x3mvz5pl5g5k asked 3 years ago
I am experiencing incorrect readings of Temp and Humidity in this project. All wiring was re-confirmed and code uploaded from the github account.
Although I am successfully connecting with nRF connect for Android, I see only notifications for humidity – nothing for temperature as depicted in the lesson.
Also, the readings for temperature and humidity output to the Serial Monitor are grossly incorrect. I double-checked with two DHT11 sensors, and confirmed their accuracy using the Asynchronous Web Server code [Module 4 – Unit 11]. Results from this show 72.32 deg F, 35.50 %, which is appropriate for my room environment. Results using BLE, however, were 0.40 deg C, 10.20 %.
Note: Due to previous issues with the Asynchronous Web Server code, version 1.8.9 was used in lieu of 1.8.10.
I would appreciate any insight on what might be the problem. I did not try 1.8.10 because it’s inconvenient to flip/flop between versions. If there is a way to have both versions installed I could try that.
Thanks!
Sara Santos Staff answered 3 years ago
Hi.
I’m sorry you’re having that issue.
When using the BLE example, do you get the wrong readings on the OLED display and in the serial monitor?
Or just in the OLED display? The wrong readings are on the client side only, or both client and server?
It is very difficult to find out what might be wrong.
Regards,
Sara
x3mvz5pl5g5k answered 3 years ago
Sara, I haven’t reached Part 2 yet. For a moment I saw both temp and humidity in nRF Connect, but they were still grossly inaccurate. Then I played around with the serial monitor and reset button and no longer got readings. I tried to unpair/pair but no readings appeared. I also noticed if I turn on the serial monitor it goes crazy “Failed to read from DHT sensor!”.
Sara Santos Staff answered 3 years ago
Hi.
That’s very weird and it is very difficult to find out what might be wrong.
Were you able to get correct temperature readings with this example at least once? Or did you always get them incorrect?
Can you take a look at this article and see if any of the suggestions may apply to your case: https://randomnerdtutorials.com/solved-dht11-dht22-failed-to-read-from-dht-sensor/?
Regards,
Sara
x3mvz5pl5g5k answered 3 years ago
This article helped me resolve the issue. I was using a smaller, 3-pin sensor as compared to the one in the lesson. I incorrectly assumed it was a DHT11, so when I changed back to the DHT22 all was good and the readings are accurate.
I think the real lesson here is when trouble-shooting, especially for complex projects involving hardware and software, after you try a few “most-likely” solutions, it might be wise to go through the entire project and systematically write down each possible step that might create a problem. Then confirm, repair or change out to other solutions for each step.
Also, in nRF Connect, could you clarify the meaning of the three down arrows? In the lesson, all are open, yet I only received readings when I crossed these symbols out.
¡Una vez más, muchas gracias por su ayuda!
Sara Santos Staff answered 3 years ago
Hi.
I’m glad the issue with the sensor is solved now.
I found this explanation about the icons on the nRF connect app on a forum:
arrow pointing down = read
arrow pointing up = write (type to be chosen on the dialog) or send notification/indication (when in Server tab)
3 arrows pointing down = enable notifications
3 arrows pointing down, crossed = disable notifications
2 arrows, one up, one down = enable indications
2 arrows, one up, one down, crossed = disable indications
I hope this helps.
Regards,
Sara