GPS-08334 Evaluation Board Issues

GPS/GNSS Development Boards
1

Hello,

We recently purchased several GPS-08334 evaluation boards with one USB connection and two serial connections.

Eval Board:

http://www.sparkfun.com/commerce/produc … ts_id=8334

GPS:

http://www.robotshop.us/lassen-iq-gps-receiver.html

We have installed the FTDI driver for Windows XP (which we are using) using the executable on the FTDI website. The coin battery is in, the USB/RS232 switch is set to RS232, and the other switch is set to Int. Not sure exactly what these do.

The unit is being powered externally, the red light is on, and a couple of seconds after turning the power switch to ON, the green status light is lit. Port 1 of the eval board is plugged into Port1 of the PC.

I am using TrimbleMon_V1-05-0.exe to connect to the unit. When I use Initialize > Detect Receiver, it detects nothing (even if all check boxes are checked – trying everything). However, I can connect to the board using Initialize > Connect using 9600-8N1 or 9600-8O1, but 9600-8O1 I think is default.

After manually connecting and with an antenna connected, I can see satellites and download the complete almanac. However, none of the satellite information is shown on the right half of the screen, and no version information is shown on the bottom of the screen. All other fields are filled in with time/position data. Further, when I go to configure the receiver, none of the options are filled it and I cannot change any of them. When I click Query on any tab, nothing happens.

I also tried Trimble GPS Studio and get the same thing. I also tried iQ_CHAT to change port settings, baud rates, etc, and nothing changes when I try to write it to NVM (“…waiting for reply”). I tried using the USB connection to do all of the same things, and the same things happen. I feel like I have literally tried everything.

As a note, when I first install the FTDI driver for the USB connection, I don’t see two COM ports show up (the lower for Port 1, the higher for Port 2). Is this all a driver problem? I have installed the driver several times. I have tried this on multiple computers. All boards we have are behaving the same way, so it doesn’t seem like it is a board problem.

Could someone please walk me through what I could be doing wrong, or what I need to do to get this to work? Hopefully the fact that I can connect and download almanac, but the configuration is not filled in or changeable, is something that indicates what the issue is.

Thank you all in advance for your help.

2

Can someone please suggest what we may be doing wrong? Why would we be able to connect to the board, have satellites show up in the GPS monitor software, but not be able to change the configuration (or even have the values filled in) and view the receiver/firmware version? We are currently stuck and do not know what to try next. Any and all help is appreciated.

Thanks in advance.

3

Looking at the schematic, the EXT/INT switch disconnects the receive lines. You would get data from the iQ module but you wouldn’t be able to send it any commands, which corresponds with what you are experiencing. Try setting to EXT.

Also, it looks like J1 is for port 1 of the iQ (TSIP) and J2 is for NMEA.

Hope this helps,

gm

4

Thank you for your reply, gm. I have tried all combinations of RS232 and EXT/INT with no luck. Still no ability to change the configuration or see what the current configuration settings are using the monitor software.

Any other suggestions?

5

The fact that the module gets a position means that it is functioning correctly. Unable to talk to the module from either RS-232 or USB indicates that the problem lies with the RX line somewhere between the Int/Ext switch and the iQ module. If you are sure that you have the switch in the correct position, I would start looking for bad solder joints at either the iQ connector or at the Int/Ext switch.

Looking at the evaluation board, I noticed that they didn’t tent their vias. This can lead to a short underneath the iQ module (don’t ask me how I know!) as the bottom of the module is metal. You might want to put some tape on the bottom of the module to insulate it from the board.

Hope this helps.

6

gm,

Thank you for your input. The solution was to place a piece of electrical tape over the exposed metal underneath the IQ module, which was in fact causing a short with the IQ module casing. Also, the switch set to INT worked.

So anyone else having this problem can provide power through the barrel connector, connect through Port 1 using a serial connection (9600-Odd-8-1, TSIP), have the switches to RS232 and INT, and put a piece of electrical tape over the exposed metal underneath the IQ module to get it working.

Thanks again for your suggestions. Your help is much appreciated.