Author Topic: Switch chattering and low voltage MCUs  (Read 2104 times)

0 Members and 1 Guest are viewing this topic.

Offline pomk

  • Thread Starter
  • Posts: 470
  • Location: Finland
Switch chattering and low voltage MCUs
« on: Fri, 11 November 2016, 03:39:41 »
Hi!

I have started to experience some strange behavior with my bluetooth board. As the batteries gradually run out of juice, the switches start to chatter more and more. At first I thought that the doubled letters were because of the voltage dropping too much and the MCU not finding the 'ack' packet on the first try, but that was confirmed not to be the case as modifying the matrix scan rate seems to mitigate the problem for the time being.

Has anyone here run low voltage & low current chattering tests on gateron switches? Cherry MX is rated to work with 2V, but what about gateron?

Does someone have good ideas on how to solve the problem without having a 30ms software debounce? One thing that came to mind was to switch from column-switch-diode-row detect high scheme to row-diode-switch-column detect low scheme and thus win some voltage margin from the diode (0,5V forward voltage).

Edit: I'm now at 5 months of daily usage using 2xAAA batteries, which now read about 1,15V. First 4 months were completely problem free. The batteries should still give me about 6 to 10 months more.
 
« Last Edit: Fri, 11 November 2016, 04:02:10 by pomk »

Offline deadall127

  • Posts: 17
  • Location: France
Re: Switch chattering and low voltage MCUs
« Reply #1 on: Sat, 12 November 2016, 05:17:56 »
are you able to reprogram your MCU?
I've made a 0ms switch debouncer if you want

Offline pomk

  • Thread Starter
  • Posts: 470
  • Location: Finland
Re: Switch chattering and low voltage MCUs
« Reply #2 on: Sun, 13 November 2016, 07:10:23 »
Yes I can, and your debounce filter is the way to go as far as debounce in concerned. It is just that 30ms is way too much for a keyboard, so I will need to figure something else out as well.

Offline deadall127

  • Posts: 17
  • Location: France
Re: Switch chattering and low voltage MCUs
« Reply #3 on: Sun, 20 November 2016, 15:29:09 »
oh, sorry, I forgot to link you my post ^^' http://geekhack.org/index.php?topic=85787.0
also, I'm not sure to understand but I didn't made a filter, this is a null delay debouncer :3