Why are the interface definitions of LED modules different?
Display interface on the LED module (unit board): The display interface is used for the connection between the control card and the module (unit board), the module (unit board) and the module (unit board), in order to carry out the control signal transfer. Different interface definitions are mainly due to the different order of the signal lines. First, follow the LED panel light manufacturer to understand what the control signals are:
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. However, since the driving circuit is controlled by OE (output enable signal), the premise of its lighting must be that OE is in an on state. The latch signal must also be coordinated with the clock signal to display a complete image. In any case, when the latch signal is abnormal, it will make the whole board display chaotic.
CLK (clock signal): The shift pulse provided to the shift register, the rising edge of each pulse will cause data to be shifted in or out 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 chaotic.
R/G/B (data signal): Provide the data needed to display the image. It must be coordinated with the clock signal to transmit data to any one of the display points. Generally, the data signals of red, green and blue are separated in the display screen. If a data signal is short-circuited to the positive or negative pole, the corresponding color will appear full on or off. When the data signal is suspended, the corresponding color will be displayed. The situation is uncertain.
ABCD (line control signal): It only exists during dynamic scanning display. Generally, the circuit will be controlled with the IC of 74HC138D. Only AB signal is required in 1/4 scanning. When the line control signal is abnormal, there will be display dislocation, highlight or image overlap.
OE (output enable signal): the whole screen brightness control signal, also used for screen blanking. Just adjust its duty cycle to control the change in brightness. When the enable signal is abnormal, the whole screen will appear dark, dark or trailing.
Since there are different scanning methods and different arrangement orders of signal lines, there are also different interface definitions. The most used are 08 interface, 12 interface, 75 interface, 40 interface. Indoor single and double color dot matrix unit boards use 08 ports, outdoor single and double color LED modules use 12 ports, scan-driven full-color LED modules use 75 ports, and statically driven full-color modules use 40 ports.
