LED digital tubeTo display normally, we need to use a driving circuit to drive the various segment codes of the digital tube, so as to display the numbers we want. Therefore, according toLED digital tubeThe driving methodIt can be divided into two categories: static and dynamic.

1、 Static display

Static drive, also known as DC drive. Static driving refers to each segment code of each digital tube being driven by an I/O port of a microcontroller, or by decoding using a binary decimal decoder such as BCD code. The advantages of static driving are simple programming and high display brightness. The disadvantage is that it occupies more I/O ports. If driving 5 digital tubes for static display, it requires 5 × 8=40 I/O ports to drive. It should be noted that only 32 I/O ports are available for an 89S51 microcontroller. In practical applications, decoding drivers must be added for driving, which increases the complexity of hardware circuits.

2、 Dynamic display

LED digital tubeDynamic display interface is one of the most widely used display methods in microcontrollers. Dynamic driving connects the same named terminals of all eight display strokes "a, b, c, d, e, f, g, dp" of digital tubes together. In addition, a bit gate control circuit is added to the common pole COM of each digital tube. The bit gate is controlled by independent I/O lines. When the microcontroller outputs character code, the microcontroller controls the bit gate COM circuit. Therefore, as long as we turn on the gate control of the digital tube that needs to be displayed, the character will be displayed. Digital tubes without gate control will not light up. By alternately controlling the COM terminals of each digital tube in a time-sharing manner, the display of each digital tube can be controlled alternately, which is called dynamic driving. During the rotating display process, the lighting time of each digital tube is 1-2ms. Due to the phenomenon of human visual persistence and the afterglow effect of light-emitting diodes, although the digital tubes are not lit at the same time, as long as the scanning speed is fast enough, it gives the impression of a stable display data without flickering. The dynamic display effect is the same as static display, which can save a lot of I/O ports and lower power consumption.