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Socket Type U

A UART serial line interface operating at TTL levels. Pin 4 (TX) is data from the mainboard to the module, and pin 5 (RX) is data from the module to the mainboard. These lines are idle high (3.3V), and can double as general-purpose input/outputs. In addition, pins 3 and 6 are general-purpose input/outputs, with pin 3 supporting interrupt capabilities.


Pin 1 Pin 2 Pin 3 Pin 4 Pin 5 Pin 6 Pin 7 Pin 8 Pin 9 Pin 10
+3.3V +5V GPIO! TX (G) RX (G) GPIO [UN] [UN] [UN] GND



A general-purpose digital input/output pin, operating at 3.3 Volts.

! Interrupt-capable and software pull-up capable GPIO (the pull-up is switchable and in the range of 10,000 to 100,000 ohms).


Modules must not connect to this pin if using this socket type. Mainboards can support multiple socket types on one socket, as long as individual pin functionalities overlap in a compatible manner, so that a pin from one socket type can overlap with a [UN] pin of another.

+3.3V Connection to the +3.3V power net.
+5V Connection to the +5V power net.
GND Connection the power ground net.

Connector Pin Numbering

Pins numbers for the male 10-pin connector standard Gadgeteer socket, as seen from above. In most cases, the ribbon cables will have the pin 1 conductor marked in red.


Last edited Mar 1, 2012 at 11:40 PM by nvillar, version 3


nvillar Mar 1, 2012 at 11:40 PM 
Well-spotted! Fixed. Thanks for pointing this out.

KennySpade Feb 15, 2012 at 1:32 AM 
The opening paragraph incorrectly lists Pin 3 as (TX) and Pin 4 as (RX). The table has the correct listing, with Pin 4 as (TX) and Pin 5 as (RX).