Data Sheet

(4) Reverse Polarity Protection

When the module is powered by the optional SIP (Breadboard) header, a P-Channel mosfet

provides reverse polarity protection and almost zero voltage drop at VIN.

(5) Power LED

The power LED remains on whilst correct polarity voltage is supplied to either the WX/XBee

socket, or the SIP (Breadboard) connector. LED’s are visible from both sides of the board.

(6) ASC “Associate” LED

In the description, bold is the wireless mode, small text indicates connectivity or lack thereof,

and after hyphen (-) indicates LED behavior and the timing.

● AP (has IP address) [Wirelessly accessible]* - ON constantly

● STA+AP (no IP on STA, IP on AP) [Wirelessly accessible]* - OFF 2000 ms, ON 2000

● STA+AP (has IP on STA and AP) [Wirelessly accessible]* - OFF 2000 ms, ON 25 ms,

OFF 150 ms, ON 2000 ms

● STA (has IP address) [Wirelessly accessible] - OFF 4000 ms, ON 25 ms

● STA (no IP address) [Not wirelessly accessible] - OFF constantly

(7) DI “Data-In” LED

The data-in LED will blink whilst serial data is being received by the module at either the WX

header, or the SIP header. LED’s are visible from both sides of the board.

(8) DO “Data-Out” LED

The data-out LED will blink whilst serial data is being transmitted by the module at either the WX

header, or the SIP header. LED’s are visible from both sides of the board.

(9) Level shifters and buffers

To ensure maximum compatibility with a wide range of 3.3V and 5V microcontrollers and

development boards, the Parallax Wi-Fi module includes voltage level shifters and buffers to

ensure that the logic voltage levels at the SIP header are set by the VIN voltage level. If you

supply 3.3V to VIN, then the IO pins logic voltage level will be 3.3V. If you supply 5V to VIN,

then the IO pins logic voltage level will be 5V.

(10) SIP “Breadboard” header

The right-angled SIP header is a standard 0.1” spaced male header, suitable for plugging

directly into a breadboard, or will accept a wide range of header cables (eg. 800-00048,

751-00010). The four pins starting GND, RES, DI, DO are also compatible with the Parallax

Prop Plug (#32201) for easy firmware re-programming and development.

ESP8266 Wi-Fi Module (#32420)

v1.0 05/12/2016 Page 5 of 12