FreeRTOS and multiple wiegand tasks

[Exboom]

Hello, community. I am using the "wiegand" example to handle the reader and it works fine, but I would like to connect multiple readers to one ESP32 controller. I tried to just create another task, having previously edited the "task" function a little so that it receives arguments indicating pins:

...
typedef struct wiegand_t {
    gpio_num_t d0, d1;
} wiegand_data_t;

...

wiegand_data_t data = *(wiegand_data_t *)arg;
ESP_ERROR_CHECK(wiegand_reader_init(&reader, data.d0, data.d1, true, CONFIG_EXAMPLE_BUF_SIZE, reader_callback,
        WIEGAND_MSB_FIRST, WIEGAND_LSB_FIRST));
...

But it obviously doesn't work. Is it possible to use the driver in multitasking mode?

[UncleRus]

Try something like this:

#define READERS_COUNT 4  // for example

static QueueHandle_t queue = NULL;

// Single data packet
typedef struct
{
    int reader_idx;
    uint8_t data[BUF_SIZE];
    size_t bits;
} data_packet_t;

// struct to hold reader description
typedef struct {
    gpio_num_t d0, d1;
    wiegand_order_t bit_order, byte_order;
} reader_descr_t;

// array to describe all readers
// replace GPIO_NUM_xx with real GPIOs
static const reader_descr_t readers_descr[READERS_COUNT] = {
    { .d0 = GPIO_NUM_xx, .d1 = GPIO_NUM_xx, .bit_order = WIEGAND_MSB_FIRST, .byte_order = WIEGAND_LSB_FIRST },
    { .d0 = GPIO_NUM_xx, .d1 = GPIO_NUM_xx, .bit_order = WIEGAND_MSB_FIRST, .byte_order = WIEGAND_LSB_FIRST },
    { .d0 = GPIO_NUM_xx, .d1 = GPIO_NUM_xx, .bit_order = WIEGAND_MSB_FIRST, .byte_order = WIEGAND_LSB_FIRST },
    { .d0 = GPIO_NUM_xx, .d1 = GPIO_NUM_xx, .bit_order = WIEGAND_MSB_FIRST, .byte_order = WIEGAND_LSB_FIRST },
};

// array for descriptors
static wiegand_reader_t readers[READERS_COUNT] = { 0 };

// single callback for all readers
static void callback(wiegand_reader_t *r)
{
    // create simple undecoded data packet
    data_packet_t p;
    p.reader_idx = -1;
    for (size_t i = 0; i < READERS_COUNT; i++)
        if (r == readers_descr + i)
        {
            p.reader_idx = i;
            break;
        }
    p.bits = r->bits;
    memcpy(p.data, r->buf, CONFIG_EXAMPLE_BUF_SIZE);

    // Send it to the queue
    xQueueSendToBack(queue, &p, 0);
}

// initialize readers
static void init_readers()
{
    for (size_t i = 0, i < READERS_COUNT; i++)
    {
        esp_err_t res = wiegand_reader_init(readers + i, readers_descr[i].d0, readers_descr[i].d1, true, BUF_SIZE, callback, readers_descr[i].bit_order, readers_descr[i].byte_order);
        if (res != ESP_OK)
             ESP_LOGE(TAG, "Error while initializing wiegand reader");
    }
}

static void task(void *arg)
{
    // Create queue
    queue = xQueueCreate(5, sizeof(data_packet_t));
    if (!queue)
    {
        ESP_LOGE(TAG, "Error creating queue");
        ESP_ERROR_CHECK(ESP_ERR_NO_MEM);
    }

    // Initialize readers
    init_readers();

    data_packet_t p;
    while (1)
    {
        ESP_LOGI(TAG, "Waiting for Wiegand data...");
        xQueueReceive(queue, &p, portMAX_DELAY);

        // dump received data
        printf("==========================================\n");
        printf("Reader: %d\n", p.reader_idx);
        printf("Bits received: %d\n", p.bits);
        printf("Received data:");
        int bytes = p.bits / 8;
        int tail = p.bits % 8;
        for (size_t i = 0; i < bytes + (tail ? 1 : 0); i++)
            printf(" 0x%02x", p.data[i]);
        printf("\n==========================================\n");
    }
}

void app_main()
{
    xTaskCreate(task, TAG, configMINIMAL_STACK_SIZE * 4, NULL, 5, NULL);
}

[reubengoh]

Hi UncleRus,

Thank you for the solution. However I have some errors implementing this code with regards to this line
if (r == readers_descr + i)

Error : "comparison between distinct pointer types 'wiegand_reader_t*' {aka 'wiegand_reader*'} and 'const reader_descr_t*' lacks a cast."

The solution works if i disable the for loop in the callback function, however I wish to understand why i'm unable to implement it.

[reubengoh]

Hi,

To anyone that encountered the same error as me. I found the solution below

static void callback(wiegand_reader_t *r)
{
    // create simple undecoded data packet
    data_packet_t p;
    p.reader_idx = -1; // Default to -1 if reader index is not found

    // Iterate through the readers to find the matching reader index
    for (size_t i = 0; i < READERS_COUNT; i++)
        if (r == (wiegand_reader_t *)(readers + i))
        {
            p.reader_idx = i;
            break;
        }
    p.bits = r->bits;
    memcpy(p.data, r->buf, BUF_SIZE);

    // Send it to the queue
    xQueueSendToBack(queue, &p, 0);
}

Hope this helps anyone :)