ESP8266 Community Forum

- Mon Apr 11, 2016 1:41 pm #45305 Hi,
We are trying to build a system that controls two relays using ESP8266-01
Does anyone know if this is possible? or we can only control a single relay.

Thanks

- Tue Apr 12, 2016 6:28 am #45348 Yes, you can use GPIO0 and GPIO2 as output; but beware of the initial state.

- Tue Apr 12, 2016 7:59 am #45356 The GPIO idle state should always be the same level as the require Boot state.
Since both GPIO2/GPIO0 need to be HIGH for proper boot, your relay circuit need to be HIGH when relay is OFF, so as explain in the last link, you need 2 NPN transistors, the first one to invert the GPIO level, and the second to drive the current to the relay. Those NPN can also be replaced by MOSFETs.

viewtopic.php?f=13&t=9441&p=45219#p45219

- Tue Apr 12, 2016 3:46 pm #45386 Thanks for your replies.
Will try your suggestions.

Also wanted to know, do we always have to hard code the wifi access point details? or can the ESP be connected to any WiFi dynamically.

For example, in my case, trying to use an iPhone app to trigger relays which are connected to ESP on a circuit board.
Hence, trying to figure out how to send access point details to ESP using iPhone.

Maybe its not easy as iPhone would not be able to communicate to ESP unless ESP is on a WiFi, right?
Would making ESP an access point itself will help?

Very new to all this, so please pardon any ignorance