SI1141(2011) 데이터 시트보기 (PDF) - Silicon Laboratories

부품명

상세내역

일치하는 목록

SI1141
(Rev.:2011)

PROXIMITY/AMBIENT LIGHT SENSOR IC WITH I2C INTERFACE

Silicon Laboratories 

Si1141/42/43

4. Programming Guide

4.1. Command and Response Structure

All Si1141/42/43 I2C registers (except writes to the COMMAND register) are read or written without waking up the

internal sequencer. A complete list of the I2C registers can be found in "4.5. I2C Registers" on page 25. In addition

to the I2C Registers, RAM parameters are memory locations maintained by the internal sequencer. These RAM

Parameters are accessible through a Command Protocol (see "4.6. Parameter RAM" on page 45). A complete list

of the RAM Parameters can be found in "4.6. Parameter RAM" on page 45.

The Si1141/42/43 can operate either in Forced Measurement or Autonomous Mode. When in Forced

Measurement mode, the Si1141/42/43 does not make any measurements unless the host specifically requests the

Si1141/42/43 to do so via specific commands (refer to the Section 3.2). The CHLIST parameter needs to be written

so that the Si1141/42/43 would know which measurements to make. The parameter MEAS_RATE, when zero,

places the internal sequencer in Forced Measurement mode. When in Forced Measurement mode, the internal

sequencer wakes up only when the host writes to the COMMAND register. The power consumption is lowest in

Forced Measurement mode (MEAS_RATE = 0).

The Si1141/42/43 operates in Autonomous Operation mode when MEAS_RATE is non-zero. The MEAS_RATE

represents the time interval at which the Si1141/42/43 wakes up periodically. Once the internal sequencer has

awoken, the sequencer manages an internal PS Counter and ALS Counter based on the PS_RATE and

ALS_RATE registers.

When the internal PS counter has expired, up to three proximity measurements are made (PS1, PS2 and PS3)

depending on which measurements are enabled via the upper bits of the CHLIST Parameter. All three PS

measurements are performed, in sequence, beginning with the PS1 measurement channel. In the same way, when

the ALS counter has expired, up to three measurements are made (ALS_VIS, ALS_IR and AUX) depending on

which measurements are enabled via the upper bits of the CHLIST Parameter. All three measurements are made

in the following sequence: ALS_VIS, ALS_IR and AUX.

PS_RATE and ALS_RATE are normally non-zero. A value of zero in PS_RATE or ALS_RATE causes the internal

sequencer to never perform that measurement group. Typically, PS_RATE or ALS_RATE represents a value of

one. A value of one essentially states that the specific measurement group is made every time the device wakes

up.

It is possible for both the PS Counter and ALS Counter to both expire at the same time. When that occurs, the PS

measurements are performed before the ALS measurements. When all measurements have been made, the

internal sequencer goes back to sleep until next time, as dictated by the MEAS_RATE parameter.

The operation of the Si1141/42/43 can be described as two measurement groups bound by some common factors.

The PS Measurement group consists of the three PS measurements while the ALS Measurement group consists of

the Visible Light Ambient Measurement (ALS_VIS), the Infrared Light Ambient Measurement (ALS_IR) and the

Auxiliary measurement (AUX). Each measurement group has three measurements each. The Channel List

(CHLIST) parameter enables the specific measurements for that measurement grouping.

Each measurement (PS1, PS2, PS3, ALS_VIS, ALS_IR, AUX) are controlled through a combination of I2C

Register or Parameter RAM. Tables 5 to 7 below can be used summarize the properties and resources used for

each measurement.

16

Preliminary Rev. 0.5

Share Link: