flow control test

repeat.c

#include <asf.h>
#include <avr/io.h>
#include <avr/wdt.h>
#include <stdint.h>

#define PIN_SET_OUTPUT(ddr, id) ddr |= _BV(id)
#define PIN_SET_INPUT(ddr, id) ddr &= ~_BV(id)
#define PIN_SET_HIGH(port, id) port |= _BV(id)
#define PIN_SET_LOW(port, id) port &= ~_BV(id)
#define PIN_IS_HIGH(pins, id) bit_is_set(pins, id)
#define PIN_IS_LOW(pins, id) bit_is_clear(pins, id)

void bluetooth_init (void);
uint8_t bluetooth_is_connected (void);
void bluetooth_read (void);
void bluetooth_write (uint8_t);
void bluetooth_request_to_send (uint8_t);
uint8_t bluetooth_is_clear_to_send (void);

void leds_init (void);
void leds_blue_on (void);
void leds_blue_off (void);
void leds_green_on (void);
void leds_green_off (void);
void leds_red_on (void);
void leds_red_off (void);

void spin_loop (uint32_t);
void spin_trap (void);
void loop (void);

int main (void)
{
	board_init();
	bluetooth_init();
	leds_init();
	
	// Insert application code here, after the board has been initialized.
	wdt_enable(WDTO_8S);
	wdt_reset();
	
	while (1)
	{
		if (bit_is_set(UCSR1A, DOR1))
		{
			leds_red_on();
			leds_green_on();
			leds_blue_on();
			spin_trap();
		}
		loop();
	}
	
	return 0;
}

void loop (void)
{
	wdt_reset();
	if (bluetooth_is_connected())
	{
		leds_blue_on();
		bluetooth_read();
	}
	else
	{
		leds_blue_off();
	}
}

void spin_trap (void)
{
	while (1)
	{
		wdt_reset();
		asm("nop");
	}
}

void spin_loop (uint32_t ticks)
{
	for (uint32_t i = 0; i < ticks; ++i)
	{
		wdt_reset();
		asm("nop");
	}
}

void bluetooth_init (void)
{
	// UART
	UBRR1L = 25; // set baud rate to 38.4k
	UCSR1A |= (1 << U2X1); // turn off double speed
	UCSR1A |= (1 << TXC1); // clear any existing transmits
	UCSR1B |= (1 << TXEN1) | (1 << RXEN1); // enable transmitter and receiver
	UCSR1C = (1 << UMSEL11) | (1 << UCSZ11) | (1 << UCSZ10); // 8 data bits, 1 stop bit

	// Reset pin
	PIN_SET_OUTPUT(DDRC, 7);
	PIN_SET_HIGH(PORTC, 7);

	// RTS
	PIN_SET_INPUT(DDRA, 2);
	PIN_SET_LOW(PORTA, 2);
	
	// CTS
	PIN_SET_OUTPUT(DDRB, 1);
	PIN_SET_LOW(PORTB, 1);
	
	// Connection status pin
	PIN_SET_INPUT(DDRC, 5);
	PIN_SET_LOW(PORTC, 5);
}

void bluetooth_request_to_send (uint8_t rts)
{
	if (rts)
	{
		PIN_SET_LOW(PORTB, 1);
	}
	else
	{
		PIN_SET_HIGH(PORTB, 1);
	}
}

uint8_t bluetooth_is_clear_to_send (void)
{
	if (PIN_IS_LOW(PINA, 2))
	{
		return 1;
	}
	else
	{
		return 0;
	}
}

void bluetooth_read (void)
{
	#define N 128 // number of bytes to buffer
	#define M 4 // number of times to repeat buffer back to the client
	
	static uint8_t buf[N]; // the buffer
	static uint8_t p = 0; // buffer read index
	static uint8_t q = 0; // buffer write index
	static uint8_t r = 0; // repeat counter
	
	bluetooth_request_to_send(1); // tell client to start sending data
	
	while (bit_is_set(UCSR1A, RXC1) || p == N) // while there is data to receive
	{
		if (p == N) // if buffer is full
		{
			bluetooth_request_to_send(0); // tell client to stop sending data
			while (r++ < M) // repeat `M` times
			{
				while (q < p) // write the read buffer back to the client
				{
					bluetooth_write(buf[q++]);
				}
				q = 0;
			}
			p = 0;
			r = 0;
			bluetooth_request_to_send(1); // tell client to start sending data again
		}
		else
		{
			buf[p++] = UDR1; // receive a byte
		}
	}
}

void bluetooth_write (uint8_t write_byte)
{
	while (0 == bluetooth_is_clear_to_send()) // the client cannot receive data now
	{
		leds_red_on(); // THIS IS WHERE THINGS GET STUCK
		wdt_reset();
		continue;
	}

	while (bit_is_clear(UCSR1A, UDRE1))
	{
		wdt_reset();
		continue;
	}
	
	UDR1 = write_byte;
	
	while (bit_is_clear(UCSR1A, TXC1))
	{
		wdt_reset();
		continue;
	}
	
	UCSR1A |= (1 << TXC1);
}

uint8_t bluetooth_is_connected (void)
{
	return PIN_IS_HIGH(PINC, 5);
}

void leds_init (void)
{
	// Blue LED
	PIN_SET_OUTPUT(DDRC, 2);
	PIN_SET_HIGH(PORTC, 2);
	
	// Green LED
	PIN_SET_OUTPUT(DDRA, 0);
	PIN_SET_HIGH(PORTA, 0);
	
	// Red LED
	PIN_SET_OUTPUT(DDRA, 7);
	PIN_SET_HIGH(PORTA, 7);
}

void leds_blue_on (void)
{
	PIN_SET_LOW(PORTC, 2);
}

void leds_blue_off (void)
{
	PIN_SET_HIGH(PORTC, 2);
}

void leds_green_on (void)
{
	PIN_SET_LOW(PORTA, 0);
}

void leds_green_off (void)
{
	PIN_SET_HIGH(PORTA, 0);
}

void leds_red_on (void)
{
	PIN_SET_LOW(PORTA, 7);
}

void leds_red_off (void)
{
	PIN_SET_HIGH(PORTA, 7);
}