mirror of
https://github.com/mytechnotalent/Embedded-Hacking.git
synced 2026-07-14 07:57:23 +02:00
Kevin Thomas
066c69f24b
Public function docstrings belong exclusively in .h headers per coding convention. Only static helper functions and static variables retain docstrings in .c files. Removed 413 duplicate docstrings across 185 files (15 CBM + 15 C SDK projects). All 30 projects rebuild with zero errors.
128 lines
3.5 KiB
C
128 lines
3.5 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 Initialize clocks, SPI peripheral, and announce over UART.
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* @retval None
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*/
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static void _spi_setup(void)
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{
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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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}
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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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_spi_setup();
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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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