SparkFun USB to Serial UART Boards Hookup Guide

Contributors:

.Brent.

Hardware Tour

The interface to this line of boards is simple. One side has a TTL-232R cable compatible 6 pin SIL, 0.1” pitch female header. This side connects to the Arduino (TTL serial UART) board. We often use right angle headers on the Arduino Pro Mini to make connecting a serial bridge trivial. Our boards have silkscreen labels of where the black and green wires of the FTDI TTL-232R cables would be.

Beefy 3 connected to an Arduino Pro Mini

Fritzing diagram showing the connection between a USB to UART bridge and a Pro Mini

6 pin SIL, 0.1” pitch header at top of PCBA

The other side has a USB mini-B or USB micro-B jack. A standard USB cable is used to connect this jack to a host computer.

This line of products comes in a few forms. Here is a table comparing the most common options.

Name	Voltage	Current Limit	Connector
SparkFun FTDI Basic Breakout - 5V	5.0 V	N/A¹	USB Mini-B
SparkFun FTDI Basic Breakout - 3.3V	3.3 V	< 50 mA	USB Mini-B
Beefy 3	3.3 V	< 600 mA²	USB Micro-B
LilyPad FTDI Basic Breakout - 5V	5.0 V	N/A¹	USB Mini-B

Table 1. Comparison of Common SparkFun Offerings

Warning: These boards are for prototyping ONLY. Unlike commercial devices, power negotiation and suspend mode do not occur, and it is possible to overload the USB host. Exercise caution when connecting a load, and never connect a load that draws too much current.

^{1. [5V is taken directly from V_BUS and is only limited by the USB host controller.]↩}
^{2. [This 3.3V regulator is powered directly from V_BUS and is only limited by the USB host controller.]↩}

For a quick comparison of a few USB to Serial boards, check out this Enginursday blog post: