day04/ex02/src/uart.c

#include "uart.h"
#include <avr/io.h>
#include "mystd.h"
#include "utils.h"

#define BAUD_RATE  115200

#define UBRR_VALUE ((F_CPU / (8UL * BAUD_RATE)) - 1)

// uart is 115200 baud rate, 8 bits per word, no parrity and 1 stop bit
// 115200 8N1
void uart_init(void) {
	// Set baud rate
	UBRR0H	= (uint8_t)(UBRR_VALUE >> 8);
	UBRR0L	= (uint8_t)(UBRR_VALUE);

	UCSR0A |= BV(U2X0);
	// Enable transmitter
	UCSR0B	= BV(TXEN0) | BV(RXEN0);

	// Set frame format: 8 data bits, no parity, 1 stop bit
	UCSR0C	= BV(UCSZ01) | BV(UCSZ00);

	// Set TX (PD1) as output
	DDRD   |= BV(PD1);
}

void uart_tx(char data) {
	// wait for transmit buffer to be empty
	while (!(UCSR0A & BV(UDRE0)))
		;
	// load data into transmit register
	UDR0 = data;
}

char uart_rx(void) {
	while (!(UCSR0A & BV(RXC0)))
		;
	return UDR0;
}

void uart_sendstring(const char* str) {
	if (!str)
		return;
	while (*str) {
		uart_tx(*str);
		str++;
	}
}
void uart_send_u8(uint8_t val) {
	char	buf[4]	= {0, 0, 0, 0};
	uint8_t idx		= 0;
	bool	print	= false;

	uint8_t modulus = 100;
	while (modulus) {
		uint8_t digit = val / modulus;
		if (print || digit != 0) {
			print	   = true;
			buf[idx++] = '0' + digit;
		}
		val		%= modulus;
		modulus /= 10;
	}

	uart_sendstring(buf);
}

void uart_send_u16(uint16_t val) {
	char	buf[6]	 = {0, 0, 0, 0, 0, 0};
	uint8_t idx		 = 0;
	bool	print	 = false;

	uint16_t modulus = 10000;
	while (modulus) {
		uint8_t digit = val / modulus;
		if (print || digit != 0) {
			print	   = true;
			buf[idx++] = '0' + digit;
		}
		val		%= modulus;
		modulus /= 10;
	}
	uart_sendstring(buf);
}

void uart_send_u8_hex(uint8_t val) {
	char buf[3] = {0, 0, 0};
	buf[0]		= "0123456789abcdef"[(val >> 4) & 0x0F];
	buf[1]		= "0123456789abcdef"[(val >> 0) & 0x0F];

	uart_sendstring(buf);
}

void uart_send_u16_hex(uint16_t val) {
	char buf[5] = {0, 0, 0, 0, 0};

	buf[0]		= "0123456789abcdef"[(val >> 12) & 0x0F];
	buf[1]		= "0123456789abcdef"[(val >> 8) & 0x0F];
	buf[2]		= "0123456789abcdef"[(val >> 4) & 0x0F];
	buf[3]		= "0123456789abcdef"[(val >> 0) & 0x0F];
	uart_sendstring(buf);
}