does anyone have OI and RC radio issues

Hi all,
We hooked up our drivetrain with the OI and RC complete. As we were testdriving our robot so far, we noticed that the radio would go to “no communication” mode and the controllers were basically dead and not controlling the robot. It is intermittent.
anyone have issues or solutions with this problem?

When the radio doesn’t work, the first response should be to tether up and see how things go. If that does not work then you can start to troubleshoot wiring errors, team number settings, dead batteries, etc.

It’s not that the radio just loses connection but that the user loses control. Even the disable switch doesn’t work. It’s my understanding that if the robot loses contact with the OI it should disable itself. It doesn’t. The user simply loses control for a short while.

We also experienced this. At the time, we were running the 2006 OI. Robot seems to be locked in the last data packet sent by the OI. Tonight we will continue testing with 2007 OI to replicate the problem. Because the robot thinks it has good data, disable switch does not work, leading to a very dangerous situation. It seems to happen for a matter of seconds, and return to normal operation. Because of the short duration, and random nature, haven’t been able to read the diagnostic lights on the OI. It has not occured with the tether cable.


I strongly suggest that you report this problem to IFI.

This sounds similar to last year’s “8.2 volt” bug. It never bit us, so I didn’t pay close attention to the prescribed fix. I think it involved modifying the linker script to make a bank of memory out of bounds. If nobody pipes up with a good pointer to the details, you can search the forums.

I believe it’s a problem with the communications. With the 8.2 problem, I didn’t see any reference to the disable switch failing. We were using the 2006 OI with the new radios, so it may be a change in the radio communications which causes a intermittent problem. I have notified IFI of the situation. We have the new libs, and linker file installed.


Have you updated the Master Code on the 2006 RC?

I believe that the new V13 master code for 2007 has changes for the new radio.

Yes, that sounds very familiar! :ahh:

Also, for those who think the problem may be completely unrelated to the 8.2v bug, remember that when you corrupt a section of memory on a running computer program, the results are (almost) completely unpredictable. A section of memory that is receiving data from the OI may be being corrupted, thereby locking in the last data frame instead of shutting down due to lost radio link.

I wonder if this may be a problem peculiar to your RC, only time will tell.

It’s the 2007 RC, which I believe has v13 master. Waiting for a return call from IFI. Were getting a “no radio” on the OI. Shouldn’t this cause the master to shut down, regardless of what the User processor is doing?

Correct, “no radio” should immediately stop the robot dead in its tracks.

Does it work fine tethered??

Spoke with the fine people at IFI. Best guess is it’s either a bad cable, or interference from another radio source. There is a half second delay after the last good packet before the robot shuts down. After a good packet is received, the counter is reset, causing an additional half second delay. Hopefully we can narrow it down tonight.

We have not seen it happen with the robot tethered. It only happens intermittently on the radio.


we were using the 2006 oi and rc with the new radio’s from 2007. Is there a difference with the 2007 oi and rc? we are going to try and run tomorrow with using the 2007 oi and rc and see if there is a problem.
when we lose the radio signal on our oi, the robot stall and shows loss signal also.
cant see how it would be intereference. nothing else around and we have always tested in the same room.

anyone? please help.

To the best of my knowledge, the 2006 and 2007 systems are identical hardware. But the 2007 RC came with v13 of the master code installed, which has specific support for the new radios. If you haven’t yet updated the master code in your 2006 RC, that might be an issue.

(To check the master code version, press the mode button on the OI until it shows the 3-digit user value. The display will show the version number briefly before changing to the user byte value. You want to see u013 appear.)

We’re still seeing this problem. After talking to IFI, we tried the following.

  1. replaced both modem cables
  2. tried using other channels
  3. moved the rc modem away from power sources
  4. switched to the 2007 OI (shouldn’t make a difference)
  5. loaded default code from IFI
  6. disconnected the power on OI to test 1/2 sec timeout (passed)

Still seeing intermittent modem losses. We did discover the RC is losing the link first. Sometimes it recovers before the OI realizes there is a problem (never see a modem light on OI).

I suggest you contact IFI. It could be an unrelated issue, but it sounds very similar.

I’ll call IFI again when the sun gets a little further west.


The condition you describe can be a power issue to the OI. Does the modem cut out when the robot is just sitting there or does it cut out when moving? There is also a possibility in antenna location and orientation. Is it possible to take a picture of the modem mounting without sacrificing team secrets? Is the radio mounted near a motor, particularly an FP or Mabuchi? Does the modem cable run near wiring that feeds any motors?

The modem was near the main breaker. We moved it away, but perhaps not far enough. What would you consider a safe distance. We’re running four CIMS on modified AM gearbox. Although it’s difficult to say for sure, it generally seems to be under power. However, it also happens with the robot on stands, with little load on the motors (free wheeling). Sorry, don’t have access to the robot now, so can’t provide pics. It’s still in the prototype phase (controls screwed to plywood). We’ll try moving the modem a greater distance tonight.


Being near the main breaker is usually not a problem, having the antenna itself near metal objects will detune the antenna and make it inefficent. Spark noise from the brushes can wreak havoc with the modem and usually unloaded motors produce more noise than normal loads so being up on blocks would produce as much or more problems than driving. It also may be the way the robot is wired. The power for the RC should come from the first breaker on the multi position breaker panel. Make sure that all connection to the RC are tight. Finally, and I should have mentioned this before, you need a fully charged Backup battery connected to the RC. The NiCads come discharged so you need to charge them at least ten hours out of the box. The backup holds up the radio modem during times the RC shuts down for low voltage.

Thanks for the help Al,

The modem is about one foot from one of the gear boxes. We’ll try mounting it on a mast tonight. I’m quite sure our wiring is correct, but we’ll double check it as well. We’re servo shifting, so I am sure we have a charged backup battery.


It wouldn’t coincide with the shift point would it? Are the servos having a hard time shifting? Try without shifting and see what happens.