 |
Photo from Flickr    cc-by-nc-nd by Ham Hock |
Adafruit created a very good tutorial explaining how to use DHT11 or DHT22 . This tutorial is available at this address: http://learn.adafruit.com/dht-humidity-sensing-on-raspberry-pi-with-gdocs-logging/wiring.
Electronic assembly
This electronic assembly is quite simple and will need:
- 1 x DHT11 or 1 x DHT22
- 1 x 4.7k resistor
 |
| Schema extracted from Adafruit but using GPIO #27 instead of GPIO #4 |
Software installation
Thanks to Adafruit ( again ;-) ) the installation is quite simple and can be done with two command lines.
Download Adafruit_DHT form Adafruit's github repository and copy is in /usr/bin as follow:
wget http://goo.gl/oadpl -O Adafruit_DHT
sudo cp Adafruit_DHT /usr/bin/
To test the electronic assembly and the software installation execute the following command (for DHT11):
pi@raspberrypi ~ $ sudo Adafruit_DHT 11 27
Using pin #17Data (40): 0x28 0x0 0x18 0x0 0x40
Temp = 24 *C, Hum = 40 %
You should see the information about temperature and humidity displayed as shown upper.
Note: The DHT11 and DHT22 sensors will only respond every second so if you are not getting data, be sure to wait few seconds before trying again.
Note: The DHT11 and DHT22 sensors will only respond every second so if you are not getting data, be sure to wait few seconds before trying again.
RPi-Monitor configuration
Warning: Be sure to use Linux linefeed format with line ending with LF (and not CR/LF like in Windows).
Let's now use this information and add humidity graphs on existing temperature graph.
We first have to extract the data. This is done like this:
As the unit are different than the one existing on the initial axis, we will add a second axis for the percentage of humidity. This is the purpose of the two last lines of the configuration bellow.
The first line is defining the usage of axis number 2 for the humidity.
The last line is defining how this graph should be drawn: On the right, starting from 0 up to 100.
graph_options can have other usefull option. They are described in the documentation of javascriptrrd.
After restarting RPi-Monotor with the command:
service rpimonitor restartYou will see a new curve in Temperature graph as shown in the screenshot bellow:
 |
| Graph with 2 Y axis: °C in left axis and % humidity (fixed from 0% to 100%) on right axis |
Hello.
ReplyDeleteI am using Rpi-monitor for use radiooaficionado Raspberry with.
But I am unable to join in a plot temp and hum with the DHT22.
Adafruit command if I read well the values, but I can not do well because the temp change I always get 0.
Can you help?
dynamic.15.name=humidity
dynamic.15.source=Adafruit_DHT 22 10
dynamic.15.regexp=Hum = (\S+)
dynamic.15.postprocess=$1/1
dynamic.15.rrd=GAUGE
dynamic.16.name=temperature
dynamic.16.source=Adafruit_DHT 22 10
dynamic.16.regexp=Temp = (\d+)$
dynamic.16.postprocess=$1/1
dynamic.16.rrd=GAUGE
==============================
web.statistics.1.content.9.name=Temperature & Humidity BOX
web.statistics.1.content.9.graph.1=humidity
web.statistics.1.content.9.graph.2=temperature
web.statistics.1.content.9.ds_graph_opts.humidity.label=Humidity (%)
web.statistics.1.content.9.ds_graph_opts.temperature.label=Temperature (*C)
web.statistics.1.content.9.ds_graph_opts.humidity.yaxis=1
web.statistics.1.content.9.ds_graph_opts.temperature.yaxis=2
web.statistics.1.content.9.graph_opts.y1axis={ position: "right", min: 0, max: 100 }
web.statistics.1.content.9.graph_opts.y2axis={ position: "right", min: 0, max: 100 }
Hello,
DeleteThe first thing is to check if the command from Adafruit is working. I guess you checked that. Be sure th install this command in /usr/bin to ensure it is in the path.
To configure rpimonitor, you should ensure that the dynamic Id (15 and 16 in your example) are immédialtely followin the last number already existing in the configuration file.
