USB Buying Guide

One day in 1994, seven world-leading technology companies sat down and created a new standard for connecting computer peripherals. By "one day," of course I mean, "over the span of several months." But all technicalities aside, the standard that they laid down became the Universal Serial Bus, or USB for short.

Today, USB is truly a 'Universal' standard and you'd be hard-pressed to find an electronic device that doesn't have a USB port of one kind or another. But how do you know which USB cable will fit your device? Hopefully this buying guide will help you find the cable that you need for your next project.

What Does USB Do?

USB cables replace the huge variety of connectors that used to be standard for computer peripherals: Parallel ports, DB9 Serial, keyboard and mouse ports, joystick and midi ports... Really, it was getting out of hand. USB simplifies the process of installing and replacing hardware by making all communications adhere to a serial standard which takes place on a twisted pair data cable and identifies the device that's connected. When you add the power and ground connections, you're left with a simple 4-conductor cable that's inexpensive to make and easy to stow.

The USB standard defines the way in which a device talks to the host. Unless you're taking advantage of a brand new standard called "USB On the Go" (USB-OTG) which allows devices limited host capabilities, you're probably going to be connecting a device directly to a host. A USB device can't initiate communication, only the host can, so even if you can find the right cable: connecting two devices with no host just doesn't work. Also, because USB cables carry both power and data, connecting two hosts without a device in-between can be disastrous (causing high-currents, short circuits, even fires).

What Kinds of Cables are Out There?

99% of host controllers will have a USB-A receptacle, so when you're looking for a USB cable, you'll usually be looking for a "USB A-to-something" cable. A lot of the time the USB-A end is assumed, since that's the connector on most PCs, and cables will be named after the connector on the opposite end. Some smaller hosts use a Mini or Micro receptacle but they usually supply a pigtail adapter to USB-A.

Some cables are also hubs, which allow multiple USB devices to be plugged into the same host port. In theory, you can stack these hubs as deep as you want to up to 127 devices, but in practice you need to consider power limitations. Some cables are extension cords, with the plug at one end and the receptacle at the other. There are limits to this as well because of the round-trip signal time of the serial data. It's suggested that USB cables are kept under 5 meters in length.

There are also some wacky, non-standard USB cables out there so you have to be careful when you're just plugging things in. Not everything that can be physically connected can be electrically connected.

What Kind of Cable Do I Need?

The best way to answer that question is to take a stroll through the types of USB cable that we sell here at SparkFun and talk a little bit about what each of them are used for. Let's get to it!

USB A to Mini-B

We have so many of these around the office, it's crazy. Mini-B is the once-great (now deprecated) standard for portable devices. The Blackberry had it, the Motorola Q had it, but most importantly, the FTDI Basic Breakout still has it.

Despite being discouraged for future devices (in favor of the Micro-B) the Mini-B connector is still fairly common. It's large enough to solder without too much trouble but small enough to fit in some seriously tight spaces. Along with the FTDI Basic Breakout, here are a few other SparkFun devices that the USB A to Mini-B cable will connect to your computer:

SparkFun XBee Explorer USB

WRL-11812

$27.95

Favorited Favorite 50

SparkFun USB to RS-485 Converter

BOB-09822

$21.50

Favorited Favorite 15

SparkFun LiPo Charger Basic - Mini-USB

PRT-10401

$10.50

Favorited Favorite 18

USB Bit Whacker - 18F2553 Development Board

DEV-00762

1 Retired

Favorited Favorite 2

USB A to Micro-B

Micro-B is the newest and smallest USB connector type. Nearly every new cell phone uses a Micro-B connector so you might already have one or two of these cables laying around. Since Mini-B is being phased out in favor of this connector, many of our products that currently have a Mini-B connector will change to Micro-B in the future.

We're already using the Micro-B on a bunch of our newer boards. Here are a few SparkFun devices that the USB A to Micro-B cable will connect to your computer:

Pro Micro - 5V/16MHz

DEV-12640

$19.50

Favorited Favorite 97

Pro Micro - 3.3V/8MHz

DEV-12587

$19.50

Favorited Favorite 41

SparkFun LiPo Charger Basic - Micro-B

PRT-10217

$9.95

Favorited Favorite 61

SparkFun Power Cell - LiPo Charger/Booster

PRT-11231

14 Retired

Favorited Favorite 33

USB A to B

This is the classic. USB A to B cables are super common for printers and other large peripheral devices. They're also the standard programming connector for the Arduino UNO.

