DNTD Dynamics — Session Context

June 24, 2026

Session Overview

Long multi-topic session covering RadarGuard software completion, PCB BOM development, firmware questions, repo cleanup, and git workflow. The repo is now in a clean, shippable state with the standalone pipeline feature-complete for the first buyer experience.

RadarGuard Software — What Was Built Today

New Files

Updated Files

Key Design Decisions

Static person detection approach: True cardiac heartbeat detection requires a dedicated slow-chirp firmware profile (TI vital-signs demo) — a completely different operating mode that would break the safety pipeline’s range/velocity performance. Instead, presence_hold.py uses micro-Doppler sway detection: the involuntary low-amplitude movement (0.02–0.25 m/s) a stationary person always generates. Achieves the same safety property without a firmware profile change.

Surgical YAML writer: First version of arm_config_gui.py used yaml.safe_load() + yaml.dump() which destroyed all 146 comment lines in dntd_mmwave_config.yaml. Replaced with targeted regex replacement — each key located by exact indentation pattern, value replaced, everything else byte-for-byte identical.

Static presence hold + occupancy hold are complementary: Occupancy hold (--occupancy-hold, 1.5s default) bridges the gap between when points drop below the velocity filter and when StaticPresenceHold has enough sway history. Both are active — they’re not redundant.

CAUTION Speed Ramp

Arduino patch document created (CAUTION_SPEED_RAMP_PATCH.md). Three edits to radarguard_arm_controller.ino:

1. Add CAUTION_SPEED_DIVISOR constant (default 2 = half speed)
2. Add currentZone tracking variable
3. Update serial command handler with CAUTION branch

Arduino .ino file not uploaded in this session — patch doc written as a diff guide rather than full rewrite to avoid introducing bugs in working ESP32 code.

PCB BOM — Both Boards

IWR6843AOP Board

• PMIC: LP87524JRNFRQ1 — available direct from TI.com (myTI account required). LP87524JRNFRQ1: ~2,947 in stock, $2.352/1ku cut tape. LP87524JRNFTQ1 (reel): ~22,520 in stock, $3.248/1ku. No purchase limit currently.
• Level shifter: TXS0104EPWR (TSSOP-14) out of stock. Switched to TXS0104EDR (SOIC-14) — pin-for-pin identical, different footprint only. ~3,644 in stock at TI.com, $0.338/1ku. Do not switch back to TSSOP when it returns — SOIC is the better long-term choice for this board.
• Estimated BOM cost: ~$36–40/board at 10 units. Assembled: ~$60–75/unit.

IWRL6432AOP Board

• Power topology: BOM-optimized single 1.8V rail. TPS62840 buck converter (60nA IQ, battery-friendly). Internal 1.2V LDO — §7.6.6 decoupling is critical per TI E2E confirmation.
• Estimated BOM cost: ~$23–28/board at 10 units. Assembled: ~$45–60/unit.

FCC Part 15.255 Board-Level Notes

• Supply noise is the #1 board-level FCC risk — 1dB increase in 1.8V ripple = 1dB increase in RX spur level (TI datasheet §7.2)
• LP87524 switches at 4MHz — route switcher traces on inner layers, keep short
• PMIC_CLKOUT → PMIC CLKIN sync trace: provision it on the PCB even if not enabled by default. Enables PMIC switching sync to radar clock if pre-compliance shows spurs near band edges
• With AOP, antenna design is TI’s responsibility — board-level concern is power supply noise coupling into LO path
• UART lines at 921600 baud: ESD array before connector, no UART traces near AOP antenna keepout zone
• Crystal harmonic at 40×N MHz: keep traces <5mm, guarded with ground stitching

SOP Pin Decision

Hard-wire for functional mode on v1 (SOP0 pull-up 1.8V, SOP1/SOP2 pull-down). Expose pads on PCB for bench flash recovery. No switches needed — you flash every board before it ships. V2: add MOSFET on SOP2 for software-controlled field firmware updates.

Host Connector (direct Jetson GPIO, no CP2105)

3 signal wires: UART1-TX, UART1-RX, UART2-TX (RX only — sensor never receives on data port). Plus NRESET, 3.3V power, GND. Level shifter required: Jetson GPIO = 3.3V, sensor UART = 1.8V. Recommended: 8-pin JST-SH 1.0mm locking connector.

Firmware / Flash

What’s on every IWR6843AOP: out_of_box_6843_aop.bin, firmware version 03.06.00.00. Flashed via TI UniFlash in SOP2 mode. This is the only thing on the chip itself — the chirp profile (profile_AOP.cfg) is NOT firmware, it’s sent over CLI UART at runtime every boot.

Production workflow: Flash chip before shipping. Buyer never needs UniFlash or SOP switches. Chirp profile delivered via private kit repo access.

Chirp Profile Strategy

Public repo (configs/profile_AOP.cfg)

Example placeholder — uses conservative TI defaults. Gets the sensor streaming valid TLV frames for hardware bring-up verification. Comments explain what the production profile changes in each section without giving away values. Will actually produce CLEAR/CAUTION/STOP transitions.

