After initialization process, the MPR121 is operational only after 1 minute or so. Reading touch registers will output zero and no interrupts are generated.
Our initialization procedure is as follows (pseudo):
1) set filters, from MHD Rising -> FDL Touched
Btw, the NHD Amount Touched, NCL Touched and FDL Touched we send = 0 since are completely undoccumented in your pdfs.
2) set thresholds as desired for all 12 elements
3) optionally set the AUTO-CONFIG registers (no difference, slow startup in either case)
4) set CDC, CDT and ECR
The following questions appears:
- why is this happening?
- how can we detect initialization is complete, we have a keypad designed which is not operational in first minute