Use same auth token on two Arduinos?

Hi all,

I have the following setup in my garage:

1 x Wemos D1 mini
1 x LCD screen
1 x indoor temp/humidity sensor
1 x outdoor temp/humidity sensors
1 x Blynk auth token which reads back to iPhone app

I would like the same setup in my house.

Do I need to fit another outside temp/humidity sensor?
As it will be the exact same readings.

Or, could I use the same Blynk auth token from above, and read the virtual pins from the garage in my 2nd Wemos sketch?

Would two instances of on two different device (same auth token) cause issues?


Although it is often possible to get things working when using the same Auth code on 2 devices, it’s not reccomended. The app now has the online status indicator for devices, and this only works correctly when using a unique Auth code on each device.
Also, device tiles don’t work correctly unless you use different Auth codes.

It’s very simple to add another device to your project and have widgets attached to the two (or more) devices displaying data on the same screen.

As you’ve identified, you only need to take outside readings on one device.


I assume you want to display the outdoor temperature and humidity on the LCD screen in your garage and on the LCD screen in your house. I’d use the Bridge Widget (it’s not really a widget per se) to communicate the outdoor temperature and humidity from the Wemos D1 mini in the garage to the Wemos D1 mini in the house. This doesn’t involve the iPhone app. From the perspective of the iPhone app, both devices will appear to have an indoor and outdoor temperature and humidity sensor. Each device will have its own auth token.


Hmmm, I obviously skipped over the bit about the LCD screen.
I couldn’t see any reason to use Bridge with the basic setup, but this approach makes sense when using LCD screens.


Thanks both - I hadn’t heard of the bridge widget, I will do some reading.

So the setup would be :
One outdoor sensor reading would be shared, and also each Wemos would have their own indoor sensor (so three sensors in total).

Cheers :grinning:

It is basically a way of controlling/reading “other” independent project’s devices from another project’s App screen, without needing much revamping at all.


In this screen, I am reading from three different sensors, the top two are on this projects physical device and the following are from separate sensors on other independent project’s physical devices outside. Bridge commands on each simply send the data to this projects vPins.

Not perfect, but here is a mini writeup I did…

Thanks @Gunner that’s great! It looks like exactly what I need.
I’ll have a good read and give it a go later!

Now I just need to get an accurate temp/humidity reading from my SHT30 :grin:

Took ages calibrating but it reads high temp/low humidity than the local weather stations. Just purchased one of these to see if it helps.

Anything with that apparent “acronym” in it’s model is either "The sh*t" or just plain "sh*t" :rofl: Ohh, marketing vs technical…

:laughing: I’m beginning to realise that!

Seems like it is a dark art getting accurate readings, I spent a few hours with Boveda 75% humidity bags and bowl of ice water and still have no clue :laughing:

Which setup do you have for your outside sensor?

Only the best… a DHT22 hanging on a wall :stuck_out_tongue:

Seems fairly accurate… it is wet and cold outside…


The thing is, wh e it comes to temperature and humidity you very rarely need an accurate reading - unless you’re planning to push your data up to weather underground or a similar service.

My sister has a thermostat in her house that can be set from 0 to 10. Putting it at 5 is comfortable most of the time and you bump it up to 6 if it’s a bit chilly.
Same with temperature/humidity readings. If it says 5°C and you know that means you need your big coat then it doesn’t really matter if that’s actually 3.5° or 7°, it’s just a number that you use as a guide.


@Gunner ha nice! Mine’s in a water bottle cut in half.

@PeteKnight yes that’s very true, it’s not actually that important. But for some irrational reason it messes with my OCD :laughing:


1 Like

Ha very true, our cat is very affectionate this time of year, always wants to sit on our laps :smile:

Here my indoor and outdoor setup, a bit bodged as I just wanted it over, and move onto the next project :laughing: :

You could always have your Wemos invoke the National Weather Service API and get rid of your outdoor sensors altogether. :grinning: Of course, you’d also get the Wind Speed, Dewpoint, Visibility, Wind Chill, … and the forecast for the next week.

You know what, I just might do that eventually :laughing:

I’m going to order a 2.4’ tft in the next order so will have a look for a project.