esp8266-01 does not boot properly when gpio02 is used

Posted:
Tue Aug 28, 2018 1:35 pm
by Gerardo Pellicer
Hello, I have a esp8266-01 connected to a LED driver, and I can control my leds using pwm, it works just fine. The problem is when I remove power and reconnect the esp, because it won't boot correctly. It starts with the blue and red led on. The problem disappears when I disconect the gpio02 from the LED driver, then it boots fine. I asume there is a "correct" way to connect the module to other devices so it boots normally. Can anyone help me? It also happens when I connect a pir sensor to my esp, I can not make it to boot normaly.
Thanks
Gerardo
Re: esp8266-01 does not boot properly when gpio02 is used

Posted:
Tue Aug 28, 2018 6:41 pm
by rudy
GPIO2 must be high at start up. If it is not then it will not run your code. This is non-negotiable.
You need to ensure that GPIO2 is high. Your circuit is loading down the pull up resistance on the port and not allowing the chip to see the required high. You may be able to compensate for the loading of your circuit by adding a lower value resistance between Vcc and GPIO2. I would try a 470 Ohm pull up resistance.
The ESP-01 is very limited. The two available port pins (other than RX and TX) have limitations. I never considered getting the ESP-01 because it is too limiting.
If you don't need RX or TX for serial then they can be used for general IO. If you go that route I would try using TX. I think (not know for sure) that RX can have issues due to how it starts. Some people have no issues with RX starting low. I and some other people have had problems when RX is low on start.
Re: esp8266-01 does not boot properly when gpio02 is used

Posted:
Wed Aug 29, 2018 7:07 am
by cactus22
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