Re: ESP pin to power 4x DHT22 or use transitor/mosfet
Posted: Mon Jan 08, 2018 1:32 pmThe maxim app note https://www.maximintegrated.com/en/app- ... mvp/id/148 provides some useful information.
Reports of successfully achieving distances of 50m seem to benefit from lower pull ups (e.g. 2.2K) and wiring the data/gnd as a pair, and the supply/gnd as another pair. Some also say some sensors benefit from being run at 5V but with the one wire pull up to 3.3V.
Having said that, my personal strategy is to avoid long cable runs which are a pain in the neck for all sorts of reasons. The big benefit of the ESP modules is to avoid this by putting them next to the sensor and letting wifi replace the cable. They are sufficiently small and cheap to sprinkle them around as required. Obviously the wifi range can become a factor but there are chaining methods that can be employed if that becomes a problem.
Reports of successfully achieving distances of 50m seem to benefit from lower pull ups (e.g. 2.2K) and wiring the data/gnd as a pair, and the supply/gnd as another pair. Some also say some sensors benefit from being run at 5V but with the one wire pull up to 3.3V.
Having said that, my personal strategy is to avoid long cable runs which are a pain in the neck for all sorts of reasons. The big benefit of the ESP modules is to avoid this by putting them next to the sensor and letting wifi replace the cable. They are sufficiently small and cheap to sprinkle them around as required. Obviously the wifi range can become a factor but there are chaining methods that can be employed if that becomes a problem.
