uart_rx.c (uart_rx sample)

/** * Copyright (c) 2020 Raspberry Pi (Trading) Ltd. * * SPDX-License-Identifier: BSD-3-Clause */ #include <stdio.h> #include "pico/stdlib.h" #include "pico/multicore.h" #include "hardware/pio.h" #include "hardware/uart.h" #include "uart_rx.pio.h" // This program // - Uses UART1 (the spare UART, by default) to transmit some text // - Uses a PIO state machine to receive that text // - Prints out the received text to the default console (UART0) // This might require some reconfiguration on boards where UART1 is the // default UART. #define SERIAL_BAUD PICO_DEFAULT_UART_BAUD_RATE #define HARD_UART_INST uart1 // You'll need a wire from GPIO4 -> GPIO3 #define HARD_UART_TX_PIN 4 #define PIO_RX_PIN 3 // Ask core 1 to print a string, to make things easier on core 0 void core1_main() { const char *s = (const char *) multicore_fifo_pop_blocking(); uart_puts(HARD_UART_INST, s); } int main() { // Console output (also a UART, yes it's confusing) setup_default_uart(); printf("Starting PIO UART RX example\n"); // Set up the hard UART we're going to use to print characters uart_init(HARD_UART_INST, SERIAL_BAUD); gpio_set_function(HARD_UART_TX_PIN, GPIO_FUNC_UART); // Set up the state machine we're going to use to receive them. PIO pio = pio0; uint sm = 0; uint offset = pio_add_program(pio, &uart_rx_program); uart_rx_program_init(pio, sm, offset, PIO_RX_PIN, SERIAL_BAUD); // Tell core 1 to print some text to uart1 as fast as it can multicore_launch_core1(core1_main); const char *text = "Hello, world from PIO! (Plus 2 UARTs and 2 cores, for complex reasons)\n"; multicore_fifo_push_blocking((uint32_t) text); // Echo characters received from PIO to the console while (true) { char c = uart_rx_program_getc(pio, sm); putchar(c); } }