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树莓派硬件相关

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硬件基础

因为我的是树莓派Model 3B+，所以GPIO引脚一共有40个
布局是这个样子的

GPIO

发现了一个特别好用的，入门级GPIO库，之前看RPi.GPIO给我整蒙了，这个是真的简单
gpiozero

随便练了一下

RGB

一开始也是不太会接线的说，但是这个库比较简单就随便接了
R - pin17
G - pin27
B - pin 18
GND - GND

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from gpiozero import LED
from time import sleep

ledr = LED(17)
ledg = LED(27)
ledb = LED(18)

while True:
    ledr.on()
    sleep(1)
    ledg.on()
    sleep(1)
    ledb.on()
    sleep(1)
    ledr.off()
    ledg.off()
    ledb.off()
    sleep(1)

Button + RGB

一开始是青色，按按钮变紫色，松开又是青色
一开始把按钮的中间的线差错位置了，中间是正极连+5V，负极连GND，另一个边上的随便连个pin，我连的17
RGB灯就是换了一下pin，其他跟上面一样

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from gpiozero import Button, LED
from time import sleep

ledr = LED(18)
ledg = LED(27)
ledb = LED(22)
btn = Button(17)

ledb.on()

while True:
    if btn.is_pressed:
        ledr.on()
        ledg.off()
    else:
        ledg.on()
        ledr.off()

Button + RGB + laster

加了个激光玩，it’s so easy
接下来就要加些传感器了


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from gpiozero import Button, LED
from time import sleep

ledr = LED(18)
ledg = LED(27)
ledb = LED(22)
btn = Button(17)

laster = LED(23)

ledb.on()

while True:
    if btn.is_pressed:
        ledr.on()
        ledg.off()
        laster.on()
    else:
        ledg.on()
        ledr.off()
        laster.off()

光敏传感器

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from gpiozero import LightSensor

sensor = LightSensor(18)

while True:
    sensor.wait_for_light()
    print("It is dark!  :(")
    sensor.wait_for_dark()
    print("It is light! :)")

温度传感器 DS18B20

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dtoverlay=w1-gpio-pull，gpioin=4
sudo modprobe w1_gpio
sudo modprobe w1_therm
lsmode
cat /sys/bus/w1/devices/28-011869db6fff/w1_slave
t=25500就是25.5摄氏度
sudo raspi-config

火焰传感器 气体烟雾传感器 MQ-2

检测到时时输出低电压，value=1, is_active=False

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from gpiozero import InputDevice
from time import sleep


mq2 = InputDevice(27)
fire = InputDevice(22)

while True:
    print(mq2.value, mq2.is_active, fire.value, fire.is_active)
    sleep(0.2)

AD/DA转换PCF8591

sudo raspi-config 打开I2C和SPI， 然后
sudo apt-get install i2c-tools python-smbus 安装依赖

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#------------------------------------------------------
#
#		This is a program for PCF8591 Module.
#
#		Warnng! The Analog input MUST NOT be over 3.3V!
#    
#		In this script, we use a poteniometer for analog
#   input, and a LED on AO for analog output.
#
#		you can import this script to another by:
#	import PCF8591 as ADC
#	
#	ADC.Setup(Address)  # Check it by sudo i2cdetect -y -1
#	ADC.read(channal)	# Channal range from 0 to 3
#	ADC.write(Value)	# Value range from 0 to 255		
#
#------------------------------------------------------
import smbus
import time

# for RPI version 1, use "bus = smbus.SMBus(0)"
bus = smbus.SMBus(1)

#check your PCF8591 address by type in 'sudo i2cdetect -y -1' in terminal.
def setup(Addr):
    global address
    address = Addr

def read(chn): #channel
    if chn == 0:
        bus.write_byte(address,0x40)
    if chn == 1:
        bus.write_byte(address,0x41)
    if chn == 2:
        bus.write_byte(address,0x42)
    if chn == 3:
        bus.write_byte(address,0x43)
    bus.read_byte(address) # dummy read to start conversion
    return bus.read_byte(address)

def write(val):
    temp = val # move string value to temp
    temp = int(temp) # change string to integer
    # print temp to see on terminal else comment out
    bus.write_byte_data(address, 0x40, temp)

if __name__ == "__main__":
    setup(0x48)
    while True:
        print('AIN0 = ', read(0))
        print('AIN1 = ', read(1))
        tmp = read(0)
        tmp = tmp*(255-125)/255+125 # LED won't light up below 125, so convert '0-255' to '125-255'
        write(tmp)
#		time.sleep(0.3)

这个文件编译一下python3 -m PCF8591.py，然后在__pycache__里面可以找到.pyc，移出来供下面的文件使用

输出烟雾传感器数据

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import PCF8591 as ADC
import RPi.GPIO as GPIO
import time
import math

DO = 17
Buzz = 18
GPIO.setmode(GPIO.BCM)

def setup():
    ADC.setup(0x48)
    GPIO.setup	(DO, 	GPIO.IN)
    GPIO.setup	(Buzz, 	GPIO.OUT)
    GPIO.output	(Buzz,	0)

def Print(x):
    if x == 1:
        print ''
        print '   *********'
        print '   * Safe~ *'
        print '   *********'
        print ''
    if x == 0:
        print ''
        print '   ***************'
        print '   * Danger Gas! *'
        print '   ***************'
        print ''

def loop():
    status = 1
    count = 0
    while True:
        print ADC.read(0)
        
        tmp = GPIO.input(DO);
        if tmp != status:
            Print(tmp)
            status = tmp
        if status == 0:
            count += 1
            if count % 2 == 0:
                GPIO.output(Buzz, 1)
            else:
                GPIO.output(Buzz, 0)
        else:
            GPIO.output(Buzz, 0)
            count = 0
                
        time.sleep(0.2)

def destroy():
    GPIO.output(Buzz, 0)
    GPIO.cleanup()

if __name__ == '__main__':
    try:
        setup()
        loop()
    except KeyboardInterrupt: 
        destroy()

接线的话，AO口接PCF的AIN0，一开始还不会接，因为我没有male-to-male的线，最后发现那上面的一个东东可以把俩female接起来=-=
SDA SCL就接树莓派上的SDA SCL

先这样，传感器目前也只用这些，其他的也都大同小异接线基本都提到过了，后面就是要看看RPi.GPIO的文档，gpiozero入门海星，功能太少，很多都不支持

参考

  • 《树莓派开发实战(第2版)》
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Have fun.