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EMX Voltage on Up, Dwn, Select Buttons


#1

I have a bare PCB with an EMX soldered onto it. I only have the 8 buttons connected to the PCB as shown in the EMX developement module. I have conected a 3.3V bench power supply to the module and fail to see 3.3V on the switches and instead am viewing 2.4V on those pins.
What could be the possible reason for this?

Thanks a lot.


#2

If nothing is connected then the pins should be 3.3V

Maybe you haven’t ran any code to set them high, which means the pins are inputs with pull ups, which explains the 2.4V


#3

Gus,

I have only loaded CLR, CLR2 & Config.hex files onto the module. No application code loaded as yet. With onyl these 3 files loaded should the pull ups on the buttons be active?

Pin 3 ,4, 7, 21, 24, 27, 53, 70 which are Down, Right, Up, Menu, Back, Left, Enable & Reset respectively.

Thanks,


#4

You didn’t load any app (C# code); therefore, the pins are all inputs with pull up resistors


#5

Gus,

The voltages we read on pins Pin 3 ,4, 7, 21, 24, 27, 53, 70 are :-
2.3V, 2.35V, 3.1V, 3.9V, 2.8V, 2.8V, 2.3V, 3.3V respectively. Is this acceptable?

Thanks,


#6

Any voltage is acceptable. Again, these have weak pull up resistors so they could have any voltage on them. Set them to outputs and you will see 3.3V on all pins