ESP8266 Community Forum

- Sun Jan 01, 2017 4:59 pm #60254 Hello Esp Gurus,

I have nodemcu boards (I think it's v1). In my project I would like to use system_uart_swap() function to use uart0 interface on GPIO13 (Rx) and GPIO15(tx) pins - simply to avoid bootloader garbage at startup.

I have wired RX pin on my PL2303 to GPIO15 on esp8266 (hooked up GNDs as well). If USB adapter isn't connected to the PC during Esp startup then everything works fine - I can see that uart data arrive at PL2303 RX pin.

The problem is, when I press RST button on my nodemcu with PL2303 connected to the PC. Esp bootloader seems to display little bit of uart garbage on uart0 (before swap: on GPIO1). Nevertheless after that Esp doesn't start.

When I disconnect PL2303 adapter and reset the board again, everything works fine.

I know that GPIO15 is pulled down to ensure proper boot up. Maybe this causes an issue ? any help will be much appreciated, Thank you in advance

Piotr

- Wed Jan 18, 2017 4:35 am #61175 Your problem is exactly that. Same happened to me. You must find a way to pull GPIO15 down during boot. Please share if you find something.

- Fri Feb 03, 2017 1:23 pm #61980 I decided to use software uart instead. it seems to be reasonable as I have clear output/input on e.g. GPIO 4,5. I don't want to touch these boot specific pins anymore When I run out of pins then I will connect gpio expander.

I wish you luck with your project

Cheers