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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


CMX System's  high level TCP/IP stack CMX-MicroNet will work with virtually all 8, 16 and 32-bit processors while only needing the minimum of ROM and RAM.   

This stack executes directly on the microcontroller generating SLIP, PPP and modem protocols via its UART.  Ethernet drivers are available for most common on chip interfaces providing fast local networks and good PC interaction.  No proprietary protocols, intermediate gateways or special hardware is required to use MicroNet.

MicronNet interfaced to Modem and Ethernet
  for STM32 - Cortex  for 8051
  ROM bytes RAM bytes ROM bytes RAM bytes
Core + UDP/IP 4,347 200 5,367 55 
Core + TCP/IP + PPP + Modem  + HTTP Web Server + Virtual File 17,594
 + HTTP pages
+ largest HTTP page
 + HTTP pages
+ largest HTTP page

Most developers using the popular 8- and 16-bit processors, as well as users of 32 bit single chip systems such as ARM and ColdFire, had given up hope of ever achieving networked communication with their products because most stacks were simply too big. MicroNet provides  these protocols running natively on even the smallest of 8 bit micros which means that now you have an economical solution to networking, especially for devices that will be running in remote locations.

How is it done ?

Well first of all this stack was written from scratch with embedded systems in mind.

Secondly the majority of applications that it will be used for will involve the development of code for both ends of the application by the same team or the use of a standard such as a browser.  Because of the level of control that this gives there are a significant number of infrequently used ( yet memory hungry ) aspects of the full TCP/IP spec which can be left out in order to keep code size down. To reduce the space overhead fragmented packets are available as an option and without it the "sliding window" option used for large blocks of data is not supported.  PPP can negotiate IP addresses and handle PAP passwords but other options are ignored.  CMX-MicroNet can run under a real time operating system such as CMX-RTX  but it does not need an RTOS and will run quite happily without one.

CMX-MicroNet was the first system available that allows TCP/IP and other protocols to be run natively on small processors, thereby enhancing design flexibility and cost effectiveness.

Why use TCP/IP as my protocol?
Using one of the TCP/IP family of protocols next time you need to communicate with or between micros makes a lot of sense.  For one thing it saves you re-inventing the wheel.  Once you are using TCP/IP you can easily take advantage of a whole group of higher level protocols that build on their foundations such as PPP, FTP, HTTP and POP3.

Whats provided

CMX-MicroNet can operate stand alone or in conjunction with an RTOS.  It provides support for multiple Sockets, TCP, PPP, UDP, SLIP, and IP with Ethernet, PPP, DHCP, TFTP, BOOTP, FTP, SMTP, SNMP and HTTP Web Server being options.  Requesting a web page can result in the display of information from the micro and mechanisms are supplied to input values and invoke functions.  Connectivity is currently supported for Dial Up or Direct serial connection as well as a number of different Ethernet chips and Wireless Ethernet for the Intersil Prism chipset.

No proprietary protocols, gateways, or hardware is required to use the system.  Source code is supplied and no license fee is required to create unlimited ROMs for a single application.  It has been designed for ease of porting to DSPs.

CPU's Supported plus some other legacy and specialist chips

ARM ColdFire Cortex M0-4 8051 family PIC 18/24/32 dsPIC
 68HC(S)12 MSP430 Z80/180 eZ80 Z8 Encore AVR
 SH H8/300H & H8S V850 C16x/C166 Sv2 M16C/32C, C80 DSPC5xx
  78K0  & KOS RX600 ST7, 10 & Super 10 TLCS-900  

Full C source is provided and it is viable for users to adapt to other CPUs including DSPs

CMX-MicroNet  TCP/IP
includes PPP or Ethernet
PPP protocol
CHAP protocol (MS & MD5)
http  Web server
FTP client/server
Flash File system
SMTP protocol (post out)
POP3 protocol (post in)
Fragmentation support
DNS support
Wireless Ethernet 802.11b
DHCP protocol Client
TFTP protocol Client
SNMP v1 & v2 protocol Client
SSH Secure shell
Telnet Server

For more Information:

TCP mnemonics Confused? - Consult our list of TCP mnemonics
TCP/IP Paper Better still download a white paper designed to introduce Embedded engineers to the possibilities and pitfalls of TCP/IP.
Literature request To receive literature tell us your CPU, Compiler and EVB of choice

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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