Computers and household appliances can be connected in many ways. TCP/IP, a widely deployed standard, is a high level protocol, supported by several physical layers, ranging from radio frequency (RF) to infra-red (IR), and, of course, wires. While full TCP/IP protocol usually require 32-bit processor with significant memory size (500kB and above), the simplified point-to-point protocols don’t require expensive processing power. The iCAP can live on small 8 bit MCU with just a few kB of memory. What this means is using iCAP will save money, and energy by having an address scheme that is local, shorter and smaller.

Figure 1: Internet connectivity
a, b, c, c1-c3 and d may be regular PCs or UNIX stations with full user’s interface. d1-d3 and e are appliances with limited user’s interface.


Figure 1, demonstrates various ways of interacting with the Internet. Commonly PCs or Workstations (often on an Intranet) connect to Internet through Ethernet via a server. These are parts of a network (often an Intranet) and connect to the Internet via a server.

Private users tend to connect via a phone line using a point-to-point protocol (PPP) to an “Internet provider”. The Internet provider is usually a group of servers that are accessed via the plain old telephone line (POTS) or some kind of higher speed connection line such as video/TV cable.

There are also many other ways to interact with the Internet, sometimes hidden. For example, a washing machine calling a technician when it needs repair. Hundreds of appliances in every house have or will have some electronics on board, ranging from toys to white goods. Every retailer has electronic scales. Every company has electronic security systems. These devices may not contain a keyboard, mouse or screen. They have limited user interface. They also have a limited quantity of information to exchange (no video, no continuous time voice), but they still have information to send and receive: status, security, and availability. This is where iCAPs prove their value.


Complete home control and monitoring is nearly here. What will be the driver for Internet connectivity? Will it be turning on the coffee machine at home from your web interface at work? What about warming up your Colorado Springs holiday house before arriving? What about your washing machine alerting the technician before an impending malfunction floods the apartment floor? What about a vending machine that is never empty because it calls the distributor when the stocks are low?

All this is already possible, but before this convenience is ubiquitous, each appliance needs its own hardware and its own software. Further the hardware and software must be compatible. Without compatibility, there isn’t any central control, or synergy, but there are higher prices.

The physical support of the protocol must be adapted to the type of situation (RF, IR, wire, POTS), but the way one interacts with appliances can be standardized to sending orders and receiving information. By standardizing this part of the protocol, one will also significantly reduce the variety of hardware needed to support it, and so simplify the introduction of new appliances in a connected environment. This increases the value of the appliance, and of the environment.


The value of iCAP as a technology is its physical layer independent protocol, and low added cost if the appliance has a small microcontroller.

The value for the manufacturing and retail sectors include appliance remote software update, remote customer survey (who uses this machine, and when), remote appliance identification and status.


The application of iCAP is very diverse. Centralized remote control of home appliances has already been mentioned. Other examples are industrial sensors with digital outputs connected to remote servers using a RF connection, small implanted medical appliances, laboratories controlling small systems using one centralized user interface and one standard protocol.


Several companies propose different iCAPs. What they have in common is that they are implemented on a point-to-point physical layer protocol, and work together with a server that handles the connection to regular TCP/IP.

XEMICS’ strength, however is its compatibility with Tetraedre(2) and emWare(3) protocols on its ultra-low-power mixed signal XE8000 MCU. Both protocols are based on a Windows or UNIX PC used as server and a point-to-point connection to the ICA. For the technical reader, these protocols use the layers 1, 2 and 7 of the OSI classification. The server can be a minimal 32-bit machine running a Java environment and doesn’t need to be a full PC.

Tetraedre’s protocol is named MSCP (for MicroSystem Communication Protocol) and includes 2 types of messages: alarm and normal. Alarm messages are shorter than normal messages and are treated in priority. The MSCP architecture is based on 3 layers: Link, Message and Command. The Link layer is hardware dependent, and can be adapted for RF, IR or wired communication. The Message and Command layers are hardware independent and are used by different types of applications. Messages are more adapted to applications that are connection oriented, whereas Commands are more oriented towards higher level applications that directly manage connectivity.