Besides the Arduino UNO, USB B is used on a lot of programmers and development boards. Here are a few other SparkFun devices that the USB A to B cable will connect to your computer:

GPIB-USB Controller

BOB-00549

$299.95

Favorited Favorite 8

JTAG USB OCD Programmer/Debugger for ARM processors

PGM-07834

1 Retired

Favorited Favorite 8

SparkFun Breadboard Power Supply USB - 5V/3.3V

PRT-08376

2 Retired

Favorited Favorite 22

USB A to A

See... This is the kind of non-standard cable that the USB-IF (USB Implementers Forum) was put together to avoid. I don't even want to think about the havoc that might ensue if you were to unwittingly connect two computers with a cable like this...

But until the Mini connectors came out, using a USB-A type connector on the device end was the only way to get around the USB-B type's space-issue. Some of the Olimex designs we used to carry used them for just that reason: The USB-B was too big. This isn't really done anymore because the Mini-B connector type exists now. That doesn't mean you can't do it on your own designs though... in fact, a pair of scissors will turn this potentially dangerous USB cable into two very useful USB bare-wire pigtails.

USB Extension Cable

USB devices are generally intended to be "near computer" devices but certain values of "near" fall outside the 6-10ft. length of standard USB cables. Some devices like webcams, WiFi adapters or XBee Explorers want to be free. In this case, the USB extension cable offers an extra 6-10ft. of freedom.

Even though you can technically connect these end-to-end, remember that you're limited to about 5 meters of functional USB cable. World record stretches of data line are probably best attempted with something more robust like Ethernet.

Table of Cables

Here's a table of the USB cables that we sell.

Cable	End 1	End 2	Length	Notes
added to your cart! SparkFun USB Mini-B Cable - 6 Foot In stock CAB-11301 This is a USB 2.0 type A to Mini-B 5-pin cable. You know, the mini-B connector that usually comes with USB Hubs, Cameras, MP3… $4.50 3 Favorited Favorite 21 Wish List	USB-A	Mini-B	6'
USB Cable A to A - 6 Foot Retired CAB-00515 These are unique A to A Male/Male USB cables. A to A cables are not usually used but on some Olimex designs, because the type… Retired Favorited Favorite 0 Wish List	USB-A	USB-A	6'	Don't use these cables to connect two Host devices, you could do some serious damage!
USB Cable A to B - 10 Foot Retired CAB-00513 Standard issue USB 2.0 cables. This is the most common A to B Male/Male type peripheral cable. Compatible with most SFE desig… Retired Favorited Favorite 1 Wish List	USB-A	USB-B	10'
added to your cart! USB Cable A to B - 6 Foot In stock CAB-00512 This is a standard issue USB 2.0 cable. This is the most common A to B Male/Male type peripheral cable, the kind that's usual… $4.50 1 Favorited Favorite 14 Wish List	USB-A	USB-B	6'
USB Cable Extension - 10 Foot Retired CAB-00518 These extension cables have a type A male connector on one end that plugs into any computer. The opposing end has a female … Retired Favorited Favorite 1 Wish List	USB-A	USB-A Receptacle	10'
USB Cable Extension - 6 Foot Retired CAB-00517 These extension cables have a type A male connector on one end that plugs into any computer. The opposing end has a female … Retired Favorited Favorite 1 Wish List	USB-A	USB-A Receptacle	6'
added to your cart! USB Micro-B Cable - 6 Foot In stock CAB-10215 USB 2.0 type A to Micro-B 5-pin. This is a new, smaller connector for USB devices. Micro-B connectors are about half the heig… $5.50 15 Favorited Favorite 23 Wish List	USB-A	Micro-B	6'
added to your cart! USB to RS232 Converter - 6ft Out of stock CAB-11304 There are a lot of devices out there that still communicate over RS232 but we bet your new laptop isn't one of them. Don't wo… $17.50 7 Favorited Favorite 5 Wish List	USB-A	DB-9	6'	This cable has an FTDI chipset inside. Along with the drivers on your PC, it provides you with an RS232 Serial Port.
SparkFun Cerberus USB Cable - 6ft Retired CAB-12016 You've got the wrong USB cable. It doesn't matter which one you have, it's the wrong one. But what if you could have the righ… 16 Retired Favorited Favorite 37 Wish List	USB-A	USB-B Mini-B Micro-B	6'	This cable doesn't have a USB splitter so don't try to connect multiple data devices, it won't work.