ESP8266

Pinout for the NodeMCU v1

A series of 32-bit microcontroller units from Espressif, followed by the ESP32. The first generation of the NodeMCU SoC was based around ESP8266.

Hardware

A Tensilica Diamond Standard 106Micro runs the Xtensa instruction set at 80MHz by default, and can be run at 160MHz. 32KB of code memory and 80KB of data are available to the user. There is no cache.

GPIO

• 17 bidirectional, non-inverting, tristate GPIO pins, with input and output buffer registers.
  • Pullup and pulldown resistors available on all pins
  • Pins can be set high-impedence
  • Edge- and level-triggered interrupts available on all pins

PWM

• Four PWM channels on pins 10, 13, 9, and 16

ADC

• There is only one (10-bit) ADC, and it reports values between [0, 1], not [0, 3.3]. This is not a scaling--the input voltage should not exceed 1V.
  • This is not true for e.g. the NodeMCU, which applies a divider network to scale the 3.3V down to 1V. This allows supplying 3.3V to the external device.
  • On the NodeMCU, this ADC can read the battery voltage instead of a connected external device. This is set in firmware.

External links

• ESP8266 on Wikipedia
• ESP8266 Technical Reference