Datasheet

Ê2 * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
Ê3 *
Ê4 * SPDX-License-Identifier: BSD-3-Clause
Ê5 */
Ê6
Ê7 #include <stdio.h>
Ê8
Ê9 #include "pico/stdlib.h"
10 #include "pico/multicore.h"
11 #include "hardware/pio.h"
12 #include "hardware/uart.h"
13 #include "uart_rx.pio.h"
14
15 // This program
16 // - Uses UART1 (the spare UART, by default) to transmit some text
17 // - Uses a PIO state machine to receive that text
18 // - Prints out the received text to the default console (UART0)
19 // This might require some reconfiguration on boards where UART1 is the
20 // default UART.
21
22 #define SERIAL_BAUD PICO_DEFAULT_UART_BAUD_RATE
23 #define HARD_UART_INST uart1
24
25 // You'll need a wire from GPIO4 -> GPIO3
26 #define HARD_UART_TX_PIN 4
27 #define PIO_RX_PIN 3
28
29 // Ask core 1 to print a string, to make things easier on core 0
30 void core1_main() {
31 const char *s = (const char *) multicore_fifo_pop_blocking();
32 uart_puts(HARD_UART_INST, s);
33 }
34
35 int main() {
36 // Console output (also a UART, yes it's confusing)
37 setup_default_uart();
38 printf("Starting PIO UART RX example\n");
39
40 // Set up the hard UART we're going to use to print characters
41 uart_init(HARD_UART_INST, SERIAL_BAUD);
42 gpio_set_function(HARD_UART_TX_PIN, GPIO_FUNC_UART);
43
44 // Set up the state machine we're going to use to receive them.
45 PIO pio = pio0;
46 uint sm = 0;
47 uint offset = pio_add_program(pio, &uart_rx_program);
48 uart_rx_program_init(pio, sm, offset, PIO_RX_PIN, SERIAL_BAUD);
49
50 // Tell core 1 to print some text to uart1 as fast as it can
51 multicore_launch_core1(core1_main);
52 const char *text = "Hello, world from PIO! (Plus 2 UARTs and 2 cores, for complex
Ê reasons)\n";
53 multicore_fifo_push_blocking((uint32_t) text);
54
55 // Echo characters received from PIO to the console
56 while (true) {
57 char c = uart_rx_program_getc(pio, sm);
58 putchar(c);
59 }
60 }
RP2040 Datasheet
3.6. Examples 373