Tested with the Robotdyn 16 Keys I2C Capacitive Touch TTP229 Module Robotdyn Capacitive Touch Disk Pad. uint16_t readKeys() - Read data from TTP229 and return states of 16 keys in bitmap ...
The PCB must be mounted floated, otherwise key presses don't work reliable. Connect pins 3 and 4 on connector P1 for 16-pin button mode. Smaller keypads with less pins may work, but are not tested.