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Topic: DHT22/AM2302 pull-up resistor yes or not (Read 1 time) previous topic - next topic

go3mon

Hi everyone,
I wanna build a little data logger for Humidity and Temperature using DHT22/AM2302 sensor and SD Card module.

I have seen some schemas connecting directly ground, 5v and data (digital port 2) to Arduino and other schemas using a pull-up resistor between data and vcc.

What's the difference?

Many thanks



wvmarle

It requires a pull-up resistor.
You can use the internal pull-up (that's why you sometimes see circuits without external pull-up resistor) but it's pretty weak, better to use a stronger pull-up (10k is a good value for this).
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Zachrey

#2
Mar 14, 2019, 10:17 pm Last Edit: Mar 14, 2019, 10:18 pm by Zachrey
I just put an ohm-meter to five AOSONG AMS2302 DHT22 devices, between VCC and DATA and am reading a surprisingly consistent 4.7K-ohms. And I stickem on an Arduino Uno R3 and an ESP-12E (MakerFocus) and works great, so far! No more monkeying around with pullup resistors!

I suspect AOSONG must've got enough complaints from people to add the bugger internally??

wvmarle

You probably have one of the versions with small PCB attached (so three pins instead of the four the sensor itself comes with), which will then also have this pull-up resistor in place.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

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