I'm trying the FreeRTOS+FAT SL on an Atmel SAM3. I used another FS library until now but it's quite dated and discontinued.
The scenario is that up to 100 files have to be kept opened. After a test run and a closer look on the f_open function I noticed that it won't work. The downloadable version of FAT SL is only able to have one file opened at a time. I cannot find any information about this limitation on the freertos web page nor am I able to find any information if there is a commercial "unlocked" version. Does anyone have an idea?
The file system you are looking at is the 'super lean' system. As in all file systems (and networking stacks, etc.) there are engineering trade offs that can be made between performance, functionality and footprint. The super lean version is at the extreme of minimising the footprint. There are other file systems in the family that compromise the footprint (i.e. use more ROM and RAM) to improve performance, and even provide some fail safe functionality and in those you can open multiple files and multiple volumes - but they are not free I'm afraid (nor are they provided by Real Time Engineers Ltd directly).
Looks like you are using the 'Petite FAT File System' (http://elm-chan.org/fsw/ff/00indexp.html) which has several limitations.
If you want to open multiple files/etc, you need the full-blown FatFS (http://elm-chan.org/fsw/ff/00indexe.html)