夏任务105：做一个桌面温湿度计

http://www.cnblogs.com/zxRPI/archive/2013/03/03/2941303.html

实验要求

用RPi采集温度、湿度和气压传感器的数据，在LCD显示

实验工具：

Raspberry Pi Model B主机，

8G c10 SD卡，

pl2303串口转usb线，

USB充电线，

电源需自备5v 1A电源充电头一个

PC机一台（这里用的操作系统是windows7 64bit旗舰版）

dht11温湿度传感器

LED面板

实验步骤：

连接dht11温度传感器如图所示

温湿度传感器dht11的lcd显示[嵌入式系统]

DHT11引脚说明：

Pin	名称	树莓派接口	注释
1	VDD	3.3V Power	供电3~5.5V
2	DATA	GPIO4	串行数据总线
3	NC	悬空	空脚
4	GND	Ground	接地

LCD的连接方法参考了李凡希学长的Blog：

http://www.freemindworld.com/blog/2013/130310_raspberry_pi_with_lcd.shtml

2在树莓派上安装树莓派的GPIO驱动库wIring pi，：教程见：http://blog.csdn.net/liang890319/article/details/8677437

3编写驱动代码dht11.c：

#include <wiringPi.h>

#include <stdio.h>

#include <stdlib.h>

typedef unsigned char uint8;

typedef unsigned int uint16;

typedef unsigned long uint32;

#define HIGH_TIME 32

int wiringPiSetup (void) ;

int pinNumber = 7; //use gpio1 to read data

uint32 databuf;

uint8 readSensorData(void)

{

uint8 crc;

uint8 i;

pinMode(pinNumber,OUTPUT); // set mode to output

digitalWrite(pinNumber, 0); // output a high level

delay(25);

digitalWrite(pinNumber, 1); // output a low level

pinMode(pinNumber, INPUT); // set mode to input

pullUpDnControl(pinNumber,PUD_UP);

delayMicroseconds(27);

if(digitalRead(pinNumber)==0) //SENSOR ANS

{

while(!digitalRead(pinNumber)); //wait to high

for(i=0;i<32;i++)

{

while(digitalRead(pinNumber)); //data clock start

while(!digitalRead(pinNumber)); //data start

delayMicroseconds(HIGH_TIME);

databuf*=2;

if(digitalRead(pinNumber)==1) //1

{

databuf++;

}

for(i=0;i<8;i++)

{

while(digitalRead(pinNumber)); //data clock start

while(!digitalRead(pinNumber)); //data start

delayMicroseconds(HIGH_TIME);

crc*=2;

if(digitalRead(pinNumber)==1) //1

{

crc++;

}

return 1;

}

else

{

return 0;

}

int main (void)

{

printf("Use GPIO1 to read data!n");

if (-1 == wiringPiSetup()) {

printf("Setup wiringPi failed!");

return 1;

}

pinMode(pinNumber, OUTPUT); // set mode to output

digitalWrite(pinNumber, 1); // output a high level

printf("Enter OS——-n");

int i;

for(i = 0; i < 2; i++)

{

pinMode(pinNumber,OUTPUT); // set mode to output

digitalWrite(pinNumber, 1); // output a high level

delay(1000);

if(readSensorData())

{

printf("Congratulations ! Sensor data read ok!n");

printf("RH:%d.%dn",(databuf>>24)&0xff,(databuf>>16)&0xff);

printf("TMP:%d.%dn",(databuf>>8)&0xff,databuf&0xff);

databuf=0;

}

else

{

printf("Sorry! Sensor dosent ans!n");

databuf=0;

}

return 0;

}

4编译运行该代码,获得温湿度数据:

温湿度传感器dht11的lcd显示[嵌入式系统]

　　从结果可得：

　　　　温度为26.0摄氏度

　　　　湿度为44.0%

5。接下来是LCD显示数据：

LCD显示模块led_dht11.pyd 参考了git上的Adafruit_CharLCD()代码，主要的功能是读取dht11的执行结果进行lcd显示

#!/usr/bin/python

# based on code from lrvick and LiquidCrystal

# lrvic – https://github.com/lrvick/raspi-hd44780/blob/master/hd44780.py

# LiquidCrystal – https://github.com/arduino/Arduino/blob/master/libraries/LiquidCrystal/LiquidCrystal.cpp

import subprocess

import re

import sys

from time import sleep

from datetime import datetime

class Adafruit_CharLCD:

