3D Renders

granit 3D blender 1 top
granit 3D blender 1 top
granit 3D blender 2 bottom
granit 3D blender 2 bottom

Schematic & PCB

Interactive BOM

For detailed circuit design notes, PCB routing guidelines, and netclass definitions, see hardware/DESIGN.md.

Key Design Decisions

  • ASM1061 over USB-to-SATA bridges: Native PCIe SATA controller using the standard Linux ahci driver. No proprietary firmware blob required — the SPI flash footprint can be left unpopulated. SMART works natively without SAT translation hacks. Full SATA III throughput on both CM4 and CM5.

  • 12V DC input: Required for 3.5" HDD support (spindle motor needs 12V). AP64501SP-13 accepts 3.8–28V. Both barrel jack and screw terminal footprints provided — populate one at assembly time.

  • Reuse from pedalboard-hw: CM connector, power supply (AP64501SP-13 buck + NCP1117 LDO), USB power switch (AP2553W6), KiCad symbol/footprint library.

  • USB-C OTG: Single USB-C connector for eMMC flashing (rpiboot) and USB mass storage gadget mode (initial backup seeding). USB 2.0 device mode only, with USBLC6-2SC6 ESD protection.

  • SATA power control: 12V and 5V to the SATA connector are software-controlled via GPIO5. HDD is off by default at boot — powered on explicitly by software. Solder jumpers (JP5, JP6) allow changing the default without a PCB respin.

  • Power budget: 12V @ 2A (3.5" HDD spin-up) + 5V @ 2.3A peak (CM4 + electronics) — use a 12V/3A+ PSU.

  • Boot and storage strategy: Full OS on CM4 eMMC (no SD card slot), SATA HDD dedicated to backup storage only. No SD card — eMMC is more reliable for a deploy-and-forget device. Backup data is encrypted client-side (e.g. by Restic or rclone crypt). Full-disk encryption via LUKS is optional.