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  • Author Author: Jan Cumps
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ROHM Colour Sensor BH1749NUC - part 2: Other Firmware Libraries

Jan Cumps

I'm Road Testing the Rohm SensorShield-EVK-003 (Arduino Compatible) and the sensors that come with it.

In this post, alternative libraries for the Colour Sensor BH1749NUCBH1749NUC.

 

image

 

This is a follow up on ROHM Colour Sensor BH1749NUC. I was planning to extend the ROHM example with support for interrupt.

During my research I stumbled over two alternative libraries, one of which has dona the legwork already.

 

FaBo library

 

FaBo is an online shop that designs and sells sensor and other breakout boards (called Bricks).

They may do other things but the website is in (I think) Japanese.

The library provided has similar functionality as the ROHM one. The OO flavour is a little different but the same functionality is supported.

The example shows how to play with the gain for the IR and RGB range (the SparkFun library below does that too).

https://github.com/FaBoPlatform/FaBoColor-BH1749NUC-Library.

 

SparkFun Library

 

SparkFun made a library for their experimental and indeterminately out of stock RGB Sensor (Qwiic).

They have a concept called SparkX, where they try out new products, often with a rough edge.

 

Even though the module is experimental, their library and examples are the most advanced that I can find.

https://github.com/sparkfun/SparkFun_BH1749NUC_Arduino_Library/blob/master/examples/Example3_NewDataInterrupt/Example3_NewDataInterrupt.ino

 

I will not elaborate here, please check for yourself.

It's worth it: they have a data ready interrupt and a threshold interrupt (I talked about the latter in my previous post) example.

 

Heads-up: I haven't been able to run that threshold trigger example successfully yet. The normal polling one works right out of the box. Investigating ...

To make the example work, you have to help the interrupt pin a little.


In this explanation, I assume that you use the unchanged example from Adafruit. and that you dock the colour sensor evaluation board in i2c dock #1 as per instructions. The Adafruit code listens to D2 for Interrupt 0;

Also as per instructions, put a jumper on INTR1 on connector J3. This ties that pin to Arduino D2, so that the Arduino INT0 can be used.

But that pin - going to the volatge translator IC - needs a pull-up. To get that extra omph to help the signal pull up, you can jump INT1 on connector J16. That adds a pull-up resistor.

 

image

The Adafruit example works just fine then. When the red component of your light drops below the low threshold or jumps above the high threshold, the serial monitor show measurements. If the red component is between both thresholds, nothing happens.

 

  // Set high and low thresholds. If red value is >HIGH_THRESHOLD or <LOW_THRESHOLD, then an
  // interrupt will be triggered
  //rgb.setThresholdHigh(HIGH_THRESHOLD);
  //rgb.setThresholdLow(LOW_THRESHOLD);
  // Alternatively, setThresholds can be used to set high and low thresholds simultaneously
  rgb.setThresholds(LOW_THRESHOLD, HIGH_THRESHOLD);

 

image

 

It's easier to dock the board in i2c location #3 and put the jumper of J3 on INTR3, the jumper of J16 on INT3. That way the interrupt pin is not also connected to D0 on the Arduino (see this post to check how things are interconnected on this shield). You have a pure situation where only D2 is connected to the interrupt pin.

 

 

 

 

 

The interrup

 

Related blog
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ROHM Magnetometer Sensor BM1422AGMV
ROHM Hall Sensor BD7411G
ROHM Colour Sensor BH1749NUC
ROHM Colour Sensor BH1749NUC - part 2: Other Firmware Libraries
ROHM Ambient Light and Proximity Sensor RPR-0521RS
Parents Comment Children
  • in reply to Jan Cumps

    Until now no success with the SparkFun trigger. I'm checking on my scope to capture the falling edge of the interrupt pin when the red light goes below 50 or above 500.

    It does not happen ...

     

    I know that the interrupt handler works, because I can manually force one on D2 with a wire attached to ground, but with the sensor it does not seem to work yet ...

  • in reply to Jan Cumps

    ... I just learned - by beeping the SensorShield out, how the interrupt jumpers work.

    You have to set the jumper depending on the docking position where you plugged in the sensor.

    That pin is then linked to Arduino D2.

    If you use the INT?x pi, the voltage is translated. If you use the INT?, it's a direct connection to pin D2.

    Trying again now ...

     

    edit: J3 ties to D2, J1 ties to D3 of the Arduino.

    D1 on the interrupt selector is pin 3 of J11, D2 is pin 4, with the voltage translator in between.

    D1 on that J11 is also directly connected to arduino D0, and D2 to Arduino D1.

     

    A bit of a bummah, because D0 (and also D1) of the arduino UNO is hard to drive, with the USB part attached to it and pulling that pin high via a 1K resistor...

  • in reply to Jan Cumps

    I was just thinking that might be it and to use the continuity tester on my DMM to test that myself.  You are flying through these sensors!  I should be ready to publish something on the RoadTest myself soon. 

  • in reply to fmilburn

    I found a way to make the interrupt work, after mapping the pins of the SensorShield out (ROHM SensorShield V3: Map PINS to Arduino).

    It's

    1: depending on where you dock it. I docked it at i2c dock #1.

    2:Then, as described in the instructions, also put jumper on conncetor J1, Pin INTR1.

    3: also pull J16 INT1 high by placing a jumper.

     

    A bad foto tells a few words:

    image