- Fri Jan 06, 2017 12:34 am
#192796
I am using the SparkFun Soil Moisture Sensor (SEN-13322, https://www.sparkfun.com/products/13322) but am having trouble getting the device to recognize moisture *content*.
The sensor's VCC and GND pins are connected to 3.3v and ground respectively. Meanwhile, the SIG pin is connected to a MCP3008 which is taking my readings. The MCP3008 returns readings as a value between 0 and 1023 (e.g. as a fraction over 1023 of 3.3v), and works just fine for other sensors.
Here are the values I read for the SEN-13322 in different locations:
* Air-dry: ~0
* Half submerged in a glass of water: ~350
* Fully submerged in a glass of water: ~700
* Half submerged in soil that hasn't been watered in two weeks: ~350
* Fully submerged in soil that hasn't been watered in two weeks: ~700
* Half submerged in freshly watered soil: ~350
* Fully submerged in freshly watered soil: ~700
In other words, the sensor doesn't seem to be reading water *content*, instead it seems to be reading water *level*. Is this the intended behaviour of the sensor?
If so, I seem to have been mislead in the function of this sensor. I'm also wondering why this sensor is being showcased as triggering a watering device when my own tests show that it'll return a saturated value even in 2-week dry soil.
The sensor's VCC and GND pins are connected to 3.3v and ground respectively. Meanwhile, the SIG pin is connected to a MCP3008 which is taking my readings. The MCP3008 returns readings as a value between 0 and 1023 (e.g. as a fraction over 1023 of 3.3v), and works just fine for other sensors.
Here are the values I read for the SEN-13322 in different locations:
* Air-dry: ~0
* Half submerged in a glass of water: ~350
* Fully submerged in a glass of water: ~700
* Half submerged in soil that hasn't been watered in two weeks: ~350
* Fully submerged in soil that hasn't been watered in two weeks: ~700
* Half submerged in freshly watered soil: ~350
* Fully submerged in freshly watered soil: ~700
In other words, the sensor doesn't seem to be reading water *content*, instead it seems to be reading water *level*. Is this the intended behaviour of the sensor?
If so, I seem to have been mislead in the function of this sensor. I'm also wondering why this sensor is being showcased as triggering a watering device when my own tests show that it'll return a saturated value even in 2-week dry soil.