hermes-bot/CONTEXT.md

Current state

Last updated 2026-10-04. HANDOFF.md is the brief; this file tracks where the work stands.

Hardware on hand

Raspberry Pi 4 (8 GB), BrainCraft HAT, Arducam UC-346 camera. Not yet: servos, USB-C splitter, printed enclosure, speakers. Work until those arrive is limited to what the Pi, HAT and camera can do.

The Pi (hermes-bot)

• Ubuntu 24.04.5 server, kernel 6.8.0-1065-raspi (fully upgraded), flashed from talos. User hermes (key-only; passwordless sudo), SSH keys for kyle@vade (talos) and kyle@straylight.
• On Wi-Fi at 192.168.88.152 (MAC d8:3a:dd:0d:66:f5); eth0 is not cabled. The owner says it has a static IP on the rack switch; that address is not recorded here yet. USB link: 10.55.0.2 (see package 0b below); ssh hermes@10.55.0.2 works from talos. avahi-daemon is installed, but mDNS is off in systemd-resolved on talos, so hermes-bot.local doesn't resolve there; use the IP.
• cloud-init applies network-config and user-data on the first boot only. To change Wi-Fi later, edit /etc/netplan/50-cloud-init.yaml on the Pi, or bump instance_id in meta-data on system-boot. pi/50-cloud-init.yaml is a template for the Wi-Fi block; it is gitignored because it holds credentials.
• Installed: ROS 2 Jazzy (ros-base, ros-dev-tools, colcon, robot_state_publisher, xacro, camera_ros); python3-numpy/pil/spidev/lgpio/rpi-lgpio; a venv ~/venv (system site packages visible) with adafruit-circuitpython-rgb-display and Blinka. Workspace: ~/ros_ws, source synced from ros/ with rsync -a --delete --exclude __pycache__ ros/ hermes@<ip>:~/ros_ws/src/, then colcon build --symlink-install.
• CPU governor is ondemand; at full clock the face costs about half as much CPU. Set performance in the installer (package 5). It is not persistent yet.

Package 0a (platform proof on Ubuntu 24.04)

