Discussions

Building my first drone.  Its a blimp inspired by the (currently unavailable) Blimpduino with a Quadcoptor-like sensor suite (ArduIMU+ v2, Sharp IR sensors, and Ultrasonic sensor).  The problem is no one seems to use the arduIMU in a stand alone configuration, even in a test/troubleshooting setup and I dont want the added complexity of adding the ardupilot since the base code isnt going to be very useful for this very simple stripped down drone implementation.  

The problem that had me stumped last night was trying to integrate my new GPS (MTK-3329 from DIYDrones) to the ArduIMU. The GPS locked but no solutions came through the serial feed from the ArduIMU via FTDI. I added debugging statements in the ArduIMU code and found that the GPS data packet is always incorrect so the Arduimu kicks out of the state machine after the first and second packets fail. I tried with all combinations of MTK firmware v1.4 and v1.6 as well as ArduIMU v1.7 and v1.8.1.  No obvious config/setup parameters seem to be the cause. All other serial data outputs from ArduIMU works fine. 

As far as I can tell the cause is one of two things.  A subtle config/setup issue that isnt discussed in forums becasue no one tries to runt he ArduIMU with GPS in a stand alone configuration. I noticed that FTDI-Rx and GPS-Rx go through a mux but Ive never worked with one of these before. I can figure this out but it will take some time to learn and troubleshoot so advice will be helpful.

Or there is a potential conflict between FTDI and GPS Tx. While mapping the pins on the ArduIMU+ I noticed on the schematic that the GPS and FTDI connectors appear to share the Tx-0 pin.  Could the FTDI serial interface be preventing the GPS from talking to the ArduIMU somehow? If so why would it always corrupt the GPS data output

Any other ideas will be helpful.