mini_GPS won't to talk to my new GPS chip

Forum 2005-2010 (read only) Hardware Interfacing
1

I'm developing the GPS part of the 'vehicle telemetry' project from Practical Arduino book. Following the book, to initialise the GPS unit (LS20031) I've wired it through a sparkfun FTDI breakout adapter to my PC and have mini-GPS software applet running on my PC, through port COM10 (confirmed in device manager as originating from FTDI USB)

Everything appears to be working except mini-GPS continually reports "no FIX" and I can't set up the GPS parameters

The red LED is flashing on the LS20031 indicating it has a GPS fix. When I send a command like "Cold Start" the red Tx led flashes on the FTDI board. The green Rx LED on the FTDI board flashes constantly, as soon as power is applied. I think this indicates the GPS is constantly generating NMEA sentences and the FTDI is it's receiving them ?

I've got the TX/RX crossed over as explained in the book. ( I tried uncrossing them but no change, except Rx/Tx LEDs don't flash :frowning: ). The GPS is receiving 3.3V power OK. All bauf rates are 9600 (factory default for the LS20031) and update rate is still 1Hz

Any suggestions on why min-GPS continually reports "no FIX".

t.i.a.

2

Dumb question: You are doing this outdoors, with a clear view of the sky, right?

:slight_smile:

3

possibly dumb answer: so far indoors only. The LS20031 GPS has a LED that flashes @ 1Hz when its got a fix, and stays off when no FIX. My LS20031 LED started flashing after about 30 secs on first power up. Now it flashes pretty much as soon as power is on. So i figure it knows where it is.

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You mentioned using a 9600bps setting. It's possible the module is running at something different: the original NMEA default was 4800bps, and I've heard of GPS units shipping with other baud rates as well. Could you try at 4800, then perhaps some other likely candidates such as 38400 and 57600, which is the max for the LS20031?