Turning an ATtiny9 microcontroller into a hardware watchdog for another processor.
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attiny-wdt: Turn an ATtiny9 uC into a watchdog for another processor

The ATtiny9 is a small, ultra low cost microcontroller available in SOT-23 package. It is lower cost (and currently better available) than dedicated hardware watchdog ICs.

So this project turns the ATtiny9 into a very simple "hardware watchdog IC" for another processor/CPU.

The watchdog starts counting immediately from power-on and will trigger a reset of the target system after 67s, unless the target system keeps refreshing the watchdog via a low edge on another signal.


The code was written against the data sheet and compiles but has currently not been tested yet with real ATtiny9 hardware.

GIT Repository

You can clone from the official repository using

git clone https://gitea.osmocom.org/electronics/attiny-wdt

There is a web interface at https://gitea.osmocom.org/electronics/attiny-wdt