This is a new thingy I am looking into. All information on it is widely available but also very fragmented. Information from the manufacturer is not always reliable and you should always doublecheck it. Most of the modules are not FCC nor are they CE approved. This makes them only suitable for non-professional use. If you are interested to make a commercial product I would suggest you to use the certified versions.

ESP-01
        Image1: Top side PCB which I reverse engineered.

ESP-01 BOM

ID Value Qty Components
1 Quartz Crystal Ceramic 24 MHz 2.5 x 2.0mm SMD 4Pad U1
2 ESP8266EX QFN32 U2
3 U3

Facts


All ESP boards by Espressif (ESP-01 .. ESP-14) have a ESP8266EX SOC which is has a QFN32 package made. It delivers Wi-Fi at a dramatically low price and is ideal for small units which need connectivity somehow. The ESP8266 offers a complete Wi-Fi stack and it is possible to include your own onboard processing and storage capability which makes it a standalone solution. It is also possible to use the ESP8266 as a bride to provide Wi-Fi to any other microcontroller.

        Image2: Bottom side PCB.

ESP-01 Boot options

GPIO0 GPIO2 Mode Comment
H H Flash Boot from SPI Flash (normal mode)
L H UART Program via UART (TX/RX)

This week I received a couple of other boards which I will also investigate.
ESP-12E
ESP-12F
ESP-13
ESP-14
ESP-32S
V3-Wireless-module-NodeMcu-4M

Main features:

(taken from the datasheet)

  • 802.11 b/g/n protocol
  • Wi-Fi Direct (P2P), soft-AP
  • Integrated TCP/IP protocol stack
  • Integrated TR switch, balun, LNA, power amplifier and matching network
  • Integrated PLL, regulators, and power management units
  • +19.5dBm output power in 802.11b mode
  • Integrated temperature sensor
  • Supports antenna diversity
  • Power down leakage current of < 10uA
  • Integrated low power 32-bit CPU could be used as application processor
  • SDIO 2.0, SPI, UART
  • STBC, 1×1 MIMO, 2×1 MIMO
  • A-MPDU & A-MSDU aggregation & 0.4s guard interval
  • Wake up and transmit packets in < 2ms
  • Standby power consumption of < 1.0mW (DTIM3)

Die-shot


The guys from http://zeptobars.com/ regularly make die-shots of everything they can find (also the 8266). My respected fellow hacker Catalin B. (author of the blog https://myesp8266.blogspot.nl) pointed me via Hackaday to the following image, how cool is that!
Image courtesy of zeptobars.com How did they decapitate the chip? Have a look at this article: http://zeptobars.com/en/read/how-to-open-microchip-asic-what-inside

On hackaday you find which area of the chip has which functionality:
Image courtsy of Hackaday, Richard Baguley: http://hackaday.com/2015/09/24/hackaday-dictionary-the-esp8266/