ESP8266

An ESP8266 module powered by a coin cell battery.

The ESP8266 is a low-cost Wi-Fi chip with full TCP/IP stack and microcontroller capability produced by Shanghai-based Chinese manufacturer, Espressif.

The chip first came to the attention of western makers in August 2014 with the ESP-01 module, made by a third-party manufacturer, AI-Thinker. This small module allows microcontrollers to connect to a Wi-Fi network and make simple TCP/IP connections using Hayes-style commands. However, at the time there was almost no English-language documentation on the chip and the commands it accepted.^[1] The very low price and the fact that there were very little external components on the module which suggests that it could eventually be very inexpensive in volume, attracted many hackers to explore the module, chip, and the software on it, as well as to translate the Chinese documentation.^[2]

Features

• 32-bit RISC CPU: Tensilica Xtensa LX106 running at 80 MHz
• 64 KiB of instruction RAM, 96 KiB of data RAM
• External QSPI flash - 512 KiB to 4 MiB (up to 16MiB is supported)
• IEEE 802.11 b/g/n Wi-Fi
  • Integrated TR switch, balun, LNA, power amplifier and matching network
  • WEP or WPA/WPA2 authentication, or open networks
• 16 GPIO pins
• SPI, I²C,
• I²S interfaces with DMA (sharing pins with GPIO)
• UART on dedicated pins, plus a transmit-only UART can be enabled on GPIO2
• 1 10-bit ADC

SDKs

In late October 2014, Espressif released a software development kit (SDK) that allowed the chip to be programmed, removing the need for a separate microcontroller.^[3] Since then, there have been many official SDK releases from Espressif; Espressif maintains two versions of the SDK — one that is based on RTOS and the other based on callbacks.^[4]

An alternative to Espressif's official SDK is the open source esp-open-sdk^[5] that is based on the GCC toolchain. ESP8266 uses the Cadence Tensilica LX106 microcontroller and the GCC toolchain is open-sourced and maintained by Max Filippov.^[6] Another alternative is "Unofficial Development Kit" by Mikhail Grigorev.^[7][8]

It can also be programmed with the help of NodeMCU.

Espressif modules^[9]

This is the series of ESP8266-based modules made by Espressif.

Name	Active pins	Pitch	Form factor	LEDs	Antenna	Shielded?	Dimensions (mm)	Notes
Espressif Espressif WROOM-02[10]	18	0.1“	2×9 DIL	No	PCB trace	Yes	18 × 20	FCC ID 2AC7Z-ESPWROOM02

AI-Thinker modules^[11]

These were the first series of modules made by third-party manufacturer, AI-Thinker with the ESP8266 and remain the most widely available.

Name	Active pins	Pitch	Form factor	LEDs	Antenna	Shielded?	dimensions (mm)	Notes
ESP-01	6	0.1“	2×4 DIL	Yes	PCB trace	No	14.3 × 24.8
ESP-02	6	0.1”	2×4 castellated	No	U-FL connector	No	14.2 × 14.2
ESP-03	10	2 mm	2×7 castellated	No	Ceramic	No	17.3 × 12.1
ESP-04	10	2 mm	2×4 castellated	No	None	No	14.7 × 12.1
ESP-05	3	0.1“	1×5 SIL	No	U-FL connector	No	14.2 × 14.2
ESP-06	11	misc	4×3 dice	No	None	Yes	14.2 × 14.7	Not FCC approved
ESP-07	14	2 mm	2×8 pinhole	Yes	Ceramic + U-FL connector	Yes	20.0 × 16.0	Not FCC approved
ESP-08	10	2 mm	2×7 castellated	No	None	Yes	17.0 × 16.0	Not FCC approved
ESP-09	10	misc	4×3 dice	No	None	No	10.0 × 10.0
ESP-10	3	2 mm?	1×5 castellated	No	None	No	14.2 × 10.0
ESP-11	6	0.05”	1×8 pinhole	No	Ceramic	No	17.3 × 12.1
ESP-12	14	2 mm	2×8 castellated	Yes	PCB trace	Yes	24.0 × 16.0	FCC and CE approved[12]
ESP-12-E	20	2 mm	2×8 castellated	Yes	PCB trace	Yes	24.0 × 16.0
ESP-12-F	20	2 mm	2×8 castellated	Yes	PCB trace	Yes	24.0 × 16.0	FCC and CE approved. Improved antenna performance. 4MB Flash
ESP-13	16	1.5 mm	2×9 castellated	No	PCB trace	Yes	W18.0 x L20.0	Marked as ″FCC″. Shielded module is placed sideways, as compared to the ESP-12 modules.
ESP-14	22	2 mm	2×8 castellated +6	No	PCB trace	Yes	24.3 x 16.2

