Basic boilerplate for programming AVR (arduino) in C.
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avr-c-boilerplate/lib/usart.h

86 lines
1.7 KiB

#pragma once
//
// Utilities for UART communication.
//
// First, init uart with usart_init().
// Then enable interrupts you want with usart_XXX_isr_enable().
//
#include <avr/io.h>
#include <avr/pgmspace.h>
#include <util/delay.h>
#include <stdbool.h>
#include <stdint.h>
#include "calc.h"
/* USART BAUD RATE REGISTER values at 16 MHz */
enum {
BAUD_9600 = 103,
BAUD_14400 = 68,
BAUD_19200 = 51,
BAUD_28800 = 34,
BAUD_38400 = 25,
BAUD_57600 = 16,
BAUD_76800 = 12,
BAUD_115200 = 8,
BAUD_250k = 3,
BAUD_500k = 1,
BAUD_1M = 0,
};
/** Init UART with a UBRR value - can use the BAUD_* constants for 16 MHz */
void usart_init(uint16_t ubrr);
/** Set Double Speed Asynchronous mode on or off */
void usart_set_2x(bool set);
/** Check if there's a byte in the RX register */
#define usart_rx_ready() bit_is_high(UCSR0A, RXC0)
/** Check if USART is ready to accept new byte to send */
#define usart_tx_ready() bit_is_high(UCSR0A, UDRE0)
// ---- Enable UART interrupts ------------
/** Enable or disable RX ISR */
#define usart_isr_rx_enable(yes) set_bit(UCSR0B, RXCIE0, (yes))
/** Enable or disable TX ISR (all data sent) */
#define usart_isr_tx_enable(yes) set_bit(UCSR0B, TXCIE0, (yes))
/** Enable or disable DRE ISR (data register empty) */
#define usart_isr_dre_enable(yes) set_bit(UCSR0B, UDRIE0, (yes))
// ---- Basic IO --------------------------
/** Send byte over USART */
void usart_tx(uint8_t data);
/** Receive one byte over USART */
uint8_t usart_rx(void);
/** Clear receive buffer */
void usart_flush_rx(void);
// ---- Strings ---------------------------
/** Send string over UART */
void usart_puts(const char* str);
/** Send progmem string `PSTR("foobar")` over UART */
void usart_puts_P(const char* str);