ESP8266 Community Forum

- Fri Jun 26, 2015 4:33 pm #21826

There's no truth-table entry anywhere I've looked for what would happen if GPIO0 is 1 and GPIO2 is 0 at boot. When I get home I'll try it on one of my sacrificial ESP-01s

2 - No-one's mentioned whether the ESP8266 has internal pullups, which are more common these days. I can't lay my hands immediately on a doc which exhaustively details what internal pullup/downs are available

I have never mentioned anywhere that GPIO2 should be low .

I have attempted to show the pin can be left unconnected , floating or used for whatever purpose you wish and quite correctly so. I have proved the case to the chargrin of martinayotte and have nothing more to say on the matter to him.

Incidentally if it helps you in the wiki it says that it can be

" 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. This provides protection from over-voltages and ESD. The output devices are also protected from reversed voltages with diodes.

GPIO0-GPIO15 can be INPUT, OUTPUT, INPUT_PULLUP, and INPUT_PULLDOWN.

Last edited by tytower on Mon Jun 29, 2015 3:41 pm, edited 1 time in total.

Get you modules here:

https://www.banggood.com/custlink/KvGGhGF4wG

- Fri Jun 26, 2015 6:30 pm #21837

That is a Phurffy presented by martinayotte to try to give his personal attack on me some credibility.

But YOU wrote :

It appears that both might work and maybe the truth table should be ammended to "x" floating ?

And I've answered :

It should NOT be amended to please end-users. [...] if GPIO2 had a X instead of H, then that would mean that we can place to LOW, but right now, in such case it does NOT boot any more !

Nothing else to say !!!

EDIT : I forgot, you've written that the Boot-Process isn't giving the true :

I don''t believe this is right see wiki/doku.php?id=getting-started-with-the-esp8266 where GPIO2 is left floating.

and you also misleaded people saying that pulling the GPIO2 to HIGH is WRONG :

GPIO2 - pull up (4k7)

I think this is wrong is should be floating or used for something else . When high on boot it pulls the chip into UART mode and thats not where you want it . See the wiki above on pin modes and connections