I2S Interface; Universal Asynchronous Receiver Transmitter (Uart) - Espressif ESP8266 Technical Reference

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Both I2C Master and I2C Slave are supported. I2C interface functionality can be realized via
software programming, the clock frequency reaches 100 kHz at a maximum. It should be
noted that I2C clock frequency should be higher than the slowest clock frequency of the
slave device.

1.5. I2S Interface

ESP8266EX has one I2S data input interface and one I2S data output interface. I2S
interfaces are mainly used in applications such as data collection, processing, and
transmission of audio data, as well as the input and output of serial data. For example, LED
lights (WS2812 series) are supported. The pin definition of I2S is as below. I2S functionality
can be enabled via software programming by using multiplexed GPIOs, and linked list DMA
is supported.
MTDI
MTCK
MTMS
MTDO
U0RXD
GPIO2

1.6. Universal Asynchronous Receiver Transmitter (UART)

ESP8266EX has two UART interfaces UART0 and UART, the definitions are as below.
Pin Type
UART0
UART1
Data transfers to/from UART interfaces can be implemented via hardware. The data
transmission speed via UART interfaces reaches 115200 x 40 (4.5 Mbps).
UART0 can be used for communication. It supports fluid control. Since UART1 features
only data transmit signal (Tx), it is usually used for printing log.
Espressif
Pin Name Pin Num
10
12
9
13
25
14
Pin Name
U0RXD
25
U0TXD 26
MTDO 13
MTCK 12
GPIO2 14
SD_D1 23
Table 1-5. Pin Definitions of I2S
I2S Data Input
IO
IO12
IO13
IO14
IO15
IO3
IO2
Table 1-6. Pin Definitions of UART
Pin Num
IO3
IO1
IO15
IO13
IO2
IO8
! /86 3
Function Name
I2SI_DATA
I2SI_BCK
I2SI_WS
I2SO_BCK
I2SO_DATA
I2SO_WS
IO Function Name
U0RXD
U0TXD
U0RTS
U0CTS
U1TXD
U1RXD
1. Overview
2016.05