dashboard: add OBD-II coolant polling over CAN

docs/dashboard-esp32s3.md

@@ -311,3 +311,11 @@ The diagnostics overlay shows dashboard version, uptime, heap, WiFi RSSI/IP, Car
 - Swipe right from the main dashboard to open Battery Detail.
 - Swipe left from Battery Detail to return to the main dashboard.
 - Diagnostics remains hidden behind the multi-tap system-card gesture.
+
+
+## OBD-II Coolant Polling
+- Dashboard ESP32-S3 Touch LCD 5B uses onboard CAN/TWAI via GPIO15 CANTX and GPIO16 CANRX.
+- First implemented PID is Mode 01 PID 05 coolant temperature.
+- Sends standard 11-bit functional request ID `0x7DF` and accepts ECU responses from `0x7E8` through `0x7EF`.
+- Diagnostics page shows TWAI state, coolant value, TX/RX counts, and last OBD status.
+- Overview coolant gauge shows `--°` until a valid OBD response is received.

firmware/esp32-s3-dashboard/dashboard_config.h

@@ -1,6 +1,6 @@
 #pragma once
 
-static const char *DASHBOARD_VERSION = "0.1.120-temp-alert-style-real-fix";
+static const char *DASHBOARD_VERSION = "0.1.121-obd-coolant-polling";
 
 // Update these if your Cargo ESP AP credentials are different.
 //static const char *CARGO_WIFI_SSID = "OverlandController";

firmware/esp32-s3-dashboard/esp32-s3-dashboard.ino

@@ -3,6 +3,7 @@
 #include <HTTPClient.h>
 #include <ArduinoJson.h>
 #include <esp_display_panel.hpp>
+#include <driver/twai.h>
 
 #include <lvgl.h>
 #include "lvgl_v8_port.h"
@@ -15,6 +16,24 @@ using namespace esp_panel::drivers;
 using namespace esp_panel::board;
 
 static DashboardStatus status_model;
+static constexpr gpio_num_t OBD_CAN_TX_PIN = GPIO_NUM_15;
+static constexpr gpio_num_t OBD_CAN_RX_PIN = GPIO_NUM_16;
+static constexpr uint32_t OBD_REQUEST_ID = 0x7DF;
+static constexpr uint32_t OBD_RESPONSE_ID_MIN = 0x7E8;
+static constexpr uint32_t OBD_RESPONSE_ID_MAX = 0x7EF;
+static constexpr uint8_t OBD_PID_COOLANT_TEMP = 0x05;
+
+static bool obd_can_ready = false;
+static bool obd_can_started = false;
+static unsigned long last_obd_poll_ms = 0;
+static unsigned long last_obd_rx_ms = 0;
+static unsigned long last_obd_tx_ms = 0;
+static uint32_t obd_tx_count = 0;
+static uint32_t obd_rx_count = 0;
+static int obd_coolant_temp_f = -999;
+static int last_rendered_obd_coolant_temp_f = -1000;
+static String obd_last_error = "not initialized";
+
 
 static lv_obj_t *battery_card_obj = nullptr;
 static lv_obj_t *battery_soc_arc = nullptr;
@@ -369,6 +388,149 @@ static String format_diag_uptime(unsigned long seconds)
     return out;
 }
 
