a brief introdction
The digital tube actually uses 7 bright line segments to represent common numbers or characters. The common ones are as follows (the picture is a screenshot from the Internet). The knowledge used in the event is still the most basic matrix scanning in the microcontroller . Remember that the important one is the "afterglow effect", which seems to be to turn off unused bright segments, otherwise it will not feel completely dark.
Common circuit connections (taking a four-digit digital tube as an example)
When there is no internal circuit, you can judge by yourself
The above circuit connection description shows that there is a common terminal and 8 corresponding diodes to control the display of one character. You can provide voltage to the digital tube yourself, but you need to pay attention to the voltage given. Generally, the voltage of light-emitting diodes cannot exceed 3v. Personally, I usually use the buzzer setting of the multimeter to test these small voltages. It feels more convenient and there is no need to worry about the device being burned out.