manchester_encoding.c

/**
 * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <stdio.h>

#include "pico/stdlib.h"
#include "hardware/pio.h"
#include "manchester_encoding.pio.h"

// Manchester serial transmit/receive example. This transmits and receives at
// 10 Mbps if sysclk is 120 MHz.

// Need to connect a wire from GPIO2 -> GPIO3
const uint pin_tx = 2;
const uint pin_rx = 3;

int main() {
    stdio_init_all();

    PIO pio = pio0;
    uint sm_tx = 0;
    uint sm_rx = 1;

    uint offset_tx = pio_add_program(pio, &manchester_tx_program);
    uint offset_rx = pio_add_program(pio, &manchester_rx_program);
    printf("Transmit program loaded at %d\n", offset_tx);
    printf("Receive program loaded at %d\n", offset_rx);

    manchester_tx_program_init(pio, sm_tx, offset_tx, pin_tx, 1.f);
    manchester_rx_program_init(pio, sm_rx, offset_rx, pin_rx, 1.f);

    pio_sm_set_enabled(pio, sm_tx, false);
    pio_sm_put_blocking(pio, sm_tx, 0);
    pio_sm_put_blocking(pio, sm_tx, 0x0ff0a55a);
    pio_sm_put_blocking(pio, sm_tx, 0x12345678);
    pio_sm_set_enabled(pio, sm_tx, true);

    for (int i = 0; i < 3; ++i)
        printf("%08x\n", pio_sm_get_blocking(pio, sm_rx));
}