Cycle start/resume pause and external buttons problem (Mesa 7i76e card)

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03 Aug 2022 14:49 - 03 Aug 2022 14:50 #248936 by raychar
Let me explain further, my MESA 767ie expansion connectors are connected with CNC4PC's C25 breakout board, that is the external button lines go through 74HC14N IC first before entering to Mesa card

Having further done the followings but all in vain (that is the cycle start button still turns on itself):
> setp deounce.0.delay15~150 and letting those gpio's input to and go out of them
> adding 47k ohm pull up resistor on those pins
> adding two 0.1uF capacitors on each those pins

Before using the Mesa card and LinuxCNC these couple of years, I used to use Mach3 Ethernet SmoothStepper card for a long time, it haven't this noise interference problem. For the Mesa card, is it really this problem this time?
As I have done all the hardwares: include building the keyboard pcb, key button switches and panel housing building. Those external buttons are of momentary switch type. I might need to change all of them. Change to normal closed type, that is they are normally at 0V voltage level, so the randomly positive voltage noise don't affect those input lines. Will this method work? Not yet test and i don't know? Please advise? There is no momentary switch of normal close type, I need to change them to toggle switches (2 positions spring back type) or limit switch (as it has NO and NC position for selection to use) but need to add separate piece of plastic button cap on top of it...Anyway, trouble...

Thanks for the reading, my English is not good
Last edit: 03 Aug 2022 14:50 by raychar. Reason: repeated wordings

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03 Aug 2022 15:01 #248937 by raychar
Missed to remind, CNC4PC's C25 breakout board socket pin outs do not match with 7i76e expansion connector pin out, i need to swap most of them when using it

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03 Aug 2022 17:52 #248955 by PCW

Missed to remind, CNC4PC's C25 breakout board socket pin outs do not match with 7i76e expansion connector pin out, i need to swap most of them when using it
 

Yes, that's expected since the C25 is expected to plug directly onto a SmoothStepper so its
connectors are on the opposite of the normal side, leading to a even/odd pin swap.

Do you have all 8 ground pins connected on each connector? You may have a ground loop
with significant HF current flowing in the cable. This can cause noise issues which will be helped
by using all grounds (the C25 plugged direct onto a SmoothStepper would be less sensitive to
ground loop issues due to the shortness of the connection.

You may (as anypugh suggested) need to debounce the signals.

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04 Aug 2022 15:03 #249046 by raychar
>all 8 ground pins were originally connected properly, so that is not the cause from.
>I finally found my wrongdoings. I missed to notice that C25 inputs are pulled down by 4.7k ohm resistor. I additionally add a 3.3k ohm pull up resistor to make it in pull-up state. This is very bad in picking up a lot of noise. After removing them, that is, one end of the external button switch straightly connected to +5V and another end goes to input of C25 breakout board (which is pulled down), also, doing some modification in the program. The problem don't happen now.
>Anyway, i think that inputs have pull down resistor and in pull down state are much better in resistance to noise interference (?)

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