The same comment goes to the Id of web.satsistics.1.content.
You don't need to pose process the result. You can let the temperature axis be defined automatically (remove y1axis).
The regexp for temperature is wrong, it should be: dynamic.16.regexp=Temp = (\S+)
I hope it will help.
You can refer to github to see how I did customize my installation.
https://github.com/XavierBerger/RPi-Monitor/blob/master/rpimonitor/custo.conf
Hello, I am having the same issue, I have changed the temp to (\S+), and my code is nearly identical. Cant quite get it to work. Any suggestions? Thanks
DeleteHello,
DeleteTo define the exact command and regular expression to add in customized configuration file, it is recommended to test and validate the command before adding it into the configuration file. This can be done easily like this:
COMMAND | perl -ne '/REGEXP/' and print "$1\n"'
Example:
Adafruit_DHT 11 27 | perl -ne '/Hum = (\S+)/' and print "$1\n"'
The expected result is a valid number (integer or real).
Note: $1 can be replaced by the porsprocessing formula.
Once you are sure the value is extracted correctly, you can check if the configuration made is not going in conflict with other definition.
In fact there is a double space after the = sign in Adafruit_DHT's output.
DeletePutting two spaces between = and (\S+) works fine in my custom config, without the additional space it was returning 0.0.
It looks like double spaces are suppressed in the comment publishing
dynamic.16.regexp=Temp = (\S+)
Hello guys,
ReplyDeleteI am also using DHT11 with adafruit code, and I found a possible bug.
In the file Adafruit_DHT.c, line 94, the while loop waits for the gpio pin to rise.
However, if for some reason this does not happens, the program hangs.
So I added a counter (named safety) to wait maximum 1 millisec.
If no answer comes, the function returns with error code 2.
int safety=0;
while (bcm2835_gpio_lev(pin) == 1 || safety > 1000) { // wait max 1000us
usleep(1);
safety++;
}
if (safety > 1000){ // if no answer, quit
return 2;
My conf
ReplyDelete########################################################################
# Living root temperature and humidity added in dedicated pages
########################################################################
dynamic.15.name=living_room_temp
dynamic.15.source=Adafruit_DHT 2302 4
dynamic.15.regexp=Temp = (\d+)$
dynamic.15.postprocess=$1/1
dynamic.15.rrd=GAUGE
web.status.2.name=Living room
web.status.2.content.1.name=Temperature
web.status.2.content.1.icon=cpu_temp.png
web.status.2.content.1.line.1="Ambiant Temperature: "+data.living_room_temp+"°C"
web.statistics.2.name=Living room
web.statistics.2.content.1.name=Temperature
web.statistics.2.content.1.graph.1=living_room_temp
web.statistics.2.content.1.ds_graph_options.living_room_temp.label=Ambient temp. (deg C)
dynamic.16.name=humidity
dynamic.16.source=Adafruit_DHT 22 4
dynamic.16.regexp=Hum = (\S+)
dynamic.16.postprocess=$1/1
dynamic.16.rrd=GAUGE
web.statistics.2.content.1.graph.2=humidity
web.statistics.2.content.1.ds_graph_options.humidity.label=Humidity (%)
web.statistics.2.content.1.ds_graph_options.humidity.yaxis=2
#web.statistics.2.content.1.graph_options.legend= { position: "sw"}
web.statistics.2.content.1.graph_options.y2axis={ position: "right", min: 0, max: 100 }
dht22 on 4
Humidty is ok but not temp. Adafruit_DHT 2302 4 write right temp and hum.
What is wrong? Please help My Raspberry http://aiamaa.no-ip.org:8888
I notice that command used as source is different... sometime 22 sontime 2302...
