mirror of
https://github.com/mytechnotalent/Embedded-Hacking.git
synced 2026-07-09 22:08:42 +02:00
Kevin Thomas
87 lines
3.1 KiB
C
87 lines
3.1 KiB
C
/**
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* @file 0x0b_spi.c
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* @brief SPI loopback demo using spi.c/spi.h driver
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* @author Kevin Thomas
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* @date 2025
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*
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* MIT License
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*
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* Copyright (c) 2025 Kevin Thomas
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* -----------------------------------------------------------------------------
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*
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* Demonstrates SPI in master mode using the spi driver (spi.h / spi.c).
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* A loopback wiring (MOSI -> MISO) is used to verify full-duplex transfer.
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* Transmitted and received data is printed over UART every second.
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*
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* Wiring (loopback test):
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* GPIO19 (MOSI) -> GPIO16 (MISO)
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* GPIO18 (SCK) -> logic analyzer or slave SCK
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* GPIO17 (CS) -> slave CS (active-low)
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*/
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#include <stdio.h>
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#include <string.h>
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#include "pico/stdlib.h"
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#include "spi.h"
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/** @brief SPI port number (0 or 1) */
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#define SPI_PORT 0
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/** @brief SPI bus clock rate in Hz */
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#define SPI_BAUD_HZ (1000 * 1000)
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/** @brief GPIO pin for SPI MISO */
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#define PIN_MISO 16
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/** @brief GPIO pin for SPI chip select */
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#define PIN_CS 17
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/** @brief GPIO pin for SPI clock */
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#define PIN_SCK 18
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/** @brief GPIO pin for SPI MOSI */
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#define PIN_MOSI 19
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/**
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* @brief Perform one SPI loopback transfer and print the result
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*
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* Asserts chip-select, transfers the buffer, deasserts chip-select,
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* prints TX and RX data over UART, then clears the receive buffer.
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*
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* @param tx_buf Transmit buffer
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* @param rx_buf Receive buffer (cleared after printing)
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* @param len Number of bytes to transfer
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*/
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static void loopback_transfer(const uint8_t *tx_buf, uint8_t *rx_buf, size_t len) {
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spi_driver_cs_select(PIN_CS);
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spi_driver_transfer(SPI_PORT, tx_buf, rx_buf, len);
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spi_driver_cs_deselect(PIN_CS);
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printf("TX: %s\r\n", tx_buf);
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printf("RX: %s\r\n\r\n", rx_buf);
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memset(rx_buf, 0, len);
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sleep_ms(1000);
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}
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int main(void) {
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stdio_init_all();
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spi_driver_init(SPI_PORT, PIN_MOSI, PIN_MISO, PIN_SCK, PIN_CS, SPI_BAUD_HZ);
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const uint8_t tx_buf[] = "SPI loopback OK";
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uint8_t rx_buf[sizeof(tx_buf)] = {0};
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while (true)
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loopback_transfer(tx_buf, rx_buf, sizeof(tx_buf));
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}
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