Freenove Ultimate Starter Kit, Руководство пользователя

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193 Chapter 18 74HC595 & 7-segment display. █ www.freenove.com
support@freenove.com █
If you want to display the decimal point, make the highest bit of each array become 0, which can be
implemented easily by num[i]&0x7f.
_shiftOut ( dataPin , clockPin , MSBFIRST , num [ i ] & 0x7f );
Python Code 18.1.1 SevenSegmentDisplay
First observe the project result, and then analyze the code.
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Use cd command to enter 18.1.1_SevenSegmentDisplay directory of Python code.
cd ~/Freenove_Ultimate_Starter_Kit_for_Raspberry_Pi/Code/Python_Code/18.1.1_SevenSegmentDisplay
2. Use python command to execute python code “SevenSegmentDisplay.py”.
python SevenSegmentDisplay.py
After the program is executed, SevenSegmentDisplay starts to display the character “0”- “F” successively.
The following is the program code:
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i m port RPi . GPIO a s GPIO
i m port time
LSBFIRST = 1
MSBFIRST = 2
#define the pins connect to 74HC595
dataPin = 11 #DS Pin of 74HC595(Pin14)
latchPin = 13 #ST_CP Pin of 74HC595(Pin12)
clockPin = 15 #CH_CP Pin of 74HC595(Pin11)
#SevenSegmentDisplay display the character "0"- "F"successively
num = [ 0xc0 , 0xf9 , 0xa4 , 0xb0 , 0x99 , 0x92 , 0x82 , 0xf8 , 0x80 , 0x90 , 0x88 , 0x83 , 0xc6 , 0xa1 , 0x86 , 0x8e ]
d e f setup ( ):
GPIO . setmode ( GPIO . BOARD ) # Number GPIOs by its physical location
GPIO . setup ( dataPin , GPIO . OUT )
GPIO . setup ( latchPin , GPIO . OUT )
GPIO . setup ( clockPin , GPIO . OUT )
d e f shiftOut ( dPin , cPin , order , val ):
f o r i i n range ( 0 , 8 ):
GPIO . output ( cPin , GPIO . LOW );
i f ( order = = LSBFIRST ):
GPIO . output ( dPin ,( 0x01 &( val >> i )== 0x01 ) a n d GPIO . HIGH o r GPIO . LOW )
e l if ( order = = MSBFIRST ):
GPIO . output ( dPin ,( 0x80 &( val << i )== 0x80 ) a n d GPIO . HIGH o r GPIO . LOW )
GPIO . output ( cPin , GPIO . HIGH );
d e f loop ( ):
w h ile T r ue :
f o r i i n range ( 0 , len ( num )):
GPIO . output ( latchPin , GPIO . LOW )
shiftOut ( dataPin , clockPin , MSBFIRST , num [ i ]) #Output the figures and the highest
level is transfered preferentially.