I recently purchased 3 LS20031’s and a “RS232 Shifter SMD” to connect them to a PC. Long term they will be connected to Micros but for now I just want to get them working with a PC.
I have only tried 2 so far but get the same with both. Apply power and the LED lights. It stays lit no flashing to show a sat fix.
I have connected the RX from GPS to the TX pin and TX from GPS to the RX pin on the level shifter, which I have had powered from 3.6V - Currently running from 3V.
I get no joy if I use MiniGPS or Realterm, the only activity I can see is a flash of the TX RX leds if I try to send config data.
It is my understanding that even if the units don’t have a fix they should still output last known data, but I am getting nothing. Tried every baud rate setting I can think of and no difference.
Anyone have any ideas for sorting this would be greatly appriciated.
Thanks for anyhelp.
Greg
Edit.
Forgot to add, tried a loopback test of the rs232 shifter and works fine.
I just checked the data sheet: you had it correct the first time. If the LED isn’t flashing it can’t be getting a fix, it shouldn’t need a serial connection for that to work.
You have to be careful with the baud rates on these guys. It appears the datasheet is wrong and I believe the chip boots up and starts sending 57,600 baud, and not whatever the datasheet says.
Also, if the red LED is staying on, that’s not good. It should either be blinking every second (meaning you have GPS fix) or off (no GPS fix).
I’ve had mine come up in a state where the LED stays on solid, but I turned it off and turned it back on and then it got GPS lock.
Don’t know exactly what was wrong but it’s up and running now.
What I was trying to do was setup a bed of nails test jig, then I could plug each unit in and test configure etc.
I checked and rechecked the test jig layout several times and still can’t fault it.
Today I soldered direct to the pins and all is good.
For anyone like me that has problems getting these to run.
Just apply power (3V) to pins 1 and 4. The red LED should light briefly and then go out. It will start flashing once it gets a sat fix.
If you use the sparkfun level shifter like I have, and it is connected to the GPS pins when powered on, the RX LED on the shifter will start flashing to indicate data is being received (this is even without the Level shifter being conected to the PC.
Even if indoors the GPS will likely get a lock. I am in my study under a tiled roof and the nearest window to my desk in under a metal roof. Definately no line of site but still get a fix.
Thanks again to everyone who responded or even took the time to read my thread.
Now it’s time for me to buy a couple of the Logomatic v2 Serial SD Dataloggers and take my project to the next level.
You might have been getting contact bounce with the original connections, preventing the device from initialising properly. Were you applying power to the connector before attaching it to the module?
Module was all strapped in and sitting down on the pogo pins before applying power.
Only thing I can think of is the underside of the board that the module sat 1/2mm above was un-grounded copper plane. I can only suspect it was creating an electromagnetic effect. That or I screwed up the wiring but I still can’t see any errors with the way it was wired up.
Once I connected power straight to the unit tonight it was a relief to see the LED flash on then stay off. Even better once I saw it get a fix and start to flash.