Custom carrier board for the Raspberry Pi CM4 Compute Module, designed as a minimal offsite backup appliance.
The 3-2-1 backup rule says: keep 3 copies of your data, on 2 different media, with 1 copy offsite. The first two are easy — a NAS with mirrored disks covers them. The offsite copy is the hard part.
Granit takes a different approach: a small, silent box you leave at a friend’s or family member’s house. It connects to their network, receives encrypted backups over a VPN, and stores them on a local hard disk. You keep full control of your data.
Key Components
| Component | Description |
|---|---|
| Raspberry Pi CM4 | Compute module (PCIe Gen 2 x1) |
| ASM1061 | PCIe to 2-port SATA III controller |
| 2.5" or 3.5" SATA HDD/SSD | Backup storage |
| DS3231 RTC | Battery-backed real-time clock with alarm wake |
| AP64501SP-13 | 3.5A DC-DC buck converter |
| USB-C | USB 2.0 OTG with ESD protection |
Architecture
