RTC WatchDog HAT

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RTC WatchDog HAT
RTC-WatchDog-HAT-1.jpg
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Introduction

RTC WatchDog HAT For Raspberry Pi, Auto Reset, High Precision RTC

More

RTC WatchDog HAT

  • MAX705 monitoring circuit with auto reset function.
  • Incorporates DS3231SN high precision RTC chip, with backup battery holder.
  • Reset pin selection for switching watchdog.
  • Indicator for watchdog output warning.

How to use

RTC

Open a terminal and run the following command to download the codes

wget https://www.waveshare.com/w/upload/b/bd/RTC_WatchDog_HAT.zip
zip RTC_WatchDog_HAT.zip
sudo chmod 777 -R RTC_WatchDog_HAT
cd RTC_WatchDog_HAT/RTC
C examples
cd ~/RTC_WatchDog_HAT/RTC/c/
make clean
make 
sudo ./main
RTC WatchDog HAT 1.png
Python example
cd ~/RTC_WatchDog_HAT/RTC/python/examples/
sudo python main.py
RTC WatchDog HAT 2.png

Add Kernel Mode Driver

Note that with this method, you cannot use the above sample program
Modify /boot/config.txt to add
at the end

 dtoverlay=i2c-rtc,ds3231

Hwclock is simple to use

Synchronize System Clock -> Hardware Clock

sudo hwclock -w

Synchronize hardware clock -> system clock

sudo hwclock -s
  #Need to close the network, or close the network time, otherwise it will be changed back

Set the hardware clock time:

sudo hwclock --set --date="9/8/2021 16:45:05"

View hardware clock

sudo hwclock -r

Display version information

sudo hwclock --verbose

WatchDog

In the WatchDog example, it feeds the watchdog chip if the D4 pin toggle. If the watchdog doesn't be feed in T time, it will cut off the power and the voltage falls to 1.25V, in this case, the MAX705 chip will reset and restart the power. About the time T:

T = 0.7*R*C+1.6s
R is default 5.1M, and C is default 44uF
Tge default delay time is 157.08s ±6%

RC are set in the board:

RTC-WatchDog-HAT-3.jpg


Support

If you require technical support, please go to the Support page and open a ticket.