Lassen IQ to 9xtend

Wireless & IoT
1

I am trying to interface a Lassen IQ gps to a 9Xtend radio. I have the old Lassen development board from Sparkfun and the development board for the Xtend moduel.

I have no problems connecting the two together with a null modem and serial cable. I run into trouble when I take the Xtend moduel off and try prototype the circut.

For the proto circut I take the GPS data out (232 levels) from the Lassen dev. board and run them through a 232 chip then to the Xtend moduels Data In pin. I have also added a tx led to the Xtend.

When powered up everything seems to work fine the Xtend Led flashes when it should. I just do not receive anything on the other end.

I used a logic analizer to try and find the problem. I connected the GPS and Radio using the null modem and serial cable. I then used the protyped circut.

What I discovered is that on the prototyped circut the CTS pin of the radio was going high 12ms after data was received.

I checked everything I can find that would make CTS go high. I checked the baud rate(9600bps) vs RF rate(115200bps). I checked the settings for PK packet size, RB packetization threshold and RO packetization timeout. Since it works with these settings on the development boards it leads me to beleive it is a problem with the circut.

I have found the schematic for the Xtend development board here

http://ftp1.digi.com/support/images/XTIB-R%20rev12A.pdf

It looks like the just convet CTS to 232 and send to the DB9.

I also found this example

http://www.vernk.com/Documents/GpsRadio … icRevB.pdf

This is much the same as I have prototyped. Except I do not have sleep or RTS connected. I have tried with them connected and it did not change.

At this point I am running out of ideas. Any suggestions?

2

Mike,

I am doing a high altitude balloon project and have been looking for a system for hooking up the Lassen iQ to a 9xTend radio transmitting that down from the balloon 100,000ft and using a second 9xTend to recieve that signal and input this data onto the TrimbleMonitor (a program trimble made that displays GPS data, compatible with the Lassen) on my laptop. I was just wondering if you ever solved your issue and if you did could you please elaborate on what you did. I am very new to electronics, so a detailed explanation would be nice. However, I understand that takes a while and would really appreciate if you gave me a nudge in the right direction.

Thanks,

Mike

P.S.: Yes my name is Mike :slight_smile: