Embedded design and development project - digital tube static display program design

1. Implemented functions

Three-digit digital tube circuit schematic diagram:

pin chip diagram:

pin function diagram:

• ①Realize 3-digit digital tube polling display to display 0~F, and display once every second;
• ② Write the display driver of the digital tube to understand the principle of the display of the digital tube;
• ③Understand the function of changing the serial data of 74LS595 chip into parallel data, and how to drive the digital tube;

2. Realize the code according to the function

1. The main file main.c

#include"key.h"
#include"led.h"
#include"lcd.h"
#include"stdio.h"
#include <stm32f10x.h>
#include"seg.h"

unsigned int uiSeg;
unsigned char ucSec,ucSec1,ucDot;
unsigned long ulTick_ms;


int main(void)
{
    
    
	SysTick_Config(72000);	//定时1ms(HCLK = 72MHz)
	KEY_Init();
	LED_Init();
	
	STM3210B_LCD_Init();
	LCD_Clear(Blue);
	LCD_SetBackColor(Blue);
	LCD_SetTextColor(White);
	
	SEG_Init();
	SEG_Disp(0x10,0x10,0x10,0);
	
	
	while(1)
	{
    
    
		if(ucSec != ucSec1)
		{
    
    
			ucSec1 = ucSec;
			
			SEG_Disp((uiSeg&0xf00)>>8,(uiSeg&0xf0)>>4,uiSeg&0xf,ucDot++);
			uiSeg +=0x111;
			if(uiSeg > 0x1000)
				uiSeg = 0;
		}
	}
}
	
	//SysTick 中断处理程序
void SysTick_Handler(void)
{
    
    
	ulTick_ms++;
	if(ulTick_ms % 1000 ==0)
	ucSec++;
}
	
	

Main function analysis: ❤️ ❤️ ❤️

1. Add the initialization function of the digital tube, and turn off the display of the 3-digit digital tube ;
2. The 3-digit digital tube displays from 0 to f, displays a number every 1s, and repeats the above actions ;

2. Nixie tube header file "seg.h"

#include "stm32f10x.h"

void SEG_Init(void);
void SEG_Disp(unsigned char ucData1,unsigned char ucData2,
	unsigned char ucData3,unsigned char ucDot);

Brief analysis: ❤️ ❤️

1. The corresponding pins of 74LS595 are initialized;
2. The display function of the 3-digit digital tube;

3. Nixie tube source file "seg.c"

#include "seg.h"

//SEG接口初始化
void SEG_Init(void)
{
    
    
	GPIO_InitTypeDef GPIO_InitStruct;
	//允许GPIOA时钟
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);
	
	//配置引脚、速率、模式
	GPIO_InitStruct.GPIO_Pin = GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3;
	GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_InitStruct.GPIO_Mode = GPIO_Mode_Out_PP;
	
	//初始化结构体
	GPIO_Init(GPIOA,&GPIO_InitStruct);
}

//SEG显示
//入口参数：ucData1，ucData2，UCData3-3个显示数据，ucDot-3个小数点
void SEG_Disp(unsigned char ucData1,unsigned char ucData2,
unsigned char ucData3,unsigned char ucDot)
{
    
    
	unsigned char i;
	unsigned char code[17]={
    
    0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,
		0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71,0x00};
	unsigned long ulData = (code[ucData3] << 16) + (code[ucData2] << 8)
		+ (code[ucData1]);
		
	ulData += (ucDot & 1) << 23;
	ulData += (ucDot & 2) << 14;
	ulData += (ucDot & 4) << 5;
	
	GPIO_ResetBits(GPIOA,GPIO_Pin_2);		//PA2(RCK)输出锁存时钟置低电平
	for(i=0;i<24;i++)
	{
    
    
		GPIO_ResetBits(GPIOA,GPIO_Pin_3);	//PA3(SCK)移位寄存器时钟置低电平
		if(ulData & 0x800000)				//从高位开始发送
			GPIO_SetBits(GPIOA,GPIO_Pin_1);//PA1(SER)串行数据置高电平
		else
			GPIO_ResetBits(GPIOA,GPIO_Pin_1);//PA1(SER)串行数据置低电平
		ulData <<= 1;
		GPIO_SetBits(GPIOA,GPIO_Pin_3);		//PA3(SCK)移位寄存器置高电平
	}
	GPIO_SetBits(GPIOA,GPIO_Pin_2);			//PA2(RCK)输出锁存时钟置高电平
}

Brief analysis: ❤️ ❤️

1. The 3 pins of 74LS595 corresponding to SER, SRCLK, and RCLK are set to push-pull output mode ;
2. The serial data of the 3-digit digital tube is encapsulated into 24 bits , consisting of 3 bytes, and the number of bytes of data corresponds to the number of digital tubes;
3. The decimal point is composed of three bytes, and the display method is opposite to that of the digital tube number ;
4. Workflow: ① Pull down RCK (latch clock) → ② Poll 24 times, first pull down the SCK shift register clock → ③ Determine whether the highest bit of the 24-bit data is equal to 1, if so, pull up SER (serial data ) high level, otherwise pull down SER (serial data) low level → ④ ulData shifts one bit to the left, pull up the SCK shift register clock, and judge the next bit again → ⑤ After polling ends, pull up RCK ( Latch clock), the data is output.
5. The numbers displayed by the digital tube can be found on the Internet for transplantation, and generally display 0 ~ 9 and a ~ F characters;

3. Attention and learning points in the process of realizing functions

1. Precautions

1. In the process of converting serial data to parallel data of 74LS595, it must be carried out in order;
2. Note that the MCU connected to the 74LS595 pin outputs high and low levels, otherwise the data cannot be displayed normally;

2. Knowledge points learned

1. ①Learn the operation of converting serial data to parallel data of the 74LS595 chip to reduce the use of the IO pins of the single-chip microcomputer;
2. ② Master the display function of the digital tube;
3. ③Learn to encapsulate three separate bytes of data into long variables;
4. ④Through circulation and shifting, the data judgment of each bit of data is realized;

❤️ ❤️ ❤️ ❤️ ❤️ ❤️