Overview on Granit

Release

Mon, 01 Jan 0001 00:00:00 +0000

Board

Mon, 01 Jan 0001 00:00:00 +0000

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.

Assembly

Mon, 01 Jan 0001 00:00:00 +0000

The PCB (92 × 99.5mm) fits both Hammond 1455 enclosure variants. PCB and HDD sit side-by-side with the SATA connector direct-mating between them. The lid (U-channel) is shown offset to reveal the internals.

End Plate

The connector-side end plate has cutouts for: barrel jack (12V DC), RJ45 (Ethernet), USB-C (OTG), tactile button, and RGB LED (light pipe).

Parametric design in OpenSCAD — generate for CNC machining or 3D printing:

# DXF for CNC laser/mill
openscad -o end-plate-slim.dxf -D 'variant="slim"' -D 'mode="2d"' end-plate.scad

# STL for 3D printing
openscad -o end-plate-slim.stl -D 'variant="slim"' -D '$fn=64' end-plate.scad

Downloads

File	Format	Description
end-plate-slim.dxf	DXF	Slim end plate — CNC cutting
end-plate-wide.dxf	DXF	Wide end plate — CNC cutting
end-plate-slim.stl	STL	Slim end plate — 3D printing
end-plate-wide.stl	STL	Wide end plate — 3D printing
assembly-slim.step	STEP	Full slim assembly
assembly-wide.step	STEP	Full wide assembly
end-plate.scad	OpenSCAD	Parametric end plate source

Enclosure Variants

Variant	Case	HDD	Internal dimensions
Slim	Hammond 1455L2201	2.5"	103 × 220 × 30.5mm
Wide	Hammond 1455T2601	3.5"	165 × 252 × 51.5mm

Software

Mon, 01 Jan 0001 00:00:00 +0000

Custom Raspberry Pi OS Lite image with Ansible-based provisioning. Source: software/

Architecture

pi-gen: builds a minimal image (packages + boot config)
Ansible: configures all services, security, and monitoring

You can also skip the custom image and provision stock Raspberry Pi OS directly.

Hardware Support

PCIe SATA (ASM1061)

dtparam=pciex1
dtparam=pciex1_gen=2

The SATA drive appears as /dev/sda once connected and powered.

DS3231 RTC

dtparam=i2c_arm=on
dtoverlay=i2c-rtc,ds3231

System clock is set from the RTC on boot. The RTC alarm triggers scheduled wake.