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Topic: 4 x Button SD Key PCB questions (sum of resistance?) (Read 144 times) previous topic - next topic


Question on how this hardware works/is set up..

I want to use this PRE-MADE 4 x switch, SD Key PCB:

ie: https://www.aliexpress.com/item/3-3V-5V-KC11B04-4-key-Analog-Buttons-AD-Keypad-Board-ADC-port-keyboard-for-Arduino/32710243294.html?spm=2114.10010108.1000023.4.44ae475aoKihoB

Image of the bottom of PCB so you can see resistor values and traces:

I want to use this in conjunction with a DFPlayer mini, in standalone mode  (ie:  not used along side an Arduino, like I normally use these)

Here is the 'chart' for the DFPlayer for reference..

** right click  >> view image to see true (larger) size.. not sure why it does this?

My question is how these values are calculated and used with this PCB?

Regardless if I decide to use ADKey1 or ADKey2.....  (which really just dictates the audio file names)...

I see that each clip is triggered based on the resistance/value of the switch that was pressed.

0K (no resistor/resistance) = triggers clip 0 (or 1, not sure yet)...
3K = triggers clip 2
6.2K = triggers clip 3

I would imagine I'll need to replace the resistors on this PCB,  to match that threshold value...  but I'm not clear on how this is calculated??

When I look at the bottom of the board and see the resistor values.. they all look to be the same?

So are they added up?  

IE: button 1 has no resistor or 0K resistor..   button 2 has a 3k resistor on it..

button 3 then.... needs another addition 3.2k to make it equal >= the 6.2k threshold it is looking for to trigger clip #3?

Or do I just use the stated value on each 'button/switch'? as stated in the diagram/schematic?

ie: button 3 gets a 6.2k resistor, as it only takes that single value into the equation?

So Im not clear is the resistance accumulative? or stand alone?

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