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'''Documentation notice:''' This technical documentation was independently rewritten from an archived supplier source. Check technical details and commands against the product version and manufacturer documentation before use.<br />
<br />
== Summary ==<br />
The Waveshare RTC WatchDog HAT pairs a high-precision RTC (DS3231) with a MAX705 watchdog that auto-resets when not fed. It is accessed over I2C and powered at 5 V.<br />
<br />
== Related products at JW Tech ==<br />
* [https://shop.jw-tech.eu/p/WSAL20374 WSAL20374 – RTC WatchDog HAT for Raspberry Pi, Auto Reset, High Precision RTC]<br />
<br />
== Technical overview ==<br />
* RTC chip: DS3231SN, high-precision real-time clock<br />
* Watchdog chip: MAX705 with auto-reset function<br />
* Communication interface: I2C<br />
* Power supply: 5 V<br />
* Dimensions: 30.5 mm x 65 mm<br />
* Mounting hole diameter: 3.0 mm<br />
* Additional features: reset pin selection for switching the watchdog and an indicator for the watchdog output warning<br />
* Supported platforms: Raspberry Pi and RDK X3<br />
* Kernel driver can be enabled via /boot/config.txt<br />
* Sample code in C and Python is available<br />
<br />
'''Commands and examples – verify before use:''' <br />
<syntaxhighlight lang="text"><br />
sudo apt-get install p7zip-full<br />
wget https://files.waveshare.com/upload/b/bd/RTC_WatchDog_HAT.zip<br />
7z x -tzip -y RTC_WatchDog_HAT.zip -o./RTC_WatchDog_HAT<br />
sudo chmod 777 -R RTC_WatchDog_HAT<br />
cd RTC_WatchDog_HAT/RTC<br />
cd ~/RTC_WatchDog_HAT/RTC/c/ && make clean && make && sudo ./main<br />
cd python/examples/ && sudo python main.py<br />
echo "dtoverlay=i2c-rtc,ds3231" >> /boot/config.txt<br />
sudo hwclock -w<br />
sudo hwclock -s<br />
sudo hwclock --set --date="9/8/2021 16:45:05"<br />
sudo hwclock -r<br />
sudo hwclock --verbose<br />
sudo apt-get install nano<br />
sudo nano rtc.py<br />
sudo cp -r /home/sunrise/X3PI_RTC_WatchDog_HAT/ /root/X3<br />
sudo chmod -R 777 /root/X3/RTC/python/examples/rtc.py<br />
sudo nano /etc/rc.local<br />
</syntaxhighlight><br />
<br />
== Notes and version constraints ==<br />
* The kernel driver method disables the provided demo scripts – do not mix both approaches.<br />
* When syncing system to hardware clock, network time sync must be disabled or it will overwrite your setting.<br />
* Watchdog timeout T depends on R and C; defaults yield about 157.08 s ±6%.<br />
* The date syntax shown in the example (9/8/2021 16:45:05) is outdated and should be updated before running.<br />
* The RDK X3 workflow assumes a specific directory (/home/sunrise/...); verify it exists on your system.<br />
* The Bullseye branch supports only Python 3 – older Python 2 scripts will not run.<br />
* All steps should be verified by a technician before deploying to production.<br />
<br />
== Source and revision record ==<br />
* [https://www.waveshare.com/wiki/RTC_WatchDog_HAT RTC WatchDog HAT - Waveshare Wiki]<br />
* Source revision: 103855<br />
* Captured: 2026-09-02T03:46:42+00:00<br />
* SHA-256: <code>057f37468df69a3796b3b62f2aeadc0215e05d9213e59a7dbac39fd55dd3727e</code></div>JWTechPublisher