FatFs R0.09 is used to access the binary file on the SD card. It has been ported to Atmel devices and is ready for usage as the third party module through Atmel Software Framework (ASF), which is released with Atmel Studio or individually. The needed source files for the FatFs module are included in the firmware pack.
In this bootloader implementation, only read operation is necessary while write operation is not. So to save memory space, the FatFs module should be configured to read-only and the table below lists some main settings.
| Setting name | Value | Description |
|---|---|---|
| _FS_TINY | 1 | When _FS_TINY is set to 1, FatFs uses the sector buffer in the file system object instead of the sector buffer in the individual file object for file data transfer. This reduces memory consumption 512 bytes each file object. |
| _FS_READONLY | 1 | Only read operation is required for the binary file |
| _FS_MINIMIZE | 3 | The minimized level to remove functions not used in this implementation |
| _VOLUMES | 1 | Only 1 volume (logical drive) is used |
| _MAX_SS | 512 | Always set 512 for memory card |
| _USE_ERASE | 0 | Disable sector erase feature |
| _WORD_ACCESS | 0 | Byte-by-byte access |