Example CAN Project integrated

esp32/src/can.cpp

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+/**
+ * @file can.cpp
+ * 
+ * Based on ESP32-TWAI-CAN example
+ */
+
+#include <ESP32-TWAI-CAN.hpp>
+#include "can.h"
+
+#ifndef CAN_TX
+#error CAN Interface not declared
+#else
+
+CanFrame rxFrame;
+
+void sendObdFrame(uint8_t obdId) {
+	CanFrame obdFrame = { 0 };
+	obdFrame.identifier = 0x7DF; // Default OBD2 address;
+	obdFrame.extd = 0;
+	obdFrame.data_length_code = 8;
+	obdFrame.data[0] = 2;
+	obdFrame.data[1] = 1;
+	obdFrame.data[2] = obdId;
+	obdFrame.data[3] = 0xAA;    // Best to use 0xAA (0b10101010) instead of 0
+	obdFrame.data[4] = 0xAA;    // CAN works better this way as it needs
+	obdFrame.data[5] = 0xAA;    // to avoid bit-stuffing
+	obdFrame.data[6] = 0xAA;
+	obdFrame.data[7] = 0xAA;
+    // Accepts both pointers and references 
+    ESP32Can.writeFrame(obdFrame);  // timeout defaults to 1 ms
+}
+
+void can_setup() {
+    // Setup serial for debbuging.
+    Serial.begin(115200);
+
+    // Set pins
+	ESP32Can.setPins(CAN_TX, CAN_RX);
+	
+    // You can set custom size for the queues - those are default
+    ESP32Can.setRxQueueSize(5);
+	ESP32Can.setTxQueueSize(5);
+
+    // .setSpeed() and .begin() functions require to use TwaiSpeed enum,
+    // but you can easily convert it from numerical value using .convertSpeed()
+    ESP32Can.setSpeed(ESP32Can.convertSpeed(500));
+
+    // You can also just use .begin()..
+    if(ESP32Can.begin()) {
+        Serial.println("CAN bus started!");
+    } else {
+        Serial.println("CAN bus failed!");
+    }
+
+    // or override everything in one command;
+    // It is also safe to use .begin() without .end() as it calls it internally
+    if(ESP32Can.begin(ESP32Can.convertSpeed(500), CAN_TX, CAN_RX, 10, 10)) {
+        Serial.println("CAN bus started!");
+    } else {
+        Serial.println("CAN bus failed!");
+    }
+}
+
+void can_loop() {
+    static uint32_t lastStamp = 0;
+    uint32_t currentStamp = millis();
+    
+    if(currentStamp - lastStamp > 1000) {   // sends OBD2 request every second
+        lastStamp = currentStamp;
+        sendObdFrame(5); // For coolant temperature
+    }
+
+    // You can set custom timeout, default is 1000
+    if(ESP32Can.readFrame(rxFrame, 1000)) {
+        // Comment out if too many frames
+        Serial.printf("Received frame: %03X  \r\n", rxFrame.identifier);
+        if(rxFrame.identifier == 0x7E8) {   // Standard OBD2 frame responce ID
+            Serial.printf("Collant temp: %3d°C \r\n", rxFrame.data[3] - 40); // Convert to °C
+        }
+    }
+}
+
+#endif