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/*
atmega88_uart_echo.c
This test case enables uart RX interupts, does a "printf" and then receive characters
via the interupt handler until it reaches a \r.
This tests the uart reception fifo system. It relies on the uart "irq" input and output
to be wired together (see simavr.c)
*/
#include <avr/io.h>
#include <stdio.h>
#include <avr/interrupt.h>
#include <avr/eeprom.h>
#include <avr/sleep.h>
#include <util/delay.h>
/*
* This demonstrate how to use the avr_mcu_section.h file
* The macro adds a section to the ELF file with useful
* information for the simulator
*/
#include "avr_mcu_section.h"
AVR_MCU(F_CPU, "atmega2560");
// tell simavr to listen to commands written in this (unused) register
AVR_MCU_SIMAVR_COMMAND(&GPIOR0);
AVR_MCU_SIMAVR_CONSOLE(&GPIOR1);
/*
* This small section tells simavr to generate a VCD trace dump with changes to these
* registers.
* Opening it with gtkwave will show you the data being pumped out into the data register
* UDR0, and the UDRE0 bit being set, then cleared
*/
const struct avr_mmcu_vcd_trace_t _mytrace[] _MMCU_ = {
{ AVR_MCU_VCD_SYMBOL("UDR3"), .what = (void*)&UDR3, },
{ AVR_MCU_VCD_SYMBOL("UDRE3"), .mask = (1 << UDRE3), .what = (void*)&UCSR3A, },
{ AVR_MCU_VCD_SYMBOL("GPIOR1"), .what = (void*)&GPIOR1, },
};
#ifdef USART3_RX_vect_num // stupid ubuntu has antique avr-libc
AVR_MCU_VCD_IRQ(USART3_RX); // single bit trace
#endif
AVR_MCU_VCD_ALL_IRQ(); // also show ALL irqs running
volatile uint8_t cnt = 0;
volatile uint8_t done = 0;
static int uart_putchar(char c, FILE *stream)
{
uint8_t startcnt;
if (c == '\n')
uart_putchar('\r', stream);
loop_until_bit_is_set(UCSR3A, UDRE3);
startcnt = cnt;
UDR3 = c;
// _delay_us(100);
// Wait until we have received the character back
while(!done && cnt == startcnt)
{
UDR1 = 'a';
UDR1 = '\n';
sleep_cpu();
}
UDR1 = 'b';
UDR1 = '\n';
_delay_us(1000);
return 0;
}
static FILE mystdout = FDEV_SETUP_STREAM(uart_putchar, NULL,
_FDEV_SETUP_WRITE);
volatile uint8_t bindex = 0;
uint8_t buffer[80];
ISR(USART3_RX_vect)
{
UDR1 = 'c';
UDR1 = '\n';
uint8_t b = UDR3;
GPIOR1 = b; // for the trace file
buffer[bindex++] = b;
buffer[bindex] = 0;
cnt++;
if (b == '\n')
done++;
// sleep_cpu();
}
int main()
{
stdout = &mystdout;
UCSR3C = (3 << UCSZ30); // 8 bits
// see http://www.nongnu.org/avr-libc/user-manual/group__util__setbaud.html
#define BAUD 38400
#include <util/setbaud.h>
UBRR3H = UBRRH_VALUE;
UBRR3L = UBRRL_VALUE;
#if USE_2X
UCSR3A |= (1 << U2X3);
#else
UCSR3A &= ~(1 << U2X3);
#endif
// enable receiver & transmitter
UCSR3B |= (1 << RXCIE3) | (1 << RXEN3) | (1 << TXEN3);
// this tells simavr to start the trace
GPIOR0 = SIMAVR_CMD_VCD_START_TRACE;
sei();
printf("Hey there, this should be received back\n");
loop_until_bit_is_set(UCSR3A, UDRE3);
while (!done)
sleep_cpu();
cli();
printf("Received: %s", buffer);
// this quits the simulator, since interupts are off
// this is a "feature" that allows running tests cases and exit
sleep_cpu();
}
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