PixArt Imaging Inc.
ADBS-A350 Optical Finger Navigation
Power on Reset (POR) During Power Cycling
t
is the power supply (VDD) rise time specification
A read to event register is required to determine the
specific event that toggles the interrupt for user to act
upon.
VRT
for a valid power on reset to happen when the sensor is
powered up from 0V to VDD. At condition whereby the
VDD of the sensor is cycled from VDD to 0 V and then to
VDD again, the two parameters that govern a valid power
The EVENT_INT will be reset after the user responds to it
by reading the respective event status register:
on reset are v
and t
Refer to timing diagram below.
OFF
OFF.
FPD – reading FPD_STATUS register (0x7a)
Soft Click – reading SC_STATUS register (0x7f)
Button – reading BUTTON_STATUS register (0x12)
VDD
Motion – reading DELTA_X and DELTA_Y registers until
0V
motion are cleared.
tVRT
GPIO Pin
The GPIO pin is a level-sensitive input/ output that can be
used as
VDD
FPD output – to display FPD status
Pulse Width Modulated (PWM) output – to control LED
driver to enable illumination feature in a product eg
mobile phone
vOFF
0V
tOFF
tVRT
Dome/ Button click input – can be connected to a
dome switch that provides an input to the sensor
and when a click is detected, sensor can respond by
triggering button interrupt and channel the interrupt
status through EVENT pin.
Figure 8. Power on Reset during power cycling
Power management modes
The ADBS-A350 has three power-saving modes. Each
mode has a different motion detection period, affecting
response time to sensor motion (Response Time). The
sensor automatically changes to the appropriate mode,
depending on the time since the last reported motion
(Downshift Time). The parameters of each mode are
shown in the following table.
Refer to A350 Firmware Design Guide for more details and
settings of registers for these features.
LED Mode
For power savings, the LED will not be continuously on.
ADBS-A350 will flash the LED only when needed.
Mode
Response Time
(nominal)
Downshift Time
(nominal)
I/O Pin Status Test
Rest 1
Rest 2
Rest 3
19.5 ms
96 ms
250 ms
9.5 s
This feature allows the user to verify the connectivity and
the state of the I/O pin.
482 ms
582 s
To run the test for input pins such as GPIO, SHUTDOWN,
NRST and IO_SELECT, first enable the PAD_Chk_On bit (or
bit-1)ofOFN_ENGINE2(0x61)register.Thenwriteanyvalue
to PAD_STATUS (0x31) register to start the test. Wait for ap-
proximately 12us before reading the actual pin status and
PAD_STATUS register. The test will be considered a PASS to
indicate the sensor is responding accordingly if the actual
pin status matches PAD_STATUS register content. Refer to
the table below for I/O pin status definition.
EVENT_INT Pin
The Event_Int pin is a level-sensitive interrupt output that
is used to trigger the host micro-controller when one of
these events occurs:
FPD – A change in finger state (finger on to finger off
and vice versa) is detected
Soft Click – Soft Click is detected
Button – Mechanical button is asserted or de-asserted
Motion – Motion delta is present.
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PixArt Imaging Inc.
E-mail: fae_service@pixart.com.tw
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