SDK • Re: Problems with SPI Example

Code:

// Copyright (c) 2021 Michael Stoops. All rights reserved.// Portions copyright (c) 2021 Raspberry Pi (Trading) Ltd.// // Redistribution and use in source and binary forms, with or without modification, are permitted provided that the // following conditions are met://// 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following//    disclaimer.// 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the//    following disclaimer in the documentation and/or other materials provided with the distribution.// 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote//    products derived from this software without specific prior written permission.// // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, // INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, // WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE // USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.//// SPDX-License-Identifier: BSD-3-Clause//// Example of an SPI bus master using the PL022 SPI interface#include <stdio.h>#include "pico/stdlib.h"#include "pico/binary_info.h"#include "hardware/spi.h"#define BUF_LEN         0x100void printbuf(uint8_t buf[], size_t len) {    size_t i;    for (i = 0; i < len; ++i) {        if (i % 16 == 15)            printf("%02x\n", buf[i]);        else            printf("%02x ", buf[i]);    }    // append trailing newline if there isn't one    if (i % 16) {        putchar('\n');    }}int main() {    // Enable UART so we can print    stdio_init_all();#if !defined(spi_default) || !defined(PICO_DEFAULT_SPI_SCK_PIN) || !defined(PICO_DEFAULT_SPI_TX_PIN) || !defined(PICO_DEFAULT_SPI_RX_PIN) || !defined(PICO_DEFAULT_SPI_CSN_PIN)#warning spi/spi_master example requires a board with SPI pins    puts("Default SPI pins were not defined");#else    printf("SPI master example\n");    // Enable SPI 0 at 1 MHz and connect to GPIOs    spi_init(spi_default, 1000 * 1000);    gpio_set_function(PICO_DEFAULT_SPI_RX_PIN, GPIO_FUNC_SPI);    gpio_set_function(PICO_DEFAULT_SPI_SCK_PIN, GPIO_FUNC_SPI);    gpio_set_function(PICO_DEFAULT_SPI_TX_PIN, GPIO_FUNC_SPI);    gpio_set_function(PICO_DEFAULT_SPI_CSN_PIN, GPIO_FUNC_SPI);    // Make the SPI pins available to picotool    bi_decl(bi_4pins_with_func(PICO_DEFAULT_SPI_RX_PIN, PICO_DEFAULT_SPI_TX_PIN, PICO_DEFAULT_SPI_SCK_PIN, PICO_DEFAULT_SPI_CSN_PIN, GPIO_FUNC_SPI));    uint8_t out_buf[BUF_LEN], in_buf[BUF_LEN];    // Initialize output buffer    for (size_t i = 0; i < BUF_LEN; ++i) {        out_buf[i] = i;    }    printf("SPI master says: The following buffer will be written to MOSI endlessly:\n");    printbuf(out_buf, BUF_LEN);    for (size_t i = 0; ; ++i) {        // Write the output buffer to MOSI, and at the same time read from MISO.        spi_write_read_blocking(spi_default, out_buf, in_buf, BUF_LEN);        // Write to stdio whatever came in on the MISO line.        printf("SPI master says: read page %d from the MISO line:\n", i);        printbuf(in_buf, BUF_LEN);        // Sleep for ten seconds so you get a chance to read the output.        sleep_ms(10 * 1000);    }#endif}