Keyboard spits out characters of column8.

[Eszett]

Hi! I have the following problem: my custom build keyboard triggers all switches of column 8 ("6", "z", "g", and "b"), like this:
6zgb6zgb6zgb6zgb6zgb6zgb6zgb6zgb6zgb6zgb6zgb............ and I dont know why. It irregularly stops somtimes, or starts flooding me with these characters again. The Teensy2.0 is well insolated, this can't be the problem. This suspect column 8 is connected on Teensy's pin PB2. When I deactivate PB2 in my firmware, the problem is gone. But why on earth does the pin PB2 detect all these switches pressed, when there is no switch pressed?
 

[njbair]

Hi! I have the following problem: my custom build keyboard triggers all switches of column 8 ("6", "z", "g", and "b"), like this:
6zgb6zgb6zgb6zgb6zgb6zgb6zgb6zgb6zgb6zgb6zgb............ and I dont know why. Sometimes it stops, but most time it is flooding me with thes characters. The Teensy2.0 is well insolated, this can't be the problem. This suspect column 8 is connected on Teensy's pin PB2. When I deactivate PB2 in my firmware, the problem is gone. But why on earth does the pin PB2 detect all these switches pressed, when there is no switch pressed?

Sounds like a short circuit is making the firmware think a switch is being pressed. Do you have a multimeter? You can do a continuity test from the teensy pin to each of the switch solder points and find the one that is misbehaving.

[Eszett]

Hi njbair! Well, the column itself seems to be fine. For example when I try to press "g" nothing happens, because this character is in row3 and row3 I have not yet connected to a Teensy I/O pin. But the pin PB2, which scans column 8, scans "6zgb", which is the whole column. How can this be?

[njbair]

Have you ruled out a firmware issue? That is, are you running a known good default keymap, or something you've customized?

[Eszett]

Yes, I'm running TMK firmware. The thing is: sometimes the keyboard works without flooding me with characters. The flooding occurs when I reboot the PC with the USB cable plugged in. But when I reboot the PC first, and then plug the USB cable in, the keyboard works fine, without flooding me with characters.

[njbair]

Yes, I'm running TMK firmware. The thing is: sometimes the keyboard works without flooding me with characters. The flooding occurs when I reboot the PC with the USB cable plugged in. But when I reboot the PC first, and then plug the USB cable in, the keyboard works fine, without flooding me with characters.

You may want to ask about this in the TMK Firmware thread. I'm not an expert but I think there's a different HID protocol for boot mode, which may come into play when you're plugged in during boot. It's probably not the whole issue, but it may be a part of it.

[Eszett]

Yes, I will do that, thanks njbair.

[hasu]

If you still have the problem, post pics, schematic or codes of your keyboard as possible.
I'll help you and you'll get many help from the GH community. I beleive you need many eyes to resolve your problem shortly in the end.