Getting Started Guide • 10/2000
Type I and II CompactFlash Cards
Type II CompactFlash memory cards are thicker (5.0mm) versions of the original (3.3mm) Type I cards. This allows more flash memory chips to fit into the cards, but also means they won’t fit into headers designed for the first generation cards. The CF8V2 will accommodate either type of card. There is no downside to this unless you also happen to be responsible for processing and archiving all the extra data the scientists can now collect.
Industrial Temperature Range
The V2 Persistor was designed to match the TT8’s industrial temperature range of -40°C to +85°C. Even so, you should keep in mind that most memory cards are specified for operation in the commercial temperature range of 0°C to +60°C. This includes standard Persistor brand cards though we can provide industrial rated cards for a premium price and with generally longer lead times.
New PicoDOS8 Flash Footprint
The latest version of PicoDOS8, which works with both V2 and classic Persistors, has a slightly larger flash memory footprint than previous versions. PicoDOS8 versions 1.50 and up now begin at location 0x28000 instead of 0x2BCF8 to allow some long needed enhancements and to provide a little room for some possible future enhancements. For backward compatibility, both 0x28000 and 0x2BCF8 are valid vectors to enter PicoDOS8, but that extra 16KB of flash between them is now used by PicoDOS8 and unavailable to your applications. This change will only impact users whose flash applications fall in the range of 155KB to 172KB.
Buffered Bus Connections
The classic Persistor design presented the flash memory card bus signals directly to the 68332 data bus and all was well until the surge in popularity of flash memory cards spawned a slew of odd brand cards with less than friendly electrical interfaces. Though never a problem for Persistor brand memory cards, the new buffers protect the TT8’s CPU from evil cards and allow the new full power-down features described ahead.
Complete Card Shutdown
The V2 Persistor can completely remove power to the flash memory card dropping the Persistor plus flash memory card current contribution to typically about 5µA. Shutdown mode happens automatically whenever the Persistor is first powered, reset, or dropped into 3.3V operation (ala LPSleep), and can be commanded to shutdown using the new V2CardPower(0) PicoDOS8 service call. The Persistor automatically exits Shutdown mode whenever PicoDOS8 makes any kind of file or card service request, or whenever you call V2CardPower(1). This means you do not have to make any software changes to take advantage of this new feature.
Like the buffered bus connections, this new shutdown capability has become even more important as the competition heats up to provide cheap digital film to the amateur photographers who don’t buy cards based on esoteric current ratings. We screen all of our Persistor brand cards to meet the 200µA@3.3V and 500µA@5V sleep specification. You might be surprised that we’ve seen some non-Persistor brand cards that exceed 5mA sleeping! Either way, 5µA is a significant improvement.