Hubitat with Homemade Temperature, Humidity, Pressure and Light sensor

Why Hubitat Elevation Here's a cool thing I did!
162

If you look inside the source code the Environment Sensor Device Driver, you will find the following section of code that makes use of the illuminance adjustment factor.

private def createIlluminanceEvent(int illum)
{
    def result = [:]
    result.name = "illuminance"
    result.translatable = true
    result.unit = "Lux"
    
    if(!illumAdj ||  illumAdj < 1.0)
    {
        if(ilumm == 0)
        {
            result.value = 0.0
        }
        else
        {
            result.value = 10.0 ** (((double) illum / 10000.0) -1.0)
        }
        
    	result.value = result.value.round(2)  
    }
    else
    {
        result.value = ((double)illum / illumAdj).toInteger()
    }
    
    result.descriptionText = "{{ device.displayName }} illuminance was $result.value"
    return result
}

I have noticed the same problem in Hubitat with preference descriptions as well.

163

Yeah, that form is a no go, always use ${variable}

1 Like
164

When I saw that syntax in Iman's code I was curious about it as well. Thanks for the confirmation.

165

I also have a driver I wrote for this device, its not option complete, I'll post it in our public repo tomorrow.

3 Likes
166

@ogiewon,

I see, adding a factor >= 1 complete changes the transfer function. Would be nice to know what the sensor was. I made a short attempt to find one that looks like the hardware without luck.

John

167

I believe he is using a TEMT6000 sensor. I would have thought he might have used an I2C sensor, since the BME280 is already I2C (unless he's using SPI?)

168

I believe from his messages he was going for low cost. However the BME is not inexpensive but perhaps still better than the alternatives.

So with the TEMT6000 sensor, the scale factor is not valid.

169

The sensor I use for light is TEMT60000 as mentioned by @ogiewon

In that datasheet, you will see a graph of how to convert current to lux value. The typical wiring diagram is to install 10K resistor at the emitter. My implementation is simply just read the ADC and use the ohm law to get the current. Then, I am using "Figure 1. Collector Light Current vs. Illuminance" to get the lux.

The BME280 is an expensive sensor. It is about $6 to $7 per sensor if you buy 10 unit or less in US. I do not think that there is a cheaper sensor than BME280. I do not want to skimp on sensor. I look somewhere else where I can get low cost to compensate for the sensor cost.

170

Please see the "MeasuredValue" as in this specification. The scale factor is just a number that divide the "MeasuredValue". They are not in Lux unit anymore. If you clear the factor setting in the preference, the DTH will go back doing the inverse calculation.

171

Hi @iharyadi,

Now I'm curious and confused. Reading the Zigbee spec you linked it stated that the specification was for a "library", and it when on to state the transfer equation. Is that saying the library does the calculation? If not then its not clear why they go into so much detail.

John

172

It's up to the driver to take any raw data and convert it per these specs.

173

I would have thought that. But then why does the spec go into so much detail?

174

Zigbee Cluster Libarary (aka ZCL) is not a library in the sense of library in c++ code.. I was confused as well when I looked into the document when I started learning about it.

ZCL is just specification. If you want to be compliant to do Illuminance Measurement, you have to send the value as in 4.2.2.2.1 MeasuredValue Attribute. ZCL is more like an RFC. It will tell you a bit in regard to their reasoning. "Where 1 lx <= Illuminance <=3.576 Mlx, corresponding to a MeasuredValue in the range 1 to 0xfffe".

175

@mike.maxwell any update on this driver?

thank you.

176

I'll try to get it cleaned up tomorrow

177

and released? :slight_smile:

178

yup:

5 Likes
179

@mike.maxwell, thank you so much.

1 Like
180

I just want to update my progress with this project. Having shared a few modules with community members here I started to get feedbacks. The most intriguing feedback is about being able to extend or expand the sensor.

In the past few weeks, I went back to drawing board and look for solution to accommodate the above. Here is what I come up with.

On the hardware side, the new board will expose analog, digital input and output pin. Access to 5 volt and 3.3 volt are also available.

IMG_20180818_225517
IMG_20180818_225517.jpg2138×2851 1.94 MB

On the firmware side, those pins are abstract out as Zigbee Basic Analog Input, Binary Input/ Output cluster. These clusters are accessible through Hubitat DH.

In layman terms, we will be able to access information from the sensors connected to the pin without needing to understand the lower level complexity of Zigbee protocol and Firmware development. Our DH will be getting one or zero from your digital sensor. Or, DH will be able to read your sensor Analog output in volt. Your DH can drive a thing using its digital output pin.

I have an example in the following video where I connect a moisture sensor, flame sensor and a relay.

I am very excited about this feature. I will have a few to share once I sort out and test them on my end. I will also share my experience connecting them with other sensors. I have motion sensor, Gas leak sensor , sound sensor in the queue.

Finally, this is still a Temperature, Humidity, Pressure and Light Sensor. It is still a Zigbee repeater to help with your Zigbee network. It is also help with your Xiaomi devices.

5 Likes
181

this is really looking cooler and cooler.

couple of questions:

  1. is it possible to add the sound sensor onboard? just having temperature, humidity, pressure, light and sound all onboard would be enormously helpful is this all-in-one compact unit.
  2. once you add motion sensor support do you plan to also add case / mounting etc? without that placing these to capture motion will be a bit trickier - no?

thank you.

1 Like