This is my first GPS experiement, I hooked up the breakout board to power, ground, with vcc to standby, and vcc to xrst through a 10k resistor. If I am reading this right, I should be able to read a bitstream from the TX_A pin, and I just get a flat 3.3v? What else should I connect to ground or vcc to get it to work?
I’ve got a similar problem, so I’d like to put in a vote for this question to be answered. Anybody else out there got this working?
I’ve hooked up my board like this, to my arduino mega:
Pin (on breakout) | name | connected to
-----------------------------------------
10 | XSTBY | 3.3v
9 | GND | GND
8 | VCC | 3.3v
7 | XRST | 3.3v
6 | BOOT | 3.3v
5 | R2 | 3.3v
4 | SHORT | nothing
3 | OPEN | nothing
2 | R1 | nothing
1 | LNA | nothing
and on the other side:
1 | R3 | nothing
2 | R4 | nothing
3 | PPS | nothing
4 | RX-B | nothing
5 | RX-A | voltage-divided output
from Arduino TX-2
6 | R5 | nothing
7 | TX-A | RX-2 on Arduino
8 | TX-B | nothing
9 | R6 | nothing
10 | R7 | nothing
From what I can tell by reading the spec, resistors seem to be optional on the 3.3v-tied pins. Am I wrong on this? I dearly hope I haven’t accidentally fried this thing.
When I test the TX-A line, my multimeter reads a 99.8% duty cycle; so I seem to have that same flat 3.3V problem. On the arduino side, it seems to be getting very few bytes on the serial connection, and the stuff that does come in looks pretty random.
I think at one point, I got it to output something, but it appeared to be a bunch of gibberish. My baud was indeed set to 9600. I am not sure what I did to make it stop working.
Anyone have any tips?
I am working with a Cyclone II board from terasic.
I have Vcc 3.3 and gnd from the cyclone board, standby and reset are connected to 2 output pins from my FPGA with current limiting resistors to protect the FPGA so I can run different combinations of highs and lows to those pins.
I put TXA into an input pin to the fpga, i get nothing, just a flat 3.3, I even used a proven program that counts rising edges from a switch and no response, not even from the PPS pin. Even if it didnt lock there should be some waveform from the TXA, right?
Tell me tbabb, what do you get if you try to run a count from your pps pin?
Anyone have any ideas.
Yahoo IM me at evil_twinzzz if anyone has any ideas, if I am at work at least I will know where to reach you
I put vcc to the boot and R2 pins, I am getting a bitstream from TXA and the pulse from PPS, tbabb, i think you should tie reset and standby to 2 more pins from your Arduino and see if that helps. I will now proceed to try and interpret the bitstream, good luck, keep hammering away.
So, I’ve tied XRST and XSTBY to the arduino module through voltage dividers; PPM is a direct input. On startup, I pull XRST low for 1000 mircoseconds (10 times the spec minimum).
I’m getting a consistent 1 second pulse from the PPM, however TX from the GPS module is still a flat 1. I’ve also tried sending XSTBY low for 3 seconds just to see if maybe that would wake it up. No dice. Do I need to send something to it first before it will start spitting out data?
I am using my own breakout board, but below is my working circuit for the Compernicus module in several of my products:
http://www.rpc-electronics.com/img/cope … ematic.jpg
Hope that helps.
I had an LED hooked up to the TXA pin that went back to my cyclone board, as it. It put was putting out the 2 default GPS strings a second, the LED looked like a sane persons EKG (heartbeat). FLASH,FLASH…FLASH,FLASH…FLASH,FLASH… 
I wasn’t even near it, I’m really upset 
i even took everything out of the breadboard and put it back together, I’ve created an expensive paperweight and I know its probably something I did. I will get another one when I get paid, maybe a diffeent one this time
FYI, I returned to this project after some time and found the problem.
TX-B is the output on the Copernicus that sends NMEA data; I was hooked up to TX-A, which sends Trimble’s proprietary data format by default. Not sure why nothing visible was coming up in the terminal, but I’ll debug that later. Baud should be set to 4800 when using TX-B/NMEA (I was using 38400 before; the default TSIP baud).
Also, I had failed to hook up the SHORT and OPEN pins correctly; SHORT should be high, and OPEN should be low.
After fixing these three things, I’m getting valid fix data.
I thought I’d post a follow-up, since I had a hell of a time finding any helpful info on this thing. Maybe this’ll help someone else get their project going.
cheers,
-tb
tbabb:
I thought I’d post a follow-up, since I had a hell of a time finding any helpful info on this thing. Maybe this’ll help someone else get their project going.
Did you even bother to look at the schematic that I posted above? It clearly showed use of TXB and RXB. Also, the SHORT and OPEN pins are not needed to aquire a standard FIX and have the module output NMEA at 4800 baud. Not sure why you needed these to get it working.