STMPE321 Capacitive touch module registers
Doc ID 15791 Rev 3 25/40
FEATURE_SELECT Feature select
Address: 0x20
Type: R/W
Reset: 0x04
Description: Controls AFS (advanced filtering system and second level filtering feature)
ETC_WAIT Wait time setting
Address: 0x21
Type: R/W
Reset: 0x27
Description: Sets the wait time between the calibration and the last button touch
76543 2 1 0
RESERVED AFS[1:0] Filter EN
[7:3] RESERVED
[2:1] AFS[1:0]:
“00’: reserved
“01’ AFS mode 1 (only 1 strongest key)
‘10’: AFS mode 2 (all keys that are above threshold)
‘11’: AFS mode 3 (the 2 strongest keys)
[0] Filter EN:
Write '1' to enable filter
76543 2 1 0
ETC_WAIT[7:0]
[7:0] ETC_WAIT[7:0]:
ETC wait time = ETC_Wait[7:0] *64 + sensor clock period
A "non-touch" condition must persist for this wait time, before an ETC operation is carried out
Range: 5 mS - 20 s
