633 multiple key press problem


New member
I have two different 633 modules. The one that is working fine is HW v1.0, FW v0.6. The one that is not working fine is HW v1.3, FW v b1.3.

The problem with the one that is not working is that some of the keys report multiple key press activities, while others seem to work fine. For example, the "up" arrow key will report 5 presses and releases (all validated with correct CRC), every time the key is pressed. Then, any slight jiggling of the key will result in a few more valid press and releases.

It is almost like the keys are not debounced properly. What is really strange, is that previous versions of the module work just fine!

Is there anyone out there with similar experiences and/or suggestions?

Hemi Thaker
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CF Support

You may want to check the supply voltage for the logic, if it's too low, then you'll experience some problems with the module.


New member
We measured the voltages as 5.16 and 11.94. I would consider this well within the specs. Have there been any firmware changes? Note that the previous versions of the 633 work just fine with this exact same power supply.
USB LCD Displays - Graphic and Character LCDs with a Keypad