main.c

#include <stdio.h>
#include <stdbool.h>
#include <esp_err.h>
#include <freertos/FreeRTOS.h>
#include <freertos/task.h>
#include <driver/spi_master.h>

#define CS_PIN      GPIO_NUM_26
#define CLK_PIN     GPIO_NUM_25
#define MOSI_PIN    GPIO_NUM_22
#define MISO_PIN    GPIO_NUM_21

void app_main(void)
{
    spi_bus_config_t buscfg;
    buscfg.miso_io_num = MISO_PIN;
    buscfg.mosi_io_num = MOSI_PIN;
    buscfg.sclk_io_num = CLK_PIN;
    buscfg.quadwp_io_num = -1;
    buscfg.quadhd_io_num = -1;
    buscfg.max_transfer_sz = 0;
    buscfg.flags = 0;

    spi_device_interface_config_t devcfg;
    devcfg.command_bits = 8;
    devcfg.address_bits = 24;
    devcfg.dummy_bits = 0;
    devcfg.mode = 0;
    devcfg.duty_cycle_pos = 0;
    devcfg.cs_ena_pretrans = 0;
    devcfg.cs_ena_posttrans = 0;
    devcfg.clock_speed_hz = 8000000;
    devcfg.spics_io_num = CS_PIN;
    devcfg.flags = 0;
    devcfg.queue_size = 7;
    devcfg.pre_cb = 0;
    devcfg.post_cb = 0;
    devcfg.input_delay_ns = 0;

    ESP_ERROR_CHECK(spi_bus_initialize(HSPI_HOST, &buscfg, 0));

    spi_device_handle_t spi_device_handle;
    ESP_ERROR_CHECK(spi_bus_add_device(HSPI_HOST, &devcfg, &spi_device_handle));

    while (true)
    {
        spi_transaction_t transaction;
        transaction.cmd = 0x8F;
        transaction.addr = 0xABCD;
        transaction.flags = 0;
        transaction.rxlength = 0;
        transaction.length = 0;
        ESP_ERROR_CHECK(spi_device_transmit(spi_device_handle, &transaction));

        vTaskDelay(50);
    }
}