Use a standard USB stick formatted to FAT32 .
Here's some useful content related to updating the software on a Blaupunkt BP 330: Blaupunkt Bp 330 Software Update
: Insert the prepared MicroSD card into the dedicated slot on the front of the unit. Use a standard USB stick formatted to FAT32
Blaupunkt San Marino 330 6.2 inch Touchscreen, Bluetooth Car Multimedia Player (2 DIN) : Amazon.in Blaupunkt Bp 330 Software Update
Note: Ensure the model number matches exactly, as using firmware for a different model can permanently disable the unit. The update process typically takes between 5 to 10 minutes :