Deboune time of keyboard matrix

RE: Deboune time of keyboard matrix

Håkon Alseth — Thu, 25 Jul 2013 08:12:14 GMT

Hi,

There is no minimum value, this is only the polling rate for when to send key and release key. A normal tap from a person is ~200 ms. You can do a tighter timing, but I do not think it is going to have a huge effect on the response time. Having a lower polling rate will give a higher current consumption as you are firing the interrupt more frequently.

Best regards Håkon

RE: Deboune time of keyboard matrix

Jeffery — Thu, 25 Jul 2013 08:01:27 GMT

Hi Håkon Thanks for your reply. Can we modify M_KEYBOARD_DEFAULT_POLLRATE to 5ms or less? What is the minimum value?

Jeffery

RE: Deboune time of keyboard matrix

Håkon Alseth — Thu, 25 Jul 2013 07:46:39 GMT

Hi Jeffery,

The default debounce (or polling rate as it's named in the keyboard) is 15 ms. It's setup with this define in m_keyboard.h: M_KEYBOARD_DEFAULT_POLLRATE

How this happens is that the keyboard uses the GPIOTE PORT event as a wakeup source. When the device is awake, it starts a timer, and when it times out, it scans the matrix.

When the button is released (see: matrix_scan_timeout_handler), the timer is stopped and a "release" command is sent. Then it's back to sleep.

Best regards Håkon