Connecting to an Arduino ESP8266 Shiald v1.0

The Arduino ESP8266 Shiald v1.0 is an Arduino UNO format shield for an ESP8266 WiFi module.

The ESP8266 WiFi module is a self contained SOC from Espressif Systems with TCP/IP stack and WiFi capability enabling any microcontroller to access a WiFi network. Out of the box the ESP8266 Shiald module is capable of operating independently without an Arduino Uno being attached

There are many different Arduino ESP8266 Shialds out there that look almost identical but come with different default software installed and variances in circuitry.


This article is about two such Shialds and describes initial findings when connecting to the board debug port from a PC and the default Access Point.

The vendor of the first Shiald is AI-THINKER and the second DOIT.AM. The names are marked on the ESP8266 module case.

AI-THINKER and DOIT.AM ESP8266 shialds

Shiald DIP settings

The Shiald has 4 DIP switches as follows (when ON):

1.  Connect ESP8266 TX to pin D0
2.  Connect ESP8266 RX to pin D1
3.  Enable ESP8266 bootloader mode
4.  Enable DFU led (purpose?)

To run the programmed software ensure DIP 3 is OFF.  To flash new software to the ESP8266 ensure DIP 3 is ON.

NB the debug TX and RX pins are permenantly connected to the ESP8266 TX and RX.

Connecting Shiald to PC via USB to TTL serial adapter

To connect to the Shiald debug port from a PC use a USB to TTL serial adapter.

USB to TTL serial adapter

Ensure voltages are matched e.g both USB to TTL serial adapter set to 5V

Connect as follows:

• Shiald Debug RXD <-> TX

• Shiald Debug TXD <-> RX

• Shiald Debug GND <-> GND

• Shiald Debug 5 V <-> VCC

PuTTY connection to Shiald Debug port

To interact with the Shiald Debug port from your PC use software like PuTTY.

Use the following serial settings

• COM port to the USB to TTL serial adapter COM port
• baud 115200

Shiald AI-Thinker

Connecting to Shiald Board debug

Pressing reset on Shiald results in the following output

Debug output from THINKER-AI Shiald

In this case the Shiald is running SDK version 0.9.2. It is using the network 192.168.4.0/24 for the wLAN, the server itself is using the IP address 192.168.4.1 and providing a DHCP service for wLAN client devices.

Many web pages state the AI-THINKER software is capable of processing AT commands. For example, sending the command 'AT' the shiald will respond with an 'OK' message.

The AT commands must end with "\r\n".  By default, PuTTY sends CR (\r) when the Enter Key is pressed therefore press Ctrl+M to send CR (\r) and Ctrl+J to send LF (\n).

Unfortunately, I was unable to get my AI-THINKER shiald to response to any AT commands. I checked the wiring and confirmed the commands were being sent but the board was unresponsive.

Connecting to AI-Thinker Shiald  Access Point wLAN

By default the board acted as an Access Point with SSID AI-THINKER and default password ai-thinker. In the debug window you see output indicating when a client wLAN deviceconnects. 

iPhone connected to Shiald wLAN

The AI-Thinker shiald web server

The AI-Thinker Shiald runs a web browser on port 80  (this is the only open port on the shiald)

To test wifi connection from your wifi device go to  http://192.168.4.1/client?command=0

Web page http://192.168.4.1/client?command=0

I could not find any other web pages supported by the web server.

DOIT.AM Shield

There are some boards out there with the wrong components installed preventing the D0 and D1 pins operating correctly as transistors marked J3Y have been installed instead of the required J1Y 3.3V/5V logic convertors.

The DOIT.AM I have is an example of a board with this problem. Testing with a multimeter for continuity between the TX / RX pins and D0 and D1 pins confirmed there was no connection. For testing purposes I used the debug TX / RX pins.

Connecting to DOIT.AM Shiald Board debug 

Connecting to the debug board and pressing reset on Shiald results in the following output. The default software on this board responds to AT commands. 

Debug output from DOIT.AM Shiald

Connecting to DOIT.AM Shiald  wLAN

The SSID is ESP_2834A6.No password required. 

The DOIT.AM Shiald web server

The DOIT.AM Shiald has no open ports which is a problem that needs further investigation (to be continued).