Hardware basics of ESP8266 ESP-12E WiFi module

Learn the basics hardware information and features of ESP8266 ESP-12E.

What is ESP8266 ESP-12E?

It is low powered and integrated Wi-Fi Chip. Manufacturer of ESP8266 is Espressif Systems. It is based in Shanghai, China.

Features or basics of ESP8266 ESP-12E
  • Flash Memory: 4 MiB
  • Wi-Fi Protocols: 802.11 b/g/n/e/i
  • Operating Voltage: 2.5V ~ 3.6V
  • Current: 80 mA (Average value)
  • Storing temperature: -40°C ~ 125°C

Basic Hardware of ESP8266 ESP-12E

Hardware Information ESP8266 ESP-12E WiFi module

Pin functionality of ESP8266 ESP-12E

  1. RST – Reset the module
  2. ADC – A/D Conversion result.Input voltage range 0-1v,scope:0-1024
  3. EN – Chip enable pin.Active high
  4. IO16 – GPIO16; can be used to wake up the chipset from deep sleep mode.
  5. IO14 – GPIO14; HSPI_CLK
  6. IO12 – GPIO12; HSPI_MISO
  7. IO13 – GPIO13; HSPI_MOSI; UART0_CTS
  8. VCC – 3.3V power supply (VDD)
  9. CS0 – Chip selection
  10. MISO – Salve output Main input
  11. IO9 – GPIO9
  12. IO10 – GBIO10
  13. MOSI – Main output slave input
  14. SCLK – Clock
  15. GND – GND
  16. IO15 – GPIO15; MTDO; HSPICS; UART0_RTS
  17. IO2 – GPIO2; UART1_TXD
  18. IO0 – GPIO0
  19. IO4 – GPIO4
  20. IO5 – GPIO5
  21. RXD – UART0_RXD; GPIO3
  22. TXD – UART0_TXD; GPIO1

Bootloader Modes of ESP-12E

Bootloader ModesThe bootloader can go into a number of modes depending on the state of GPIOs 0, 2 and 15. The two useful modes are the UART download mode (for flashing new firmware) and the flash startup mode (which boots from flash).
Flash Startup (Normal)                                GPIO0: 1    GPIO2: 1    GPIO15: 0
UART Download Mode (Programming)       GPIO0: 0    GPIO2: 1    GPIO15: 0
SD-Card Boot                                               GPIO0: 0    GPIO2: 0    GPIO15: 1

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