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Elan VPU16550 and 551 UARTs - More Information for Design Engineers

Design Process

Logic Diagram for the Elan VPU16550 & 551

  1. Identify serial interface in target design and partition circuitry with split at this interface
  2. Miniaturize the circuitry on the "outside" of the serial connection (this is the part that will go into the card)
  3. Use the VPU16550 as the connection between the PC Card or CF connector, and wire up the serial connection from your circuitry to the VPU's TX,RX and modem signals as required.
  4. Add an EEPROM as shown in the VPU16550 data sheet. (this could also be a small Flash chip or any other parallel access non-volatile memory but staying with an EEPROM will allow use of the in-circuit programming tools supplied with the VPU reference kit).
  5. Program your desired Card Information Structure data into the EEPROM.
  6. Plug your card into a laptop or other PCMCIA / CF slot.
  7. For Windows Operating Systems, you'll need to create an INF file for the Plug-n-Play process.

The Elan Advantages

Schematic Review Service offered
  1. Elan have been doing PCMCIA design for over 6 years. We have combined the best of our knowledge into the VPU design, accumulated from dozens of PCMCIA and Compact Flash designs.
  2. Elan offer more than just a chip; you also get the benefit of our technical support that includes assistance with the host driver issues and applications.
  3. With the VPU solution, you can leverage with the benefits of the reference kit into your design and achieve better times to market.
  4. Competing solutions don't offer you much help with points 4 through 7 listed above. With Elan's VPU, the reference kit addresses all these points and gets you up and running fast.
  5. The VPU has a parallel port (output) that can be accessed via the normal serial services in Windows. This could allow you to implement proprietary schemes like power switching, serial protocols and more.
  6. The VPU is low power and can be used in a whole range of applications
  7. With the VPU, we only include features that can already be used by the standard kernel device drivers; after all, who wants to write special kernel drivers to support non-standard features like FIFOs bigger than 16-bytes, or transfer rates above 1MBaud ??

Schematic Review Service : if you would like us to review your schematic please contact your Elan sales rep. or email us at sales@elandigitalsystems.com attaching your schematic as a JPG or PDF format file.

About Host Software

The VPU implements a set of features that can be used by the standard O.S. Drivers in Windows. This means you don't need to get slowed down writing VxDs, WDMs, or SYS drivers. If you are targeting your card at Windows CE or PocketPC, this is very important. If you try to do something non-standard, like using 128byte deep FIFOs, you're going to have to write a driver to support this, and here's the catch; you'll need to create and support multiple versions to cover the various hardware architectures found in popular PDAs, that's assuming you can get enough in-depth platform information to make this viable.

With the VPU, and using a CIS generated by the tools included in the reference kit, the only thing you'll need to worry about is application software. In fact, because your card is using the VPU chip, it'll configure as a COM port and so your existing application software will work unaltered. Oh, and the VPU chip doesn't limit itself to COM1 to 4, it can also configure to COM5 and above giving even greater flexibility in systems with multiple pre-existing hardware and virtual COM ports.


If you need a variation of the VPU, perhaps a different package style or some alteration of the internal operation, then please fill in the information request form and we'll take a look.