Single-line serial communication method for LED display system

With the rapid development of economy and society, LEDs with high luminous efficiency, safety and reliability, long service life and environmental protection and energy conservation have received extensive attention. In the LED application system, since the number of unit lamps that can be driven by each LED chip is limited, in order to realize a large-scale system, it is necessary to serially connect the LED driving circuits to drive more unit lamps. The unit lamp is a pixel and can be composed of three LED lamps, such as a red LED lamp, a blue LED lamp and a green LED lamp. In large-scale LED display systems, the large number of signal lines between unit lamps and poor connection stability have always been difficult applications. Therefore, it is necessary to start from the LED communication system and communication method. The new single-wire serial communication method introduced in this paper is an effective method to solve the current problem.

2 commonly used LED communication system and communication method

At present, in most large-scale LED display systems, the main body of the communication system composed of the LED control circuit and the LED drive circuit often uses four or more serially connected transmission lines to realize signal transmission. The LED control circuit and the plurality of LED driving circuits are connected in series by the data line, the clock signal line and the latching signal line are connected in parallel, and the LED control circuit sequentially sends the data to the serial connection through the serial connection of the data line and the cooperation of the clock signal line. LED drive circuit. The LED control circuit simultaneously issues a data latch command to all of the LED drive circuits through the parallel latched signal lines. The LED drive circuits are sequentially serially transmitted to complete the transmission of the serial signal, and at the same time, the control of the lamp points controlled by the LED chips is realized by the serial signals. Since the clock signal line and the latch signal line are connected in parallel, the clock signal line and the latch signal line output by the LED control circuit are limited by the driving capability, and if a large number of LED driving circuits need to be driven, more clock signal lines and latch signals are required. The number of wires, or the port drive circuit between the LED control circuit and the LED drive circuit, enhances the drive capability of the clock signal line and the latch signal line, as shown in Figure 1:

Figure 1 commonly used LED display drive system

The communication method requires strict timing matching relationship between the signals on the four transmission lines. Once the timing coordination is inaccurate, the data signal cannot be correctly transmitted, and the serial signal of the entire LED display system cannot be correctly transmitted, resulting in the entire LED display. The flaws of the system.

3 new LED display system

And its single-line serial communication method This paper proposes a new type of LED display system for LED display systems, especially large-scale LED display systems and single-wire serial communication methods. The communication system is based on a single-line communication protocol, and realizes transmission of RGB three-color signals and other signals on one data transmission channel by means of data encoding. The LED control circuit and the plurality of LED drive circuits are connected in series by a single line, and the circuit required for data transmission is reduced relative to the system shown in FIG. 1, and the line is simple to implement. The communication method is the key of the LED communication system. This paper focuses on an advanced single-line serial communication method. The communication method has the characteristics of high communication efficiency, rich instructions, flexible control and good synchronization effect. It can effectively solve the stringent timing cooperation problem of traditional LED communication system signal transmission, improve the stability and control flexibility of the whole LED display system, and also has higher efficiency than the current LED communication system.

3.1 System Architecture

The communication system is composed of an LED control circuit and a plurality of LED driving circuits connected in series, including an LED control circuit and a plurality of LED driving circuits, and the number of driving circuits depends on the scale of the LED display system. The system is based on a single-wire communication protocol and has the characteristics of simple bus structure, convenient interface and strong anti-interference ability, which simplifies the complexity of the communication system in the traditional LED display system. The system architecture diagram is shown in Figure 2.

Figure 2 LED serial communication system