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OPT3002: Configuration of OPT3002

Gaurav Aggarwal
Expert 2935 points
Part Number: OPT3002
Other Parts Discussed in Thread: , OPT3004

Hi,

In our application, we are using OPT3002 sensor to control the brightness of LCD as well as Bezel keys on the basis of day and night. We have implemented this sensor with Sitara AM335x processor. I am working from scratch on this sensor. 

Can you give me some clarity on the values of result register, low limit register and high limit register. Currently, I don't know what values I have to give and on what basis.

On what basis of the value of result register I should control the brightness of LCD and Bezel keys.

Please provide me any example if you have.

Can I evaluate performance of this sensor implemented on custom board through OPT3002EVM software.

Regards,

Gaurav

  • 0
    TI__Mastermind 25815 points

    Hi Gaurav,

    Are you asking about how to define an optical power value using the result, low, and high registers? If you refer to section 7.6.1.1.1 Result Register (address = 00h) in the datasheet and see equation (2) on that page it shows how to convert exponent/mantissa to optical power.

    Why are you using OPT3002 over OPT3004? The reason I ask if that OPT3002 is a wide band sensor whereas OPT3004 mimics the human eye response. This is the reason OPT3004 output units are lux and OPT3002 output units are W/cm^2. Lux correlates directly with visible light intensity and is usually used for these types of display brightness adjustment. This link provides some common lux levels in the table that helps correlate with actual lighting levels. https://docs.microsoft.com/en-us/windows/win32/sensorsapi/understanding-and-interpreting-lux-values

    If you are wanting to use OPT3002 then we need to convert lux to W/cm^2. This requires assuming some properties of the incoming light spectrum. We also have a video series coming out soon that will cover this topic in more detail if you would need more info here.

    You can wire the EVM USB board to your custom board through I2C. You just need to either disconnect the existing opt3002 on the EVM or change it's address so you don't get an I2C address conflict.

    The EVM GUI has a simulated birghtness dimmer demo - not sure if this helps you?

    Best,

    Alex

  • 0 in reply to Alex Bhandari-Young
    Expert 2935 points

    Hi Alex,

    Thanks for your answer. We don't want human eye response in our application that's why we use OPT3002.

    If I required any information further, I'll let you know.

    Regards,

    Gaurav