DHT11/DHT22

Temperatursensor.

DHT11/DHT22/AM2302/AM2320

Innehåll.

Tillbaka till Raspbery Pi
Inledning.
Installation.
C-program DHT11.
C-program DHT22.
Python-program AM2320.
Python-program BMP280.
BME280 alternativ.
Lagra i databas.
Lagra i databas med Python.
Crontab.
Support/Hjälp.
Problem.
Referens.

Inledning.

DHT11 är en fukt- och temperatursensor som använder i2c för kommunikation med omvärlden.
DHT11s mätområde är 0 - 50 grader C. Är fuktkänslig, klarar inte regn.
DHT22s mätområde är -40 - 80 grader C.
AM2320 är likvärdig DHT22. Dock inte vad gäller mekaniskt utförande.
BME, BMP280 är en temperatur- och trycksensor. Mätområde -40 - 85 grader C. Tryck 300 - 1100 hPa.

Till början.

Installation.

Koppla in DHT11 enligt vad nedanstående bild visar.

Raspberry Pi _____________ DHT11 Module
3.3v P1 ————————— VCC (V)
GND P6 ————————-- GND (G)
GPIO4 P7 ———————–--DATA (S)

Koppla in DHT22/AM2302 enligt vad nedanstående bild visar.

Raspberry Pi _____________ DHT22 Module
3.3v P1 ————————— VCC (1)
GND P6 ————————-- GND (4)
GPIO4 P7 ———————–--DATA (2)
Används ej _______________NC (3)

Koppla in AM2320 enligt vad nedanstående bild visar.

Raspberry Pi _____________ AM2320 Module
3.3v P1 ————————— VDD (1)
GND P6 ————————-- GND (3)
GPIO4 P7 ———————–- DATA (2)
GPIO3 P5 _______________SCL (4)

Montera ett motstånd på 4.7 kOhm mellan pinne 2 och pinne 1 samt mellan pinne 4 och pinne 1.

Till början.

C-program DHT11.

Kompilera programmet: gcc -o dht11 dht11.c -lwiringPi -lwiringPiDev
Exekvera programmet: sudo ./dht11
Avbryt programmet med: ctrl-c

dht11.c
/* * dht11.c: * Simple test program to test the wiringPi functions * DHT11 test */ #include <wiringPi.h> #include <stdio.h> #include <stdlib.h> #include <stdint.h> #define MAXTIMINGS 85 #define DHTPIN 7 int dht11_dat[5] = { 0, 0, 0, 0, 0 }; void read_dht11_dat() { uint8_t laststate = HIGH; uint8_t counter = 0; uint8_t j = 0, i; float f; /* fahrenheit */ dht11_dat[0] = dht11_dat[1] = dht11_dat[2] = dht11_dat[3] = dht11_dat[4] = 0; /* pull pin down for 18 milliseconds */ pinMode( DHTPIN, OUTPUT ); digitalWrite( DHTPIN, LOW ); delay( 18 ); /* then pull it up for 40 microseconds */ digitalWrite( DHTPIN, HIGH ); delayMicroseconds( 40 ); /* prepare to read the pin */ pinMode( DHTPIN, INPUT ); /* detect change and read data */ for ( i = 0; i < MAXTIMINGS; i++ ) { counter = 0; while ( digitalRead( DHTPIN ) == laststate ) { counter++; delayMicroseconds( 1 ); if ( counter == 255 ) { break; } } laststate = digitalRead( DHTPIN ); if ( counter == 255 ) break; /* ignore first 3 transitions */ if ( (i >= 4) && (i % 2 == 0) ) { /* shove each bit into the storage bytes */ dht11_dat[j / 8] <<= 1; if ( counter > 16 ) dht11_dat[j / 8] |= 1; j++; } } /* * check we read 40 bits (8bit x 5 ) + verify checksum in the last byte * print it out if data is good */ if ( (j >= 40) && (dht11_dat[4] == ( (dht11_dat[0] + dht11_dat[1] + dht11_dat[2] + dht11_dat[3]) & 0xFF) ) ) { f = dht11_dat[2] * 9. / 5. + 32; printf( "Humidity = %d.%d %% Temperature = %d.%d *C (%.1f *F)\n", dht11_dat[0], dht11_dat[1], dht11_dat[2], dht11_dat[3], f ); }else { printf( "Data not good, skip\n" ); } } int main( void ) { printf( "Raspberry Pi wiringPi DHT11 Temperature test program\n" ); if ( wiringPiSetup() == -1 ) exit( 1 ); while ( 1 ) { read_dht11_dat(); delay( 1000 ); /* wait 1sec to refresh */ } return(0); }

