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Embedded Systems: Ethernet Modules Act Like SBCs

Tue, 12/23/2008 - 8:45am
Jon Titus, Senior Technical Editor

Ethernet Modules Act Like SBCs

Small Ethernet modules include processors that handle much more than communication tasks.

by Jon Titus, Senior Technical Editor

Jon TitusManufacturers offer a variety of small modules that let engineers easily add an Ethernet port to a design. They may need only a UART or I2C port in a main system to communicate with and control one of these modules. But if engineers stop there they will miss many other capabilities offered by these modules--actually single-board computers (SBCs).

Along with 10/100 Ethernet capability, modules also provide  general-purpose I/O pins, I2C, SPI, UARTs, CAN, ADCs, PWMs, timers and software features that go beyond basic communications. "We have a customer who uses our modules and a language called AJAX [Asynchronous JavaScript And XML] to control generators and battery chargers," said Chris Uribe, sales and marketing manager at NetBurner. "The engineers used the module's built-in Web server and AJAX to create a GUI on a user's browser. The served code runs within the browser and lets users control distant equipment. You could serve JAVA or Adobe Flash applications, too."

"Our customers like modules that simply plug into a socket and work," noted Joel Young, CTO and vice president of R&D at Digi International. "But they often want a bit of customization. For example, they want to filter on a regular expression or send an alarm message when a count hits a limit. So we put our Python engine and our management framework into products like the Digi Connect ME and Digi Connect EM modules. Now you can use Python code to produce XML documents, filter on expressions, or do protocol conversions. And you don't have to do any deep-down embedded development."

01ECN-Titus ES Ethernet Fig 1Engineers may not understand that many Ethernet modules give them a complete single-board computer. "We have modules such as our MatchPort AR that have a 159-MIPS processor, eight megabytes of SDRAM and many I/O lines," said Daryl Miller, vice president of engineering at Lantronix.
"You could put much application code in the module and take some tasks away from your system's main CPU."

Core Modules from Netburner use a 32-bit Freescale ColdFire processors, and a typical module includes flash memory, SDRAM, and an Ethernet connection along with a variety of I/O ports. "In effect, engineers have access to the CPU's I/O and control lines, including address and data buses for off-module expansion," said Uribe. "So, someone could use a module as the main controller for a product or as a network subprocessor."

Digi's Young explained that engineers can buy a Digi Connect ME 9210 JumpStart development kit that operates with either embedded Net+OS or Linux so they can write C code for embedded applications. Modules offer an ARM9 CPU along with two Mbytes of Flash memory and four Mbytes of RAM. "We upgraded to the ARM9 because we can give customers greater processor 'headroom' to include security functions," noted Young. "We see a greater emphasis on, and need for, secure systems. Engineers tell us, 'I'm not sure what IPsec does, but I think I need it,' or 'We must have the Advanced Encryption Standard [AES].' When engineers run the code to secure a system they need more processor power."

"Because we include security features such as AES and triple-DES, engineers can focus on what they do best--MRI machines, PLCs, security equipment, and so on," stressed Miller of Lantronix. "They need to know about security techniques and how to apply them, but the need not turn into security-algorithm experts."

Engineers should recognize a different type of network-security issue--getting through firewalls. Although a security system behind a firewall can transmit its status, it might not receive queries because a corporate firewall blocks them. That's an IT-department challenge and not a problem caused by Ethernet modules. "We have a product called ManageLinx that lets you use existing openings in corporate fire walls to access equipment," said Miller. "So, if you install PLCs at a cookie factory, you can 'manage' them even if there’s a firewall in between." Lantronix also offers Device Installer software that will "discover" connected devices and manage them.

In this context, management means overseeing remote devices connected to a network. "You need to give customers some way to access their equipment remotely," stresses Digi's Young. "You can't simply hope for the best. So, we build that management capability into our modules and offer Connectware software to oversee networked devices. That software lets equipment manufacturers offer their customers extra services. They can easily check the status of devices, get alarms or email messages, and remotely download new firmware into one or many devices. They also can reconfigure network parameters and other operating characteristics." Young noted the "management agent" goes into small devices such as the Digi Connect ME and the Digi Connect EM modules and it’s the same client that Digi puts into its larger cellular-network products. "We slim it down a little bit but it plugs into the same Connectware software.

As engineers consider using a plug-in module for Ethernet communications they might keep wireless communications in mind, too. Some suppliers offer both wired and wireless modules that plug into the same socket and provide the same functions. Thus, a product remains the same but a quick module swap switches from wired to wireless communications.

Acknowledgement
Although not quoted, Steve Eo, US marketing manager for WizNet contributed information for this article. His company manufactures Ethernet modules that include hardwired TCP/IP stacks.

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