The CC3135 device maintains a proprietary file system on the sFLASH. The CC3135 file system stores the service pack file, system files, configuration files, certificate files, web page files, and user files. By using a format command through the API, users can provide the total size allocated for the file system. The starting address of the file system cannot be set and is always at the beginning of the sFLASH. The applications microcontroller must access the sFLASH memory area allocated to the file system directly through the CC3135 file system. The applications microcontroller must not access the sFLASH memory area directly.

The file system manages the allocation of sFLASH blocks for stored files according to download order, which means that the location of a specific file is not fixed in all systems. Files are stored on sFLASH using human-readable filenames rather than file IDs. The file system API works using plain text, and file encryption and decryption is invisible to the user. Encrypted files can be accessed only through the file system.

All file types can have a maximum of 100 supported files in the file system. All files are stored in 4-KB blocks and thus use a minimum of 4KB of Flash space. Fail-safe files require twice the original size and use a minimum of 8KB. Encrypted files are counted as fail-safe in terms of space. The maximum file size is 1MB.

Table 9-2 lists the minimum required memory consumption under the following assumptions:

• System files in use consume 64 blocks (256KB).
• Vendor files are not taken into account.
• Gang image:
  • Storage for the gang image is rounded up to 32 blocks (meaning 128-KB resolution).
  • Gang image size depends on the actual content size of all components. Additionally, the image should be 128-KB aligned so unaligned memory is considered lost. Service pack, system files, and the 128-KB aligned memory are assumed to occupy 256KB.
• All calculations consider that the restore-to-default is enabled.