Has anyone made a custom input for Vegetronix VH400?


Just checking to see if anyone has made a custom input for the Vegetronix VH400, it’s read with an ADC but has a custom conversion to get the more linear.

Voltage Range Equation
0 to 1.1V VWC= 10*V-1
1.1V to 1.3V VWC= 25*V- 17.5
1.3V to 1.82V VWC= 48.08*V- 47.5
1.82V to 2.2V VWC= 26.32*V- 7.89




this sensor is very temperature dependant so you need a correction coefficient like:

def VH400_TempCorr(temp,u_vh400) :


   return u_vh400+(temp-20)*coeff20


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Thank you, much arppreciated

That looks like a pretty nice soil moisture meter. It lists on their website it is in the category of “low-cost” soil moisture sensors, but their lowest priced model is priced $42, not exactly a sensor I’d call low-cost. Regardless, I am curious if it actually overcomes the issues of other soil moisture sensors, as they claim.

This is the first I’ve heard of this sensor, but it should be fairly simple to interface with an ADC and develop an Input to acquire a measurement and apply a calculation based on the voltage value and temperature.

Hi Kyle,

I agree with the price works out to about $70NZ each, but they seem to go up pretty steeply price wise from here with other products. Have you had any sucess with any other soil moisture sensors? I have a few of them running on Arduino board and they seem pretty reliable. eg. take the sensor out put it back very similar reading. I’ve tried lots of Aliexpress type sensors they either corrode very quickly or readings seem very random.

I’ve only ever played with Arduino level C programming and not python. I can get to the point of connecting a ADS1115 to the Raspberry Pi and read the values of that. Would I copy one of your existing inputs that deals with ADS1115 and try to manipulate the C code to work in Python?