AVR_ATMEGA_USART/avr_usart.c

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/*
* Author: Jake Goodwin
* Date: 2023
* Description: Small library to communicate with the AT-09 bluetooth module.
*/
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>
#include <util/delay.h>
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#include "avr_usart.h"
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//#############################
//Globals
//#############################
int main() {
unsigned char* tx_buffer[16];
unsigned char* rx_buffer[16];
led_blink();
led_blink();
led_blink();
_delay_ms(1000);
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_delay_ms(1000);
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init_usart0();
//enable interrupts
sei();
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unsigned char data[] = "AT+WAKE";
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while(1) {
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_delay_ms(1000);
//led_blink();
for(uint8_t i = 0; i < 7; i++) {
tx_usart0(data[i]);
}
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}
return 0;
}
//#############################
//FUNCTIONS
//#############################
/*
* Input: None
* Output: None
* Description: init usart0 hardware in async mode
*/
void init_usart0(void) {
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//DDRB |= (1<<TX_DDR)|(0<<RX_DDR);
//PORTD |= (0<<TX_PIN)|(0<<RX_PIN);
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//setup stuff for usart communications.
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//set baud rate, this is 9600Baud with a 8Mhz clock
//UBRR0H |= (uint8_t) (BT_UBRR>>8);
//UBRR0L |= (uint8_t) BT_UBRR;
UBRR0H |= (uint8_t) (0x33>>8);
UBRR0L |= (uint8_t) 0x33;
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//Enable recv and Transmit pins, overrides other uses.
//IN the usart control and status register 0B
UCSR0B = (1<<RXEN0) | (1<<TXEN0);
//setting the data frame format
//We leave the 2MSB zero for async serial. And we also don't enable
//parity bits for now. We set a 2bit stop bit and 8bit char size.
UCSR0C = (1<<USBS0) | (3<<UCSZ00);
}
/*
* Input: a 8bit char
* Output: None
* Description: Sends a char over usart0
*/
void tx_usart0(unsigned char data) {
//first wait for the transmit buffer to be empty
while(!(UCSR0A & (1<<UDRE0))) {
;//Equiv of continue
}
//now that it's empty, fill buffer with TX data.
UDR0 = data;
}
/*
* Input:None
* Output: a 8bit char
* Description: Recvs a char over usart0
*/
unsigned char rx_usart0(void) {
//first wait for the data to be received.
while(!(UCSR0A & (1<<RXC0))) {
;//Equiv of continue
}
//now return the data
return (unsigned char) UDR0;
}
/*
* Input: None
* Output: None
* Description: Toggles the pin for the LED indicator.
*/
static void led_blink(void) {
//Set the DDR for output.
DDRC |= (1<<LED_PIN);
PORTC ^= (1<<LED_PIN);
_delay_ms(250);
PORTC ^= (1<<LED_PIN);
_delay_ms(250);
}