ESP8266 Community Forum

- Sat Apr 08, 2023 12:40 pm #96213 Hello,

I have a problem when I connect TTP 223 at GPIO02. If the module is plug and I add TTP 223, ESP8266 work well. If I plug all it same time, ESP not work. I try the same with switch close at start time and the système work. I inverse the output of TTP 223 (welded A) and it's work. GPIO02 have a led and I confirm with this led that the input work properly or not.

Why, I don't enderstand?

Thank you!

- Mon Apr 10, 2023 3:14 am #96217 GPIO02 is one of the three pins that determine the boot mode of an ESP8266 during start up. For the ESP8266 to run its code normally from Flash then GPIO02 must be high during reset /start up. Once the boot mode has been determined then the app is free to use GPIO02.

The TTP223 touch sensor has a low output when not touched / activated. Attaching it to GPIO02 will prevent normal start up unless it is activated.

Best course is to use a different GPIO pin.

- Mon Apr 10, 2023 7:23 am #96219 Ok, The ESP8266-1s as only 2 GPIO + 2 RX/TX pin. I see that for boot mode all pin must be high. So, I think that it's not possible to have to have a swith at low or a output with low impedense connect to. True?

Thank you!