Rv1106

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What this chip lacked in the hardware it made up for in the software side of things -- BSP is absolutely terrible, outdated, barely documented (though with a lot of spelling mistakes).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

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

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/:

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):

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.

WiFi setup

The WiFi interface (ESP32-C6 running ESP-Hosted firmware over SDIO) is set up at boot on a running system, it is not configured during the image build. The helper script overlayfs/usr/local/bin/start-network (installed on the image at /usr/local/bin/start-network) performs the entire sequence:

1. Module reset - GPIO 2 is exported, pulsed low and released, which resets the ESP32. The pin is then unexported and the script waits 2 s.
2. Driver loading - the required modules are inserted from /lib/modules/5.10.252/: the crypto primitives (libaes, libarc4, ecc, ecdh_generic), bluetooth, the wireless stack (cfg80211) and finally the ESP-Hosted SDIO host driver (esp32_sdio.ko). The script then waits 5 s for the module to appear as wlan0. (The host driver is built separately with make espdriver.)
3. Association - wpa_passphrase <ssid> <password> generates a config into /tmp/wpa.conf and wpa_supplicant -iwlan0 is started in the background, followed by a 15 s wait for the connection to come up.
4. Addressing - static IP configuration: 192.168.0.100/24 on wlan0 with the default route via 192.168.0.1.

Configuring the network

The SSID, passphrase and addresses are hardcoded in /usr/local/bin/start-network, so edit them on the board (or in overlayfs/usr/local/bin/start-network and rebuild/flash the image):

sudo vi /usr/local/bin/start-network

Replace ssid and password in the wpa_passphrase call with your network name and passphrase, and adjust the ip addr add and ip route replace default via lines for your address and gateway. There is no DHCP client call for wlan0.

systemd service

The script runs automatically at boot via the systemd unit overlayfs/etc/systemd/system/start-network.service (/etc/systemd/system/start-network.service on the image) - a oneshot service started after network.target, running as root with RemainAfterExit=yes, and logging all output to /tmp/wifi.log. Use it to start/stop the WiFi bring-up manually or to check the log:

sudo systemctl start start-network
sudo systemctl status start-network
less /tmp/wifi.log

Note: the ESP32 must already carry the ESP-Hosted firmware (flash the bootloader/ESP before soldering it, see the PCB section above).