Keyboard Matrix behaviour

GTT TFT Support

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Keyboard Matrix behaviour

Post by RonS » Sun Nov 02, 2014 1:07 pm


this week I have received one of your GTT70A units and I have started to make some tests with it.
I have noticed that the device does not detect more than one keypress at the same time when using the matrix keyboard feature.
As long as one of the keys is pressed no other keypress will be detected and reported.
This behaviour makes it impossible to use the key matrix for things like Shift+<second key> or Shift+Ctrl+<second key> sequences, where it would be necessary to press two or three keys at the same time.

Do you think this extended functionality can be added to the firmware of the device or is it technically impossible?


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Re: Keyboard Matrix behaviour

Post by Clark » Mon Nov 03, 2014 12:28 pm

Hi Ronny,

Multiple key presses can be detected using the current GTT70A hardware, but implementing the functionality in firmware will require significant changes including a new, unique return value for each multiple key combination.

If possible, I would recommend implementing a simpler toggle style shift key in your host code. This will provide the ability to extend the number of inputs available from your 25 keys, without the need for multiple key press detection.

Should multiple key press detection be absolutely necessary to your application, we can explore a custom firmware for your unit. Custom firmware development will require a minimum ordering quantity and carry pricing implications. If you'd like to discuss a custom firmware for your application, please contact me directly at

Troy Clark
Design & Development
Matrix Orbital

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