I’m currently working on a revision of the PCB to correct issues with the first version, notably
- Lack of RC circuit on RESET/DTR line which prevents the Arduino IDE from properly resetting the MCU and loading new firmware. I was able to get around this with the V1.0 board by adding a resistor on the back side and putting a capacitor in series with the reset pin going to the FTDI adapter.
- Changing the sockets for the GPS module. I had originally planned on just soldering pin headers onto the Inventeksys GPS module itself, but they were a weird spacing (1.9mm) and it didn’t work out so well. The new design will replace the 10-pin 2mm headers with standard size XBee socket. This will allow you to use an XBee or a (to be designed) GPS module board in either socket, one with hardware serial and one with software serial.
- Adding LED(s) for GPS and XBee link status
- Connecting GPS power control to MCU to enable power-saving functions
- Other minor improvements including better RF coil for GPS antenna to improve sensitivity. Previous one had a low Q value at the L1 frequency and was self-resonant below that frequency.