14 DAY TRIAL // There are functionality issues related to Windows Mobile PocketPCs and SD memory cards following a suspend/resume. Namely, any application using the SD will stop responding. The SD memory cards are Secure Data cards based on nand flash memory. Mike Calligaro, working with the Windows Mobile Team has offered an explanation for the functionally problems.
The issues involve the suspend mode of a PocketPC that shuts off power for the hardware. In suspend mode, the part of the SD slot that detects the presence of a card is also without power. "While the system is suspended, you could potentially eject the card and stick a different one in. If you did that, any apps that have files open on the card would get very confused. This almost never happens, but it's something we need to guard against. So, when we power the system back on, we check to see if there's a card there. If it is, we check with it to see if it's the same one as was there before. If it doesn't respond, or responds differently than we expect, we unload it and close any files that were open before," explained Calligaro.
In order not to affect the overall functionality of the PocketPC, Microsoft has limited the period of time the system will wait for a response from the card. If the card fails to issue a response it will simply be unloaded. "Some phones can power on their SD system quickly and some take more time. Because of this, the OEM chooses the correct PnPUnloadDelay for his hardware, and we rely on his setting. If something happens that makes the SD card not respond in the time specified by the PnPUnloadDelay, we assume it's a new card," added Calligaro.
In this context, there might not be a correlation between the hardware response time as defined by PnPUnloadDelay and the one of the SD card. If this is the case, the card will also be unloaded, although it is not a different card.