ESP32 Forum

Hello,

I am trying to interface a GPIO Expander MCP23S18 (using SPI) with my ESP32-S2. The library used is spi_slave/sender/app_main.c and driver spi_master.h from components/drivers.
I don't understand what is going wrong and why it fails to work. My code is as below. Please help me with your inputs.

#include <stdio.h>
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include <stdbool.h>

#include "gpio_expander.h"

#include "definitions.h"
#include "driver/gpio.h"
#include "esp_timer.h"
#include "esp_log.h"
#include "esp_spi_flash.h"
#include "esp_system.h"
#include "driver/spi_master.h"

#include <stdbool.h>

#define GPIO_MOSI 35
#define GPIO_MISO 37
#define GPIO_SCLK 36
#define GPIO_CS 41

static uint8_t state_low = 0;
static uint8_t state_high = 1;

#define WRITEADDR 0x40
#define IO_DIR_REG 0x00
#define GPIO_REG 0x09

#define SENDER_HOST SPI3_HOST

static const char *TAG = "GPIOEXP833";

esp_err_t ret;
spi_device_handle_t handle;
spi_transaction_t t;

uint8_t addrbuf;
uint8_t databuf[4];


int initgpio(task_t *_this)
{
if(_this->state > TASKSTATE_UNINITIALIZED) {
return -1;
}

gpio_config_t io_conf;

io_conf.intr_type = GPIO_PIN_INTR_DISABLE;
io_conf.mode = GPIO_MODE_OUTPUT;
io_conf.pin_bit_mask = (1ULL<<GPIO_CS);
io_conf.pull_down_en = 0;
io_conf.pull_up_en = 0;
gpio_config(&io_conf);

gpio_reset_pin(GPIO_CS);
gpio_set_direction(GPIO_CS, GPIO_MODE_OUTPUT);

//Configuration for the SPI bus
spi_bus_config_t buscfg={
.mosi_io_num=GPIO_MOSI,
.miso_io_num=GPIO_MISO,
.sclk_io_num=GPIO_SCLK,
.quadwp_io_num=-1,
.quadhd_io_num=-1
};

//Configuration for the SPI device on the other side of the bus
spi_device_interface_config_t devcfg={
.command_bits=8,
.address_bits=8,
.dummy_bits=0,
.clock_speed_hz=5000000,
.duty_cycle_pos=128, //50% duty cycle
.mode=1,
.spics_io_num=GPIO_CS, //(1ULL<<GPIO_CS),
.cs_ena_posttrans=3, //Keep the CS low 3 cycles after transaction, to stop slave from missing the last bit when CS has less propagation delay than CLK
.queue_size=3
};

//Initialize the SPI bus and add the device we want to send stuff to.
ret=spi_bus_initialize(SENDER_HOST, &buscfg, SPI_DMA_CH_AUTO);
assert(ret==ESP_OK);

if (ret != ESP_OK) {
ESP_LOGI(TAG, "initialization failed");
}
else {
ESP_LOGI(TAG, "SPI initialized");
}

ret=spi_bus_add_device(SENDER_HOST, &devcfg, &handle);
assert(ret==ESP_OK);

t.flags = 0x0000;
t.tx_buffer=NULL;
t.rx_buffer=NULL;

t.user=IO_DIR_REG;

_this->state = TASKSTATE_RUNNING;
return -1;
}

void execgpio(task_t *_this) {
gpio_set_level(GPIO_CS, state_low);
t.cmd=WRITEADDR;
t.addr=GPIO_REG;
t.user=0x02;
// memset(&t, 0, sizeof(t));
ret=spi_device_transmit(handle, &t);
gpio_set_level(GPIO_REG, 0x02);
gpio_set_level(GPIO_CS, state_high);
}

I have been scratching my head at similar problems with a "FreeNove" "ESP32 Basic Starter Kit"

It has the chip at 40mhz, 8mb psram 4mb spi
It has a 32, I believe, GPIO output extension that makes the board (with 2 buttons and strip for camera 640-v2.0 [No idea which board] it's a wrover dev but seems painted over for the brand.

If it helps I've been digging in there files and using continuity tests to verify what it says it what it is circuit wise.