Other boards

Name	Active pins	Pitch	Form factor	LEDs	Antenna	Shielded?	dimensions (mm)	Notes
Olimex MOD-WIFI-ESP8266[13]	2	0.1“	UEXT module	Yes	PCB trace	No	?	Only RX/TX are connected to UEXT connector
Olimex MOD-WIFI-ESP8266-DEV[14]	20	0.1“	2×11 DIL + castellated	Yes	PCB trace	No	?	All available GPIO pins are connected, also has pads for soldering UEXT connector (with RX/TX and SDA/SCL signals)
NodeMCU DEVKIT	14	0.1“	2×15 DIL	Yes	PCB trace	Yes	?	Uses the ESP-12 module, includes USB serial interface
Adafruit Huzzah ESP8266 breakout[15]	14	0.1“	2×10 DIL	Yes	PCB trace	Yes	25 × 38	Uses the ESP-12 module
SparkFun ESP8266 Thing[16] WRL-13231	12	0.1“	2×10 DIL	Yes	PCB trace + U.FL socket	No	58 x 26	FTDI serial header, Micro-USB socket for power, includes Li-ion battery charger
KNEWRON Technologies smartWIFI[17]	12	0.1“	2×20 DIL	Yes 1 RGB	PCB trace	Yes	25.4 x 50.8	CP2102 USB bridge, includes battery charger, micro-USB socket for power and battery charging, 1 RGB LED and USER / Reflash button
WeMos D1[18]	12	0.1“	Arduino Uno	Yes	PCB trace	Yes	53.4 × 68.6	Uses the ESP-12F module, Micro-USB socket
WeMos D1 R2[19]	12	0.1“	Arduino Uno	Yes	PCB trace	Yes	53.4 × 68.6	Uses the ESP-12F module, Micro-USB socket
WeMos D1 Mini[20]	12	0.1“	2×8 DIL	Yes	PCB trace	Yes	25.6 × 34.2	Uses the ESP-12F module, Micro-USB socket
ESPert ESPresso Lite[21]	16	0.1"	2x8 DIL	Yes	PCB trace	Yes	26.5 x 57.6	Uses the WROOM-02 module. Produced in limited quantity as beta version.
ESPert ESPresso Lite V2.0[22]	24	0.1"	2x10 DIL	Yes	PCB trace	Yes	28 x 61	Improved design and feature to ESPresso Lite.
In-Circuit ESP-ADC[23]	18	0.1"	2x9 DIL	No	U.FL socket	No	22.9 x 14.9	Uses the ESP8266EX

References

1. Brian Benchoff (August 26, 2014). "New Chip Alert: The ESP8266 WiFi Module (It’s $5)". hackaday. Retrieved 2015-06-24.
2. Brian Benchoff (September 6, 2014). "The Current State of ESP8266 Development". hackaday. Retrieved 2015-06-24.
3. Brian Benchoff (October 25, 2014). "An SDK for the ESP8266 WiFi Chip". hackaday. Retrieved 2015-06-24.
4. Espressif Systems (July 29, 2015). "Official SDK release from Espressif for ESP8266". Espressif. Retrieved 2015-08-08.
5. https://github.com/pfalcon/esp-open-sdk
6. Max Filippov (Feb 15, 2015). "ESP8266 GCC Toolchain". Retrieved 2015-08-08.
7. https://github.com/CHERTS/esp8266-devkit>
8. http://programs74.ru/udkew-en.html
9. "ESP8266 | Espressif 乐鑫". espressif.com. Retrieved 2016-02-10.
10. "Espressif WROOM-02". Espressif. Retrieved 2015-07-29.
11. "ESP8266 module family". esp8266.com wiki. Retrieved 2015-06-24.
12. "2ADUIESP-12 by Shenzhen Anxinke technology co., LTD for WIFI Module". FCC. December 30, 2014. Retrieved 2015-06-24.
13. "MOD-WIFI-ESP8266". Olimex. Retrieved 2015-06-25.
14. "MOD-WIFI-ESP8266-DEV". Olimex. Retrieved 2015-06-25.
15. "Adafruit HUZZAH ESP8266 Breakout". Adafruit Industries. Retrieved 2015-06-25.
16. "SparkFun ESP8266 Thing". SparkFun. Retrieved 2015-06-27.
17. "KNEWRON smartWIFI". KNEWRON. Retrieved 2016-03-04.
18. "WeMos D1". WeMos. Retrieved 2016-01-05.
19. "WeMos D1 R2". WeMos. Retrieved 2016-01-05.
20. "WeMos D1 Mini". WeMos. Retrieved 2016-01-05.
21. "Espert". Espert. Retrieved 2016-01-07.
22. "Cytron Technologies - ESPresso Lite V2.0". www.cytron.com.my. Retrieved 2016-02-10.
23. "ESP-ADC DIL18 development board". In-Circuit Wiki. Retrieved 2016-02-03.

External links

• BBS.espressif.com - Espressif's Forum with complete documentations on the ESP8266
• ESP8266.com - community forum
• SUPLA - Open source building automation system based on ESP8266
• WiFi-IoT - universal firmware WEB-builder from Maxim Miklin. The firmware is written in pure C language.