ESP8266 Community Forum

- Thu Feb 11, 2016 11:38 am #40925 Hi everyone,

So I've seen a lot of tutorials where people have set up a transmitter on their esp8266 but I haven't seen anything where someone has set up a receiver for 433MHz. I have a pretty specific purpose for this which is why its probably a wierd request. Just wondering if anyone has any advice because I'm having trouble working with any exosting libraries and im also not sure how to wire it as some libraries require interrupts?

I'm using an ESP-12E and these: http://www.gearbest.com/development-boa ... oCsvTw_wcB

Hopefully someone can help me out.

Thanks

- Thu Feb 11, 2016 12:45 pm #40929 I had success with the library and example code here: https://github.com/sui77/rc-switch/. I also have a 12E and the same radio module.

The only thing to note with the example code, is that you don't need to map pin numbers - just enter the actual number of the GPIO pin. (The example says something like enableReceive(0) # which is #2 - but for the ESP8266 you would use enableReceive(2) instead. (Assuming you've connected DATA to GPIO.2)).

I've not done much work with this - I was just testing the concept. One thing I noticed was that it was quite unresponsive; it needs a long blast of RF to decode it. This may well be customisable in the library.

Also, that RF receiver requires a 5V supply- it won't work at 3.3V. Obviously the data stream coming out is at 5V as well, so I used a resistor divider to lower it. I've since discovered that the ESP8266 can tolerate 5V on its inputs, so that's not necessary. (Well mine's survived )

Stockport, UK

- Thu Feb 11, 2016 2:17 pm #40933 AJ for the wireless on an Arduino there is a library called Virtual wire which I believe works very well. Whether or not it would work on an ESP using the esp/Arduino IDE I do not know. Presumably you already have some device that uses 433 Mhz but might you not be better off just using the ESP module driving a relay to operate your end device?

Phil, I think that the collective wisdom is that whilst some on line information suggests the ESP inputs 'tolerate' 5 volts it is bad practise to feed them with 5 volts as it renders them unreliable. Sadly there is a lot on information on the net about ESP's that is just plain wrong!
Your initial plan to use a resistor divider is one of the ways of achieving logic level matching as long as it is suited to the signals being transmitted. i.e. it doesn't work well with some SD cards, but is fine for slow logic signals.

hope that helps
Bob (Bakewell)

- Thu Feb 11, 2016 8:28 pm #40948

Phil, I think that the collective wisdom is that whilst some on line information suggests the ESP inputs 'tolerate' 5 volts it is bad practise to feed them with 5 volts as it renders them unreliable.

I certainly found conflicting information on the subject, but the datasheet says:
"All digital IO pins are protected from over-voltage with a snap-back circuit connected between the pad and ground. The snap-back voltage is typically about 6V, and the holding voltage is 5.8V"

Now I will admit to not understanding precisely what that means - and it may well have lost something in translation - but it was enough encouragement for me to try it...
...I'll report back if anything goes bang!

Stockport, UK