1. OE enable signal: the entire screen brightness control signal, also used for display blanking. Just adjust its duty cycle to control the change of brightness. When the enable signal is abnormal, the whole screen will appear dark, dark or smeared.

2. ABCD line signal: only exists during dynamic scan display. ABCD is actually a binary number, A is the lowest bit. If the ABCD signal is expressed in binary, the maximum control range is 16 lines (1111), and only AB is required in 1/4 scan. The signal is fine, because the AB signal range is 4 lines (11). When the line control signal is abnormal, there will be display misalignment, highlighting or image overlap.

3. CLK clock signal: the shift pulse provided to the shift register, each pulse will cause the data to be shifted in or out of one bit. The data on the data port must be coordinated with the clock signal to transmit data normally, and the frequency of the data signal must be 1/2 times the frequency of the clock signal. In any case, when the clock signal is abnormal, it will make the whole board display disorderly.

4. Data signal: R (DR.r), G (DG.g), B (DB.b) represent three data signals of red, green, and blue respectively, which are the data required for displaying text images. It must be coordinated with the clock signal to transmit the data to any display point. Generally, the red, green and blue data signals are separated in the display screen. If a certain color data signal is short-circuited to the positive or negative pole, the corresponding color will appear full or not bright. When a certain color data signal is suspended in the air, the color display will be unstable or not.

5. STB latch signal: send the data in the shift register to the latch, and display the data content through the drive circuit to light up the LED. But because the drive circuit is controlled by the EN enable signal, the prerequisite for its lighting must be that the enable is turned on. The latch signal must also be coordinated with the clock signal to display a complete image. In any case, when there is an abnormality in the latch signal, the entire board will be displayed in a disorderly manner