ESP8266 Community Forum

- Fri Jul 22, 2016 2:22 am #51242 Hi,
I'm not 100% sure on the DHTxx but in general if the sensor has a wider supply range (e.g. 1.8-5V) it is totally ok to connect its Vcc to a gpio to control supply.

One thing to obey: if you use external pull-ups on i2c, several sensors will not accept Vcc disconected while parasiticly being supplied via pull-ups on i2c (e.g. BME280 specifically warns about!).

If you're not using external pull-ups (only esp8266 internal), keep connections short.
If you power pull-ups and sensor via gpio, think on providing time for Vcc to settle and sensor to startup.

BUT: most modern sensors usually go to deep sleep (only several µA) between measurements, making this "trick" unnecessary.

Last edited by schufti on Fri Jul 22, 2016 11:58 am, edited 1 time in total.

- Fri Jul 22, 2016 7:40 am #51256 Thank you for the explanation this is working perfectly. Will now try with the moisture sensor.

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- Fri Jul 22, 2016 9:00 am #51262

Hi schufti & martinayotte, I think the method of connecting RESET and GPIO16 hasn't really been discussed properly and deserves its own post rather than distracting this one. I suggest a new post tomorrow as I think there are some interesting arguments.

Of courses we should avoid distractions, but here it was to remove the confusion about the "direct wire" usage, so I've posted this history reminder (as people usually doesn't do searches). There is no real needs for separate thread since it have been thoroughly discussed back in February when discovered, but also in March and April :
viewtopic.php?p=41537#p41537
viewtopic.php?p=43300#p43300
viewtopic.php?p=45650#p45650

- Fri Jul 22, 2016 9:48 am #51265 The info was useful thanks. Also using light sleep and powering up the sensors from gpio I now have the moisture sensor and the dht running one is being tested on a 9v and one on two x aa batteries will pos how long they last for when tested thanks for the help guys.

Amazing selection of ESP8266 and ESP32 modules can be found here.