Nodemcu / Nodemcu Pin Configuration
GPIO means General-purpose input/output is a pin on an Integrated Circuit (IC) can be either input pin or output pin, whose behavior can be controlled at the run time. The processor has around 16 GPIO lines and some are used internally to interface with other components of the SoC, like flash memory. GPIO pins allow connecting the board with other peripherals and are capable of generating PWM, I2C, SPI, and UART serial communications. GPIO pin can be used as digital inputs to read a digital voltage or digital outputs to output either 0V (sink current) or 3.3V (source current).
Voltage and current restrictions
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Single GPIO pin draws
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12mA maximum current.
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Power < 3.3 V
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Low Power for chip
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Power = = 3.3 v
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Normal power
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Power >3.3 V
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kill the chip
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Functions
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A0
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A0 is a function (analogRead()) is used to read external voltage applied
on ADC pin of module. ESP.getVcc() This function is used to read NodeMCU module
VCC voltage. ADC pin must be kept unconnected.
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G
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Power Supply ground.
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S3
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S0 to S3: Data lines (Quad-I/O mode).
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S2
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S0 to S3: Data lines (Quad-I/O mode).
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S1
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S0 to S3: Data lines (Quad-I/O mode).
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SC
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SC: SPI Chip Select.
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SK
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Serial Clock.
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3V
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3 volts power supply.
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EN
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Chip enable pin.
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RST
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Reset the chip.
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GPIO pins
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D0
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GPIO16
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It is a general purpose I/O pin used as GPIO read/write; no special
functions are supported on it.
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D1
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GPIO5
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9 general purpose I/O pins
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D2
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GPIO4
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D3
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GPIO0
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D4
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GPIO2
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D5
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GPIO14
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D6
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GPIO12
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D7
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GPIO13
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D8
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GPIO15
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D9/RX
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GPIO1
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RX and TX in order to communicate with a host PC from which compiled
object code is downloaded.( 2 pins)
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D10/TX
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GPIO1
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D11/SD2
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GPIO9
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Not mostly used
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D12/SD3
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GPIO10
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It is used to respond for GPIO/PWM/interrupt like functions.
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