
// ****************************************************************************
//
//                                 Main code
//
// ****************************************************************************
// Use some other UART features like RX interrupts, hardware control flow,
// and data formats other than 8n1. Program will echo characters back, incremented.

// We are using pins 0 and 1, but see the GPIO function select table in the
// datasheet for information on which other pins can be used.

#include "include.h"

#define UART_ID uart0
#define BAUD_RATE 115200
#define DATA_BITS 8
#define STOP_BITS 1
#define PARITY    UART_PARITY_NONE

#define UART_TX_PIN 0
#define UART_RX_PIN 1

static int chars_rxed = 0;

// RX interrupt handler
void on_uart_rx()
{
	while (uart_is_readable(UART_ID))
	{
		uint8_t ch = uart_getc(UART_ID);
		// Can we send it back?
		if (uart_is_writable(UART_ID))
		{
			// Change it slightly first!
			ch++;
			uart_putc(UART_ID, ch);
		}
		chars_rxed++;
	}
}

int main()
{
	// Set up our UART with a basic baud rate.
	uart_init(UART_ID, 2400);

	// Set the TX and RX pins by using the function select on the GPIO
	// Set datasheet for more information on function select
	gpio_set_function(UART_TX_PIN, GPIO_FUNC_UART);
	gpio_set_function(UART_RX_PIN, GPIO_FUNC_UART);

	// Actually, we want a different speed
	// The call will return the actual baud rate selected, which will be as close as
	// possible to that requested
	int actual = uart_set_baudrate(UART_ID, BAUD_RATE);

	// Set UART flow control CTS/RTS, we don't want these, so turn them off
	uart_set_hw_flow(UART_ID, false, false);

	// Set our data format
	uart_set_format(UART_ID, DATA_BITS, STOP_BITS, PARITY);

	// Turn off FIFO's - we want to do this character by character
	uart_set_fifo_enabled(UART_ID, false);

	// Set up a RX interrupt
	// We need to set up the handler first
	// Select correct interrupt for the UART we are using
	int UART_IRQ = UART_ID == uart0 ? UART0_IRQ : UART1_IRQ;

	// And set up and enable the interrupt handlers
	irq_set_exclusive_handler(UART_IRQ, on_uart_rx);
	irq_set_enabled(UART_IRQ, true);

	// Now enable the UART to send interrupts - RX only
	uart_set_irq_enables(UART_ID, true, false);

	// OK, all set up.
	// Lets send a basic string out, and then run a loop and wait for RX interrupts
	// The handler will count them, but also reflect the incoming data back with a slight change!
	uart_puts(UART_ID, "\nHello, uart interrupts\n");

	while (1)
	{
		tight_loop_contents();
	}
}