Resultat.
Raspberry Pi wiringPi DHT11 Temperature test program Data not good, skip Humidity = 18.0 % Temperature = 25.0 C (77.0 F) Humidity = 18.0 % Temperature = 25.0 C (77.0 F) Data not good, skip Humidity = 18.0 % Temperature = 25.0 C (77.0 F) Humidity = 18.0 % Temperature = 25.0 C (77.0 F) Humidity = 18.0 % Temperature = 25.0 C (77.0 F) Humidity = 18.0 % Temperature = 25.0 C (77.0 F) Humidity = 18.0 % Temperature = 25.0 C (77.0 F) Humidity = 18.0 % Temperature = 25.0 C (77.0 F) Data not good, skip Humidity = 18.0 % Temperature = 25.0 C (77.0 F)

Modifierat program.

dht11_3v4.c
Programmet läser av värdena en gång per timme. Ifall data icke är OK läser programmet av data flera gånger tills data är OK. Programmet startas via crontab en gång per timme.

/*
 *  dht11_3v4.c:
 *	Simple test program to test the wiringPi functions
 *	DHT11 test
 *  Kompilera: gcc -o dht11_3v4 dht11_3v4.c -lwiringPi -lwiringPiDev 
 *  Exekvera: sudo ./dht11_3v4
 */
 
#include <wiringPi.h>
 
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <time.h>

#define MAXTIMINGS	85
#define DHTPIN		7
int dht11_dat[5] = { 0, 0, 0, 0, 0 };
 
int read_dht11_dat()
{
	uint8_t laststate	= HIGH;
	uint8_t counter		= 0;
	uint8_t j		= 0, i;
	float	f; /* fahrenheit */
	char buffer[40];
 	time_t curtime;
	struct tm *loctime;

/* Get the current time.  */
	curtime = time (NULL);

/* Convert it to local time representation.  */
	loctime = localtime (&curtime);

FILE *fp;
	
	dht11_dat[0] = dht11_dat[1] = dht11_dat[2] = dht11_dat[3] = dht11_dat[4] = 0;
 
	/* pull pin down for 18 milliseconds */
	pinMode( DHTPIN, OUTPUT );
	digitalWrite( DHTPIN, LOW );
	delay( 18 );
	/* then pull it up for 40 microseconds */
	digitalWrite( DHTPIN, HIGH );
	delayMicroseconds( 40 );
	/* prepare to read the pin */
	pinMode( DHTPIN, INPUT );
 
	/* detect change and read data */
	for ( i = 0; i < MAXTIMINGS; i++ )
	{
		counter = 0;
		while ( digitalRead( DHTPIN ) == laststate )
		{
			counter++;
			delayMicroseconds( 1 );
			if ( counter == 255 )
			{
				break;
			}
		}
		laststate = digitalRead( DHTPIN );
 
		if ( counter == 255 )
			break;
 
		/* ignore first 3 transitions */
		if ( (i >= 4) && (i % 2 == 0) )
		{
			/* shove each bit into the storage bytes */
			dht11_dat[j / 8] <<= 1;
			if ( counter > 16 )
				dht11_dat[j / 8] |= 1;
			j++;
		}
	}
 
