/* ESP32 TWAI transmit example.
  This transmits a message every second.

  Connect a CAN bus transceiver to the RX/TX pins.
  For example: SN65HVD230

  The API gives other possible speeds and alerts:
  https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/twai.html

  created 27-06-2023 by Stephan Martin (designer2k2)
*/

#include "driver/twai.h"

// Pins used to connect to CAN bus transceiver:
#define RX_PIN 21
#define TX_PIN 22

// Intervall:
#define TRANSMIT_RATE_MS 1000

#define POLLING_RATE_MS 1000

static bool driver_installed = false;

unsigned long previousMillis = 0;  // will store last time a message was send


void setup() {
  // Start Serial:
  Serial.begin(115200);

  // Initialize configuration structures using macro initializers
  twai_general_config_t g_config = TWAI_GENERAL_CONFIG_DEFAULT((gpio_num_t)TX_PIN, (gpio_num_t)RX_PIN, TWAI_MODE_NORMAL);
  twai_timing_config_t t_config = TWAI_TIMING_CONFIG_500KBITS();  //Look in the api-reference for other speed sets.
  twai_filter_config_t f_config = TWAI_FILTER_CONFIG_ACCEPT_ALL();

  // Install TWAI driver
  if (twai_driver_install(&g_config, &t_config, &f_config) == ESP_OK) {
    Serial.println("Driver installed");
  } else {
    Serial.println("Failed to install driver");
    return;
  }

  // Start TWAI driver
  if (twai_start() == ESP_OK) {
    Serial.println("Driver started");
  } else {
    Serial.println("Failed to start driver");
    return;
  }

  // Reconfigure alerts to detect TX alerts and Bus-Off errors
  uint32_t alerts_to_enable = TWAI_ALERT_TX_IDLE | TWAI_ALERT_TX_SUCCESS | TWAI_ALERT_TX_FAILED | TWAI_ALERT_ERR_PASS | TWAI_ALERT_BUS_ERROR;
  if (twai_reconfigure_alerts(alerts_to_enable, NULL) == ESP_OK) {
    Serial.println("CAN Alerts reconfigured");
  } else {
    Serial.println("Failed to reconfigure alerts");
    return;
  }

  // TWAI driver is now successfully installed and started
  driver_installed = true;
}

static void send_message() {
  // Send message

  // Configure message to transmit
  twai_message_t message;
  message.identifier = 0x0F6;
  message.data_length_code = 4;
  for (int i = 0; i < 4; i++) {
    message.data[i] = 0;
  }

  // Queue message for transmission
  if (twai_transmit(&message, pdMS_TO_TICKS(1000)) == ESP_OK) {
    printf("Message queued for transmission\n");
  } else {
    printf("Failed to queue message for transmission\n");
  }
}

void loop() {
  if (!driver_installed) {
    // Driver not installed
    delay(1000);
    return;
  }
  // Check if alert happened
  uint32_t alerts_triggered;
  twai_read_alerts(&alerts_triggered, pdMS_TO_TICKS(POLLING_RATE_MS));
  twai_status_info_t twaistatus;
  twai_get_status_info(&twaistatus);

  // Handle alerts
  if (alerts_triggered & TWAI_ALERT_ERR_PASS) {
    Serial.println("Alert: TWAI controller has become error passive.");
  }
  if (alerts_triggered & TWAI_ALERT_BUS_ERROR) {
    Serial.println("Alert: A (Bit, Stuff, CRC, Form, ACK) error has occurred on the bus.");
    Serial.printf("Bus error count: %lu\n", twaistatus.bus_error_count);
  }
  if (alerts_triggered & TWAI_ALERT_TX_FAILED) {
    Serial.println("Alert: The Transmission failed.");
    Serial.printf("TX buffered: %lu\t", twaistatus.msgs_to_tx);
    Serial.printf("TX error: %lu\t", twaistatus.tx_error_counter);
    Serial.printf("TX failed: %lu\n", twaistatus.tx_failed_count);
  }
  if (alerts_triggered & TWAI_ALERT_TX_SUCCESS) {
    Serial.println("Alert: The Transmission was successful.");
    Serial.printf("TX buffered: %lu\t", twaistatus.msgs_to_tx);
  }

  // Send message
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= TRANSMIT_RATE_MS) {
    previousMillis = currentMillis;
    send_message();
  }
}
