Recommendation for external light sensor


#1

We would need for a POC to read light level / luminous flux with good accuracy and high frequency (around 100 times / sec). Would you know of any appropriate external light sensor that could be attached to and used with the MongoH Red board? We are rather novice with the MangoH red and we’d appreciate any hint. Thanks.


#2

mangOH Yellow prototypes contain an OPT3002 I2C light sensor. The datasheet says that it takes either 100 ms or 800 ms to perform the measurement, so I think the maximum it will do is 10 times per second based on the 100 ms measurement time. The quality of the result is reduced compared to the 800 ms measurement time. Maybe there are other sensors that are better suited for your application. Can you share why you have to sample the light level at such a high frequency?


#3

Thanks @dfrey. The use case is about capturing a light level profile along a track, the data being captured from a fast vehicle (speed over 200 km/s). We’d like at least one data point per meter.


#4

At this point we have not investigated that data rate. As a note, youvshould look for a sensor with a SPI interface and not i2c


#5

really?!?!
:open_mouth:

That’s going on for 100 times the speed of sound!
:open_mouth:

Sounds like rather a specialist application!


#6

Ok, you got me, @awneil. That was 200 km/h. Sorry for the confusion. That is fast but not as fast as sound :wink:


#7

Thanks @asyal. I’ll have a look at a sensor with SPI interface. I guess I can search for sensors which can be attached to a RasperryPi – as far as I understand correctly, they can also be used with the MangoH Red board.


#8

Raspberry Pi - like mangOH - really doesn’t know or care anything about the sensor: it just provides a set of standard interfaces.

So you just need to find a sensor with an interface that the mangOH - or Raspberry Pi - supports.

Both Raspberry Pi and mangOH support the common interfaces:

  • SPI
  • I2C
  • UART

mangOH also has analogue inputs, and there are IoT cards for others such as CAN …