Stream OBD2 CAN Bus Data via Bluetooth to Android with Arduino

Are you looking to monitor your car’s performance data on your Android device? This guide explores how to bridge your car’s OBD2 CAN bus system to your Android phone using an Arduino Uno, a CAN-bus shield, and a Bluetooth module. Specifically, we’ll delve into using the HC-06 Bluetooth module to transmit data from your car’s Engine Control Unit (ECU) to the Torque Android application for real-time virtual gauges.

Many car enthusiasts and DIYers want to access and visualize their vehicle’s data, such as fuel pressure, timing, and air-fuel ratio. The ECU broadcasts this data over the CAN bus in OBD2 format. By tapping into this data stream and relaying it wirelessly, you can create a custom dashboard on your smartphone. This project outlines the steps and considerations for achieving this using readily available components.

To set up this system, you will need:

• Arduino Uno R3: The microcontroller to process and route data.
• CAN-BUS Shield (like Seeed CAN-BUS Shield V2.0): To interface with your car’s CAN bus network.
• HC-06 RS232 Bluetooth Serial Transceiver Module: For wireless data transmission to your Android device.
• Android Device with Torque App: To receive and display the car’s data.

The basic architecture of this project is as follows:

[ECU] ---CAN H, Can L (in OBD format) --- [CAN-bus Shield/UNO R3] --> [HC-06] ---> [Torque Application]

Initial steps often involve verifying each component individually. Many users successfully read CAN data on their Arduino serial monitor using libraries and examples provided with the CAN-bus shield. This confirms the Arduino and CAN-bus shield are correctly reading data from the ECU.

// demo: CAN-BUS Shield, receive data with check mode
// send data coming to fast, such as less than 10ms, you can use this way
// loovee, 2014-6-13
#include <spi.h>

#define CAN_2515
// #define CAN_2518FD

// the cs pin of the version after v1.1 is default to D9
// v0.9b and v1.0 is default D10
// Set SPI CS Pin according to your hardware
// For Wio Terminal w/ MCP2518FD RPi Hat：
// Channel 0 SPI_CS Pin: BCM 8
// Channel 1 SPI_CS Pin: BCM 7
// Interupt Pin: BCM25
// *****************************************
// For Arduino MCP2515 Hat:
// SPI_CS Pin: D9
#ifdef CAN_2515
#include "mcp2515_can.h"

const int SPI_CS_PIN = 9;
const int CAN_INT_PIN = 2;

mcp2515_can CAN(SPI_CS_PIN); // Set CS pin
#endif

void setup() {
  SERIAL_PORT_MONITOR.begin(1000000);

#ifdef CAN_2518FD
  while (0 != CAN.begin((byte)CAN_1M)) {
    // init can bus : baudrate = 500k
#else
  while (CAN_OK != CAN.begin(CAN_1000KBPS)) {
    // init can bus : baudrate = 500k
#endif
    SERIAL_PORT_MONITOR.println("CAN init fail, retry...");
    delay(100);
  }
  SERIAL_PORT_MONITOR.println("CAN init ok!");
}

void loop() {
  unsigned char len = 0;
  unsigned char buf[8];

  if (CAN_MSGAVAIL == CAN.checkReceive()) {     // check if data coming
    CAN.readMsgBuf(&len, buf);    // read data,  len: data length, buf: data buf

    unsigned long canId = CAN.getCanId();

    SERIAL_PORT_MONITOR.println("-----------------------------");
    SERIAL_PORT_MONITOR.print("Get data from ID: 0x");
    SERIAL_PORT_MONITOR.println(canId, HEX);

    for (int i = 0; i < len; i++) {
      SERIAL_PORT_MONITOR.print(buf[i], HEX);
      SERIAL_PORT_MONITOR.print("t");
    }
    SERIAL_PORT_MONITOR.println();
  }
}

Similarly, establishing a Bluetooth connection between the HC-06 and an Android phone, and confirming communication with the Torque app separately, are crucial preliminary steps. This often involves using simple serial communication examples to ensure the Bluetooth module is functioning and paired correctly.

The core challenge lies in effectively routing the CAN data received by the Arduino to the HC-06 Bluetooth module for transmission. This involves modifying the Arduino code to take the CAN bus data and send it out through the serial port connected to the HC-06 TX pin. Since the Torque app is designed to read OBD2 formatted data, you likely won’t need to heavily modify the raw CAN data itself. The goal is to transparently pipe the data from the CAN bus to the Bluetooth module so the Torque app can interpret it.

To move forward, focus on adjusting your Arduino code to redirect the CAN bus data stream. Instead of printing to the serial monitor, your code should send this data via the serial connection to the HC-06. Ensure your Bluetooth module is correctly paired with your Android device and that the Torque app is configured to receive data via Bluetooth OBD2 adapters. By successfully bridging these components, you can unlock a wealth of real-time vehicle data directly on your Android device.