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uart_raw.c
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uart_raw.c
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/*
A raw and not accurate way of sending some debug lines using serial communication.
This snippet uses a TX pin to send raw bytes in a fixed speed. There's no error checking
nor any clock / speed / transfer / whatever control, so it may fail in some complex
transactions timing or complexity is more critical than the few times I've used it.
Wanna try a version that uses interrupts? This post talks about it! https://marcelmg.github.io/software_uart/
*/
#ifndef UARTRaw_c
#define UARTRaw_c
#include <stdlib.h>
#define UART_TX_PIN 4 // ol' led pin
#define DELAY_US 104 // 1/9600 = 104 (other close values may work better)
void uart_raw_init() {
DDRB |= (1 << UART_TX_PIN); // port as output
}
void uart_raw_tx_1() {
PORTB |= (1 << UART_TX_PIN); // set port to 1
}
void uart_raw_tx_0() {
PORTB &= ~(1 << UART_TX_PIN); // set port to 0
}
void uart_raw_send_byte(unsigned char byte) {
// bit 1 to start transaction
uart_raw_tx_0();
_delay_us(DELAY_US);
for (unsigned char i = 0; i < 8; i++) {
if (byte & 0x01) uart_raw_tx_1();
else uart_raw_tx_0();
_delay_us(DELAY_US);
byte >>= 1;
}
// stop
uart_raw_tx_1();
_delay_us(DELAY_US);
}
void uart_raw_send_string(char *string, unsigned char length) {
for (unsigned char i = 0; i < length; i++) {
uart_raw_send_byte(string[i]);
}
}
// append a \n\r at the end of the string
void uart_raw_send_line(char *string, unsigned char length) {
char *string_2;
char length_2 = length + 2;
string_2 = malloc(length_2);
strcat(string_2, string);
strcat(string_2, "\n\r");
uart_raw_send_string(string_2, length_2);
free(string_2);
}
// borrowed from the log functions from the v-usb library
char hex_ascii(char h) {
h &= 0xf;
if(h >= 10)
h += 'a' - (char)10 - '0';
h += '0';
return h;
}
void uart_raw_send_hex_line(char *string, unsigned char length) {
for (unsigned char i = 0; i < length; i++) {
uart_raw_send_byte(hex_ascii(string[i] >> 4));
uart_raw_send_byte(hex_ascii(string[i]));
}
uart_raw_send_byte('\n');
uart_raw_send_byte('\r');
}
#endif