Hardware basics of ESP8266 ESP-12E WiFi module

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

What is ESP8266 ESP-12E?

It is low powered and integrated Wi-Fi Chip. The 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

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 several 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