Feature: SD Card support library

[Dilu9218]

Expected: Firmware needs to support SD Card read/write functions in PSLab-v6 design

Actual: Current firmware doesn't have any functionality to support this feature

I would like to add required library files and I will refer this open source FatFS library which comes with a GNU GPL licence. Since I don't have the device with an SD card mounted, I would try out the code with existing PSLab device and an external SD Card Module connected with SPI protocol. Once that is done, @CloudyPadmal, could you please check it with the new prototype and provide feedback?

[CloudyPadmal]

Hello @Dilu9218 , Yes this seems like a possible approach. Please send us code in a PR to review. I'll check with my prototype. Thanks.

[CloudyPadmal]

Just to define things clearly, following is the pins assigned;

• SPI Clock RC3
• SPI Data In RA9
• SPI Data Out RA4
• Chip Select RB9
• Switch RC5
• Status LED RB15

[CloudyPadmal]

Will address in #46