	/*
	 * check we read 40 bits (8bit x 5 ) + verify checksum in the last byte
	 * print it out if data is good
	 */
	if ( (j >= 40) &&
		(dht11_dat[4] == ( (dht11_dat[0] + dht11_dat[1] + dht11_dat[2] + dht11_dat[3]) & 0xFF) ) )
	{
		strftime (buffer, 40, "%Y-%m-%d %H:%M", loctime);
		f = dht11_dat[2] * 9. / 5. + 32;
		printf( "Datum = %s Humidity = %d.%d %% Temperature = %d.%d *C (%.1f *F)\n",
			buffer, dht11_dat[0], dht11_dat[1], dht11_dat[2], dht11_dat[3], f );
		fp=fopen("/home/pi/Documents/Data/temp2.txt", "a+");
		fprintf(fp,"%s %d.%d  %d.%d\n",buffer,dht11_dat[0],dht11_dat[1],dht11_dat[2],dht11_dat[3]);
		fclose(fp);
		return 0;
	}else  {
		printf( "Data not good, skip\n" );
		return 1;
	}
}
 
int main( void )
{
	int flag=0;
	printf( "Raspberry Pi wiringPi DHT11 Temperature test program\n" );
 
	if ( wiringPiSetup() == -1 )
		exit( 1 );
	flag=1;
	while ( flag==1 )
	{
		flag=read_dht11_dat();
		printf("flag=%d\n");
		delay( 2000 ); /* wait 1 hour to refresh */
	}
 
	return(0);
}

Resultat.

Till början.

C-program DHT22.

Kompilera programmet: gcc -o dht22 dht22.c -lwiringPi -lwiringPiDev
Exekvera programmet: sudo ./dht22
Avbryt programmet med: ctrl-c

dht22.c
/* * dht22.c: * 2017-08-13 Jan Pihlgren * * read temperature and humidity from DHT11 or DHT22 sensor * Kopilera: gcc -Wall dht22.c -o dht22 -lwiringPi -lwiringPiDev * Exekvera: sudo ./dht22 */ #include <wiringPi.h> #include <stdio.h> #include <stdlib.h> #include <stdint.h> #include <time.h> #define MAX_TIMINGS 85 #define DHT_PIN 7 /* GPIO-04 */ int data[5] = { 0, 0, 0, 0, 0 }; int read_dht22_data() { uint8_t laststate = HIGH; uint8_t counter = 0; uint8_t j = 0, i; // float f; /* fahrenheit */ char buffer[40]; time_t curtime; struct tm *loctime; /* Get the current time. */ curtime = time (NULL); /* Convert it to local time representation. */ loctime = localtime (&curtime); FILE *fp; data[0] = data[1] = data[2] = data[3] = data[4] = 0; /* pull pin down for 18 milliseconds */ pinMode( DHT_PIN, OUTPUT ); digitalWrite( DHT_PIN, LOW ); delay( 18 ); /* prepare to read the pin */ pinMode( DHT_PIN, INPUT ); /* detect change and read data */ for ( i = 0; i < MAX_TIMINGS; i++ ) { counter = 0; while ( digitalRead( DHT_PIN ) == laststate ) { counter++; delayMicroseconds( 1 ); if ( counter == 255 ) { break; } } laststate = digitalRead( DHT_PIN ); if ( counter == 255 ) break; /* ignore first 3 transitions */ if ( (i >= 4) && (i % 2 == 0) ) { /* shove each bit into the storage bytes */ data[j / 8] <<= 1; if ( counter > 16 ) data[j / 8] |= 1; j++; } } /* * check we read 40 bits (8bit x 5 ) + verify checksum in the last byte * print it out if data is good */ if ( (j >= 40) && (data[4] == ( (data[0] + data[1] + data[2] + data[3]) & 0xFF) ) ) { strftime (buffer, 40, "%Y-%m-%d %H:%M", loctime); float h = (float)((data[0] << 8) + data[1]) / 10; if ( h > 100 ) { h = data[0]; // for DHT11 } float c = (float)(((data[2] & 0x7F) << 8) + data[3]) / 10; if ( c > 125 ) { c = data[2]; // for DHT11 } if ( data[2] & 0x80 ) { c = -c; } float f = c * 1.8f + 32; printf( "Datum = %s Humidity = %.1f %% Temperature = %.1f *C (%.1f *F)\n",buffer, h, c, f ); fp=fopen("/home/pi/Documents/Data/temp_dht22.txt", "w+"); fprintf(fp,"%s %.1f %.1f\n",buffer,h,c); fclose(fp); //delay(60000); return 0; }else { printf( "Data not good, skip\n" ); return -1; } } int main( void ) { int flag=0; printf( "Raspberry Pi DHT22 temperatur test program\n" ); if ( wiringPiSetup() == -1 ) exit( 1 ); flag= -1; while ( flag== -1 ) { flag=read_dht22_data(); printf("flag=%d\n",flag); delay(2000); /* wait 2 seconds before next read */ } return(0); }

