Hardware: PaperDIY, microSD card formatted FAT32, PC. 2. Insert the microSD card into the side slot. Ensure gentle insertion. 3. In IDE, add SD.h library. 4. Write simple code: initialize card with SD.begin(CS_PIN). Note CS pin is specific to PaperDIY schematic (check docs). 5. Create 'test.txt' on card from PC with text. 6. Upload code that reads this file and prints content to Serial Monitor. 7. If content displays, SPI bus is functional. 16 MB flash storage is separate, useful for firmware. 8. Verify writing works by creating a new file. 9. To go deeper, store bitmap images for e-paper display.