capacitive soil moisture sensor v1.2 again

[Dick60]

I tried to get this device working on an esp8266 and an esp32 (preferable) but did not had any sucees in it. I use the ESPEasy_binaries27042022 and connected the soil moister sensor to the 5v, Gnd and an Analog port (in my case on the esp32 pen nr 25 (ADC2-ch8). Also put the sensor in some soil. No messurement are visible. I did not activate the oversampling or the calibration. I tries to put an formula in it ((%value%-350)/(800-350)*100) as mentioned in an old post but also no result. Any suggestions to give this project a push?

[TD-er]

First, see: https://espeasy.readthedocs.io/en/lates ... ty-and-adc
Do not use an analog input connected to ADC2 when you also use WiFi.

Second, what resistors do you use to get the measured voltage between 0 and 3V3?
See: https://randomnerdtutorials.com/esp32-a ... duino-ide/

[Dick60]

I switched to the esp8266 because it is more convinient for me to test the sensor. I use A0 port and connected a 10k potmeter to 3.3vplus, to the GND and in the middle to A0. Als paralel to the potmeter I connected the Sensor. Turning the Potmeter I see a change in messurments but putting the sensor in the wet soil, no difference is messured. Any idea?

[TD-er]

I assume it is similar to this one:



Are you sure about the connected pins?
Can you measure a voltage over the analog output pin on the sensor when keeping it dry and putting it in wet soil (or a wet paper towel wrapped around the sensor)

[Dick60]

it is like tris one

[Ton_vN]

@Dick60,

In your message of 17:02, I read

Als paralel to the potmeter I connected the Sensor. Turning the Potmeter I see a change in messurments but putting the sensor in the wet soil, no difference is messured.

Don't parallel connect, because then you only see the potmeter which probably is 'more powerful' than the sensor-output!
It should be:
either potmeter,
or sensor, like in your latest message.

[Dick60]

I tested like my last picture, with ONLY the Sensor. In that case I see no difference between the messurements in the wet soil and the dry soil. It is a nem sensor and tested also a second sensor withthe sam result. I think it isnt working with the ESPeasy firmware.

[Ath]

Turning the Potmeter I see a change in messurments

I think it isnt working with the ESPeasy firmware.

Your first statement proves that your second statement is incorrect.

I'd have a good look at that sensor again, and use a multi-meter to see if the output voltage actually changes between wet and dry measurement.

[Dick60]

I did some mesurements on the sensor and the spare sensor. I used my multimeter and connected the senser to 5v and mut my multimeter on the data line of the sensor and the plus (later the gnd) but there is no difference between wet soil and dry soil. No voltage change discovered during these mesurements.

[TD-er]

What voltage do you measure (between out and GND) ?
Maybe it improves when you add a small resistor over the output and GND?
Not sure how the internal circuit does work, but typically they charge a capacitor. But if it doesn't get discharged it will slowly increase to the charge voltage (e.g. 5V) without any significant change in voltage due to soil humidity changes.

[Dick60]

unfortunately no better news, also with a small resister, no change between the two messurments. I will try an external power source instead of the 5v of my ESP8266.

[manjh]

I got this to work, hardware is straightforward.
But I am struggling with the formula....

My upper value (dry) is 419.
Lower value (immersed in water) is 53.
Meaured value is somewhere in between.

I have been breaking my head on how to map the measured value into a moisture percentage..... any ideas?

[manjh]

I got this to work, hardware is straightforward.
But I am struggling with the formula....

My upper value (dry) is 419.
Lower value (immersed in water) is 53.
Meaured value is somewhere in between.

I have been breaking my head on how to map the measured value into a moisture percentage..... any ideas?

I think I found the formula :
(419-%value%)/(419-53)*100
Where 419 is the upper value (dry) and 53 the lower (immersed).

[Haldi_2]

I have been breaking my head on how to map the measured value into a moisture percentage..... any ideas?

Uhm... it's an Analog input right?
Just use Two Point Calibartion?

del.jpg (24.08 KiB) Viewed 488 times

[TD-er]

I don't think it is a linear relation between voltage and what you're measuring.
The formula suggested in the post before yours can be entered in the formula field at the bottom of the task.

[manjh]

I have been breaking my head on how to map the measured value into a moisture percentage..... any ideas?

Uhm... it's an Analog input right?
Just use Two Point Calibartion?
del.jpg

Where can this be entered?