• Step 1 done: host/check-pi-platform.sh passes.
• Step 2 done: flashed, booted, upgraded; ROS installed; ros2 topic list works.
• Step 5 (display) done. ST7789 works on lgpio through Blinka (rpi-lgpio, no RPi.GPIO). Two gotchas: pass cs=None (the kernel drives CE0; claiming GPIO8 raises "GPIO busy"), and the 240x240 glass sits at y_offset=80 in the controller's RAM, for every rotation (the driver rotates in software and leaves the scan direction fixed). Mounted pose (microSD end up, USB-C edge on the left) needs content turned 90 degrees clockwise: rotation=270. Full-frame push is ~23 fps through the driver; the face pushes raw RGB565 with _block and reaches ~27-28 fps.
• Camera: works with the Raspberry Pi libcamera fork, not with the stock stacks. The OV5647 is detected (ov5647 10-0036) and Ubuntu's libcamera 0.2.0 lists it once libcamera-ipa is installed, but capture dies in the Pi IPA (assertion "it != buffers_.end()" in prepareIsp()), and ROS Jazzy's libcamera 0.7.2 dies with FATAL … A list of V4L2 controls requires a ControlInfoMap right after configure. Both are deterministic whatever the stream format or size. Fix: build the fork (github.com/raspberrypi/libcamera, commit 6c1dd9d, 2026-08-17) with -Dpipelines=rpi/vc4 -Dipas=rpi/vc4 -Dcam=enabled -Dv4l2=false … into /opt/libcamera-rpi; its cam then captures 1296x972 RGB888 at ~16 fps (dim room). pi/capture_still.py takes a still with it. camera_ros still has to be built against this fork (the apt one uses ROS's broken libcamera). Frames are padded (stride 3936) and B,G,R in memory.
• camera_ros 0.7.0 is built from source against the fork in ~/camera_ws (overlay on ROS; at runtime the fork must come first in LD_LIBRARY_PATH, which source ~/robot-env.sh does; copy from pi/robot-env.sh). Verified: ros2 run camera_ros camera_node --ros-args -p width:=1296 -p height:=972 -p format:=RGB888 publishes /camera/image_raw, /camera/image_raw/compressed (~26 Hz) and /camera/camera_info. It costs ~140% of a core with raw and compressed both on; lower the frame rate or size before running everything together. No calibration file yet.
• ros/hermes_vision: hermes_vision.detect (YuNet, Haar fallback; no ROS imports) and a node face_detector that subscribes to the compressed image and publishes /vision/faces (vision_msgs/Detection2DArray, bbox centre/size in pixels, class_id: face, score), at rate_hz (default 4, ~47% of a core on a Pi 4); publish_debug:=true adds an annotated image. CLI: python -m hermes_vision.detect_cli IMAGE. YuNet 2023mar needs OpenCV 4.8+, so ~/venv has opencv-python-headless==4.10.0.84 with numpy<2 (system NumPy stays 1.26.4 for ROS), and robot-env.sh puts the venv first on PYTHONPATH; YuNet also needs input sides that are multiples of 32. Tested on a sample image and on a live frame (one face found, upright, no flip needed).
• Audio capture works (verified 2026-10-04). The stock wm8960-soundcard overlay fails every stream with wm8960: No MCLK configured on Ubuntu 24.04: it puts the 12.288 MHz fixed clock on the sound card's codec link, but the codec driver reads mclk from its own node. pi/overlays/hermes-wm8960.dts is the stock overlay plus clocks/clock-names on the codec node; pi/install-audio-overlay.sh compiles it to /boot/firmware/overlays/hermes-wm8960.dtbo, sets dtparam=audio=off and dtoverlay=hermes-wm8960. Capture then opens at 8-48 kHz. Address the card by name (hw:CARD=wm8960soundcard,DEV=0): its index changes (it was card 1, then 0).
• The HAT's hardware Audio ON/OFF slide switch (right edge, by the "Audio" label) must be ON. With it off, the codec still answers on I2C and every software check looks right, but all recordings are exactly zero. That cost an hour of debugging; check it first.
• Mixer: Left/Right Input Mixer Boost Switch default to off and must be on. Settings in use: Capture 47/47 (+18 dB), Left/Right Input Boost Mixer LINPUT1/RINPUT1 volume 1, input mixer boost on. Singing at arm's length: RMS -34 to -49 dBFS, peaks -18 dBFS, no clipping, channels within 1-2 dB. Saved with alsactl store and exported as pi/wm8960_asound.state; restoring at boot is not yet verified. No speakers on hand, so playback is untested.
• Not done: PWM (waits for servos). Ask before rebooting the Pi.

Package 0b (USB link): Pi side and talos side working

• Pi: dtoverlay=dwc2,dr_mode=peripheral; robot-usb-gadget.service builds a configfs gadget (NCM usb0 + ACM ttyGS0, host MAC 02:68:65:72:6d:01, robot MAC 02:68:65:72:6d:02) before networking; serial-getty@ttyGS0 is enabled; /etc/netplan/60-usb0.yaml gives usb0 10.55.0.2/30 with no gateway, so the default route stays on Wi-Fi. Installed by pi/install-usb-gadget.sh (a backup of config.txt is config.txt.bak-usbgadget). NCM works on the Pi 4 with kernel 1065; ECM was not needed.
• netplan gotcha: match the gadget interface by name: usb0. A macaddress: match becomes PermanentMACAddress= in networkd, which a gadget interface lacks, so it stays unmanaged.
• talos (Omarchy, NetworkManager): host/omarchy/robot-usb-link.sh (needs sudo) adds profile hermes-robot-usb: 10.55.0.1/30 on the interface with MAC 02:68:65:72:6d:01, priority 100, never-default. Verified from talos: ping ~2.4 ms, SSH over the link.
• Not yet verified: serial login prompt (talos's /dev/ttyACM0 is root:uucp; use sudo screen /dev/ttyACM0 115200). The hermes account has no password, so the console shows a login prompt but cannot log in until the owner sets one; no autologin by design. Also not done: the nftables rewrite, the Pi booting with Wi-Fi off, replug and second-host recovery, get_throttled after a servo sweep on the splitter, the NixOS snippet, and straylight/other-host testing. Currently the Pi is powered from talos's USB port (bench test, no servos).

