BH1750FVI

Technical Note

5/17

www.rohm.com

2009.04- Rev.B

© 2009 ROHM Co., Ltd. All rights reserved.

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Instruction Set Architecture

Instruction

Opecode

Comments

Power Down

0000_0000

No active state.

Power On

0000_0001

Waiting for measurement command.

Reset

0000_0111

Reset Data register value. Reset command is not acceptable in

Power Down mode.

Continuously H-Resolution Mode

0001_0000

Start measurement at 1lx resolution.

Measurement Time is typically 120ms.

Continuously H-Resolution Mode2

0001_0001

Start measurement at 0.5lx resolution.

Measurement Time is typically 120ms.

Continuously L-Resolution Mode

0001_0011

Start measurement at 4lx resolution.

Measurement Time is typically 16ms.

One Time H-Resolution Mode

0010_0000

Start measurement at 1lx resolution.

Measurement Time is typically 120ms.

It is automatically set to Power Down mode after measurement.

One Time H-Resolution Mode2

0010_0001

Start measurement at 0.5lx resolution.

Measurement Time is typically 120ms.

It is automatically set to Power Down mode after measurement.

One Time L-Resolution Mode

0010_0011

Start measurement at 4lx resolution.

Measurement Time is typically 16ms.

It is automatically set to Power Down mode after measurement.

Change Measurement time

( High bit )

01000_MT[7,6,5]

Change measurement time.

※

Please refer "adjust measurement result for influence of optical window."

Change Masurement time

( Low bit )

011_MT[4,3,2,1,0]

Change measurement time.

※

Please refer "adjust measurement result for influence of optical window."

※

Don't input the other opecode.

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Measurement mode explanation

Measurement Mode

Measurement Time.

Resolurtion

H-resolution Mode2

Typ. 120ms.

0.5 lx

H-Resolution Mode

Typ. 120ms.

1 lx.

L-Resolution Mode

Typ. 16ms.

4 lx.

We recommend to use H-Resolution Mode.

Measurement time ( integration time ) of H-Resolution Mode is so long that some kind of noise( including in 50Hz / 60Hz

noise ) is rejected. And H-Resolution Mode is 1 l x resolution so that it is suitable for darkness ( less than 10 lx )

H-resolution mode2 is also suitable to detect for darkness.

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Explanation of Asynchronous reset and Reset command "0000_0111"

1) Asynchronous reset

All registers are reset. It is necessary on power supply sequence. Please refer "Timing chart for VCC and DVI power

supply sequence" in this page. It is power down mode during DVI = 'L'.

2) Reset command

Reset command is for only reset Illuminance data register. ( reset value is '0' ) It is not necessary even power supply

sequence.It is used for removing previous measurement result. This command is not working in power down mode, so

that please set the power on mode before input this command.