Data Sheet
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Espressif Systems
ESP8266 Datasheet
provides protection from over-voltages and ESD. The output devices are also protected from
reversed voltages with diodes.
3.2. Secure Digital Input/Output Interface (SDIO)
One Slave SDIO has been defined by ESP8266EX, the definitions of which are described in Table 7
below. 4bit 25MHz SDIO v1.1 and 4bit 50MHz SDIO v2.0 are supported.
Table 7 Pin Definitions of SDIOs
3.3. Serial Peripheral Interface (SPI/HSPI)
Currently, one general Slave/Master SPI, one Slave SDIO/SPI, and one general Slave/Master HSPI
have been defined by ESP8266EX. Functions of all these pins can be implemented via hardware. The
pin definitions are are described below:
3.3.1. General SPI (Master/Slave)
Table 8 Pin Definitions of General SPIs
Pin Name
Pin Num
IO
Function Name
SDIO_CLK
21
IO6
SDIO_CLK
SDIO_DATA0
22
IO7
SDIO_DATA0
SDIO_DATA1
23
IO8
SDIO_DATA1
SDIO_DATA_2
18
IO9
SDIO_DATA_2
SDIO_DATA_3
19
IO10
SDIO_DATA_3
SDIO_CMD
20
IO11
SDIO_CMD
Pin Name
Pin Num
IO
Function Name
SDIO_CLK
21
IO6
SPICLK
SDIO_DATA0
22
IO7
SPIQ/MISO
SDIO_DATA1
23
IO8
SPID/MOSI
SDIO_DATA_2
18
IO9
SPIHD
SDIO_DATA_3
19
IO10
SPIWP
SDIO_CMD
20
IO11
SPICS0
U0TXD
26
IO1
SPICS1
GPIO0
15
IO0
SPICS2
Espressif Systems / August 1, 2015
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