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ESP8266 ESP-12E breakout card



  • ESP-12E - ESP8266 WiFi Module (On ebay)
  • GVS connections
  • I2C connector
  • FTDI connector
  • On-board Power Supply
    • 7-9 VDC power input
    • 3.3V power regulator for the ESP-8266
  • 49x49mm form factor

ESP8266 Features

  • MicroPython - Getting started with MicroPython on the ESP8266
  • SDIO 2.0, SPI, UART
  • 32-pin QFN package
  • Integrated RF switch, balun, 24dBm PA, DCXO, and PMU
  • Integrated RISC processor, on-chip memory and external memory interfaces
  • Integrated MAC/baseband processors
  • Quality of Service management
  • I2S interface for high fidelity audio applications
  • On-chip low-dropout linear regulators for all internal supplies
  • Proprietary spurious-free clock generation architecture
  • Integrated WEP, TKIP, AES, and WAPI engines
  • Supports APSD for optimal VoIP applications
  • Patented spurious noise cancellation algorithm for integration in SOC applications
  • Supports Bluetooth co-existence interface
  • Self-calibrated RF to ensure optimal performance under all operating conditions
  • Zero factory tuning
  • No external RF components
  • 802.11 b/g/n
  • WiFi Direct (P2P), soft-AP
  • Integrated TCP/IP protocol stack
  • Integrated TR switch, balun, LNA, power amplifier and matching network
  • Integrated PLLs, regulators, DCXO and power management units
  • +19.5dBm output power in 802.11b mode
  • Power down leakage current of <10uA
  • Integrated low power 32-bit CPU could be used as application processor
  • SDIO 1.1/2.0, SPI, UART
  • STBC, 1×1 MIMO, 2×1 MIMO
  • A-MPDU & A-MSDU aggregation & 0.4ms guard interval
  • Wake up and transmit packets in < 2ms
  • Standby power consumption of < 1.0mW (DTIM3)

Connectors - Revision board

FTDI Connector (6-pin BERGSTIK)

FTDI Pinout

Pin Description

Direction (Card Relative)

1 GND Common
2 CTS Input
3 VCC Output
4 TX Output
5 RX Input
6 RTS Output

I2C Connector (4-pin BERGSTIK)

Pin Description

Direction (Card Relative)

1 GND Common
2 VCC Input
3 SDA Output
4 SCK Output

DC Power

  • Center = 7-9V
  • Outside = Gnd

GVS connectors

  1. Gnd
  2. +3.3V
  3. Signal


  • Signal names
    • GPIO2
    • GPIO15
    • GPIO10
    • GPIO9
    • GPIO13
    • GPIO12
    • GPIO14
    • GPIO16
    • A0

SPI connectors

  1. GND
  2. +3.3V
  3. MOSI
  4. MISO
  5. SCK
  6. CSN

FTDI/Reset Circuit


FTDI Cable

FTDI-USB-TTL - Connects to this card


WeMos D1 Mini schematic (For Reference)



ESP Arduino Reference

  • Pin numbers in Arduino correspond directly to the ESP8266 GPIO pin numbers.
    • pinMode, digitalRead, and digitalWrite functions work as usual, so to read GPIO2, call digitalRead(2).
  • Digital pins 0—15 can be INPUT, OUTPUT, or INPUT_PULLUP.
    • Pin 16 can be INPUT, OUTPUT or INPUT_PULLDOWN_16. At startup, pins are configured as INPUT.
  • Pins may also serve other functions, like Serial, I2C, SPI.
    • These functions are normally activated by the corresponding library.

Over the Air Programming

  • OTA (Over the Air) update is the process of loading the firmware to ESP module using Wi-Fi connection rather that a serial port.
  • OTA page


  • From this site When ESP restarts, the bootloader prints some data at 74880 baud.
  • If your terminal is configured for 115200, you will see some garbage at startup. This is normal behavior for the 8266 chip.
  • Putting scope probe on U1 pin 3 or
  • Touching U1 pin 3 to ground
AT version:  8 2015 14:45:58)
SDK version:1.3.0
Ai-Thinker Technology Co.,Ltd.
Build: Sep 11 2015 11:48:04
  • Had to hit ^J (LF) after commands





Reset and the Serial Port

Note that some serial terminal programs (not will 
assert both RTS and DTR when opening the serial port, pulling them
low together and holding the ESP8266 in reset. If you've wired RTS 
to the ESP8266 then you should disable RTS/CTS "hardware flow control" 
in the program. Development boards like NodeMCU use additional 
circuitry to avoid this problem - if both RTS and DTR are asserted 
together, this doesn't reset the chip.
  • Lifted FTDI pin 6 (RTS)

Esp8266 esp 01 module pinout diagram cheat sheet by adlerweb-d9iwm7a.png

3.3V Power from FTDI Cards

  • The FTDI chip does not have enough drive on the 3.3V to power the ESP-12E-01 card.
  • Lifted FTDI pin 3 (+3.3V)

USB-TTL Handshake lines

FTDI Pinout

Pin Description

Direction (Card Relative)

1 GND Common
2 CTS Input
3 VCC Output
4 TX Output
5 RX Input
6 RTS Output

Assembly Sheet

ESP-12E Assembly Sheet

Qty Value RefDes Qty Value RefDes
2 0.1uF C2,C3 1 1x6-RightAngle P1
1 0.1uF C4 9 CONN_01X03 P2-P10
1 22uF C1 1 CONN_01X04 P11
1 B5819W D1 1 CONN_01X06 P13
4 10K R1-R3,R6 1 DCJ0202 J1
1 3.3K R5
1 DNP R4
1 AP1117-3.3V U2
1 ESP-12E-sides U1