MTGcompanion/main/rfid_manager.c

/*
 * MTG RFID Companion - MFRC522 RFID manager (Core 0)
 */

#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_log.h"
#include "esp_event.h"
#include "rc522.h"
#include "rc522_picc.h"
#include "driver/rc522_spi.h"
#include "hw_pins.h"
#include "spi_bus_manager.h"
#include "rfid_manager.h"

static const char *TAG = "rfid";

#define RC522_TASK_NAME "rc522_polling_task"
#define RC522_POLL_INTERVAL_MS (100)
#define RC522_TASK_STACK_SIZE  (6 * 1024)
#define RC522_TASK_PRIORITY    (4)

/* Conservative clock for MFRC522 clones. If the FIFO self-test still
 * reports a mismatch error, lower further (e.g. 1000000) or check
 * power/wiring. Many clone readers glitch at 4MHz on a shared bus. */
#define RC522_SPI_CLK_HZ (1000000)
#define RC522_START_ATTEMPTS (3)

static rc522_driver_handle_t s_driver;
static rc522_handle_t s_scanner;

static char s_last_uid[RFID_UID_STR_MAX_LEN] = {0};
static bool s_pending_card = false;

static void uid_to_hex_string(const rc522_picc_uid_t *uid, char *out)
{
    int i;
    for (i = 0; i < uid->length && i < RC522_PICC_UID_SIZE_MAX; i++) {
        snprintf(out + (i * 2), 3, "%02X", uid->value[i]);
    }
}

static void on_picc_state_changed(void *arg, esp_event_base_t base, int32_t event_id, void *data)
{
    rc522_picc_state_changed_event_t *event = (rc522_picc_state_changed_event_t *)data;
    rc522_picc_t *picc = event->picc;

    (void)arg;
    (void)base;
    (void)event_id;

    if (picc->state == RC522_PICC_STATE_ACTIVE) {
        uid_to_hex_string(&picc->uid, s_last_uid);
        s_pending_card = true;
        ESP_LOGI(TAG, "Card scanned: UID=%s (%d bytes, %s)",
                 s_last_uid, picc->uid.length, rc522_picc_type_name(picc->type));
    } else if ((picc->state == RC522_PICC_STATE_IDLE || picc->state == RC522_PICC_STATE_HALT)
               && event->old_state >= RC522_PICC_STATE_ACTIVE) {
        ESP_LOGI(TAG, "Card removed");
    }
}

esp_err_t rfid_manager_init(void)
{
    rc522_spi_config_t driver_config = {
        .host_id = HW_SPI_HOST,
        /* Bus already owned by spi_bus_manager: attaching as an extra device. */
        .bus_config = NULL,
        .dev_config = {
            .spics_io_num = HW_RC522_CS_GPIO,
            .clock_speed_hz = RC522_SPI_CLK_HZ,
        },
        .dma_chan = SPI_DMA_CH_AUTO,
        .rst_io_num = HW_RC522_RST_GPIO,
    };

    esp_err_t ret = rc522_spi_create(&driver_config, &s_driver);
    if (ret != ESP_OK) {
        ESP_LOGE(TAG, "rc522_spi_create failed: %s", esp_err_to_name(ret));
        return ret;
    }
    ESP_ERROR_CHECK(rc522_driver_install(s_driver));

    rc522_config_t scanner_config = {
        .driver = s_driver,
        .poll_interval_ms = RC522_POLL_INTERVAL_MS,
        .task_stack_size = RC522_TASK_STACK_SIZE,
        .task_priority = RC522_TASK_PRIORITY,
    };

    ret = rc522_create(&scanner_config, &s_scanner);
    if (ret != ESP_OK) {
        ESP_LOGE(TAG, "rc522_create failed: %s", esp_err_to_name(ret));
        return ret;
    }

    ESP_ERROR_CHECK(
        rc522_register_events(s_scanner, RC522_EVENT_PICC_STATE_CHANGED, on_picc_state_changed, NULL));

    return ESP_OK;
}

esp_err_t rfid_manager_start(void)
{
    esp_err_t ret = ESP_FAIL;
    for (int attempt = 1; attempt <= RC522_START_ATTEMPTS; attempt++) {
        ret = rc522_start(s_scanner);
        if (ret == ESP_OK) {
            break;
        }
        ESP_LOGW(TAG, "rc522_start attempt %d/%d failed: %s",
                 attempt, RC522_START_ATTEMPTS, esp_err_to_name(ret));
        vTaskDelay(pdMS_TO_TICKS(250));
    }

    if (ret != ESP_OK) {
        ESP_LOGE(TAG, "MFRC522 self-test failed (%s). Check: reader powered "
                      "(3.3V), SPI wiring (SCK=18/MOSI=23/MISO=19, CS=5, RST=22), "
                      "and if it is a clone try lowering RC522_SPI_CLK_HZ", esp_err_to_name(ret));
        return ret;
    }

    /* Pin the library's polling task to Core 0 so that RFID I/O never
     * competes with the UI renderer on Core 1. */
    TaskHandle_t task = xTaskGetHandle(RC522_TASK_NAME);
    if (task != NULL) {
        vTaskCoreAffinitySet(task, (UBaseType_t)(1U << 0));
        ESP_LOGI(TAG, "RC522 polling task pinned to Core 0");
    } else {
        ESP_LOGW(TAG, "rc522_polling_task handle not found, affinity not set");
    }

    ESP_LOGI(TAG, "RFID scanner ready (SPI2_HOST, CS=%d, RST=%d)",
             HW_RC522_CS_GPIO, HW_RC522_RST_GPIO);
    return ESP_OK;
}

const char *rfid_manager_last_uid(void)
{
    return s_last_uid;
}

bool rfid_manager_has_pending_card(void)
{
    return s_pending_card;
}

void rfid_manager_consume_card(void)
{
    s_pending_card = false;
}