OBS! Data skickas till /home/pi/Documents/Data/temp_dht22.txt. Ändra så det passar dig.

Python-program AM2320.

Exekvera programmet: ./code.py
Avbryt programmet med: ctrl-c

code.py

#!/usr/bin/python3
# -*- coding: utf-8 -*-
#**************************************
# code.py
# Modified 2019-02-07 av Jan Pihlgren
#**************************************/

import time
import board
import busio
import adafruit_am2320
# create the I2C shared bus
i2c = busio.I2C(board.SCL, board.SDA)
am = adafruit_am2320.AM2320(i2c)
while True:
    print("Temperature: ", am.temperature)
    print("Humidity: ", am.relative_humidity)
    time.sleep(2)

Till början.

Python-program BMP280.

Först behöver man installera nödvändiga python-bibliotek.

pip3 install adafruit-blinka
pip3 install pureio
pip3 install spidev
pip3 install adafruit-GPIO
pip3 install adafruit-circuitpython-bme280

bme280sensor.py

#******************************************
# bme280sensor.py
#
#******************************************/

import time 
import board
import busio
import adafruit_bme280
from ISStreamer.Streamer import Streamer

# Create library object using our Bus I2C port
i2c = busio.I2C(board.SCL, board.SDA)
bme280 = adafruit_bme280.Adafruit_BME280_I2C(i2c)
 
# --------- User Settings ---------
SENSOR_LOCATION_NAME = "Office"
BUCKET_NAME = ":partly_sunny: Room Temperature"
BUCKET_KEY = "temp1"
ACCESS_KEY = "YOUR ACCESS KEY HERE"
# change this to match the location's pressure (hPa) at sea level
bme280.sea_level_pressure = 1013.25
MINUTES_BETWEEN_READS = 10
METRIC_UNITS = False
# ---------------------------------

# OR create library object using our Bus SPI port
#spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
#bme_cs = digitalio.DigitalInOut(board.D10)
#bme280 = adafruit_bme280.Adafruit_BME280_SPI(spi, bme_cs)

streamer = Streamer(bucket_name=BUCKET_NAME, bucket_key=BUCKET_KEY, access_key=ACCESS_KEY)
while True:
        humidity = format(bme280.humidity, ".1f")
        pressure = format(bme280.pressure, ".1f")
        temp_c = bme280.temperature
        if METRIC_UNITS:
                streamer.log(SENSOR_LOCATION_NAME + "Temperature(C)", temp_c)
        else:
                temp_f = format(temp_c * 9.0 / 5.0 + 32.0, ".1f")
                streamer.log(SENSOR_LOCATION_NAME + " Temperature(F)", temp_f)
        streamer.log(SENSOR_LOCATION_NAME + "Humidity(%)", humidity)
        streamer.log(SENSOR_LOCATION_NAME + "Pressure(hPA)", pressure)
        streamer.flush()
        time.sleep(60*MINUTES_BETWEEN_READS)

Programmet exekveras med:
python3 bme280sensor.py

BME280 alternativ.