DeleteYou also use a postprocess command which have no sense: $1/1
Did you check the regular expression? I would advise to read the comments I mase upper, you will certainly find interresting tips helping you to find the solution.
rpi-monitor 2.0
ReplyDelete/etc/rpimonitor.conf
part of this file
########################################################################
# Living root temperature and humidity added in dedicated pages
########################################################################
dynamic.15.name=living_room_temp
dynamic.15.source=Adafruit_DHT 22 4
dynamic.15.regexp=Temp = (\d+)$
dynamic.15.postprocess=$1/1000
dynamic.15.rrd=GAUGE
web.status.2.name=Living room
web.status.2.content.1.name=Temperature
web.status.2.content.1.icon=cpu_temp.png
web.status.2.content.1.line.1="Ambiant Temperature: "+data.living_room_temp+"°C"
web.statistics.2.name=Living room
web.statistics.2.content.1.name=Temperature
web.statistics.2.content.1.graph.1=living_room_temp
web.statistics.2.content.1.ds_graph_options.living_room_temp.label=Ambient temp. (deg C)
dynamic.16.name=humidity
dynamic.16.source=Adafruit_DHT 22 4
dynamic.16.regexp=Hum = (\S+)
dynamic.16.postprocess=$1/1
dynamic.16.rrd=GAUGE
web.statistics.2.content.1.graph.2=humidity
web.statistics.2.content.1.ds_graph_options.humidity.label=Humidity (%)
web.statistics.2.content.1.ds_graph_options.humidity.yaxis=2
#web.statistics.2.content.1.graph_options.legend= { position: "sw"}
web.statistics.2.content.1.graph_options.y2axis={ position: "right", min: 0, max: 100 }
not working.
Adafruit_DHT 22 4 command working ok. Where is error ?
What's not working? You description of the problem is not detailled enough to allow me to help you but I'll try....
DeleteDid you check the regular expression as proposed in my previous answer? (Ref comment of September 10, 2013 at 11:34 AM) ... I guess no :-(.
If the output of DHT22 is the same as DHT11:
Temp = 24 *C, Hum = 40 %
Then, your regular expression for tempetature is wrong. Remove the tailing $ and check the RegExp with the command line described upper.
Once your regular expression will work, then add it into the configuration file.
Good morning Xavier,
ReplyDeletefirst thanks very much for your nice and valuable monitor!!
I added the DHT11 to my RPI and found, thst every 2nd or 3rd measurement goes to zero, and so there are gaps in the graph. I think this is due to much to short delays between triggering of the readout program.
My question is, how to stretch the delay between the measurements?
Many Regards,
Christoph
Hi Christoph,
DeleteThe delay is configurable. There is a parameter to set into /etc/rpimonitord.conf.
I let you read the comment in this file to find the parameter to update.
This value will be active after restarting rpimonitord: sudo service rpimonitor restart
Cheers,
Xavier
Hi Xavier
ReplyDeleteI really appreciate you making this tool available. Thank you.
I am having trouble with a DHT22 and version 2.5.1. When I run on 2.4 version 2.4 I get nice clean graph.
After updating to 2.5.1 I get a very noisey graph with lots of 0 values.
If I downgrade to 2.4.1 the graph becomes clean again
I think its because the DHT22 gives lots of unknown data readings and because the two versions of RPi-Monitor treat unknown data differently.
Can you tell me a little about what
"Update rrd graph with unkown data if fetched information is not a valid number"
means in the 2.5.1 release notes?
Regards
Brian Pratt
Hi Brian,
DeleteRPi-Monitor is designed to graph the data extracted. In previous version the behavior of the graph was not reliable since sometime no data were stored in the RRD. Now, it stored the data extracted or unknow, there is no more hole in the RRD.
You are experiencing a side effect now and it let me wonder if your previous graph was correct or not... Not sure that the timeline was correct.
With a sensor which is not reliable, I would propose to do like this:
1/Create a script which is getting the info from the sensor and updating a file when the data is correct.
2/Configure Rpi-Monitor to read the information in this file.
Like this, if your sensor doesn't send information, the data stored in RRD will be the same as the previous one.
I think this will solve your issue.
