STMPE16M31PX datasheet(49/75 Pages) STMICROELECTRONICS

49 / 75 page

STMPE16M31PX

Touch sensor controller

Doc ID 17058 Rev 2

49/75

13.2

Sensor resolution

The capacitive sensor hardware in the STMPE16M31PX devices has a sensitivity of 15 fF

and a range of 512 steps giving it a dynamic range of 7.5 pF.

The impedance reading is the output of an internal MAF (median averaging filter). As up to

16 samples are taken for each reading, the impedance reading is the sum of 16 of 9-bit

samples.

To allow maximum consistency, the 3 impedance readings are always 13-bit, whichever

MAF setting is used.

The touch variance (TVR) and enviromental variance (EVR) registers are specified in a 9-bit

format. For comparison with the impedances, the TVR and EVR would be internally shifted

4 bits up.

13.3

Auto-tuning

The capacitive sensor hardware in the STMPE16M31PX devices has a sensitivity of 15 fF

and a range of 512 steps giving it a dynamic range of 7.5 pF. This means that at any time,

the device is able to sense a change in capacitance up to 7.5 pF. When the channel

capacitance moves out of the 7.5 pF window, the auto tuning feature kicks in to ensure

proper sensing operation.

Obsolete

Product(s)

- Obsolete

Product(s)

STMPE16M31PX Fiches technique(PDF) 49 Page - STMicroelectronics