High state at IO0 on startup - ESP8266
Posted:
Wed Sep 18, 2019 12:06 pmby donsergio
Hi, I have a relay module for ESP-01 and when I power it the relay close and open (because IO0 state is high at startup for short time)....
Is any way to do that no high output for IO0 at startup?
Thanks!!
Re: High state at IO0 on startup - ESP8266
Posted:
Fri Sep 20, 2019 2:14 amby QuickFix
donsergio wrote:Is any way to do that no high output for IO0 at startup?
No, GPIO0 has to be pulled high at boot to enable running-mode: a low-state would set the ESP into upload-mode.
ESPModes.png
Re: High state at IO0 on startup - ESP8266
Posted:
Mon Oct 14, 2019 8:57 amby donsergio
Hi, but... I have this board, the board of the pic in the main post.... when power on the board the relays turn on and off.... this is the "trouble that I have".... the IO0 for a while, when power up ESP8266 it get high state for a short time.... enough to energize the relay....
Re: High state at IO0 on startup - ESP8266
Posted:
Thu Oct 17, 2019 2:42 amby QuickFix
Read this post:
GPIO Pin states after reset/during startup:
RFZ wrote:Hey,
GPIOs 4 and 5 are the only ones that are always high impedance. All others do have internal pull-ups or are even driven low/high during boot.
GPIOs 3, 12, 13 and 14 pulled HIGH during boot. Their actual state does not influence the boot process.
GPIOs 0, 1, 2 and 15 are pulled HIGH during boot and also driven LOW for short periods.
The device will not boot if 0, 1 or 2 is driven LOW during start-up.
GPIO 16 is driven HIGH during boot, don't short to GND.
Or this one:
On powerup, GPIO state, relay drive problemOr even this one:
Prevent GPIO 2 keep in High voltage when reboot ESP8266This topic as well:
ESP8266-01 Boot up GPIO spikeAnd there are many, many more topics about this subject...