Face (ros/hermes_face)

• render.py: numpy port of docs/face-prototype.html, flat face only (head and lowpoly not ported). Phosphor and vector styles. States: sleeping idle listening thinking looking speaking. sleeping (new) is the "no agent connected" pose: eyes closed to thin lines, mouth short, dim and slowly breathing. looking returns to the state it interrupted. Tone mapping is a lookup table (RGB and RGB565 tables), glow is computed at half resolution, rotation is a free np.rot90.
• display.py: ST7789 driver plus an async pusher (render overlaps the SPI transfer).
• face_node.py: node hermes_face; subscribes /hermes/state (std_msgs/String) and /joint_states (pan_joint, tilt_joint, radians); starts in initial_state (sleeping), so it runs with nothing else up. Parameters: rotation (270), x_offset (0), y_offset (80), baudrate, fps, output (st7789 or none), phosphor (P7), style, persistence_ms, focus, jitter, intensity, initial_state.
• demo.py: no ROS. python -m hermes_face.demo --sequence cycles the states on the panel; --png-dir DIR writes a PNG per state without hardware.
• Tests: python3 -m pytest test in ros/hermes_face (25 pass on the Pi). Renderer parameters (focus, persistence_ms, intensity, jitter) are clamped; fps is clamped to 1-60.
• Measured on the Pi 4: ~9 ms per frame in isolation. With the CPU at full clock: 24% of a core at 20 fps and 40% at 30 fps (target was under 40% at 20 fps or more). Under ondemand the same load reads 40% at 20 fps and ~67% at 30 fps. No C++ rewrite was needed.
• Not yet: audio levels for the mouth (/audio/levels), hermes_mcp publishing states, launch file in hermes_bringup, head/lowpoly shapes, DotStar LEDs, button mute.
• Open: IPS black level. The backlight is on at full brightness, so black reads dark gray on camera. Dimming it needs a software PWM on GPIO26 (not a hardware PWM pin).

Next

1. Finish package 0b: Wi-Fi-off boot test, replug recovery, serial login check, NixOS snippet in host/nixos/, and make the firewall load at boot. A new Omarchy host with a GPU (runs the local model "ornith") arrives this week: it needs only host/omarchy/robot-usb-link.sh and its SSH key added to the Pi.
2. Audio (package 1; needs the wm8960-soundcard overlay and a reboot), camera (package 3), then the rest of the packages in HANDOFF.md.

Repository

Branch master. .gitignore covers .remember/, caches, .venv/, *.orig, *.rej and pi/50-cloud-init.yaml. tools/check-pi-platform.sh duplicates host/check-pi-platform.sh and can probably go.

Security review notes (parked until the USB link is up)

An automated review of the initial commit flagged three items. All stem from the code predating the USB-gadget design (HANDOFF.md package 0b); none is exposed until the Pi runs the services.

• pi/robot_mcp_server.py: plain HTTP, ROBOT_MCP_BIND defaults to 0.0.0.0. Plan: default to 10.55.0.2, start after usb0.
• pi/pipewire/50-network-server.conf: TCP 4713 on all interfaces, unrestricted. Plan: keep, comment that the firewall is the protection.
• pi/nftables-robot.nft: still the Pi Zero version (single host IP, any interface). Package 0b rewrites it to accept only on the USB interface from 10.55.0.1.
• pi/install.sh permissions looked fine (/etc/robot-mcp.env is root:$USER, 640).

The owner wants to confirm the real IPs on the link before changing any of this. If the USB link doesn't work, revisit: TLS or a Tailscale-only bind for MCP and audio.