Rgds,
Xavier
Hi Xavier,
ReplyDeleteI can't put temperature readings from DHT22 to RPi-mon statistics. My DHT22 (AM2302) are working fine and I am able to get temp and hum data from it:
sudo Adafruit_DHT 2302 18
Using pin #18
Data (40): 0x0 0xd1 0x1 0x2c 0xfe
Temp = 30.0 *C, Hum = 20.9 %
Can you help me to add both temperature and humidity data from DHT22 to RPi-monitor?
Here is my config:
Deletedynamic.21.name=t5
dynamic.21.source=Adafruit_DHT 2302 18
dynamic.21.regexp=Temp = (\S+)
dynamic.21.postprocess=
dynamic.21.rrd=GAUGE
dynamic.22.name=humidity
dynamic.22.source=Adafruit_DHT 2302 18
dynamic.22.regexp=Hum = (\S+)
dynamic.22.postprocess=
dynamic.22.rrd=GAUGE
web.statistics.1.content.8.graph.7=t5
web.statistics.1.content.8.ds_graph_options.t5.label=t5 (deg C)
web.statistics.1.content.8.graph.8=humidity
web.statistics.1.content.8.ds_graph_options.humidity.label=Humidity (%)
web.statistics.1.content.8.ds_graph_options.humidity.yaxis=2
web.statistics.1.content.8.graph_options.y2axis={ position: "right", min: 0, max: 100 }
What's wrong with it?
Nothing obvious...
DeleteI would advise to read upper comments about perl command to check the regular expression and to have a look to the sample files in github like https://github.com/XavierBerger/RPi-Monitor/blob/master/rpimonitor/custo.conf
Solved:
ReplyDeletedynamic.21.regexp=Temp =<--!!ADD TWO SPACES HERE!!-->(\S+)
So, the line should be:
dynamic.21.regexp=Temp = (\S+)
And only ONE space for Humidity line:
dynamic.22.regexp=Hum = (\S+)
Take care!
Hi Xavier,
ReplyDeletefirst I would like to thank you for this great tool!
It took me a bit of tinkering but now I got it (mostly) to show what I want.
There is one thing that I would like to correct: I am reading information from a remote sensor into a file. Among other I read the voltage of the battery in form of a number like 115. Then I calculate the voltage 115*0.02+1 (3.3V) this value is stored in the database.
dynamic.24.name=voltage
dynamic.24.source=/home/pi/script/sensor.txt
dynamic.24.regexp=/(.*?)/(.*?)/(.*)
dynamic.24.postprocess=$3*0.02+1
dynamic.24.rrd=GAUGE
The status page shows 3.3 which is correct but the statistic page shows values like:
3.3000000000000007
3.2999999999999994
Is there a way to correct this?
Cheers
Harry
Ok here is how I solved the problem:
Deleteweb.statistics.2.content.3.graph_options.yaxis={min: 3, max: 5}
This prevents it from auto-scaling the y-axis.
Cheers
Harry
Xaiver:
ReplyDeleteThis is a great tool, thanks for pulling it together.
The DHT22 has an issue where it returns bad data if you query it too often. To work around that, I've created a script that queries the sensor once for temperature and humidity and then appends it to a file. The script is executed by cron on a periodic basis.
I then configured rpimonitor to read that file for the values as follows:
dynamic.17.name=ambient_humid
dynamic.17.source=/home/pi/humid.out
dynamic.17.regexp=Hum = (\S+)
dynamic.17.postprocess=
dynamic.17.rrd=GAUGE
dynamic.18.name=ambient_temp
dynamic.18.source=/home/pi/humid.out
dynamic.18.regexp=Temp = (\S+)
dynamic.18.postprocess=($1*1.8)+32
dynamic.18.rrd=GAUGE
Collection and graphing seem to be working as I expect, but I'm curious as to what method rpimonitor uses to read a file.
If I'm reading the code right, sub Process() in package Monitor handles this. It looks to me as though it iterates through all lines in the data file and will write each value into the RRD. However, when I dump the rrd, I see far fewer datapoints than I'd expect if it were doing that. Instead, rpimonitor looks as though it is looking at the last line in the file only. (Which is what I want it to do.)
