I have an Arduino Uno and the new version arduino-1.0. I have downloaded the program and the *.h, *.cpp files from Arduino Playground - HomePage.

When compiling I get the error message:
dht11_test1.cpp.o: In function loop': C:\.../dht11_test1.cpp:72: undefined reference to dht11::read(int)'

On line 72 of the dht11_test1.cpp there is not read(int).
The strange thing is that the file is called dht11.cpp and I did not find any reference to dht11_test1.cpp.

Any ideas.

Thanks in advance

Do you have the updated version 0.4.0? That is supposed to be the 1.0 compatible version...

Hello MarkT,

sure I use 0.4.0. 8)


Hi LeseLaster,

I just tested the code if it would compile and it did without errors. (I could have made an error when uploading it)

Can you check if you have installed the library in the right place? That would cause same error.

Remember the library needs to be installed with no instance of the IDE running as the IDE seems to read the libs at startup (for the menu I guess).

Hello robtillaart,

sorry for occupying the bandwidth. I erased everything on the disk which had the dht11 in the filename and installed the files new and it: Worked.

Thanks for your advice and patience. I made a longer pause programming with the Arduino and noticed that since the new version a lot has changed and I have to adapt my older programs.


I've written another lib that supports the DHT22 too. The DHT22 has more precission - Arduino Playground - HomePage - might be worth a look.

Thanks for the hint. I will have a look and afterwards I have to buy the dht22 :cold_sweat: