SolarExpress USB Host Card Review

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The latest smartphones are as powerful as notebooks of a few years ago, but there’s one feature that’s missing: the ability to control USB devices like keyboards and flash drives.

SolarExpress USB Host CardThe SolarExpress USB Host Card add this to Windows Mobile handhelds with a CompactFlash card.

A Welcome from Your Host

To explain what this card actually does, I have to start with a quick primer on USB. There are two parts of a USB connection: the “Host,” meaning the computer, and the “Device,” which is what you’re connecting to it, whether that’s a keyboard or a cell phone.

Almost all mobile devices are USB Devices, meaning they can be hooked up to a PC, but not to a USB hard drive, or printer, or keyboard. The SolarExpress card is designed to add USB Host to any device that has a CompactFlash slot. For the purposes of testing it, I used an HP iPAQ 210.

The card itself is fairly low-profile, a fact that’s helped by its use of a dongle to connect to USB peripherals rather than a full size port. This might be a little inconvenient if you don’t want to carry a ton of parts, but it makes for a much less awkward protrusion from the handheld.

When I first tried to fire it up, I thought that the card’s drivers weren’t loading properly because I couldn’t seem to get it to recognize the USB devices I was plugging in. After a little troubleshooting, however, I found out the problem. The USB Host card is apparently a little bit picky about what USB Mass Storage devices it recognizes. My 256 MB flash drive and SanDisk-branded SDHC reader were apparently not on the good citizens list. I did, however, find success with others — including the rather bizarre sight of using my own Samsung BlackJack as a USB flash drive hooked up to an iPAQ 210 over USB.

SolarExpress USB Host CardAnother thing to note, which while obvious in hindsight, I forgot when I began testing: Windows Mobile won’t read NTFS-formatted hard drives. Any storage items must be formatted FAT or FAT32 to be usable.

Once you get it running, the setup is fairly plug-and-play, the way USB is supposed to be. A USB drive shows up in the file explorer in the same way a memory card would, with a distinctive name. You can add and remove files, install programs, play back media — all of the things you’d do with a typical memory card on a Windows device.

The biggest drawback to USB Host capability isn’t really the fault of the card, but a limitation of the Windows Mobile platform. With so few devices being Host-capable, and even fewer people buying USB Host cards like this one, there’s been fairly little development of USB drivers for this operating system.

Windows Mobile already includes support for Mass Storage devices — hard drives, flash drives, etcetera — as well as printers and “Human Interface Devices,” meaning keyboards. The SolarExpress driver takes this base and extends it as far as possible. Beyond that, though, any drivers need to be supplied supplied by someone or built custom. There’s few of either, meaning that unless you’re a software engineer, you’ll be somewhat limited to the basic repertoire.


SolarExpress USB Host CardThe SolarExpress USB Host card is most definitely a niche item. That’s not in doubt. But for the people in that niche, it’s an invaluable tool to enable development and field use of USB devices that might otherwise require a much bulkier device to deal with, like an Eee PC or other laptop.

And for those whose goal is just the highest end handheld system, it’s the only game in town to give you 60, 80, maybe 100 GB of file access.


  • USB Host on any CompactFlash equipped device


  • Limitations on Mass Storage device compatibility
  • Not a wide variety of drivers

 Bottom Line:

Expensive and niche oriented, but one of the few ways to get true USB Host on a Windows Mobile device.




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