Usage for LVD

Update dtoverlay

cd lvd/dtoverlay
dtc -@ -I dts -O dtb -o ed-pca953x.dtbo ed-pca953x-overlay.dts
sudo cp ./ed-pca953x.dtbo /boot/overlays/

Modify config.txt

sudo nano /boot/config.txt
#Modify dtoverlay=ed-pca953x according to the following parameters
#For IPC21xx,IPC26xx,HMI21xx series
dtoverlay=ed-pca953x,ipc2110,addr=0x20
#For IPC22xx,HMI22xx series
dtoverlay=ed-pca953x,ipc2210,addr=0x20

Reboot the device after completing the modifications.

Install gpiod library

sudo apt-get -y install libgpiod-dev
sudo apt-get install gpiod

Compile and Run

cd lvd
make

You will get an executable file lvd.

Manual testing

./lvd

Turn off the 12V main power supply of the device, you will obtain the following output:

Low voltage
LVD trigger callback script

NOTE: You can modify the macro LVD_ HOOK_ EXEC specifies a custom callback script

Using the lvd-detect.service

sudo cp lvd /usr/sbin/
sudo cp lvd-callback.sh /usr/sbin/
sudo cp service/lvd-en.sh /usr/sbin/
sudo cp service/lvd-detect.service /lib/systemd/system/

sudo systemctl enable lvd-detect.service
sudo systemctl start lvd-detect.service

The output of sudo cat /sys/kernel/debug/gpio:

gpiochip2: GPIOs 488-503, parent: i2c/10-0020, 10-0020, can sleep:
 gpio-488 (5V_GOOD             )
 gpio-489 (LVD                 |falling edge        ) in  hi IRQ
 gpio-490 (BUZZER_EN           )
 gpio-491 (4G_RST              )
 gpio-492 (4G_LED              )
 gpio-493 (USER_LED            )

NOTE: For IPC2110 and IPC2210, the LVD signal is connected to the Pin1 of gpiochip2

Turn off the 12V main power supply of the device, run the following command line

tail /var/log/messages

You will obtain the following output:

raspberrypi root: LVD trigger callback script

NOTE: You can modify the content of the script lvd-callback.sh according to the needs of your application

LVD GPIO

Add read config: /etc/lvd/config.ini

[gpio]
gpiochip=0
line=11