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Hello
to finich my program http://www.matrixmultimedia.com/mmforum ... =3&t=11509
I need a help to program the sensor DHT 11 with flowcode using 16f877A
Does somebody worked with this sensor ?
Really I need your help
Thank you

Hi
Sorry , Im not familiar with that sensor.
I've just looked on you-tube and there are a lot of tutorials about it with both PICs and Arduinos
Maybe you will find some information on that site.

Hi

I am writing code for you for the chip with the help of Ben's earlier post. Hopefully I can finish that tonight.

Thanks,

have a look here may be of some use

http://embedded-lab.com/blog/?p=4333

Steve

Hi Steve

I am using that link and Ben's macro for data read to write flowcode file. You have guided to right one.

thank you for you help
I m also trying to write the code in flowcode but i didn't arrive yet

this is a part of the code by ben
http://www.matrixmultimedia.com/mmforum ... T11#p36845

Yes, I have seen that.

Here is the code I have been working on..I have followed the c code given in the following link
http://embedded-lab.com/blog/?p=4333
Most of the thing I have tried to follow and even PIC but you can change that to any PIC you want. Please let me know how it's behaving. I don't have the sensor that's why I can't test it but hopefully it will work.

Thank you so much ; I will test it in the test board and i will tell you the result
I hope that it work

Hello Enamul
The code of the dht11 doesn't work , it shows always No response from the sensor
I tested he .hex of http://embedded-lab.com/blog/?p=4333 and it works correctly
so I am trying to change some parametres

Hi

I think there is a problem in the code for managing TMR0..I have modified that. Can you please try now? By the way what crystal frequency you are using for the code I have posted? Time is very critical for this device and the code.
It need to be 4MHz..

yes I am using the 4MHZ crystal
ok i will try this code now

now it didn't show anything ! I wrote "hello" in the beginnig of the program to see if te program is running and it is shown
then nothing in te LCD ! and when I remove the data pins it shows checkSum ERROR
that means that CheckSum is not equal to (RH_Byte1 + RH_Byte2 + T_Byte1 + T_Byte2)
so the program entred in the working mode .

Yes, you are right. If it's showing nothing in the LCD that means program entered in the working mode. That's a good sign. But it seems to me now that Read_Byte macro is not working properly. If it stuck at some point only then LCD can be blank otherwise LCD should say "Checksum error!" or right results. I have to have a look again in the Read_Byte macro..but that is ok I think as Ben has written that.

Hi
I have checked the code but I can't get any issue. Just disabled TMR0 after timing requirements. You can try if still don't work what I can do I have to order one for me to test practically. You have to wait couple of days in that case.

Hi

I have ordered one for me..I will get that in Friday..so hopefully we can solve that by Friday

Hi

One more try with change in checksum...as the datasheet says checksum will be the last byte of the summation of first 4 bytes.

Nothing has changed
OK Enamul ; until that moment I will try with it again
Tank you so much

Have you tried my last post?

yes I tried it but nothing new ; when I removed the dht11
and I start the lcd shows CheckSum Error !! Normally it goes to NOT response , isn't ?

After spending one whole evening I have manged to make the sensor working...

I will make a separate thread for that...I will post link to you..but you need 20MHz crystal 4MHz isn't enough for this.

Good work , what was the problem in the precedent proram ? No problem for the quartz
I think it's the same thing when I use it with another pic 18f , I mean th horloge doesn't change
Thanks

Here is the link of the post...
http://www.matrixmultimedia.com/mmforum ... =7&t=11555