UM96 Reciever/Transmitter

Jessica Uelmen

Hello!

I am setting up an IMU device to place in a rocket that will measure different values such as roll, pitch, yaw, etc. I am using the HAC-UM96 from Sparkfun to transmit and receive the data. The manual can be found here:

www.sparkfun.com/datasheets/RF/HAC-UM96_manual.pdf

I have no jumpers attached and have found the device is using an odd parity with an RS-485 interface. I am using the FullDuplexSerial object to get the devices to communicate and display the values from the transmitter to the PropTerminal. Using the rxcheck command I found that the receiver is sporadically receiving data in the following pattern: 0 0 -1 0 -1. However, no matter what value I send the transmitter outputs a 0. I think the issue is that I need to make the FDS a HalfDuplexSerial object, but I am not sure how to go about this. I also may not be using the commands correctly, I am not sure. I've attached my coding and the schematic for my circuit.

Any nudge in the correct direction would be appreciated! Thank you!

SRLM

Something to think about it you are using electronics in a rocket.

Thread

Jessica Uelmen

Oh I haven't flown anything yet. This is simply a ground test to make sure I get the parts communicating correctly. Then I'll tackle those challenges.

SRLM

Shouldn't you think of such things before you build the system? You can't exactly remake the chips...

Jessica Uelmen

I appreciate your concern, but yes we do have planned everything out. I didn't mean to make it sound like I was just launching electronics for the heck of it. It's for our Senior Design Project at the University of Central Florida - the rocket won't be going that high or far, and by all theoretical accounts everything should be able to operate during the launch. And the rocket isn't nearly the size as the one in the thread you posted.

My first part of the project is simply to get the parts working correctly on the ground first. Once I get the receiver receiving the correct data while they're sitting near to each other on my desk, I can move on to testing over longer distances (although all datasheets do show that transmission should be possible over our desired distance). I was hoping to get some input on my coding techniques to see if anyone else can see if I'm missing something - or perhaps not even calling FullDuplexSerial correctly. I am not sure, but as I am the only coder on the project, I figured that sometimes it helps to have a second pair of eyes look at something.

Thank you!

John Abshier

Why not use COM1 (TTL RS232) and set the jumper for 8N1? Then Full Duplex Serial should just work.

John Abshier

Jessica Uelmen

I had found a FullDuplexSerial_parity object on the forums, which people had listed their successes with - unfortunately it didn't help my situation. I just got my jumpers in the mail today (they had forgotten to include them) and tried the FullDuplexSerial without parity with the jumper on E and got the same response. I also tried with the jumper across D which allows the module to use RS-232 instead of RS-485, same response. So now this brings me back to issues with my coding and if I'm not calling the object correctly...

Jessica Uelmen

The problem has been fixed! Simply required pulling the reset and sleep pins to high and low. Also had some slight mistakes when setting the direction of the pins. Always something simple!

Thanks!