Tetraedre MSCP is very light and uses less than 5.5kB of program memory and 64 B of data memory. emWARE EMIT is bigger, and includes extra functionality, including a description of the internal variables of the microcontroller. EMIT includes service packages that are very important for implementing a complete Internet based system. Both can directly interface an RS-232 physical layer. Or RF via the XE1201 transceiver.

A key reason for the success of emWare’s EMIT protocol is its wide acceptance by companies providing complementary levels of services through the ETI Alliance (Extend The Internet). The ETI alliance includes companies like SAP, Computers Associates, AT&T, Invensys and many others. All these companies provide or plan to provide services built around emWARE technology. By providing low-power support for the EMIT protocol, XEMICS enables connection of battery powered appliances and RF linked appliances.

Using the XE8000 for iCAP applications has several advantages. Xemics’ advantages include high code efficiency, integrated 1 clock cycle multiplication, ultra low-power (300 uA @ 1 MIPS), integrated UART up to 115 kbaud, MCU-RF chip set available with a development kit (XE1201CDK). Also, there is multiple time programmable memory and versions with 16+6 bits Zooming ADC. These advantages lead to miniaturized solutions, making use of a minimal number of external components. Reducing external components number also leads to higher reliability and lower system costs.

Implementing iCAPs on an 8-bit RISC MCU like the XE8000 can be made using a C-compiler or Assembler.

iCAP can be slow or fast, depending on their physical layer and the overhead needed for message handling. A fast RS-232 link can support voice quality audio, whereas a slow RF link may be limited to on/off messages.


Many applications of iCAP can be given, but we will mention just two here:

Barometer – iCAP demonstration based on a pressure sensor and an RS 232 physical layer

A barometer application has been modified to show basic functionality of Tetraedre MSCP on an XE8000 microsystem. With this implementation, any PC can take control of the RS232 connected barometer via an http address.

The following command in an HTML file will get the information back from the microsystem to the browser that will display it, or do whatever it must do:

The first part of the command is the server address, then selection of the iCA port, then selection of the command (read sensor) and then the data to retrieve.

iCAP demonstration based on a gas sensor and a RF physical layer

The approach is quite similar to the barometer above, but the physical layer is now a low-power RF link. From the point of view of the PC there is absolutely no difference. But the microsystem will first encode the data to access the RF transceiver, and an RF-to-RS 232 interface is connected to the PC.

For this application, the chosen sensor is a gas sensitive element from Microsens that can measure several gases, including CO, CH4, VOC (alcohol and odors), O3 and NOx. The transceiver is an XE1201 from XEMICS, with 433 MHz FM modulation.


The XE8000 also directly connects to several other Internet chips, including Seiko S-7600A (chip that integrates TCP, UDP, IP and PPP protocols), Domosys U-chip (chip for direct connection to the power line) and most RF chips.

Adding the XE8000 to your Internet chip makes a complete, extremely compact solution. The XE8000 can directly handle your sensors, actuators, and the power management of the local system, making it completely autonomous with a very minimal number of external components.


Complete development tools are available for XEMICS controllers, including C-compiler, source level debugger, simulator, linker, and Pro Start (Programmer and Starter Kit). An ICE (In-Circuit-Emulator) is in preparation. Software examples are available on XEMICS web site, and more will come.

A complete example of an Internet connected house will be available on XEMICS web site by end Q1/2001 (this will be the documented software and hardware used for the “smart house” demonstration made during the Electronica fair in Munich, Germany, November 2000).

EMIT protocol will be made available with future versions of the Pro Start.


They are several iCAP corresponding to different needs, from minimal systems to complete Internet connectivity. All support several physical communication layers, including RF, RS232 and IR.

The XE8000 is perfectly adapted to low footprint iCAP, thanks to its fast processing unit and its good communication capabilities for RS-232 or RF. Internet appliances are here to stay, and 8-bit mcu’s from XEMICS are here to make them work.


(1) XEMICS, XE8000:
(2) Tetraedre, MSCP:
(3) emWare, EMIT: