oyama / pico-littlefs-usb Goto Github PK

Good if it can be used for about the FAT12 limit (4077 files). Currently, there is a restriction of up to 16 entries for both the root directory and subdirectories.

Split Pico dependencies to facilitate porting to other platforms.

Don't overdo it.

Consider seamless feasible ways to achieve this.

First of all, I would like to thank you for this project, which allows to use the capabilities of the standard usb msc interface with flash memory. But, during the process of testing on the MCU, I experienced a number of difficulties that I hope you can help overcome.
To begin with, I made a change so that the project could be compiled by toolchains other than gcc:

• replacing non-standard \e with \x1b in ANSI color macros

Then I caught stack overflow and exception thrown, but did not investigate the reasons that caused them:

• stack overflow: unsigned char buffer in bulk_update_fat function, so just added one more byte
• exception thrown: added the real_filesystem.cfg check before calling lfs_unmount

After analyzing the contents of the first sectors received via USB, I noticed that less was allocated for FAT12 than required. Here I corrected the code:

• fat_sector_size()

To view and analyze USB packet sequences from the PC to the MCU and back, I used Wireshark and saved the sessions in pcap files. To simulate this actual traffic on PC only, I wrote a program that uses the same mimic_fat and littlefs source code as the MCU. To obtain "perfect synchronization" I temporarily replaced the rand library function with a simple increment and added the memory cleaning in mimic_fat_read.

The program (Win10 executable is included, the same one for Ubuntu can be built from source code) and test results can be found here. Unfortunately, some tests failed. I hope you can help me figure this out.

To be used up to the FAT12 limit.

Currently, it is limited to 170KB because the calculation is hard-coded to mimic the FAT location. This limitation can be addressed by modifying it to mimic the file system according to the file system parameters (BPB_BytsPerSec, BPB_SecPerClus) constants.

The file names that can be used are limited to 8.3 short file names. Long file names are supported.