) >> 8); // 20.11.5 : UBRRnL and UBRRnH – USART Baud Rate Registers
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UBRR0L = (unsigned char) BAUD_PRESCALER(USART_BAUDRATE);
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UCSR0C |= ASYNCHRONOUS | PARITY_DISABLED | STOP_ONE_BIT | DATA_EIGHT_BIT; // 20.11.4 : set Frame Format
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UCSR0B |= RECEIVER_ENABLED | TRANSMITTER_ENABLED; // 20.11.3 : enable Receiver and/or Transmitter
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}
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void uart_tx(char c) {
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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)
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UDR0 = (unsigned char) c; // 20.11.1 : Put data into buffer, UDRn – USART I/O Data Register (read and write)
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}
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char uart_rx(void) {
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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)
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return UDR0; // 20.11.1 : get data in buffer, UDRn – USART I/O Data Register (read and write)
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}
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// send back caracters received on serial port
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// `screen /dev/ttyUSB0 115200`
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int main() {
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uart_init();
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char received_char;
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while(1) {
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received_char = uart_rx();
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uart_tx(received_char);
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}
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}
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