87 lines
2.5 KiB
C
87 lines
2.5 KiB
C
/**
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* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include "pico/stdlib.h"
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#include "hardware/uart.h"
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#include "hardware/irq.h"
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/// \tag::uart_advanced[]
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#define UART_ID uart0
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#define BAUD_RATE 115200
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#define DATA_BITS 8
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#define STOP_BITS 1
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#define PARITY UART_PARITY_NONE
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// We are using pins 0 and 1, but see the GPIO function select table in the
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// datasheet for information on which other pins can be used.
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#define UART_TX_PIN 0
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#define UART_RX_PIN 1
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static int chars_rxed = 0;
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// RX interrupt handler
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void on_uart_rx() {
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while (uart_is_readable(UART_ID)) {
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uint8_t ch = uart_getc(UART_ID);
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// Can we send it back?
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if (uart_is_writable(UART_ID)) {
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// Change it slightly first!
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ch++;
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uart_putc(UART_ID, ch);
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}
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chars_rxed++;
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}
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}
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int main() {
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// Set up our UART with a basic baud rate.
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uart_init(UART_ID, 2400);
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// Set the TX and RX pins by using the function select on the GPIO
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// Set datasheet for more information on function select
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gpio_set_function(UART_TX_PIN, GPIO_FUNC_UART);
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gpio_set_function(UART_RX_PIN, GPIO_FUNC_UART);
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// Actually, we want a different speed
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// The call will return the actual baud rate selected, which will be as close as
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// possible to that requested
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int actual = uart_set_baudrate(UART_ID, BAUD_RATE);
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// Set UART flow control CTS/RTS, we don't want these, so turn them off
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uart_set_hw_flow(UART_ID, false, false);
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// Set our data format
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uart_set_format(UART_ID, DATA_BITS, STOP_BITS, PARITY);
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// Turn off FIFO's - we want to do this character by character
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uart_set_fifo_enabled(UART_ID, false);
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// Set up a RX interrupt
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// We need to set up the handler first
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// Select correct interrupt for the UART we are using
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int UART_IRQ = UART_ID == uart0 ? UART0_IRQ : UART1_IRQ;
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// And set up and enable the interrupt handlers
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irq_set_exclusive_handler(UART_IRQ, on_uart_rx);
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irq_set_enabled(UART_IRQ, true);
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// Now enable the UART to send interrupts - RX only
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uart_set_irq_enables(UART_ID, true, false);
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// OK, all set up.
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// Lets send a basic string out, and then run a loop and wait for RX interrupts
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// The handler will count them, but also reflect the incoming data back with a slight change!
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uart_puts(UART_ID, "\nHello, uart interrupts\n");
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while (1)
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tight_loop_contents();
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}
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/// \end:uart_advanced[]
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