After using SiRFDemo to change message intervals, the unit stopped working entirely. It is connected to the SFE eval board, then to the computer via USB. I have tried using using the program as well as basic NMEA input commands.
I know that it is connected to com4, but at this point I have tried all baud rates with no luck. Is there a way to (1) first have a program recognize the unit, (2) reset it to factory defaults, or any other settings with which I can work.
I am obviously new at this and any help would be greatly appreciated.
Unless you mis-powered the module, it’s hard to imagine that the module is cooked.
Are you sure you have a stable source of 3.3V to power the module? Do you have a pull-up resistor (5K is good) on the enable pin to +3.3V? Are you using a 3.3V compatible RS-232 converter chip (example: MAX3232) to connect to the PC? Are you sure you haven’t reverse the modules Rx and Tx lines?
If you have a scope, can you seen anything happening on the Tx line? That will be the definitive test!
If all else fails, I can check the module for you, but you’d have to mail it to me.
I am using the Sparkfun GPS eval module and am getting 2.98V to the module and measured the pull-up resistor at 4M. Also, I have run the module via USB with the eval board before with no problems and have checked all the lines to confirm the correct connections.
I there anything else you can suggest? I might be taking you up on your offer to take a look at it.
No, not really, it could be the module itself, or the interface circuitry used to connect the module to your PC. This is the type of problem where an oscilloscope is king. I could tell where the problem was in less than 5 minutes with a scope. Either the module is sending data or not, and if it is, there has to be a reason it’s not being transfered to the PC via USB.
I’ve used the EM-408 with a PIC directly, with a MAX3232, and with an FDTI USB chip, all without any problems.
The problem is the change that you did with sirftdemo put the gps as i was nmea fabric with the sirftdemo (i passed the same problem and it was solved)