J1850 VPW Arduino Library

This Arduino library allows the user to receive and send messages on Chrysler's PCI-bus. It uses interrupts to decode and encode J1850 VPW protocol.

Supported Hardware

• Arduino Uno (ATmega168/ATmega328P)
• Arduino Mega (ATmega1280/ATmega2560)
• Teensy 4.0 (iMXRT1062)
• Teensy 4.1 (iMXRT1062)
• Teensy MicroMod (iMXRT1062)

Pin Requirements

RX-pin must be external interrupt capable:

• Arduino Uno: pins 2 or 3
• Arduino Mega: pins 2, 3, 18, 19, 20, or 21 (pins 71 and 72 are not broken out to the connector)
• Teensy 4.x: any digital pin (all pins support interrupts)

TX-pin can be any unused pin.

Message reception and transmission are handled simultaneously.

Timer Usage

Arduino Uno/Mega:

• Bus-idle condition is measured with Timer 2
• Protocol encoder uses Timer 1 (Uno) or Timer 4 (Mega) for TX pin state changes
• Make sure that these timers are not used by other functions

Teensy 4.x:

• Uses 2 IntervalTimer instances (out of 4 available)
  • One for protocol encoder (TX timing)
  • One for bus-idle detection
• Leaves 2 IntervalTimer instances available for user code
• All other Teensy timers (FlexPWM, QuadTimer, GPT) remain free for other uses

Without a suitable transceiver circuit/chip and live PCI-bus network the library is easy to test with the loop-back method: short selected RX/TX pins, upload J1850VPWWrite example, open Arduino Serial Monitor and observe the repeated test message.

To be used with the CCD/PCI-bus Transceiver Development Boards.