Pivariety AR0234 Global Shutter Camera having an external trigger function, which is used to capture the image and helps in synchronized streaming by connecting two or multiple cameras. In production applications (such as assembly line production), the external trigger mode can easily synchronize the camera with other devices. In addition, the sensor (AR0234) enables the sleep state will greatly reduce the power consumption.
1.Hardware
First of all, You need to solder the headers on the TRIGGER and GND pins, TRIGGER is connected to the external trigger signal, and GND is connected to the ground.
Note
It is required that the voltage of the trigger signal is 1.8V, you need to convert the 3.3V or 5V to 1.8V. The trigger signal pulse width TTPW is not less than 2us, and the frequency cannot exceed the highest external trigger frame rate supported by the current frame rate. 
2.Software
2.1 Enable the camera
libcamera-still -t 0
2.2 Enable the external trigger snapshot mode
v4l2-ctl -c trigger_mode=1
2.3 Input the external trigger signal at TRIGGER pin and capture the image
2.4 Disable the external trigger signal snapshot mode
v4l2-ctl -c trigger_mode=0
2.5 Flash signal
The FLASH pin outputs a flash signal synchronized with the exposure by default. The signal high-level time is the exposure time, and the voltage is 1.8V.
