I am a Newbie and I do not have a lot of expirience. The circuit has been put together from pieces I have found on the internet. My goal is to develop a reliable wireless solenoid circuit to water my tomato plants on my balkony.
The circuit I have developed so far. https://easyeda.com/editor#id=b929cf452b52475bb0b40aca272a42e8.
In order to make the circuit failsafe, I came up with the following idea:
- Circuit turns on, valve is closed, watchdog is disabled
- ATTiny85 receives periodic PING from Master station
- First PING will enable watchdog
- ATTiny85 sends periodic heartbeat to watchdog for each subsequent received PING
- Missing heartbeat/PING will reset the microsontroller and close the valve
I would really appreciate if someone from the community could look over the design and let me know how to improve the circuit and if above approach is OK to avoid a permanent open valve.