// 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 slave using the PL022 SPI interface #include <stdio.h> #include <string.h> #include "pico/stdlib.h" #include "pico/binary_info.h" #include "hardware/spi.h" #define BUF_LEN 0x100 void 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_slave example requires a board with SPI pins puts("Default SPI pins were not defined"); #else printf("SPI slave example\n"); // Enable SPI 0 at 1 MHz and connect to GPIOs spi_init(spi_default, 1000 * 1000); spi_set_slave(spi_default, true); 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) { // bit-inverted from i. The values should be: {0xff, 0xfe, 0xfd...} out_buf[i] = ~i; } printf("SPI slave says: When reading from MOSI, the following buffer will be written to MISO:\n"); printbuf(out_buf, BUF_LEN); for (size_t i = 0; ; ++i) { // Write the output buffer to MISO, and at the same time read from MOSI. spi_write_read_blocking(spi_default, out_buf, in_buf, BUF_LEN); // Write to stdio whatever came in on the MOSI line. printf("SPI slave says: read page %d from the MOSI line:\n", i); printbuf(in_buf, BUF_LEN); } #endif }

This firmware image was imported from the pico-examples repository. 


Copyright 2020 (c) 2020 Raspberry Pi (Trading) Ltd.

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