mirror of
https://github.com/mytechnotalent/Embedded-Hacking.git
synced 2026-06-06 06:13:59 +02:00
Kevin Thomas
123 lines
3.4 KiB
C
123 lines
3.4 KiB
C
/**
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******************************************************************************
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* @file main.c
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* @author Kevin Thomas
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* @brief SPI loopback demonstration.
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*
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* Performs a full-duplex SPI0 transfer in master mode with
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* MOSI wired to MISO for loopback verification. Prints TX
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* and RX data over UART every second.
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*
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* Wiring (loopback test):
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* GPIO0 -> UART TX (USB-to-UART adapter RX)
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* GPIO1 -> UART RX (USB-to-UART adapter TX)
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* GPIO19 (MOSI) -> GPIO16 (MISO)
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* GPIO18 (SCK) -> logic analyzer (optional)
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* GPIO17 (CS) -> active-low slave (optional)
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*
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******************************************************************************
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* @attention
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*
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* Copyright (c) 2026 Kevin Thomas.
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* All rights reserved.
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*
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* This software is licensed under terms that can be found in the LICENSE file
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* in the root directory of this software component.
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* If no LICENSE file comes with this software, it is provided AS-IS.
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*
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******************************************************************************
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*/
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#include "rp2350_spi.h"
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#include "rp2350_uart.h"
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#include "rp2350_delay.h"
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#include "rp2350_xosc.h"
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/**
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* @brief Hex digit lookup table for byte-to-hex conversion.
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*/
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static const char _hex_lut[16] = "0123456789ABCDEF";
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/**
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* @brief Print a byte as a two-digit hex string over UART.
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* @param value byte to print
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* @retval None
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*/
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static void _print_hex(uint8_t value)
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{
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char buf[3];
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buf[0] = _hex_lut[value >> 4];
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buf[1] = _hex_lut[value & 0x0FU];
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buf[2] = '\0';
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uart_puts(buf);
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}
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/**
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* @brief Print a buffer as hex bytes separated by spaces over UART.
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* @param label text label to print before the data
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* @param buf byte buffer to print
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* @param len number of bytes in buffer
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* @retval None
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*/
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static void _print_buffer(const char *label, const uint8_t *buf, uint32_t len)
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{
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uart_puts(label);
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for (uint32_t i = 0; i < len; i++) {
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_print_hex(buf[i]);
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if (i + 1 < len)
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uart_putchar(' ');
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}
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uart_puts("\r\n");
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}
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/**
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* @brief Perform one SPI loopback transfer and print TX/RX over UART.
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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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* @retval None
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*/
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static void _loopback_transfer(const uint8_t *tx_buf, uint8_t *rx_buf, uint32_t len)
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{
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spi_cs_select();
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spi_transfer(tx_buf, rx_buf, len);
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spi_cs_deselect();
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_print_buffer("TX: ", tx_buf, len);
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_print_buffer("RX: ", rx_buf, len);
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uart_puts("\r\n");
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}
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/**
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* @brief Clear a byte buffer to zero.
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* @param buf pointer to buffer
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* @param len number of bytes to clear
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* @retval None
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*/
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static void _clear_buffer(uint8_t *buf, uint32_t len)
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{
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for (uint32_t i = 0; i < len; i++)
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buf[i] = 0;
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}
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/**
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* @brief Application entry point for the SPI loopback demo.
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* @retval int does not return
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*/
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int main(void)
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{
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/** @brief Transmit test pattern for SPI loopback. */
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static const uint8_t tx[] = {0xDE, 0xAD, 0xBE, 0xEF};
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/** @brief Buffer length for SPI loopback transfer. */
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static const uint32_t len = sizeof(tx);
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uint8_t rx[sizeof(tx)] = {0};
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xosc_set_clk_ref();
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spi_release_reset();
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spi_init();
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uart_puts("SPI loopback initialized (MOSI->MISO on GPIO19->GPIO16)\r\n");
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while (1) {
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_loopback_transfer(tx, rx, len);
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_clear_buffer(rx, len);
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delay_ms(1000);
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}
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}
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