• Electrical Design Considerations
• Pins, Ports, Inputs and Outputs
• Source Files
• Known Issues
• Future Work

The version of the reference VI currently being shipped by Ford (in limited quantity) has v0.3 of the PCB, and there are no known electrical issues.

For greater detail, see the changelog in the source files (.xls).

v0.3

• No known electrical issues.

v0.2

This was the first test run of the schematic.

• Output Power Jack Polarity is incorrect - The output power jack should be configured such that Pin 1 (the keyed pin) is Ground, and Pin 2 is +12V. This is flipped on the R0.2 PCB. A custom cable was created to patch this issue, and is labeled R0.2 Only. Only use this cable with R0.2 prototypes, otherwise the KBoard TVS Diode D2 and/or the VI power switch IC7 may be damaged or destroyed.
• JTAG CLK line - the JTAG signal RTCK was disconnected on R0.2 boards. It has manually been replaced with a wire. Occasionally the additional capacitance of this wire can cause JTAG errors - try reducing the JTAG clock rate.
• JTAG Ground noise - Occasionally JTAG errors can be caused by a ground loop between a USB JTAG adapter and the MicroUSB port on the VI. Try removing one or more connections to ground: IE, try powering the prototype from ONLY +5V USB verses the +12V OBD-II supply.
• Bluetooth connection dropout - Under some circumstances, the RN-41 bluetooth chipset will lock up and drop an active bluetooth connetion when under heavy load:
  • The most common cause of this problem is software flow control: make sure to use the RTS and CTS pins for UART1.
  • The RN-41 configuration timer can also cause the RN-41 input buffer to fill. From the LPC1769, enter configuration mode by transmitting $$$, disable the configuration timer with ST,0\r\n and then exit configuration mode by entering ---\r\n. Finally, power cycle the VI. The test firmware rn42-passthrough enables serial data to be relayed between UART0 (the 6-pin ISP header) and UART1 (the bluetooth interface).