Data Sheet

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Espressif Systems
ESP8266 Datasheet
Table 11 Pin Definitions of I2C
Both I2C-Master and I2C-Slave are supported. I2C interface functionality can be realized via software
programming, the clock frequency can be up to around 100KHz at most. It should be noted that I2C
clock frequency should be higher than the slowest clock frequency of the slave device.
3.5. I2S
Currently one I2S data input interface and one I2S data output interface are defined. I2S interface is
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 defined below:
Table 12 Pin Definitions of I2S
I2S functionality can be realized via software programming, the GPIOs that will be used are
multiplexed, and linked list DMA is supported.
3.6. Universal Asynchronous Receiver Transmitter (UART)
Two UART interfaces, UART0 and UART1, have been defined by ESP8266EX, the definitions are as
below:
Pin Name
Pin Num
IO
Function Name
MTMS
9
IO14
I2C_SCL
GPIO2
14
IO2
I2C_SDA
I2S Data Input
Pin Name
Pin Num
IO
Function Name
MTDI
10
IO12
I2SI_DATA
MTCK
12
IO13
I2SI_BCK
MTMS
9
IO14
I2SI_WS
I2S Data Output
Pin Name
Pin Num
IO
Function Name
MTDO
13
IO15
I2SO_BCK
U0RXD
25
IO3
I2SO_DATA
GPIO2
14
IO2
I2SO_WS
Espressif Systems / August 1, 2015
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