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danjperron / PicoDHT22

Micropython DHT22 class using PIO
MIT License
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additional sleep time after powering up DHTxx #2

Closed allyourcodearebelongtous closed 2 years ago

allyourcodearebelongtous commented 3 years ago

Datasheet states: "When power is supplied to the sensor, do not send any instruction to the sensor in within one second in order to pass the unstable status." So after poweing up the sensor using the powerPin wait an additional 800ms to stay within specs

danjperron commented 3 years ago

Hi Allyourcodearebelongtous. Where di you get this spec ?
The only thing I found out was 2 seconds! But in reality mine never had problem with 100ms.

allyourcodearebelongtous commented 3 years ago

Hi Daniel,

 

sorry for being late...

 

Infos can be found in the datasheet https://www.mouser.com/datasheet/2/758/DHT11-Technical-Data-Sheet-Translated-Version-1143054.pdf

 

  1. Power and Pin

DHT11’s power supply is 3-5.5V DC. When power is supplied to the sensor, do not send any instruction to the sensor in within one second in order to pass the unstable status. One capacitor valued 100nF can be added between VDD and GND for power filtering.

 

But you are right, it worked with the shorter timeout as well. 

 

Cheers,

Hampf

 

Gesendet: Freitag, 09. April 2021 um 16:25 Uhr Von: "Daniel Perron" @.> An: "danjperron/PicoDHT22" @.> Cc: "Hampf" @.>, "Author" @.> Betreff: Re: [danjperron/PicoDHT22] additional sleep time after powering up DHTxx (#2)

 

Hi Allyourcodearebelongtous. Where di you get this spec ? The only thing I found out was 2 seconds! But in reality mine never had problem with 100ms.

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