Installation:
git clone https://github.com/pimoroni/bme280-python
cd bme280-python
sudo ./install.sh
Aktivera I2C:
i2c: sudo raspi-config nonint do_i2c 0

Ett test kan göras genom att exekvera programmet /home/pi/bme280-python/examples/all-values.py
Programmet avbryts med Ctrl-C

Till början.

Lagra data i en databas.

Avlästa data kan lagras i en MySQL-databas. Här beskrivs hur man skapar en MySQL-databas. Exemplet nedan använder databasen temperatur. Databasen har en tabell, temp med kolummerna datum, tid, fukt och temp.

Program för att läsa in data i databasen.

insert_v4.c

/*************************************************
 * insert_v4.c
 * Jan Pihlgren  2016-07-27
 * Kompilering: gcc insert_v4.c -L/lib64/mysql -L/usr/lib64 -lmysqlclient -o insert
 * Exekvering: ./insert
 * 
 *************************************************/ 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include </usr/include/mysql/mysql.h>

int main(int argc, char **argv)
{
  
  FILE *fp;

MYSQL *conn;
  MYSQL_RES *result;
  MYSQL_ROW row;

int num_fields;
  int i;

char *server = "localhost";
  char *user = "root";
  char *password = "raspberry"; /* sätt lösenordet för root först. Ange detta här. */
  char *database = "temperatur";
  char *query = NULL;

char datum[11];
  char tid[6];
  char fukt[5];
  char temp[5];
 
  int storlek=28;
  int postnr;
  char oldtid[6];
  char sql[256]="INSERT INTO temp(datum,tid,fukt,temp) VALUES(";
  char sqlquery[256];
  
  conn = mysql_init(NULL);
   
  if (mysql_real_connect(conn, server, user, password, database, 0, NULL, 0) == NULL) {
         fprintf(stderr, "%s\n", mysql_error(conn));
         mysql_close(conn);
         exit(1);
  }
    
  fp=fopen("/home/pi/Documents/Data/temp2.txt", "r");
  //fseek(fp,SEEK_SET,0);
  //fscanf(fp,"%s %s %s %s",datum,tid,fukt,temp);

postnr=0;
  while (!feof(fp)){
	fseek(fp,0,SEEK_CUR); //offset = 0 för textfiler.
	fscanf(fp,"%s %s %s %s",datum,tid,fukt,temp);
	if(strcmp(tid,oldtid) != 0){
	//printf("postnr=%d Datum = %s Tid = %s Fukt = %s Temp = %s\n",postnr,datum,tid,fukt,temp);
		postnr++;
		strcpy(sqlquery,sql);
		strcat(sqlquery,"'");
		strcat(sqlquery,datum);
		strcat(sqlquery,"'");
		strcat(sqlquery,",'");
		strcat(sqlquery,tid);
		strcat(sqlquery,"',");
		strcat(sqlquery,fukt);
		strcat(sqlquery,",");
		strcat(sqlquery,temp);
		strcat(sqlquery,")");
	
		//printf("sqlquery = %s\n",sqlquery);
	
		if(mysql_query(conn,sqlquery)){
			fprintf(stderr,"%s\n",mysql_error(conn));
			mysql_close(conn);
			exit(1);
		}
	}
	strcpy(oldtid,tid);
  }

fclose(fp);
  mysql_close(conn);
  sleep(60);
  system("rm /home/pi/Documents/Data/temp2.txt");
}

Crontab.

Exempel på hur crontab kan se ut. Här körs programmet en gång per timme, 5 minuter över heltimme.

Lagra i databas med Python.

