Keyboard: keys fail or stick randomly

[audiodef]

I've seen information about keys failing or sticking (producing things like "apt-geeeeeeeeeeeeeeeeeeeeeeeeeeee" or whatever) being related to the power supply; however, I'm using the wall outlet adapter and cord that came with my Nook. The adapter is rated for 5V, 0.85A. It seems this should be sufficient power. Am I wrong?

[Jim JKla]

Some of these plug fittings are unreliable so it could be this dispite the adequate rating.

You could get another and find it works perfectly.

[dom]

I've seen information about keys failing or sticking (producing things like "apt-geeeeeeeeeeeeeeeeeeeeeeeeeeee" or whatever) being related to the power supply; however, I'm using the wall outlet adapter and cord that came with my Nook. The adapter is rated for 5V, 0.85A. It seems this should be sufficient power. Am I wrong?

There's numerous causes for this. Power supply is one, and checking the voltage between TP1 and TP2 could rule that out:
http://elinux.org/R-Pi_Troubleshooting# ... r_problems

There's also issues with interrupt latency causing problems. There's been some recent fixes that could help. Try updating firmware:
http://elinux.org/R-Pi_Troubleshooting# ... g_firmware

[mahjongg]

Its impossible to say about any charger you use as a power supply if it is really suitable, that it says 5V and 0.85A doesn't mean that it can supply exactly 5V while 0,85A is drawn from it. It could be that it can give 5.0 Volt, and it can give 0.85A but not both at the same time! Charging circuits are much less fussy on stable input voltage than USB devices, and may work fine with 4.5 volt, so some charger makers don't take quality of the voltage level quite serious.

If you get repeating characters (a failing keyboard) may depend (together with potential software issues) on how much power (voltage) actually reaches the keyboard. That depends on if you have bad or good USB fuses, (or non at all, as on some newer boards the fuses are replaced by wire bridges) AND how much voltage your PSU actually generates AND the quality of the cable between the PSU and the PI AND how much current the keyboard uses AND whether the keyboard is truly designed to USB specs, and thus can work with some loss of power.

You can measure how much power the PI actually reaches by using a voltmeter and measuring between test points TP1 and TP2, if you see less than 4.8 volt there you may have cause for concern, but it really depends on how much current the keyboard uses, and on the status of the polyfuse how much voltage the keyboard actually gets, and it depends on the keyboard if that amount is enough. If it is designed according to USB specifications it should work with voltages as low as 4.4 Volt, but some keyboards do not.

Most people solve the problem by either using a different PSU or a different keyboard, for the former solution I would look for a good reliable brand (not some cheap Chinese thing, which may not at all do what it states on the label) with a rating of 5V and at least 1A. If you go for another keyboard you should use the most simple and cheap wired keyboard, without any frills, these tend to work the best.

[liz]

Closing thread as dupe - please follow Dom's links above.

[audiodef]

Thanks for the responses. That was fast!

It looked like I had a recent firmware version (dated August this year), but I ran rpi-update anyway, and my RPi wouldn't boot. It just sat there blinking the OK LED in a series of 5-6 blinks. I'm trying a new image on my SD card, as my first guess would be my image got bjorked.

[audiodef]

The new image still has the same problem. Since someone suggested that even with the correct rating, one adapter could simply not work well with the unit, I'm going to go look for another one somewhere.

[dom]

The new image still has the same problem. Since someone suggested that even with the correct rating, one adapter could simply not work well with the unit, I'm going to go look for another one somewhere.

Was this just a new image, or new image + rpi_update?
There was a relevant update to firmware today, which you'll only get from rpi-update.

[liz]

...actually remembering to hit the close thread button this time!