I was experimenting with the MPR121 for proximity, and have managed to get a basic demo up and running. I am getting the distance as 2-3 cm, is there anyway we can increase the distance?
Some suggestions with the register values might help, as well as suggestions for electrode material ? I am currently using aluminium foil as a test.
The current configuration of the registers I am using is :
// prox sensing rising
MaxHalfDeltaRising, 0x3F
NoiseHalfDeltaAmountR, 0x5F
NoiseCountLimitRising, 0x04
FilterDelayLimitR, 0x00);
// prox sensing falling
MHDF, 0x01
NHDAF, 0x01
NCLF, 0x1F
NDLF, 0x04
// Section D - Set the touch filter Configuration
FIL_CFG, 0x24
I have disabled auto config and auto reconfig, but here were the original settings
ElectrodeConfig, 0x30
You can increase the distance by increasing the charge/discharge current and more importantly, increasing the size of the electrode.
Michael Steffen
Senior Field Applications Engineer
Freescale Semiconductor
Cell 815-519-1567