ESP32 Forum

Code: Select all

#include <stdio.h>
#include <string.h>
#include "esp_err.h"
#include "esp_log.h"
#include "driver/spi_slave.h"
#include "driver/gpio.h"
#include "freertos/task.h"


// Logging Tag
static const char* TAG = "TEST";

// Define SPI pins
#define GPIO_MISO 20
#define GPIO_MOSI 19
#define GPIO_CLK  18
#define GPIO_CS   9

// Transaction buffer size
#define TRANSACTION_SIZE 4 // bytes


// Task for handling SPI transactions
void spi_task(void* parameters) {
    ESP_LOGI(TAG, "SPI Task Start");

    // Send and recieve buffers
    uint8_t rx_buffer[TRANSACTION_SIZE];
    uint8_t tx_buffer[TRANSACTION_SIZE];

    // spi transaction struct
    spi_slave_transaction_t trans;
    memset(&trans, 0, sizeof(trans));

    while (true) {
        ESP_LOGI(TAG, "SPI Loop Start");

        // Initialize transmit buffer
        tx_buffer[0] = 0x33;
        tx_buffer[1] = 0x33;
        tx_buffer[2] = 0x33;
        tx_buffer[3] = 0x33;

        // Initialize receive buffer
        memset(rx_buffer, 0, TRANSACTION_SIZE);

        // Prepare the transaction
        trans.length = TRANSACTION_SIZE * 8; // Transaction length in bits
        trans.rx_buffer = rx_buffer;
        trans.tx_buffer = tx_buffer;

        // Wait for a transaction from the master
        ESP_ERROR_CHECK(spi_slave_transmit(SPI2_HOST, &trans, portMAX_DELAY));
        ESP_LOGI(TAG, "SPI Transaction Completed");
        
        // Print the received data
        printf("Received data: ");
        for (int i = 0; i < TRANSACTION_SIZE; i++) {
            printf("0x%02X ", rx_buffer[i]);
        }
        printf("\n");
    }

    ESP_LOGI(TAG, "SPI Task End");
}


void app_main(void) {
    ESP_LOGI(TAG, "App Main Start");

    // Setup GPIO
    gpio_set_pull_mode(GPIO_MOSI, GPIO_PULLUP_ONLY);
    gpio_set_pull_mode(GPIO_CLK, GPIO_PULLUP_ONLY);
    gpio_set_pull_mode(GPIO_CS, GPIO_PULLUP_ONLY);

    // Configuration for SPI slave interface
    spi_bus_config_t spi_bus_cfg = {
        .mosi_io_num = GPIO_MOSI,
        .miso_io_num = GPIO_MISO,
        .sclk_io_num = GPIO_CLK,
        .quadwp_io_num = -1,
        .quadhd_io_num = -1,
        //.max_transfer_sz = TRANSACTION_SIZE,
        .flags = SPICOMMON_BUSFLAG_SLAVE,
    };

    spi_slave_interface_config_t spi_slave_cfg = {
        .mode = 2,
        .spics_io_num = GPIO_CS,
        .queue_size = 1,
        .flags = 0,
    };

    // Initialize SPI slave
    ESP_ERROR_CHECK(spi_slave_initialize(SPI2_HOST, &spi_bus_cfg, &spi_slave_cfg, SPI_DMA_CH_AUTO));

    // Start SPI Task
    BaseType_t task_status = xTaskCreate(spi_task, "SPI_TASK", 4096, (void*)1, 2, NULL);
    if (task_status != pdPASS) {
        ESP_LOGE(TAG, "SPI Task Creation Failed");
        abort();
    }

    ESP_LOGI(TAG, "App Main End");
}