Raven1106

Raspberry Pi-like single board computer based on the Rockchip RV1106G3.

Overview

Raven1106 is a custom open-hardware SBC. This repository contains everything related to the project including: the board schematics and the PCB design, build scripts, configurations, device trees and file system overlays for the operating system images and all the patches needed to get everything working.

• CPU: Single-core Cortex-A7 @ 1.6 GHz
• RAM: 256MB DDR3L @ 924MHz
• Storage: SD card
• Ethernet: Full-size 100 MBit/s Ethernet port
• USB: Four USB-A ports routed through CH334F or one OTG USB-C port
• WiFi: ESP32C6 with ESP-Hosted firmware (currently not functional)
• Kernel: Linux 5.10 (Rockchip BSP)
• U-Boot: 2017.09 (Rockchip BSP)
• OS images: Debian 12 (bookworm, armhf)

Why does it exist?

TLDR: It's a learning project

The main goal of this project was to be a learning experience for designing complex high-speed digital PCBs. Creating an SBC that is almost capable enough to do basic tasks like hosting simple servers or running AI harnesses is a nice bonus. RV1106 was chosen specifically for its simplicity, integrated RAM meant no DDR routing and QFN package meant I could solder the board manually relatively easily.

What this chip lacked in the hardware it made up for in the software side of things -- BSP is absolutely terrible, outdated, barely documented (though with a lot of spelling mistakes). Programming it wasn't much better either with only a few barely working flashing tools and a USB controller that might not actually be compliant with the USB spec, as most machines can't even enumerate it. It might have been genuinely easier to make this project around a more complex BGA part than this SoC.

PCB

The board is designed in KiCad (4-layer). pcb/ contains two revisions:

• pcb/v1.0 — first revision
• pcb/v1.1 — revision with component value fixes (no PCB layout changes)

Layer 1 - Signal	Layer 2 - Ground Plane	Layer 3 - Power Planes	Layer 4 - Signal

Known v1.0 hardware issues and their fixes

USB Impedance Miscalculation - Turns out that FSUSB42MUX doesn't act as a retransmitter but like a normal switch which adds ~10 ohm impedance to the line. Fix: Swap RN301 with 0-ohm and change R301 and R302 from 22 ohm to 10 ohm. This results the line impedance that is well in spec.

No pullups on FSPI Flash - Speaks for itself, thankfully the RV1106 has internal pull-ups that enable the chip and disable the write protection. And we don't even use it so it's a non-issue. Cannot fix this without board changes.

LED resistors too small - The LEDs shine too brightly with 1k resistors. Fix: Change R3, R4 and R5 from 1k to 10k resistors.

USB Hub crystal load too large - The CH334F is designed to work with a crystal with no load caps, adding them causes the oscillation to die down. Fix: Change R309 from 1k to 10 ohm, remove C302 and C303.

Boot button pull-up too strong - With 1k the button does not affect the chip's boot at all. Fix: Change R6 from 1k to 10k.

Wrong ESP_BOOT pin exposed - It should be pin 9, not pin 8. Fix: No way to fix it without modifying the board unfortunately, just flash the bootloader before soldering the ESP.

Reference clock not connected to the camera - Turns out not all camera modules have their own crystal oscillators. SC3336 requires a reference clock; RV1106 has two reference clock outputs, one of them is connected to the camera's reset and the other one to the IMU interrupt pin. Fix: Add a jumper from R508 to R515.

Most of these problems could have been prevented with "RTFM" (Reading The F***ing Manual).

Repository layout

Path	Contents
configs/	Defconfigs (kernel, U-Boot, crosstool-ng), device tree source, SD image layout, U-Boot env, user table
kernel/	Linux 5.10 Rockchip BSP kernel
uboot/	U-Boot 2017.09 Rockchip BSP
debian/, overlayfs/	Debian rootfs staging area and overlay
crosstool-ng/, legacy-toolchain/	Legacy uClibc toolchain (kernel/U-Boot builds)
esp-hosted/	ESP32-C6 host driver source (esp_hosted_ng)
rkbin/	Rockchip binary blobs (DDR init, trust)
scripts/build.sh	Image assembly, Debian rootfs, Docker environment
images/	Build artifacts and final sdcard.img
pcb/	KiCad hardware design
docs/	RV1106 datasheet / reference manuals

Building

Build environment

All builds run inside a Docker container. The first invocation builds the rv1106-build image, then drops you into a shell with the repository mounted at /work:

make docker

Toolchain

Before building any image build the legacy toolchain for the Kernel and U-Boot.

make toolchain

Debian image

make            # default target: debian-image
# or explicitly:
make debian-image

Known issue: If build fails on stage 2 debootstrap because of "Invalid format", just delete the debian/ directory, restart the container and try to build again. It does that sometimes...

This builds the kernel, device tree, and U-Boot, then creates a Debian 12 (bookworm, armhf) rootfs with debootstrap (using qemu-user-static/binfmt for the second stage) and assembles images/sdcard.img.

Notes:

• Default login: user debian, password raven (sudo user, SSH enabled). Override with the BOARD_USER and DEBIAN_PASSWORD environment variables.
• Included packages: systemd, ifupdown, openssh-server, sudo, dhcp client, busybox, vim-tiny, ca-certificates (see DEBIAN_PACKAGES in scripts/build.sh).
• Rootfs image size: 1 GB (DEBIAN_ROOTFS_SIZE).
• For now there's no autoresize, run sudo resize2fs /dev/mmcblk1p5 after the first boot.

Component targets

Target	Description
make kernel	Build the kernel using the legacy toolchain
make dtb	Preprocess and compile configs/device-tree.dts into images/
make uboot	Build U-Boot (SPL + idblock + uboot.img)
make espdriver	Build the ESP32-C6 host driver against the kernel
make toolchain	Build the crosstool-ng uClibc toolchain
make docker	Build/enter the Docker build environment
make *-clean	Clean kernel / U-Boot build trees

Configuration targets

Each of these copies the stored defconfig from configs/, opens menuconfig, and saves the result back to configs/:

make kernel-config
make uboot-config
make toolchain-config

Output artifacts

All artifacts land in images/:

File	Description
sdcard.img	Final flashable SD card image
download.bin, idblock.img, uboot.img	Bootloader stages
Image, zImage, device-tree.dtb	Kernel and device tree
env.img	U-Boot environment (from configs/image-env.txt)
boot.vfat	FAT32 boot partition (kernel + dtb)
rootfs.ext4, rootfs.tar	Root filesystem

SD card layout

The image has no MBR/GPT; partitions are defined by the kernel command line (blkdevparts, see configs/sdcard-image.cfg and configs/image-env.txt):

Partition	Offset	Size	Contents
env	0x0	32 KiB	U-Boot environment
idblock	0x8000	512 KiB	Rockchip ID block (SPL)
uboot	0x88000	256 KiB	U-Boot
boot	4 MiB	64 MiB	FAT32: kernel image + device tree
rootfs	68 MiB	remainder	ext4 root filesystem

Flashing and first boot

sudo dd if=images/sdcard.img of=/dev/sdX bs=4M status=progress conv=fsync

Serial console: ttyFIQ0 at 115200 baud.