Study on display principle of seven segment digital tube

    stay 51 SCM learning process , A relatively basic experiment is to use seven segment digital tubes to display numbers in turn 0-9. A lot of times , We are required to , Built the circuit , The corresponding display control program is written , Last run , There may be no in-depth study on the principle of seven segment digital tube displaying numbers . Today, with my own understanding , The principle of seven segment digital tube display is given .

      Seven digital tubes , It uses the principle of LED , Form a '8' The shape of the , This '8' It's just seven paragraphs , So it is generally called seven segment digital tube .

      Make up this 7 Each part of the segment nixie tube is divided into a,b,c,d,e,f,g part , Corresponding to the following ：

    Connection mode of seven segment nixie tube , According to the way of actual wiring , It can be composed of common positive digital tube and common negative digital tube , The so-called Gongyang , That is, one pole of the nixie tube is all connected to the power supply , And the diode according to the light-emitting principle , Only the positive pole is connected to the power supply , Connect to the breadboard , So the first stage of the nixie tube is all connected to the power supply , It is called Gongyang digital tube , As shown below ：

 

      stay proteus In the component library , The name of Gongyang digital tube is ：7SEG-COM-AN-[COLOR] 

      Common cathode nixie tube , That is, all the common poles are grounded , As shown below ：

      stay proteus In the component library , The name of Gongyang digital tube is ：7SEG-COM-CAT-[COLOR] 

    The two figures above , You may not see the problem , The main difference is that the power and ground icons in the circuit diagram are different ：

      Power Supply vcc：

      Grounding vss： 

    In actual programming , Basically, one type of digital tube is used for display , By default, the common cathode nixie tube is selected , That is, we need to make the output voltage of the development board high , Light up the corresponding nixie tube .

    In the seven segment nixie tube corresponding to the above letters , To display the 0-9, The required levels are as follows ：

a	b	c	d	e	f	g	The font	Required alphanumeric segment
1	1	1	1	1	1	0	0	abcdef
0	1	1	0	0	0	0	1	bc
1	1	0	1	1	0	1	2	abdeg
1	1	1	1	0	0	1	3	abcdg
0	1	1	0	0	1	1	4	bcfg
1	0	1	1	0	1	1	5	acdfg
1	0	1	1	1	1	1	6	acdefg
1	1	1	0	0	0	0	7	abc
1	1	1	1	1	1	1	8	abcdefg
1	1	1	1	0	1	1	9	abcdfg

    Light this watch , I can't see how to set the level of the pin , But we can deduce the table from the values in the code , In general, our code may have such an array of display numbers ：

unsigned char led[] = {0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f}; 

    This set of data , In fact, it corresponds to the above common Yin nixie tube table , It's understandable , Put the digital tube g,f,e,d,c,b,a Seven segments , Plus one. 0 position , Just make up eight bits of binary , among 0 Corresponding 0x3f, Namely 0011 1111, It just corresponds to the sequence in the table above 1111 110 The reverse means .1 Corresponding 0x06, That is to say 0000 0110, It also corresponds to the above table 0110 000 The reverse means . The following are similar laws . Show numbers 8, All on , That is to say 1111 111, In turn, the binary representation is 0111 1111, Exactly corresponds to hexadecimal 0x7f.

    Understand these rules , In turn, understand the display of the nixie tube , In fact, it's not difficult .

    The above is the number displayed on the seven segment nixie tube 0-9 The study of , In fact, the nixie tube can also display many other letters , At least in capital letters E,F,L Can be simulated , The same goes for the law , Light up some segments of the seven segments of the digital light , You can display the corresponding font style , In fact, it doesn't really show a certain font style , Instead, it uses the method of piecing together shapes to make the diode light up .