Rodrigo Fraga asked 6 years ago
I have HELTEC and TTGO boards and these one have GPIO pins INPUT ONLY and when I connect any sensor in these pins I don´t have the informations.
I tryed to use DHT22, soil humidity, pir and many others.
Does anyone know why or does it have any tips?
Sara Santos Staff answered 6 years ago
Hi Rodrigo.
As I said in my previous response, the input-only pins can be used to read digital inputs or analog inputs. The DHT22 won’t work with those pins as it requires a communication protocol.
The PIR sensor is a digital input, so it was supposed to work.
If your soil moisture sensor is a simple analog input that changes the output voltage accordingly to water content, it should also work.
I have no idea why that is happening 😐
So, if anyone has any idea why those pins may not work, please share.
Rodrigo Fraga answered 6 years ago
Hi Sara thanks for your explanation. I found a site that make a explanation about DHTXX after you told me about protocol. Every document that I had read just say OUTPUT DIGITAL SIGNAL.
http://www.ocfreaks.com/basics-interfacing-dht11-dht22-humidity-temperature-sensor-mcu/
Look, a new topic in your book…. SENSORS
Sara Santos Staff answered 6 years ago
Yes, the DHT sensors use onewire protocol. So, you can’t use them with those pins.
I’m glad that helped!
Regards,
Sara 🙂