Level Shifter necessary?

[SpatialJ]

Hi,
usually the esp8266 are 5v 'tolerant', has anyone tried to connect an esp without the extra levelshifter?

[DYLaKo]

As far as I know, the ESP8266 as used (The Wemos D1) only supplies 5V, but does not accept 5V on the inputs. That is what the level shifter is used for.

[SpatialJ]

I have a pzem-004t directly connected with 5v ttl on an esp, and it works.
Also see https://ba0sh1.com/2016/08/03/is-esp8266-io-really-5v-tolerant/
That's why I was wondering if anybody tried it yet. It might of course decrease the lifespan of the esp.

[absalom-muc]

According to the electrical characteristics the esp8266 is not 5V tolerant. I'm sure the vendor would release the devices for 5V if they could guarantee that it would work for all operating conditions.

[SpatialJ]

Well, as desceibed in the link I provided, it is :-D absalom-muc ***@***.***> schrieb am Sa., 14. Aug. 2021, 09:24:

…

According to the electrical characteristics the esp8266 is *not* 5V tolerant. I'm sure the vendor would release the devices for 5V if they could guarantee that it would work for all operating conditions. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#65 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAC3NS5KJNNEOYFRUKC4IYTT4YK2TANCNFSM47NY2U5Q> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&utm_campaign=notification-email> .

[absalom-muc]

Well, as desceibed in the link I provided, it is :-D

Sorry, but your conclusion is wrong. There might be some examples (maybe 10 or 100) where the user haven't observed a wrong behavior or damage when using 5V for the port inputs. But it is wrong to conclude that this is valid for all ESP8266 (maybe many millions).

[dasrue]

Hi, I have set mine up with no level shifter today. I needed to put a pullup resistor (I used 12K) on the MISO line to stop it picking up a frequency on the line. It works. Beforehand I also tested putting 5V into the pins and found the draw was only a few uA so I don't think there will be any damage to the pins

[nmg196]

The CEO of Espressif (Tao Swee Ann) has officially stated that the IO pins (only!) are 5V tolerant:

....and the reason it doesn't mention this in the data sheet is apparently due to user confusion:

(Source: https://www.facebook.com/groups/1499045113679103/permalink/1731855033731442/?hc_location=ufi)

So it seems a level shifter is definitely not necessary. This also means that for Mitsubishi Electric units (which supply 5V) you can wire something like a Wemos S2 Mini directly to the connector without any kind of PCB or other components. For MHI units, these are 12V and will need an inline buck converter to reduce 12v to 5v.

[absalom-muc]

Thanks for sharing it @nmg196. It sounds strange for me considering a Facebook statement, but not the datsheet. This is for me more confusing, especially because I don't understand the statement

Does he mean "open drain"? Is it a hint that a resistor should be used?
Maybe I'm being overly cautious but I will continue using the level shifter - just my 2 cents.

[nmg196]

Fair enough - I'll try it without a level shifter for a while and report back here if my board goes on fire ;)

I would have no idea how to get the PCB made up here and I doubt a custom one would be cheap?