# commands

LCD_CLEARDISPLAY = 0×01

LCD_RETURNHOME = 0×02

LCD_ENTRYMODESET = 0×04

LCD_DISPLAYCONTROL = 0×08

LCD_CURSORSHIFT = 0×10

LCD_FUNCTIONSET = 0×20

LCD_SETCGRAMADDR = 0×40

LCD_SETDDRAMADDR = 0×80

# flags for display entry mode

LCD_ENTRYRIGHT = 0×00

LCD_ENTRYLEFT = 0×02

LCD_ENTRYSHIFTINCREMENT = 0×01

LCD_ENTRYSHIFTDECREMENT = 0×00

# flags for display on/off control

LCD_DISPLAYON = 0×04

LCD_DISPLAYOFF = 0×00

LCD_CURSORON = 0×02

LCD_CURSOROFF = 0×00

LCD_BLINKON = 0×01

LCD_BLINKOFF = 0×00

# flags for display/cursor shift

LCD_DISPLAYMOVE = 0×08

LCD_CURSORMOVE = 0×00

# flags for display/cursor shift

LCD_DISPLAYMOVE = 0×08

LCD_CURSORMOVE = 0×00

LCD_MOVERIGHT = 0×04

LCD_MOVELEFT = 0×00

# flags for function set

LCD_8BITMODE = 0×10

LCD_4BITMODE = 0×00

LCD_2LINE = 0×08

LCD_1LINE = 0×00

LCD_5x10DOTS = 0×04

LCD_5x8DOTS = 0×00

def __init__(self, pin_rs=14, pin_e=15, pins_db=[17, 18, 27, 22], GPIO = None):

# Emulate the old behavior of using RPi.GPIO if we haven’t been given

# an explicit GPIO interface to use

if not GPIO:

import RPi.GPIO as GPIO

self.GPIO = GPIO

self.pin_rs = pin_rs

self.pin_e = pin_e

self.pins_db = pins_db

self.GPIO.setmode(GPIO.BCM)

self.GPIO.setup(self.pin_e, GPIO.OUT)

self.GPIO.setup(self.pin_rs, GPIO.OUT)

for pin in self.pins_db:

self.GPIO.setup(pin, GPIO.OUT)

self.write4bits(0×33) # initialization

self.write4bits(0×32) # initialization

self.write4bits(0×28) # 2 line 5×7 matrix

self.write4bits(0x0C) # turn cursor off 0x0E to enable cursor

self.write4bits(0×06) # shift cursor right

self.displaycontrol = self.LCD_DISPLAYON | self.LCD_CURSOROFF | self.LCD_BLINKOFF

self.displayfunction = self.LCD_4BITMODE | self.LCD_1LINE | self.LCD_5x8DOTS

self.displayfunction |= self.LCD_2LINE

“”" Initialize to default text direction (for romance languages) “”"

self.displaymode = self.LCD_ENTRYLEFT | self.LCD_ENTRYSHIFTDECREMENT

self.write4bits(self.LCD_ENTRYMODESET | self.displaymode) # set the entry mode

self.clear()

def begin(self, cols, lines):

if (lines > 1):

self.numlines = lines

self.displayfunction |= self.LCD_2LINE

self.currline = 0

def home(self):

self.write4bits(self.LCD_RETURNHOME) # set cursor position to zero

self.delayMicroseconds(3000) # this command takes a long time!

def clear(self):

self.write4bits(self.LCD_CLEARDISPLAY) # command to clear display

self.delayMicroseconds(3000) # 3000 microsecond sleep, clearing the display takes a long time

def setCursor(self, col, row):

self.row_offsets = [ 0x00, 0x40, 0x14, 0x54 ]

if ( row > self.numlines ):

row = self.numlines – 1 # we count rows starting w/0

self.write4bits(self.LCD_SETDDRAMADDR | (col + self.row_offsets[row]))

def noDisplay(self):

“”" Turn the display off (quickly) “”"

self.displaycontrol &= ~self.LCD_DISPLAYON