Can you shed some light on this? Does rpimonitor read all lines and aggregate the data, or does it just read the last?
Thanks.
Hello,
DeleteI didn't design rpimonitor to read more than one postprocess line and I don't know how it will behave if more than one.
Cheers,
Xavier
Hello Xavier!
ReplyDeleteThank you for your RPI monitor, its awesome, but something is not working for me.
Well the DHT22 is works fine i get temperatures. But the graph is wrong, i can't do the same like your. This is my config and graph:
https://dl.dropboxusercontent.com/u/13922338/Screen%20Shot%202013-12-31%20at%2017.18.07.png
All i want same the cpu temperature or your graph, but i can't fix that. :(
Best Regards,
Szergely
Everything worked perfectly, thanks Xavier.
ReplyDeleteHello Xavier, when I try to test Adafruit_DHT it says: sudo: Adafruit_DHT: command not found
ReplyDeleteFirst I run:
wget http://goo.gl/oadpl -O Adafruit_DHT
sudo cp Adafruit_DHT /usr/bin/
Do I need to chmod Adafruit_DHT?
Thanks
Alright, I installed like the tutorial link above and copied to /usr/bin, now it works in terminal, I just have to write:
ReplyDelete'sudo Adafruit_DHT 2302 4' instead of 'Adafruit_DHT 2302 4', don't know why I need sudo...
Xavier, I edit the /etc/rpimonitord.conf/default.conf and added this:
ReplyDelete'dynamic.17.name=humidity
dynamic.17.source=Adafruit_DHT 2302 4
dynamic.17.regexp=Hum = (\S+)
dynamic.17.postprocess=
dynamic.17.rrd=GAUGE'
and this:
'web.statistics.1.content.8.graph.3=humidity
web.statistics.1.content.8.ds_graph_options.humidity.label=Humidity (%)
web.statistics.1.content.8.ds_graph_options.humidity.yaxis=2
web.statistics.1.content.8.graph_options.y2axis={ position: "right", min: 0, max: 100 }'
But know when I go to Statics in Rpi-monitor it gimes me the following error:
'File stat/null.rrd is not a valid RRD archive!'
note that I used 'dynamic.17.source=Adafruit_DHT 2302 4' instead of Adafruit_DHT 11 27
Hope you can help me.
On the basis of all of the above I was able to do so. Everything works.
ReplyDeletedynamic.16.name=humidity
dynamic.16.source=/home/pi/humid.out
dynamic.16.regexp=Hum = (\S+)
dynamic.16.postprocess=
dynamic.16.rrd=GAUGE
dynamic.17.name=temperature
dynamic.17.source=/home/pi/humid.out
dynamic.17.regexp=Temp = (\S+)
dynamic.17.postprocess=
dynamic.17.rrd=GAUGE
web.statistics.1.content.9.name=Temperature & Humidity
web.statistics.1.content.9.graph.1=humidity
web.statistics.1.content.9.graph.2=temperature
web.statistics.1.content.9.ds_graph_opts.humidity.label=Humidity (%)
web.statistics.1.content.9.ds_graph_opts.temperature.label=Temperature (*C)
web.statistics.1.content.9.ds_graph_opts.humidity.yaxis=1
web.statistics.1.content.9.ds_graph_opts.temperature.yaxis=2
web.statistics.1.content.9.graph_opts.y1axis={ position: "right", min: 0, max: $
web.statistics.1.content.9.graph_opts.y2axis={ position: "right", min: 0, max: $
Script that writes data to a file:
#!/usr/bin/python
import subprocess
import re
import sys
while(True):
output = subprocess.check_output(["./Adafruit_DHT", "22", "4"]);
f1 = open("humid.out", 'w')
f1.write (output)
f1.close()
print output
matches = re.search("Temp =\s+([0-9.]+)", output)
if (not matches):
time.sleep(2)
continue
temp = float(matches.group(1))
matches = re.search("Hum =\s+([0-9.]+)", output)
if (not matches):
time.sleep(2)
continue
humidity = float(matches.group(1))
sys.exit()
Alezxxx when I try to run your script this is what I get:
Delete"pi@raspberrypi ~ $ ./humid.out
File "./humid.out", line 8
output = subprocess.check_output(["./Adafruit_DHT", "22", "4"]);
^
IndentationError: expected an indented block"
Already tried with sudo and the result is the same.
