Freenove Ultimate Starter Kit, Руководство пользователя

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199 Chapter 18 74HC595 & 7-segment display. █ www.freenove.com
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Code
In this code, we use 74HC595 to control 4-Digit 7-segment display, and use dynamic scanning way to show
the changing numbers.
C Code 18.2.1 StopWatch
First observe the project result, and then analyze the code.
1.
Use cd command to enter 16.1.1_SteppingMotor directory of C code.
cd ~/Freenove_Ultimate_Starter_Kit_for_Raspberry_Pi/Code/C_Code/18.2.1_StopWatch
2. Use following command to compile "StopWatch.c" and generate executable file "StopWatch".
gcc StopWatch.c -o StopWatch -lwiringPi
3. Run the generated file "SteppingMotor".
sudo ./StopWatch
After the program is executed, 4-Digit 7-segment start displaying a four-digit number dynamically, and the
will plus 1 in each successive second.
The following is the program code:
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#include <wiringPi.h>
#include <stdio.h>
#include <wiringShift.h>
#include <signal.h>
#include <unistd.h>
#define dataPin 5 //DS Pin of 74HC595(Pin14)
#define latchPin 4 //ST_CP Pin of 74HC595(Pin12)
#define clockPin 1 //CH_CP Pin of 74HC595(Pin11)
const int digitPin []={ 0 , 2 , 3 , 12 }; // Define 7-segment display common pin
// character 0-9 code of common anode 7-segment display
unsigned char num [ ] ={ 0xc0 , 0xf9 , 0xa4 , 0xb0 , 0x99 , 0x92 , 0x82 , 0xf8 , 0x80 , 0x90 };
int counter = 0 ; //variable counter,the number will be displayed by 7-segment display
//Open one of the 7-segment display and close the remaining three, the parameter digit is
optional for 1,2,4,8
void selectDigit ( int digit ) {
digitalWrite ( digitPin [ 0 ],(( digit & 0x08 ) = = 0x08 ) ? LOW : HIGH ) ;
digitalWrite ( digitPin [ 1 ],(( digit & 0x04 ) = = 0x04 ) ? LOW : HIGH ) ;
digitalWrite ( digitPin [ 2 ],(( digit & 0x02 ) = = 0x02 ) ? LOW : HIGH ) ;
digitalWrite ( digitPin [ 3 ],(( digit & 0x01 ) = = 0x01 ) ? LOW : HIGH ) ;
}
void _shiftOut ( int dPin , int cPin , int order , int val ) {
int i ;
f o r ( i = 0 ; i < 8 ; i + + ){
digitalWrite ( cPin , LOW );
i f ( order = = LSBFIRST ){
digitalWrite ( dPin ,(( 0x01 &( val >> i )) = = 0x01 ) ? HIGH : LOW ) ;
delayMicroseconds ( 1 );