I want to share my own made loara node. My idea is to try to make a cheap node that will measure temperature humidity and soilmoisture (capacitive soil moisture sensor) for appel farmers in my area.
The specs are as follow:
MCU: Is a atmega 644p running at 3.3v 8mhz internal crystal.
Power: 5.4v 7.5F super capacitor
Charging: 6V 35mA solar panel.
I/O: 7 analog 8 digital
Sensor power:A extra LDO which can be turned on and off when power needed for sensors which draw more current
than the MCU digital i/o.
Housing: standard PVC pipe parts
Design had a RTC but did not see a need for it.
The current node has a dth22 to measure inside temperature. An digital i/o is used as power supply
for the dth22.
I want to know how hot it is getting inside of the housing.
A Soilwatch10 as capacitive soil moisture sensor. This is fed trough the second ldo because it draws 25 mA.
Did not measure how much power my setup uses but with a full charge of 5.4V and
no solar panel attached it can run 2 days while measuring battery voltage,
temperature, humidity and soil moisture every 30 minutes. After 2 days voltage dropped around 3.5V. So it can run 2.5 days (till 3.3V)without charging.
When it is using the solar panel it will drop from 5.4 volt till 4.8 in the morning. In the morning behind my house in the shade the capacitor get charged in around 2 hours.
For this setup the solar panel is too big but it was the smallest I could find.
For the next version I will make the pcb a bit smaller and fix some mistakes.
Total cost of lora node in the picture without the sensors (dth22 and soilwatch) 32euro.
Now I’m busy with the web-application and I still need to find a farmer where I can test 10 nodes out.
Keep on hacking