USB Mass Storage Device not enough bandwidth
I am using PIC32 module with Explore 16, USB adaptor card, and SD/MMC adaptor card and try to implement USB mass storage device per AN1169. I am successfully got it to work with 1GB SD card, but it does not works with 2GB SD card. So I contact microchip techsuport and this is what there response:
I aplogize for the delay. With the help of our applications engineer, we were able to track down the problem and along the way find a bug and made some improvements. However, the bad news is that we will not be able to support 2GB cards at this time. The reason is that 2GB has a sector size of 1K where card less than 2GB have a sector size of 512. Because of this, we would not be able to support the sector size of 1k right now. This is not to say that we WILL not be able to support this card size in the future. We do not have the bandwidth to make the modifications and test the code right now for that feature update.
We also found some bugs that were preventing the 1GB cards to work properly. Part of the problem was that the CSD (SD card structure) was not being read properly. On some 1GB cards reading the CSD work properly and on some others did not. This problem is now corrected.
We also found an error in the MSD source file. The routine that sends the card data, from the CSD, was calculating the size incorrectly. This issue has also been resolved.
I am attaching the modified msd.c and mediasd.c files that reflect the above mentioned corrections. You can use them with the 1GB or less capacity card.
Again, sorry for the inconvinience.
Have any of you guys try to implement same thing that I am trying to do and run into the same problem? also what your guys take on microchip techsupport answer?