+static void update_vehicle_coolant_widget()
+{
+    if (vehicle_coolant_value_label == nullptr || vehicle_coolant_meter == nullptr || vehicle_coolant_needle == nullptr) {
+        return;
+    }
+
+    if (obd_coolant_temp_f == last_rendered_obd_coolant_temp_f) {
+        return;
+    }
+
+    last_rendered_obd_coolant_temp_f = obd_coolant_temp_f;
+
+    lvgl_port_lock(-1);
+
+    if (obd_coolant_temp_f > -100) {
+        int bounded_temp = clamp_int(obd_coolant_temp_f, 100, 260);
+        lv_meter_set_indicator_value(vehicle_coolant_meter, vehicle_coolant_needle, bounded_temp);
+        lv_label_set_text(vehicle_coolant_value_label, (String(obd_coolant_temp_f) + "°").c_str());
+    } else {
+        lv_meter_set_indicator_value(vehicle_coolant_meter, vehicle_coolant_needle, 100);
+        lv_label_set_text(vehicle_coolant_value_label, "--°");
+    }
+
+    lvgl_port_unlock();
+}
+
+static bool init_obd_can()
+{
+    if (obd_can_ready && obd_can_started) {
+        return true;
+    }
+
+    twai_general_config_t general_config = TWAI_GENERAL_CONFIG_DEFAULT(OBD_CAN_TX_PIN, OBD_CAN_RX_PIN, TWAI_MODE_NORMAL);
+    general_config.tx_queue_len = 5;
+    general_config.rx_queue_len = 20;
+
+    twai_timing_config_t timing_config = TWAI_TIMING_CONFIG_500KBITS();
+    twai_filter_config_t filter_config = TWAI_FILTER_CONFIG_ACCEPT_ALL();
+
+    if (!obd_can_ready) {
+        esp_err_t install_result = twai_driver_install(&general_config, &timing_config, &filter_config);
+        if (install_result != ESP_OK && install_result != ESP_ERR_INVALID_STATE) {
+            obd_last_error = "driver install failed: " + String((int)install_result);
+            Serial.println("OBD CAN: " + obd_last_error);
+            return false;
+        }
+
+        obd_can_ready = true;
+    }
+
+    esp_err_t start_result = twai_start();
+    if (start_result != ESP_OK && start_result != ESP_ERR_INVALID_STATE) {
+        obd_last_error = "start failed: " + String((int)start_result);
+        Serial.println("OBD CAN: " + obd_last_error);
+        return false;
+    }
+
+    obd_can_started = true;
+    obd_last_error = "started";
+    Serial.println("OBD CAN: TWAI started on TX GPIO15 / RX GPIO16 at 500 kbps");
+    return true;
+}
+
+static void send_obd_coolant_request()
+{
+    twai_message_t message = {};
+    message.identifier = OBD_REQUEST_ID;
+    message.extd = 0;
+    message.rtr = 0;
+    message.data_length_code = 8;
+    message.data[0] = 0x02;
+    message.data[1] = 0x01;
+    message.data[2] = OBD_PID_COOLANT_TEMP;
+    message.data[3] = 0x55;
+    message.data[4] = 0x55;
+    message.data[5] = 0x55;
+    message.data[6] = 0x55;
+    message.data[7] = 0x55;
+
+    esp_err_t result = twai_transmit(&message, 0);
+    if (result == ESP_OK) {
+        obd_tx_count++;
+        last_obd_tx_ms = millis();
+        obd_last_error = "coolant request sent";
+    } else {
+        obd_last_error = "tx failed: " + String((int)result);
+    }
+}
+
+static void handle_obd_can_message(const twai_message_t &message)
+{
+    if (message.extd || message.rtr) {
+        return;
+    }
+
+    if (message.identifier < OBD_RESPONSE_ID_MIN || message.identifier > OBD_RESPONSE_ID_MAX) {
+        return;
+    }
+
+    if (message.data_length_code < 4) {
+        return;
+    }
+
+    // Single-frame OBD-II response:
+    // byte0 length, byte1 0x41 response mode, byte2 PID, byte3 value A.
+    if (message.data[1] == 0x41 && message.data[2] == OBD_PID_COOLANT_TEMP) {
+        int coolant_c = (int)message.data[3] - 40;
+        obd_coolant_temp_f = (int)roundf((coolant_c * 9.0f / 5.0f) + 32.0f);
+        obd_rx_count++;
+        last_obd_rx_ms = millis();
+        obd_last_error = "coolant response OK";
+
+        Serial.print("OBD CAN: coolant=");
+        Serial.print(obd_coolant_temp_f);
+        Serial.println(" F");
+
+        update_vehicle_coolant_widget();
+    }
+}
+
+static void process_obd_can()
+{
+    if (!init_obd_can()) {
+        return;
+    }
+
+    if (millis() - last_obd_poll_ms >= 1000) {
+        last_obd_poll_ms = millis();
+        send_obd_coolant_request();
+    }
+
+    twai_message_t message = {};
+    while (twai_receive(&message, 0) == ESP_OK) {
+        handle_obd_can_message(message);
+    }
+
+    if (millis() - last_obd_rx_ms > 5000 && obd_coolant_temp_f > -100) {
+        obd_coolant_temp_f = -999;
+        update_vehicle_coolant_widget();
+    }
+}
+
+
 static void update_diagnostics_overlay()
 {
     if (diagnostics_overlay == nullptr || diagnostics_label == nullptr) {
@@ -442,6 +604,21 @@ static void update_diagnostics_overlay()
     text += String(status_model.cell_delta_mv);
     text += " mV";
 
+    text += "\n\nOBD-II / CAN\n";
+    text += "  TWAI: ";
+    text += obd_can_started ? "started" : "offline";
+    text += "\n  Pins: TX GPIO15 / RX GPIO16";
+    text += "\n  Coolant: ";
+    text += obd_coolant_temp_f > -100 ? String(obd_coolant_temp_f) + "°F" : String("--");
+    text += "\n  TX/RX: ";
+    text += String(obd_tx_count);
+    text += "/";
+    text += String(obd_rx_count);
+    text += "\n  Last RX age: ";
+    text += last_obd_rx_ms > 0 ? String((millis() - last_obd_rx_ms) / 1000) + "s" : String("--");
+    text += "\n  Last status: ";
+    text += obd_last_error;
+
     text += "\n\nControls\n";
     text += "  Relays visible: ";
     text += String(relay_count);
@@ -1885,7 +2062,7 @@ lv_obj_t *system_card = create_card(screen, "", 960, 48, LV_ALIGN_TOP_MID, 0, 12
     lv_meter_set_indicator_end_value(vehicle_coolant_meter, hot_arc, 260);
 
     vehicle_coolant_needle = lv_meter_add_needle_line(vehicle_coolant_meter, coolant_scale, 4, lv_color_hex(0xFFFFFF), -14);
-    lv_meter_set_indicator_value(vehicle_coolant_meter, vehicle_coolant_needle, 188);
+    lv_meter_set_indicator_value(vehicle_coolant_meter, vehicle_coolant_needle, 100);
 
     lv_obj_t *vehicle_coolant_center_cap = lv_obj_create(vehicle_coolant_meter);
     lv_obj_set_size(vehicle_coolant_center_cap, 54, 54);
@@ -1897,7 +2074,7 @@ lv_obj_t *system_card = create_card(screen, "", 960, 48, LV_ALIGN_TOP_MID, 0, 12
 #endif
 
     vehicle_coolant_value_label = lv_label_create(vehicle_card);
-    lv_label_set_text(vehicle_coolant_value_label, "188°");
+    lv_label_set_text(vehicle_coolant_value_label, "--°");
     lv_obj_set_style_text_color(vehicle_coolant_value_label, lv_color_hex(0xFFFFFF), 0);
     lv_obj_set_style_text_font(vehicle_coolant_value_label, &lv_font_montserrat_40, 0);
     lv_obj_set_width(vehicle_coolant_value_label, 120);
@@ -2037,6 +2214,7 @@ void loop()
     update_system_status_label();
     process_pending_relay_command();
     poll_status_api();
+    process_obd_can();
     process_dashboard_page_switch();
 
     delay(50);