Thanks. I dont have a multimeter but I put the diode in the wrong direction and the output was 0.4V instead of the usual 3.2V. So the diode seems to be OK.
Also, with the cable disconnected from the pin P06, the output is 0.2V.
It’s looked like the Moisture Sensor is faulty ? The 2 i have ordered do have the same behavior.
Fixed : Both sensors i received have a faulty PCB which seems to be a common occurence.
It is caused by the 1 Mega-Ohm resistor in R4 not being connected to GRD.
After some soldering, the sensor is correctly reporting 2.4V dry and 0.9V wet.
Glad to hear that the sensor is now working for you as well!
Thanks for this tutorial. I flashed the firmware on my CC2530 + CC2591. Now trying without a diode, but I measure already 3,3V on P06, is this correct? Is the diode only for better reading or absolutely necessary?
The diode is an absolute necessity, you can try for yourself 
It looks like a new custom firmware has been released for the CC2530 with a Low Power consumption mode.
How can this feature be used for this sensor to allow usage of a battery ?
I have measured the current used by the capacitive soil moisture device: 5 mA This is excluding the CC2530 device: 
A bit too much for a battery operated device.
I dont know how far the firmware can be configured but it seems that sleep mode can be enabled which can provide up to 20mA to sensor when needed.
https://ptvo.info/zigbee-configurable-firmware-features/power-saving-mode/
Hello ! please tell me which diode are you using?
I have used IN5401 Rectifier Diode This is of course ridiculous heavy for this application but I had a few spare ones lying around 
I have not tested this.
Great great work!
Would you mind sharing the flashing and pairing part a bit more in detail? I have never seen/done anything diy with zigbee devices and it seems like there is not much info for the ptvo firmware (apart from russian).
thanks!
Flashing is quite straight forward:
by using the free software from TI: SmartRF Flash programmer http://www.ti.com/tool/flash-programmer ( NOT V2 ).
Daaang and the e-ink model looks snazzy too!
As well as this “DIYRuZ Flower” Soil Moisture Sensor
PS: I posted a similar question in this Home Assistant community forum thread but got no suggestions there as of yet Zigbee flower sensors for soil moisture + light + temperature + humidity?
Thanks for the inspiration! I tried at first without the diode, and you’re right. It is not working. Hehe. But after adding it I think it is working just fine.
Tip is to also check out the related discussion here:
I’m looking for something like this too, but i’ve got 4 borders with plants outside. I think it’s cheaper to just buy 4 Mi Flower Care Plant sensors and replace battery every year instead of making this by my own, buy 4 cc2530, a IP67 box, power adapters, etc etc.
What should you do?
I personally went the Mi Flora way with ble integration. I would have preferred ZigBee but the lack of battery powered solution make me change my mind.
So far, the Mi Flora’s have been reliable since the Bluetooth integration revamped in HA.
