RTC WatchDog HAT

RTC WatchDog HAT

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Primary Attribute Category: Expansions, Raspberry Pi {{{userDefinedInfo}}}: {{{userdefinedvalue}}} Brand: Waveshare

Website International: Website Chinese: 官网

Onboard Interfaces RPi USB

Related Products

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.

Parameters

• RTC Communication Interface: I2C
• RTC Chip: DS3231
• WatchDog Chip: MAX705
• Power Supply: 5V
• Dimensions: 30.5mm x 65mm
• Mounting Hole Diameter: 3.0mm

How to use

Working With Raspberry Pi

PS: The system of the Bullseye branch only supports Python3.

RTC

Open a terminal and run the following command to download the demos.

sudo apt-get install p7zip-full
wget https://www.waveshare.com/w/upload/b/bd/RTC_WatchDog_HAT.zip
7z x -tzip -y RTC_WatchDog_HAT.zip -o./RTC_WatchDog_HAT
sudo chmod 777 -R RTC_WatchDog_HAT
cd RTC_WatchDog_HAT/RTC

C Example

cd ~/RTC_WatchDog_HAT/RTC/c/
make clean
make 
sudo ./main

Python Example

cd python/examples/
sudo python main.py

Add Kernel Mode Driver

Note that with this method, you cannot use the above sample demo.
Modify /boot/config.txt and add the following commands 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 the 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:

Working With Horizon Sunrise Pi X3

RTC

Download the sample demo, extract it to a specified directory, and run the sample demo:

sudo apt-get install p7zip-full
wget https://www.waveshare.com/w/upload/f/fe/X3PI_RTC_WatchDog_HAT.zip
7z x -tzip -y X3PI_RTC_WatchDog_HAT.zip -o./X3PI_RTC_WatchDog_HAT
sudo chmod 777 -R X3PI_RTC_WatchDog_HAT
cd X3PI_RTC_WatchDog_HAT/RTC

C

cd c/
make clean
make 
sudo ./main

Python

cd python/examples/
sudo python main.py

Resource

Documentation

• Schematic
• Schematic V2

• MAX705 Datasheet
• DS3231 Datasheet

Demo codes

• Raspberry Pi demo
• Horizon Sunrise X3 Pi demo

Support

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