Production profile (private)

Stays local on Jetson only, protected by .gitignore. Backed up to private Gitea dntd-mmwave repo on NucBox (192.168.254.117:3000, ShireFolk account). Kit buyers get access to private repo.

Security note: Hiding values in the example file (white text, prompt injection) is not a viable protection strategy — LLMs read raw text regardless of visual formatting. The .gitignore + private repo approach is the correct mechanism.

Git / Repo Cleanup

.gitignore rules added

configs/profile_AOP.cfg
*.bak
__pycache__/
*.pyc
*.pyo
.DS_Store

Sequence that was executed

1. git pull --rebase — resolved two conflicts (README merge, profile_AOP.cfg delete/modify)
2. git rm configs/profile_AOP.cfg.bak and git rm src/main.py.bak — removed backup files that slipped into the commit
3. git rm -r --cached src/__pycache__ — removed pycache that had been tracked since early in the project
4. All cleanup committed and pushed — repo now clean

Profile gitignore sequence (correct order)

# 1. Add ignore rule FIRST
echo "configs/profile_AOP.cfg" >> .gitignore

# 2. Stop tracking current file (doesn't delete local copy)
git rm --cached configs/profile_AOP.cfg

# 3. Commit
git add .gitignore
git commit -m "stop tracking production chirp profile"
git push

# 4. Back up real file somewhere safe
cp configs/profile_AOP.cfg ~/profile_AOP_REAL_BACKUP.cfg

# 5. Put example file in place
cp ~/Downloads/profile_AOP_example.cfg configs/profile_AOP.cfg

# 6. Force-add example (overrides ignore rule, one time only)
git add -f configs/profile_AOP.cfg
git commit -m "add example chirp profile for public repo"
git push

# 7. Restore real file
cp ~/profile_AOP_REAL_BACKUP.cfg configs/profile_AOP.cfg

Key behavior: After .gitignore + git rm --cached, git pull will NEVER overwrite the local file. The ignore rule protects it from both push and pull. Only a fresh git clone on a new machine gets the example — which is correct behavior.

Private Gitea Backup

Gitea: NucBox K6 at 192.168.254.117:3000, Docker container, SSH port 222, username ShireFolk
Existing repo: dntd-mmwave — use this for private files
Push method: HTTP (SSH auth to Gitea still unresolved from earlier sessions — needs docker ps | grep gitea on NucBox to confirm port mapping)

To push real profile to Gitea:

git clone http://192.168.254.117:3000/ShireFolk/dntd-mmwave.git ~/mmwave-private
cd ~/mmwave-private
cp ~/mmwave/configs/profile_AOP.cfg .
git add profile_AOP.cfg
git commit -m "production chirp profile - validated arm-mounted config"
git push

Post-Session Git Cleanup (completed after context first written)

• src/classifer.py renamed to src/classifier.py via git mv — import in dntd_mmwave_safety_node.py line 47 updated from from classifer import to from classifier import. Old misspelled file explicitly removed with git rm src/classifer.py after rename left both files tracked.
• __pycache__/, *.bak, *.pyc, *.pyo, .DS_Store added to .gitignore
• configs/profile_AOP.cfg protected by .gitignore — example placeholder in repo, real file local only
• Real profile_AOP.cfg now backed up in three locations: Jetson local, Gitea dntd-mmwave private repo (192.168.254.117:3000/ShireFolk/dntd-mmwave), MSI desktop

URL: https://github.com/DNTD-Dynamics/RadarGuard-mmwave-cobot-safety-system

src/ contents

• arm_config_gui.py — new today
• arm_controller_gui.py — existing (runtime arm control, different from config GUI)
• arm_controller_node.py — existing
• background_model.py — existing
• classifer.py — existing (note: filename typo is in repo, leave as-is)
• cluster.py — existing
• dntd_mmwave_driver_node.py — existing
• dntd_mmwave_launch.py — existing
• dntd_mmwave_safety_node.py — existing
• fake_joint_states.py — existing
• live_angle.py — existing
• main.py — updated today
• presence_hold.py — new today
• raw_dump.py — existing
• swept_volume.py — existing
• tlv_parser.py — existing
• uart_reader.py — existing
• zone_logic.py — updated today

configs/ contents

• dntd_mmwave_config.yaml — unchanged
• dntd_mmwave_driver_config.yaml — unchanged
• profile_AOP.cfg — example placeholder (NOT the production-tuned version)

Immediate Next Steps

1. Push real profile_AOP.cfg to Gitea ✅ Done — backed up to Gitea dntd-mmwave repo AND MSI desktop
2. Drop example profile_AOP.cfg onto Jetson ✅ Done — example version now in configs/ on Jetson
3. Arduino CAUTION patch — follow CAUTION_SPEED_RAMP_PATCH.md, three edits to .ino
4. EB300 kinematic chain — measure link lengths from printed parts, fill in joint_geometry in config using arm_config_gui.py
5. ROS2 end-to-end test — run full stack with fake_joint_states.py, validate pipeline runs without crashing

Outputs from This Session