Hi All -
I'm building a GPS tracker that can log data coordinates using an Arduino MEGA 2560 and a GPS/GPRS/GSM shield from DFRobot.
We are having problems with the board that are hard to reproduce, so I thought I will describe the circumstances and hopefully you can suggest a way to fix it, or a way to gather more information.
RIght now for testing, It's being powered from an AC-to-DC converter at 7.7 volts. We've measured Vin on the shield at 7 volts.
We're using the code hosted here: http://www.cooking-hacks.com/documentation/tutorials/geolocation-tracker-gprs-gps-geoposition-sim908-arduino-raspberry-pi
In the section "Realtime geolocation tracking". We have modified it a bit, but not much.
Most recently, we've been having problems with the section of the code that establishes a GPRS connection to upload the GPS coordinates to a webserver. When the arduino sends this command:
The shield returns the following:
This behavior is intermittent. Sometimes it works, then a day later it doesn't. We can't figure out what the difference is, because we're not changing hardware or software. We also sometimes have problems with these commands:
Sometimes, the failure is because the shield returned "ERROR". Other times, the shield returns nonsense strings (i.e. ÿÿÿÿÿÿÿÿÿÿ).
Any ideas about what could be causing these failures?