Recent Posts

1

SoilWatch 10 / Re: SoilWatch Life expectancy

« Last post by CyBaart on November 10, 2020, 07:15:03 AM »

Hi Piotr,

I think the takeaway from this is if you are putting together a monitor using soilwatch 10 sensors then for sensor longevity, use a 3V3 supply. Let’s face it, you can buy a couple of thousand ldo regulators for the cost of one sensor and most Arduinos/arduino-alikes have 3V3 anyway.

Steve.

2

SoilWatch 10 / Re: SoilWatch 10 monitored by XBee 3; sleep mode

« Last post by pinolec on September 08, 2020, 04:36:55 PM »

With 100uA you can run 2000mAh battery for just over 2 years. But you don't want to run just in sleep mode so this will leave some energy for other tasks.
Run the numbers through the calculator at digikey.com and see how long will your device last.

I just found better calculator: https://www.geekstips.com/battery-life-calculator-sleep-mode/

Regards,
Piotr

3

SoilWatch 10 / Re: SoilWatch 10 monitored by XBee 3; sleep mode

« Last post by mattsj on September 08, 2020, 04:50:58 AM »

thanks Piotr
Where does the 100uA constraint come from, in your comment "keep the power down during the sleep below 100uA"

4

SoilWatch 10 / Re: SoilWatch 10 monitored by XBee 3; sleep mode

« Last post by pinolec on September 05, 2020, 11:23:37 AM »

Hi,

I have no experience with Xbee or Zigbee at all. So I cant help you on that.

The SoilWatch 10 will continuously consume around 14mA (since rev 2). 
The startup time of the sensor is less than 100ms. So 100ms wait is enough.

As long as you keep the power down during the sleep below 100uA and limit the on time to minimum then it should last around 1 year.
here you can calculate how long the battery will last: https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-battery-life

Kind regards,
Piotr

5

SoilWatch 10 / SoilWatch 10 monitored by XBee 3; sleep mode

« Last post by mattsj on September 04, 2020, 01:08:16 AM »

Hello, I am planning to monitor a SoilWatch 10 (3 Volt version) using an XBee 3 (Zigbee), both powered by battery.

Can you see any reason why this would not work?

I may have to use a switch mode regulator to provide steady voltage to XBee (and from XBee to SoilWatch 10), e.g. from 4-6V down to 3.3V?

Once I get it working, I will refine it to use a sleep mode in the XBee, to save battery.  e.g. take a soil moisture reading every 6 hours. (I want the battery to last several weeks, e.g. using four 2000mAh AA cells).  Will the SoilWatch 10 draw 24 milliAmps all the time if I do not switch it off between my 6-hourly samples? 

If I do switch the SoilWatch 10 off and on, e.g. using a transistor, how long should I wait after turning it on, before taking a reading from the SoilWatch 10?

6

SoilWatch 10 / Re: Coating sides of PCB

« Last post by pinolec on August 18, 2020, 02:15:47 PM »

Hi,

Thank you for your question.
The PCB is made of FR4 material which is nothing more than epoxy resin and fibreglass. The sensor electrodes are sandwiched between epoxy resin and fibreglass material so there is no need to seal the sides with the epoxy resin.

Kind regards,
Piotr

7

SoilWatch 10 / Coating sides of PCB

« Last post by ByTrit on August 18, 2020, 12:46:24 PM »

Hi,
I'm bit worried about consistency of measurement after a prolonged period of time when the sensor will be placed in soil.
The sides of the PCB seems to be uncoated and I'm afraid that water will eventually get into the PCB and mess with measurement accuracy.
Is there some form of protection against water ingress into the PCB through the sides?
If not I was thinking about coating the sides with epoxy resin. Can it somehow affect the measurements?

Thanks.

8

SoilWatch 10 / Re: sleep mode for soil watch 10

« Last post by pinolec on June 15, 2020, 10:05:04 AM »

Hi Piotr!
So I have two options to solve this, right?
- If I use a 5v arduino I can connect directly to the pin without worrying about the voltage drop,
- But if i want to use a 3.3 volt arduino, i must use transistors to drive the sensor.
It is correct?
Thanks!

This is correct.
The first option is not pretty but it will work. Just make sure you do not overload the microcontroller and stay below the maximum current per pin and for the whole microcontroller.
The second option is my favourite.

Kind regards,
Piotr

9

SoilWatch 10 / Re: sleep mode for soil watch 10

« Last post by javierb on June 15, 2020, 07:48:03 AM »

Hi Piotr!
So I have two options to solve this, right?
- If I use a 5v arduino I can connect directly to the pin without worrying about the voltage drop,
- But if i want to use a 3.3 volt arduino, i must use transistors to drive the sensor.
It is correct?
Thanks!

10

SoilWatch 10 / Re: Soil Specific Calibration

« Last post by pinolec on June 13, 2020, 08:07:02 AM »

Hi Piotr!
Yes, i connect direct to the pin.
Why this is not recommended? Obviously before a set the pin as output.
Regards

Please see this post: https://pino-tech.eu/forum/soilwatch-10/sleep-mode-for-soil-watch-10/

For the other question, you should use the value for your calculations based on your voltage reference. Please read: https://www.arduino.cc/reference/en/language/functions/analog-io/analogreference/

By default in many Arduino supported boards the reference voltage is the supply voltage.
If you power your Arduino pro mini with 3.3V then you should use 3.3 in your calculations. Make sure your supply voltage is stable as the results of your measurements depend on it.

Also do not power the sensor straight from the pin. With 3.3V there will be too big voltage drop to power the sensor.

Kind regards,
Piotr