STM8T143 datasheet(30/65 Pages) STMICROELECTRONICS

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Device operation

STM8T143

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DocID18315 Rev 6

6.2.2

Control mode

In Control mode, pin 8 can be used to halt the conversion or to freeze the reference (refer to

Section 5.4: Dynamic calibration (DYCAL)).

Halt conversion control mode

When the conversion is halted, the device is in low power consumption state (see device

electrical characteristics). In this state, the CTRL pin can be used to manage the power

consumption and/or control the acquisition to synchronize the sampling burst with external

events. This can be useful, for example, to halt acquisitions during noisy operations or to

synchronize an acquisition with the noise period.

When the CTRL pin is tied high for longer than tCTRL, the charge conversion cycle is halted,

once the current conversion has been completed. The device remains in this halt mode until

the CTRL line is tied low again. An automatic recalibration is performed directly after the

CTRL pin is released to compensate for any environmental changes which might have

occurred during the halt duration.

Reference freeze control mode

In this mode, the device reference evolution can be frozen according to the CTRL pin state.

The CTRL pin has precedence over the configuration bits selected for the reference freeze

timeout.

This function can be used to implement user-dedicated ECS management.

When the CTRL pin is tied high for longer than tCTRL, the filter is halted until this pin is tied

low.

If the host freezes the reference at device startup, the calibration starts after the reference

freeze is released.

Forced recalibration

Generating a pulse of trecal_control duration on the CTRL pin recalibrates the reference. The

ECS is reset, clearing the output state. Please refer to Table 16: General capacitive sensing

characteristics for trecal_control constraints.

If the signal value is outside its allowable range, the device forces an AET process event.

(refer to Section 5.1: Automatic electrode tuning (AET))

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