I have 2 boards that are giving me trouble when connected to battery.
AB02A v1.0
AB02 (dev-6502)
Both boards have a DHT22 connected to them.
AB02A
Powered by USB, the board sends Temp/Humid/Voltage to the LoRaWan network.
Powered by Battery, the board does NOT connect to the LoRaWan network.
Voltage is at 3.7
AB02
Powered by USB, the board sends Temp/Humid/Voltage to the LoRaWan network.
Powered by Battery, the board sends only Voltage.
Voltage is at 3.8
How is the DHT22 connected to the board?
Measure and compare the voltage on DHT22 while on battery and USB.
Posting the Code without keys would help too.
What all have you tried to diagnose the problem?
@dstacer Thanks for replying.
The DHT22 in connected to pin 5.
Vlt/Gnd have been connected to both VEXT and VIN (oops that in isn’t it), anyway the behavior was the same.
What all have you tried to diagnose the problem?
Uh… Cried out for help on this forum. 30 yrs of biz coding, but kinda new at this game.
Let me check the volt on the DHT.
I will post code then.
Thanks.
@dstacer Thank you for asking me about the volts on usb and on bat. I checked and they were both 3.3.
Now I know to check things like that.
The AB02 works on battery and is sending Temp/Humi/Volts.
I am now connected to VDD, not VIN or VEXT.
Thanks again.
With my new debugging skills, (thanks to you) I checked the AB02A.
Battery out of the board: Volts 3.6
Battery in the board: Volts: 1.52
DHT: Volts: 1.50
Why would the battery itself drop so much when I put it in the board?
I have exactly same issue with distance sensor and temp sensor.
Battery out of the board 3.6V
Battery in the board 2.6V
I use standard pin for sensor (Vext,Gnd,Scl,Sda)
I tried with battery fenso 14505 and ls saft 1400
Battery voltage drops under a load. Make sure your battery is charged or try another larger capacity battery. Temperature has a big impact on voltage too.
https://learn.adafruit.com/dht/connecting-to-a-dhtxx-sensor says the DHT22 sometimes has problems at 3.3v so not much hope of it working at 1.5v.
https://resource.heltec.cn/download/CubeCell/HTCC-AB02/AB02.pdf table 3.2 and 3.4 show voltage and power requirements for the AB02 board, then add the load from the sensors for your total load requirements.
because the circuit needs for a short time “a lot of power” while sending data I suggest to add an electrolytic capacitor of about 47 to 150uF to stabilize it