Buttons


 

JHalasz

TVWBB Fan
I found a few old 4.2 boards laying around and figure I would put them together for some friends, I had all the parts except for the stupid buttons, which I got a from John (thanks).

I put them in the boards... the correct way, but they don't work, any way to troubleshoot what the issue could be with them?
 
You can check the operation with a multimeter. It's just a button-- put one lead on the common pin, and one on a direction pin, then press in that direction. Continuity as expected? Great!
 
You can check at the output pin... I think I he common pin? I am not near a computer to reference the schematic, but it should be 0v then raise to various different consistent voltages when you press different directions. You can also verify at the atmega itself, I believe it is the 6th pin from the end.
 
Here is the button circuit from HMv4.2. The circuit is very simple, voltage is fed through the various resistors to the various pins on the switch, then when you press the button in the various directions the respective voltages appear on the COM pin of the switch.
So, you can measure the voltage on all of the pins, when you press the switch in each direction you should see the voltage from that pin appear on the COM (and at the ATMega)
HM_Switch.jpg
 
ok so, on the common and one of the directions i get about 3.2v, when i push the button in the direction of that pin, it drops to zero, same on all pins
 
Eee the common should always be 0V unless a button is pressed, and all the other pins (apart from the one that isn't connected) should be 3.3V until a button is pressed, and then drop to their appropriate voltage in the middle. The circuit is ridiculously simple as 3.3V -> Resistor -> Switch for every direction. If they are ALL acting funny, then either R1 isn't connected to the switch / GND, or the switch isn't right.
 
pin check from common, to direction pin on the switch, correct? 3.3ish, then 0 when pressed in that direction... should be 3.3ish, then 680, 390... when pressed in respective direction?
 
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Make sure you didnt jam the button in there backwards. THe middle pin is offset a bit to show orientation, but not offset enough to prevent forcing the button in the wrong way
 
Oh no not the voltage between the direction pin and the common pin, the voltage between the direction pin and GND pressed and unpressed. If it looks good there, then check it between the button ADC pin and GND doing the same thing (pin 23, 6 up from the bottom right corner).
 
i checked to ground, all good, will check from ADC next... maddening I tell you... :) my friends are about get get HM's without a working button
 
Reprogram the Atmega. I have seen it happen before. If you have the correct readings at the Atmega then it's the chip that the problem.
 

 

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