I'm working with this IC (MPR121) and I have developed it with PIC32. Problem is I can't get the enough sensitivity I need. I tried to modify:
-Electrode size and form.
-Even USL/TL/LSL following the right config.
I have worked before with Atmel capacitive buttons driver, even Microchip, and, better or worse (I preffer Atmel) I can get over than 3mm (even higher). With MPR121 I cant get 1mm. If I push with much force, it detects (not always), but is impossible to get a correct capacitive effect.
I'm losing something? (about SW /HW MPR121). Is there a limitation in this IC?
I think the electrode/PCB HW is working perfect because I have tested this MPR121 with some prototypes that are working perfect with other drivers. Anyway, I have checked MPR121 with some specific electrodes to this task.
Thanks a lot.