How to teardown a Parrot Flower Power ?

[plantgrower]

I am wanting to do a tear down of a Parrot Flower Power the first hurdle is how to crack open the plastic casing without damaging the PCB which it wraps around.It appears to be in two halves that have been sonically welded together. One of the twigs has a metal lining where the battery goes with three grub screws to hold the battery cover on. I have seen Mikes vids where he cracks them open by hitting them. I am concerned that with the plastic casing surrounding the PCB this will damage the PCB.

I think all the components are mounted onto the PCB that comprises the soil sensor part. The one thing I am interested in is how they are testing the soil for water/fertilizer levels. There are two small metal studs that Parrot say are used for moisture levels and the rest of the PCB fork is used for EC testing. I don't currently have an oscilloscope with which to test the frequency they are using.

Any advice on what to look for is welcome.

[Alexei.Polkhanov]

I would be more curious how they do "fertilizer level" testing? I think for that they need a pH sensor at minimum and that would be expensive. If they just test resistance then that is BS in my opinion.

[SeanB]

I would guess the water level is simply a conductivity limit test, and then the fertiliser level is actually looking at a trend of the soil ionic resistance with time, using the watering peaks to gauge how it increases with time as the ions are washed out.

Simple enough if you have the probes permanently in the soil, though I have had a simple unit that used a moving coil meter and 2 probes, with the one being copper/zinc for the water level and the other an aluminium/steel one IIRC, to do 2 different tests. You did not leave it in though, just push one or the other in to see.

[miceuz]

This is interesting. Try cutting along the seam with a dremel tool, go easy in small bites, let the plastic to cool between bites.

[plantgrower]

This is interesting. Try cutting along the seam with a dremel tool, go easy in small bites, let the plastic to cool between bites.

I ended up using a break away utility knife to cut the two outer seams this took a while to do. Then I gently lifted either side apart and the middle seam snapped cleanly.

There seems to be a conformal coating? over the components and solder joints. What is the best way to remove this for testing ?

The black plastic piece I guess is covering some component the ADC ? Any ideas on how to remove this without damaging the pcb or the components underneath.

I am wanting to create something similar to this myself instead of using the cc2540 I want to use the nrf51822.

miceuz do you have any interest in creating something like this ?

[miceuz]

cc2540 is actually a 8051 microcontroller on it's own and it has a 12bit ADC on board. I don't believe they are using a resistive measurement method. It's not clear what's under the blob and it's hard to say if it's possible to etch it with acid like they do when decapping chips. I'd try to trace connections that go between the sensor and the MCU, then poke with a scope at them. BTW is sensor PCB 2 layer or 4 layer?

miceuz do you have any interest in creating something like this ?

actually I already have


https://www.tindie.com/products/miceuz/chirp-plant-watering-alarm/

[robinxu]

Dear all,
I am a college student, and quite interested in the smart garden water sensors, but quite confused in the theories of the sensor. Could you help me to understand of the theory of the parrot flower power sensor.
1. For the capacitance method to measure the moisture level of the soil, what are the drawbacks of the capacitance/ conductivity method?
2. Is there any method to calibrate the dielectric conductivity measurement , especially in DC voltage supply?
3. On the market, there are several kinds of sensor with different number of prongs, usually come with two prongs, also, three/ four prongs can be founded as well. Is that means with more prongs, the measurement will be more accurate? Are they all based on the same theory( soil capacitance method?)?
 Look forward your reply!
Regards