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After supplying all your  Embedded Development Tool needs for 42 years
 Computer Solutions Ltd and its web shop are now closed.



 Having reached the grand old age of 75 it is time to relax and fulfil other ambitions.

 Its been an exciting ride with you, our customers, often on the bleeding edge of technology
 and I thank you for your friendship, your trust, and your orders.

Stay well        I wish you all success in your future projects.

Chris Stephens.



     But what to do with the web site ?  It has taken >12 man years of work to create a repository of knowledge on many aspects of the art and science of embedded microprocessor development and even after closing the shop it still gets over 4,000 visitors per month.  So as a service to my customers I have decide to keep it live providing my technical insights on the products and then redirecting viewers to sites where they can purchase the items they used to buy from us. Follow the link   "Home"

       The  "Information zone"  consists of articles produced as background tutorials on subjects of interest to those designing new products.  As different CPUs have became available this has lead to new development techniques and in particular to new ways of communicating between nodes.


Home Information Zone

USB stacks for embedded micros

If you are not familiar with the details of interfacing to USB you may find our Embedded USB tutorial helpful.


Using a USB software stack allows your embedded application to....

Device Stack Link to a PC that can control your device and exchange data with it using USB pipes  USB Host Stack Literature
Appear to a PC as a Thumb Drive, Serial device or a Mouse
Host Stack Control a network of up to 127 devices
Use a Thumb Drive as data storage that is then PC readable
Use USB devices that conform to the USB standard ( eg Keyboard, Printer, Serial or Mass Storage)


The On-The-Go standard allows your device to decide if it is going to act as a Slave or as the Networks Host



These software stacks from CMX and they will operate with the CMX-RTX, Standalone or with most other Real Time Executives.  A FAT32 file handling package is available for creating Thumb Drive based applications.USB Drivers for Embedded Micros

Written in ANSI C for portability.

Available for a wide range of processors from Microchip to ARM, ColdFire and PPC

Fully compliant with the USB 2.0 specification at Low, Full and High speeds

Support all 4 data transfer mechanisms ( Control, Bulk, Isochronous and Interrupt)

Run standalone, under CMX-RTX or portable to other OSs

Support a wide range of on and off chip USB interfaces

Class drivers are available for Mass storage, HID, Printers, Audio, Midi,
                        Serial devices, Media Transfer, Hub, Pictbridge and Personal Healthcare

Evaluation versions are available for a number of popular boards


Interfacing to a Thumb Drive / Memory Stick

The most common question we get is "What do I need if I am going to interface my micro to a Thumb drive ? " but often the problem needs some clarification.

There are two possible scenarios.....

1) The questioner is building a product that already has some local storage and the device will itself be connected via USB to a PC and will appear to the PC as a Thumb Drive.  To do this you need a Device stack and a FAT file system.

2) The questioner is building a product that requires some mass storage which can also be used as a mechanism for transferring data from or too a PC.  USB on the product enables cheap and portable Thumb Drives to be used.  To do this you need a Host stack and FAT32 File System 

The CMX file system provides a way of handling mass storage that is Windows compatible (FAT16,32,VFAT) including long names. It uses the "PC standard" C API (fopen,fread etc) for ease of programming and is re-entrant so safe for use on multi-tasked embedded systems.

We have packages that include Host or Device stacks integrated with FAT file systems to simplify adding this functionality to USB enabled embedded systems.


Demos available on common EVBs

We have a large number of preconfigured demonstration systems that run on the most popular evaluation boards please enter the board number into our contact page, and tell us which packages you wish to use and we will try to supply you with an evaluation system


Home Information Zone
Computer Solutions Ltd
87 Briar Road,  Shepperton,  Middx,  TW17 0JB
Telephone: +44 (0) 77 4342 2526   
Email:      Web:
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