Let's Control It

i read this on the net: the GPIOs can take 5V.

http://www.ba0sh1.com/2016/08/03/is-esp ... -tolerant/

i did not tried myself, but there are good explanation and graphs, how it works..
if it is true, one could spare some level-shifting on certain projects?

Wow, interesting.... Good find Tozett

the article say:

Conclusion

I believe the experiment result is conclusive. The ESP8266 I/O is 5V tolerant unless couple of uA current can destroy the chip. Except for completely wrong wiring, such as feed 5V into 3.3v rail or feed 5V into output pin (in output low state or in output high with push-pull mode), 5V on GPIO pins will not destroy ESP8266.

Though that was exactly what I did some time ago.
By accident I feeded a ESP07 with 5V instead of 3.3V-3.6V for about 5 minutes and it survived.
The ESP-module still works.

Hi All,

It is true, and the data sheet even eludes to the fact, that the GPIO are 5V tolerant but here's the rub. The pins have protection clamping diodes on the pins that protect the circuitry from over voltage. The problem is that they usually can only take 20-25ma of current. If you want to use these pins with 5V it is best to include a series resistor. This technique has been used many times in some uncomfortably puckering situations. One ap-note I read from Atmel many years ago used an AVR input pin to sense the AC line directly to get the mains line frequency as a time base for a digital clock. They actually put a several meg ohm resistor on one of the I/O lines and plugged it into the wall!! On that processor The current was limited to 25ma max so as long as the series resistor limited the current to less than 25 ma all was fine.
I use a similar technique on my ESP designs to interface the 5V 315mhz receivers to the ESP8266. I run everything through 10K ohm resistors and it all works happy.

Regards

Dave

thats is very gud stuff, where you find this??