When I run: sudo ./Adafruit_DHT 22 4
Using pin #4
Data (40): 0x2 0x17 0x0 0xa9 0xc2
Temp = 16.9 *C, Hum = 53.5 %
The results are ok, but if I try to run without sudo this is what I get:
"bcm2835_init: Unable to open /dev/mem: Permission denied"
What I'm doing wrong?
Hope you can help me.
Thanks.
This comment has been removed by the author.
DeleteWhat is the problem with sampling? It's common for an undefined value. I have DHT11.
ReplyDeleteScrenshot from graph:
http://dl.dropbox.com/u/3577295/Kijel%C3%B6l%C3%A9s_015.png
I often answer to such a question...
DeleteYou will now find the answer into the FAQ page.
Try to record the temperature and humidity readings in a file with check writing the correct value, and then add the file to the chart.
DeleteThe following bash script helped me about this problem:
Deletehttps://github.com/gajdipajti/munin-rpi-temp/blob/master/rpi-dht-sensor_
:-)
Dear Xavier,
ReplyDeletefirst of all, thank for sharing your work with us. I am not a programmer just a computer enthusiast. I am trying to do something...easy I think but due to lack of knowledge I stuck. I want to graph 3 sources on the same graph (I have a BMP085 sensor connected to a Pi), Temp, Hum and Pressure. The problem is the value of the barometric pressure which is hundred of times higher that the temperature and humidity and can't be represented on the same axis without jeopardizing the other two. I want to transfer the Pressure values on the left vertical axis of the graph table but...I don't know how! I have tried several things but no luck. Could you please help me ?
Thanks in Advance!
RPi-Monitor is fully configurable. Each configuration is different and have his specificity. It is not possible to provide a configuration for each situation.
DeleteNevertheless, to reach you objective, I would advise you to read carefully this article and try to reproduce what is described here sharply. Once this will work, you will have enough knowledge to update and customize your configuration file to your wishes.
Thanks for your reply. I solved it somehow by following your example. This is my configuration:
Deletedynamic.17.name=pressure
dynamic.17.source=bmp085
dynamic.17.regexp=Pressure (\S+)
dynamic.17.postprocess=
dynamic.17.rrd=GAUGE
dynamic.18.name=humidity
dynamic.18.source=nice -20 loldht 7
dynamic.18.regexp=Humidity = (\S+)
dynamic.18.postprocess=$1/1
dynamic.18.rrd=GAUGE
dynamic.19.name=temperature
dynamic.19.source=bmp085
dynamic.19.regexp=Temperature (\S+)
dynamic.19.postprocess=$1/1
dynamic.19.rrd=GAUGE
web.statistics.1.content.9.name=PC Room
web.statistics.1.content.9.graph.1=humidity
web.statistics.1.content.9.graph.2=pressure
web.statistics.1.content.9.graph.3=temperature
web.statistics.1.content.9.ds_graph_options.humidity.label=Hum (%)
web.statistics.1.content.9.ds_graph_options.pressure.label=Bar (hPa)
web.statistics.1.content.9.ds_graph_options.temperature.label=Temp (*C)
web.statistics.1.content.9.ds_graph_options.humidity.yaxis=1
web.statistics.1.content.9.ds_graph_options.pressure.yaxis=2
web.statistics.1.content.9.graph_options.y1axis={ position: "right", min: 0, max: 100 }
web.statistics.1.content.9.graph_options.y2axis={ position: "left", min: 0, max: 1150 }
Thanks again and keep up good work.
This comment has been removed by the author.
ReplyDelete