Touch Shield

Hi,

Over 2 years ago a British nationwide electronics stored closed.  I picked up so many bargains I forgot about some.  This one came to mind after watching a DroneBot video about touch sensitive keypads.

The device is a numeric keypad built into a shield with stackable header already soldered on.   The packaging says it’s a Maplins device but it says LinkSprite Touch Shield on the actual device. I’ve attached links to the LinkSprite an SparkFun sites below.

I cannot find a Maplin link for this bug I did find one for LinkSprite.  Sadly all the links to drivers and sketches are dead.  I have emailed LinkSprite but so far there has been no reply.

The packaging just says it is an MPR121 IC.  There is a very small pamphlet with it that calls it an N93DG.  It explains what it does and the pin connections used. But very little else

I found an almost identical item from SparkFun.  I managed to get mine working in a basic manner using the information from SparkFun and Github.

There are three pins used to add extra pads.  I have followed the sketch format and got these pins to send ‘&’, ‘.’ and ‘-‘ when selected. Here’s where the fun begins 😁

if I touch the “extra” pins with my finger, or something conductive, it displays what I’ve programmed it to and the rest of the pad works properly too.  If I attach a wire to the pin, the wire becomes sensitive and displays what it should but now all the pads display the same thing, for example ‘&’

Does anyone have any knowledge or info on this device or any insight into how the extra pins work.

https://www.linksprite.com/wiki/index.php?title=Touch_Shield_for_Arduino

https://s3.amazonaws.com/linksprite/Shields/touch_shield/touchshield_sch.pdf

https://learn.sparkfun.com/tutorials/mpr121-hookup-guide/touch-shield

https://cdn.sparkfun.com/assets/1/f/c/0/9/524f198f757b7f96648b4568.pdf

Thanks in advance.

Regards 

Old Codger