I have noticed that the following breakouts have LEDs that you can turn on or off. I have no idea what they are for, or when they should be on or off? Anybody have any insight into this?
LTR-559 Light & Proximity Sensor Breakout
BH1745 Luminance and Colour Sensor Breakout
AS7343 14-Channel Multi-Spectral Sensor Breakout
I have a couple of LTR-559 being used as light sensors for auto brightness on LED matrixes. LED’s off. I’m guessing they are more for the proximity function?
I’m guessing on the BH1745, turning them on lets you measure the color of the reflected light? IE the color of the surface of the object in front of the sensor. I have one setup to measure the background light, LEDs are off. An ambient light sensor if you will.
I do have an AS7343 ordered an on the way. This one is the one that picked my interest into what the LEDs are for?
Having worked as a performance electrician (lighting and sound) in a former life. I find light to be a fascinating thing. I have many of the components and breakouts you mention.
The shortest possible answer is that the onboard LED’s provide illumination.
A less obtuse response would be, that they provide a controlled level of illumination for accurate measurements of close up objects. They are colour balanced to a certain colour temperature expressed in Kelvin. In certain use case scenarios, say for example on a production line QA. The LED’s will ensure a uniform reading of the item being measured. Say the colour of a fluid, or a part. In a measured way. In general usage the LED’s wouldn’t be needed.
I have the LRT559, the BH1745 and the AS7262 in everyday usage. I could share some of the data output from them, if you’re interested.
I saw the AS7343 breakout and decided that I wouldn’t need one, the AS7262 more then meets my needs.
I don’t believe that the LTR559 has onboard LED’s, there’s a couple of surface mount resistors that could easily be mistaken for them though.
Yes you are correct, the LTR-559 doesn’t have any LED’s. I use these for auto brightness on my Galactic Unicorn and i75W LED matrix.
Right now I’m tinkering with a BH1745. My original plan was for ambient lighting. That’s not working out so well so far. I’ll be starting a dedicated thread on that in the next day or two.
Don’t have the AS7343 just yet. Hopefully next week some time.
I have the basic Enviro’s in every room, which have the LTR559 on board. Purley to assess and measure the available levels of light around my home. An Enviro+ with the PM sensor in the hallway. Upgraded a while back they’re now all all running on Zero2W’s. Finally managed to snag some after the chip crunch.
I have also built and coded another “enviro” board (Just a ZeroW with a mini BOG hat) for the north end of my bedroom. Just a BME280 and a LTR559. The same as the Enviro basic. Just for the learning from it.
Another sensor cluster in my lounge on a Pi4, which measures air quality and more in depth light data. Running SCD41, SGP30, MICS6814 for air quality. And the LTR559, BH1745 and the AS7262 for the light sensing.
I have also made a daylight sensor, for upstairs. It’s south facing so ideal for that. (Also just a ZeroW with a mini BOG hat) using the LTR559 and the BH1745. Have pondered putting an AS7262 on that as well, never found the time.
They are running my own code, not the vendor provided. To better meet my own specific needs. The displays aren’t used as they all MQTT into a homeassistant instance, which is then archived into an influxDB database. Where it can then be analysed and graphed in a more focused way using grafana.
What started out as a thing to tinker with and learn python coding, that became something of a hobby. I’m sure that’s relatable!
Interesting use of the LTR’s for auto brightness on the matrixes. I wouldn’t have thought of that. Do the Unicorns not have a light sensor built in?
Most artificial domestic lighting is higher in red content. Where as sunlight is higher in green and blue. So the BH1745 could be coded to tune domestic smart lighting for a uniform light in a room perhaps? Once you have the measurement capture sorted, it could be done. I asses your Python-fu as being superior to mine, I’d be interested in what roles you find for your sensors. Screenies below of just homeassistant. I’ll happily provide some of the processed grafana stuff if your interested. (I didn’t want to flood the thread with lots of screen grabs) Unknown if you use homeassistant, if not, you may find it interesting. It can run quite happily on a Pi.
Another ops moment, the Galactic Unicorn does have a LUX sensor.
Remember this.
On devices with no built in LUX sensor I used the LTR-599. My Interstate 75 w for example.
I have an outdoor weather station I’ve been tinkering with on and off. I have a VEML6075 to measure UV light so I can and then calculate the UV index. The AS7374 is going to be paired with that for more light measuring.
I have many Enviro based cloned builds. Pi and Pico Based. Nothing saved to the cloud of even logged to a file. I just look at the LCD to see what’s happening at the moment. That will likely change once I finally get my outdoor weather station up and running. I have the wind and rain sensors. ICP10125 for the pressure, BME280 for temp, and humidity. The two light sensors and an RV3028 for time keeping.
