AN3404 datasheet(23/30 Pages) STMICROELECTRONICS

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AN3404

Low power mode management by the STM8TL5x STMTouch Library

Doc ID 018847 Rev 3

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Average value targeted when there is no touch

The average value targeted when there is no touch is set in the

TSLPRM_KEY_TARGET_REFERENCE definition. This value defines how long the

acquisition lasts. If this value is set to 1000, the acquisition of a receiver set lasts

approximately 1000 times the ProxSense cycle length. The lower this value, the lower the

consumption but, the lower the key sensitivity.

7.1.2

LOW_POWER bit

The LOW_POWER bit is set if TSLPRM_PXS_LOW_POWER_MODE is defined as 1.

The firmware library detects if several acquisitions are launched successively. In this case,

the LOW_POWER bit is reset until the last acquisition is launched. This avoids having to

wait for the stabilization time at each acquisition.

7.1.3

Stabilization time

The stabilization time is defined by the TSLPRM_PXS_STAB definition. It can be set to:

●

LONG_STAB (default stabilization time) for 1.7 ms

●

MEDIUM_STAB for 500 µs

●

SHORT_STAB for 250 µs

7.1.4

Bias parameter

The bias parameter is defined by the TSLPRM_PXS_BIAS definition. It can be set to:

●

HIGH_BIAS for 10 µA (default bias)

●

MEDIUM_BIAS for 7.5 µA

●

LOW_BIAS for 5 µA

●

VERY_LOW_BIAS for 2.5 µA

Table 4.

ProxSense cycle length

TSLPRM_PXS_UP_LENGTH and

TSLPRM_PXS_PASS_LENGTH value

ProxSense cycle length (in HSI_PXS period)

410

518

634

766

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