Humidity effects on Prop?

squidx

Has anyone else noticed a problem with USB communications with the Prop or the Prop Dev Kit in cases of high humidity?

I'm trying to isolate a problem I've had sporadically: one evening, about a month ago, during a rainstorm, my prop started requiring multiple attempts to download a program, either to RAM or EEPROM. About 1/3 of attempts would work, otherwise, I would get most of the way, and then during the Verifying RAM process, I would get a "Propeller chip lost on COM7" message.

I wondered at the time if it might be due to the humidity/lightning, but as the problem stopped the next day, I didn't think much about it. In the meantime, once on board, the programs run fine.

This happened again last night, except that with the exception of a very small demo program, I was entirely unable to load anything onto the prop. I checked, and the humidity here in Boston was listed as 100%. Now today, I am able to load a very short LED blinking program, but no long programs (like something including BS2_Functions object. Humidity is currently 73%.

Am I confusing correlation with causation? Could I even consider it correlation? Has anyone else encountered this?

Thanks,

Alex

Paul Baker

If you are having issues it's due to exposed traces partially shorting. The Propeller has been tested to make sure it's packaging is impervious to high humidity.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

squidx

Thanks for the reply, Paul.

I just tried the same on a backup prop kit I just opened. Same problem: short program took 4 downloads, long program won't work at all. I'm using a different power supply, but same computer.

Any thoughts about what the problem could be?

Thanks,

Alex

Paul Baker

One way of noting whether it is humidity is to place a blow dryer on low over the board, this will evaporate any droplets of water.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

squidx

Let's say I was barking up the wrong tree and it isn't humidity. How can I debug this problem?

I'm currently set up with my backup prop kit, *no* external connections, just the power supply and USB.

When I go to download anything to RAM, the first time it says, "no propeller chip found", and reboots chip. Then the next time I usually hit F7 first, and it finds the chip, then I hit F10, and it locates the chip, begins download, etc etc until during verification, it says the chip is lost.

Post Edited (squidx) : 6/5/2007 3:47:00 PM GMT

Leon

There could be some flux residue on the board that is becoming conductive in high humidity. Scrubbing it with some IPA might help.

Leon

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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

squidx

Thanks Leon. I'll give that a try. (Assuming IPA == isopropyl alcohol)

squidx

OK, sorry all, I should have done a better forum search. Reboot of computer cleared it all up.

Thanks again,

Alex

Paul Baker

The non-exhaustive list:

• insufficient power supply
• PC has too much latency (try rebooting)
• USB cable has an intermittant connection (try using another cable)
• homemade board has RESn and/or BOEn wired incorrectly
• homemade board has residual flux
• an RF emitting device is located near the USB cable

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.