VD5377 datasheet(28/88 Pages) STMICROELECTRONICS

28 / 88 page

I/O description

VD5377

28/88

Doc ID 022952 Rev 2

5.3

MOTION

The MOTION pad is a 3.0 V digital I/O pad referenced to VTOP and can be configured

either as a push/pull output or open-drain. It combines the functions of motion pending flag

and power-on reset indicator (see Figure 14). The MOTION signal is driven low at power-up

and stays low until the internal MCU boot sequence is completed. Once the boot sequence

is completed the MOTION signal goes high and remains high until the device is configured

and enters the AUTOMATIC or MANUAL RUN state. Thereafter the level on the MOTION

pad depends on the MOTION pin polarity setting (register 0x5 SYSTEM_CONFIG bit 2).

Note:

In Powerdown, a 35 kOhm pull-down resistor is activated in the Motion pad. This may result

in leakage current in the external circuit. Also, in open-drain configuration, careful choice of

pull-up resistor is required to ensure the resultant intermediate voltage on the Motion pad

does not induce leakage current in the Motion input gate.

Figure 14. MOTION behavior at power-up

POR

MOTION

STATE

Power Up

SW STDBY

AUTO RUN or MANUAL RUN

MCU BOOT

Table 16. Control register for motion pin polarity

Addr

(Hex)

SIgnal name

Bit

Type

Default

(Hex)

Comment

SYSTEM_CONFIG

automatic_power_mode

PRW

Power mode scheme

0 = Manual

1 = Automatic

motion_pin_polarity

PRW

MOTION pin polarity (in non

IDLE system state)

0 = MOTION pin LOW when

motion detected

1 = MOTION pin HIGH when

motion detected

host_config_done

PRW

Bit needs to be set by host

when configured after power

up.

use_standby_pin

PRW

STANDBY pin is used as chip

select to enable I2C in AUTO

power mode and STANDBY pin

is used to wake up the

OSC/DVREG (in sleep states in

auto power mode).

0 = STANDBY pin not used

1 = STANDBY pin is used

system_state

7:5 RW

Legacy register - please use

system_state (0x91) instead.

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