Bean muliplex is a communication protocol developed by Toyota for body control system in passenger cars. Its a single wire 12 volt serial communication. As bean multiplex isn't very common i created bean multiplex interpreter using an Arduino.

Why do this?

The ecu is responsible to feed information to the combination meter, if say the ecu was replaced for an aftermarket unit the temperature gauge will not work.

Here is an example circuits to use for transmit/receive, the MCP2515 module integration can be ignored

To begin work with BeanMPX, download the ZIP file and include it into the Arduino IDE. Next open the example sketch provided.

There is one optional parameter which can be set, its the Acknowledge Messages. BeanMPX can send acknowledge response to messages with a particular destination id.

  bean.ackMsg((const uint8_t[]) {0xFE}); // Messages to acknowledge

Bean Multiplex repeated the message 3 times if no acknowledgement was received

Receive message is configured similar to arduino SoftwareSerial implemenatition.

Sending message, requires Destination id, Message id, and Data. Priority, Message length, CRC, and End of Message bytes will be generated.

  bean.sendMsg(engTemp, sizeof(engTemp));