Arduino Forum

Using Arduino => General Electronics => Topic started by: xl97 on Feb 14, 2019, 09:06 pm

Title: 4 x Button SD Key PCB questions (sum of resistance?)
Post by: xl97 on Feb 14, 2019, 09:06 pm
Question on how this hardware works/is set up..

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


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?

Title: Re: 4 x Button SD Key PCB questions (sum of resistance?)
Post by: xl97 on Feb 15, 2019, 09:32 pm
^ bump..

I guess I can remove the resistors.. and temporarily use some thru-hole resistors to test this out.