ESP8266 UART

1 概述

UART0

U0TXD --- PIN26 
U0RXD --- PIN25
U0CTS --- PIN12 (MTCK)
U0RTS --- PIN13 (MTDO)

UART1 -- Only ouput pin, used for printing of debug information

 U1TXD --- PIN14 (GPIO2)

Downloading: U0TXD+U0RXD or GPIO2+U0RXD

Communicating: UART0: U0TXD, U0RXD, MTDO(U0RTS), MTCK(U0CTS)

Debugging: UART1_TXD (GPIO2) can be used to print debugging information.

By default, UART0 will output some printed information when the device is powered on and is booting up. If this issue exerts influence on some specific applications, users can exchange the inner pins of UART when initializing, that is to say, exchange U0TXD, U0RXD with U0RTS, U0CTS

2 SDK API

After calling void system_uart_swap():

U0TXD --- PIN13 (MTDO)   ---> Output pin, NOT be pulled up externally in the initiallization stage
U0RXD --- PIN12 (MTCK)
U0CTS --- PIN25
U0RTS --- PIN26