IP and Ethernet Interfaces

There is a general consensus that in years to come more and more Internet devices will be embedded and not PC oriented. Just one such prediction is that by 2010, 95% of Internet-connected devices will not be computers. So if they are not computers, what will they be? Embedded Internet devices.

One popular solution is to use an 8 bit microcontroller such as a Rabbit 2000, AVR or PIC and a Ethernet MAC such as a CS8900A or RTL8029AS hanging of it’s parallel port pins in 8 bit mode. A TCP/IP stack is normally written in C and can be striped of features and ported to these resource limited microcontrollers. While this works and we detail many such boards below, a little debate is brewing over it’s reliability and functionality.

With DOS (denial of service) attacks becoming more and more common, it doesn’t take much to knock your little 8 bit microcontroller off the network. In fact some configurations have a little trouble keeping up with the high volume of broadcast packets floating around a loaded network, let alone any malicious attacks.

One solution of course is to put in a bigger processor. This is the case with Embedded Linux devices such as Coldfire, DragonBall or ARM based devices. They are quite powerful enough to allow a suitable bandwidth and not be susceptible to someone’s malicious intent.

The other solution is to use a hardware TCP/IP stack. A hardware based stack is not new. If you have followed this site, you will be aware of the Sekio S-7600A hardware stack which incorporated a TCP/IP stack with a PPP controller so you could connect it to a modem. Sekio had licensed the technology from Iready Corporation. While it had it’s place in data logging or dial on demand applications where your device could dial up the Internet and send you an email to the effect that your house has been broken into or the past 24 hours logged data etc, it wouldn't connect to the popular ethernet networks present everywhere today.

The next logical progression had to be the Ethernet interface. Sekio has exited the embedded Internet business discontinuing it’s S-7600 on the 1st September. However the concept is still alive.

A hardware TCP/IP stack has a couple of advantages. Firstly as they are hardware based, most run at close to line speeds encapsulating and striping streams of data on the fly. This makes it increasingly more difficult to cause a DOS attack and almost impossible to run malicious code using principals of buffer overruns etc. However being hardware makes it difficult to upgrade should little quirks be found allowing say SYN attacks for example.

Later we detail some devices from Ipsil and Connect One. Both have the ability to upload new firmware which future proofs the designs in these peripheral devices. However the Ipsil and Connect One devices on the market today rely on an external ethernet MAC such as the popular CS8900A or RTL8029AS. This contributes to the chip count.

Ipsil has preliminary data on their IPµ8932 which combines a webserver, Ethernet MAC layer, and TCP/IP controller all on a single chip. This allows the one chip with 20 digital or analog inputs to display webpages without the need of a microcontroller. Ipsil has WebHoles™ technology which allows holes (simular to server side includes principles) to be filled in with values from the I/O ports. If you do happen to need more complexity, you can add a microcontroller and talk via standard TCP/IP socket calls.

However WIZnet Inc already has a simular device on the Market. The W3150A incorporates a TCP/IP stack and a future proofed 10/100 Ethernet MAC. So when it comes to chip count, it makes sense to off load the burden of the TCP/IP stack into a second peripheral chip complete with Ethernet MAC. It can reduce time to market, as the design of the TCP/IP stack is omitted (or saves costs of licensing one), plus you have a more stable product. Your 8 bit micro effectively has more grunt now, as it's no longer responsible for the lower TCP/IP protocols and ethernet encapsulation. All these advantages and yet, still only two chips.

How long before the leading microcontroller manufacturers are going to integrate a hardware TCP/IP stack and ethernet MAC into their microcontrollers making a one chip solution?

Answer : WIZnet Inc. and Atmel Corporation to jointly develop and market Internet connectivity solutions.

WIZnet Inc. and Atmel Corporation has forged a strategic partnership to develop and co-market Internet connectivity solutions. As part of this agreement WIZnet will manufacture OEM products around Atmel’s AVR microcontrollers. Both have agreed to move in the direction of system-on-chip (SoC) which will see WIZnet’s TCP/IP hardwired technology be integrated with Atmel’s MCU cores. Outcome? An AVR with \ hardware TCP/IP stack and ethernet in the one chip. I can't wait. . . .