In the DHT22, why we are using pull up resistor, instead of a pull down? : Tech Explorations Help Desk

In the DHT22, why we are using pull up resistor, instead of a pull down? Print

Created by: Peter Dalmaris

Modified on: Thu, 22 Feb, 2018 at 12:46 PM

To understand the reason, please start by having a look at the datasheet for this sensor (attached with this article), and scroll down to section 7.

Just before the header for section 7, you will see this line:

If signal from DHT22 is always high-voltage-level, it means DHT22
is not working properly, please check the electrical connection status.

This information answers the question.

If there is a problem with the sensor, the data signal will be constantly HIGH because of the pull-up resistor, and this is something that the DHT library can use to detect the problem.

Peter is the author of this solution article.

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In the DHT22, why we are using pull up resistor, instead of a pull down? Print

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