Espressif Systems ESP8266EX - Page 11

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Espressif Systems
ESP8266EX
Hardware User Guide
Table 2 Attributes and Functions of Pins
Note: GPIO2, GPIO0, MTDO can be configurable as 3-bit SDIO mode.
Pin
Name
Type
Function
24
GPIO5
I/O
GPIO5
25
U0RXD
I/O
UART Rx during flash programming; GPIO3
26
U0TXD
I/O
UART Tx during flash progamming; GPIO1; SPI_CS1
27
XTAL_OUT
I/O
Connect to crystal oscillator output, can be used to provide BT
clock input
28
XTAL_IN
I/O
Connect to crystal oscillator input
29
VDDD
P
Analog Power 3.0V~3.6V
30
VDDA
P
Analog Power 3.0V~3.6V
31
RES12K
I
Serial connection with a 12 kΩ resistor and connect to the
ground
32
EXT_RSTB
I
External reset signal (Low voltage level: Active)
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