Program: DHT-temp-sql.py

#!/usr/bin/python
# DHT22-temp-sql.py
# Modifierad av: Jan Pihlgren 20190209
# Copyright (c) 2014 Adafruit Industries
# Author: Tony DiCola

# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:

# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
import sys

import Adafruit_DHT
from datetime import datetime
import mysql.connector

mydb = mysql.connector.connect(
	host="Localhost",
	user="root",
	passwd="raspberry",
	database="temperatur"
	)
	
# Parse command line parameters.
sensor_args = { '11': Adafruit_DHT.DHT11,
                '22': Adafruit_DHT.DHT22,
                '2302': Adafruit_DHT.AM2302 }
if len(sys.argv) == 3 and sys.argv[1] in sensor_args:
    sensor = sensor_args[sys.argv[1]]
    pin = sys.argv[2]
else:
    print('Usage: sudo ./Adafruit_DHT.py [11|22|2302] <GPIO pin number>')
    print('Example: sudo ./Adafruit_DHT.py 2302 4 - Read from an AM2302 connected to GPIO pin #4')
    sys.exit(1)

# Try to grab a sensor reading.  Use the read_retry method which will retry up
# to 15 times to get a sensor reading (waiting 2 seconds between each retry).
humidity, temperature = Adafruit_DHT.read_retry(sensor, pin)

# Un-comment the line below to convert the temperature to Fahrenheit.
# temperature = temperature * 9/5.0 + 32

# Note that sometimes you won't get a reading and
# the results will be null (because Linux can't
# guarantee the timing of calls to read the sensor).
# If this happens try again!
if humidity is not None and temperature is not None:
    now = datetime.now()
    date_date = now.strftime("%Y-%m-%d")
    date_time = now.strftime("%H:%M")
    print "Datum = ",date_time, ('Temp={0:0.1f}*  Humidity={1:0.1f}%'.format(temperature, humidity))
    mycursor = mydb.cursor()
    sql = "INSERT INTO temp (datum,tid,temp,fukt) VALUES (%s,%s,%s,%s)"
    val = (date_date,date_time, ('{0:0.1f}'.format(temperature)),('{0:0.1f}'.format(humidity)))
    print val
    mycursor.execute(sql, val)
    mydb.commit()
#    file = open("/home/pi/Documents/Data/temp3.txt","w")
#    file.write(date_time)
#    file.write(' {0:0.1f} {1:0.1f}'.format(temperature, humidity))
#    file.close()
else:
    print('Failed to get reading. Try again!')
    sys.exit(1)

Programmet exekveras med kommandot: sudo DHT22-temp-sql.py 22 4
22 = DHT22, 4 = GPIO 4(Rpi nr 7)

Support/Hjälp.

Vi har noterat att exemplet dht11.c ibland förlorar data. Detta beror på att Raspberry Pi inte är ett realtidssystem, tidshanteringen i programmet är inte tillräckligt noggrant, och detta leder i bland till ett fel i i överföringen. På grund av att C är ett lågnivåspråk, kontrollerar det GPIO pinnarna på ett mer direkt sätt, så examplet i C har en mindre chans att falera.
Som ett sätt att gå runt problemet kan vi köra programmet flera gånger för att fånga upp det rätta resultatet. Detta kan även lösas programmässigt.
I programmet dht11_3v4 har vi ordnat så att ogiltiga data spolas.

Till början.

Problem.

20190205, strax efter klockan 1, avbröts inhämtningen av aktuell temperatur i en av mina Raspberry Pi Zero. Först trodde jag att databasen blivit full. Efter att jag kontrollerat att så icke var fallet försökte jag att manuell köra programmet som avläser DHT22. Resultatet uteblev. Varpå jag tog in sensorn och fann att två av anslutningspinnarna "rostat" av.
Jag införskaffade då nya sensorer men erhöll AM2320 som skulle vara eqvivalent med DHT22 men det visade sig att så icke var fallet.
Nu har jag beställt DHT22 och hoppas att jag verkigen får rätt den här gången.
Jag fick AM2302 som vad jag förstår är ekvivalent med DHT22. Mitt C-program fungerade inte men jag har hittat ett Python-program som fungerar som jag vill. Jag ska bara göra en mindre justering så kommer det att fungera utmärkt.

Referens.

Kjell & Co.
UUGear.
Datablad AM2320.
AM2302 Temp/Humidity Sensor.

Till början.

Erfarenheter av DHT11, DHT22/AM2302och BMP280 sensor.

Erfarenheter av DHT11, DHT22/AM2302
och BMP280 sensor.