Our own circuit boards, in the tipping bay's signal head

Boards we design for the smart bay light, with every chip soldered on them: the RK3576J processor and its memory, the bay and approach camera chips, the heat chip, the radar chip, LTE-M with a soldered eSIM, the 72 aspect LEDs, the horn amp, the security chip, and on its own board the mains supply, a backup cell and the fire-panel relay. They line the walls of the same 300 × 260 × 860 mm signal head; flexes join them, and one latched lead carries 5 V from the power board. No plugs, ribbons or adapters inside.

Stage 1 of 6 done: shape and placementNot yet ready to manufactureUpdated 4 November 2026 · rev A-0

Design files Design review Quote pack Who can make it Our board platform

The board in 3D

Every part at its real size, in its real place. Turn it, zoom in, switch between the boards in the signal head and laid flat, and click any part to see what it is. The chip bodies are simple blocks until each part's own 3D model is added.

Show the head

Loading the 3D board…

Drag to turn · scroll to zoom · right-drag to move · click a partDrag to turn · tap a part

Where everything is in the signal head

Bay and heat camerasback wall

A bare Sony IMX415 camera chip under a 102° M12 lens and a Melexis MLX90640 heat chip, each on a tab behind the back wall, looking down the bay 45 mm from its edge: every tipped load, banned items, the 4 m line, smoke, and heat on the pile that keeps growing.

Bay radarbay-side wall

A TI IWRL6432AOP 60 GHz radar chip with its antennas on the package, 40° down behind the radome: a person behind the reversing truck, near the loader or across the bay mouth.

Approach camerabehind the door

A second IMX415 between the green and amber aspects, 15° down to the yard: the truck reversing in, its fleet number, the next truck and anyone in the lane.

Aspectsfront board

24 LEDs behind each 200 mm lens with a driver that reports a dead aspect: green when the bay is clear, red flashing with the horn for a person, red held for a banned item, amber to check.

Processor and radiosfloor and top

The RK3576J with its memory flat on the head floor, a heat block to an aluminium spreader bolted to the steel base plate; LTE-M with a soldered eSIM and BLE for the loader driver’s phone, their antennas in the door’s solid top corners.

Power, cell and relayleft wall

The head’s own mains feed into a class II 5 V supply on its own board, one soldered 18650 cell with a thermistor that keeps the heat watch going through a power cut, and the supervisory relay to the site’s fire panel.

The signal-head boards laid flat, both sides, every part at its real size

Laid flat: the power board on the left; the main board with the back strip above it (F1), the radar strip to its right (F3) and the front board below (F2, drawn short); the four sensor tabs on the right. Tap the drawing to open it full size.

Design review: checked before we order

Every board-level number BayOne's calls depend on, checked against its target with the source of each number, using the rules every one of our boards shares (products/_shared/board-rules.mjs). Fixed means a lesson changed this board; to prove means it passes on paper and is measured on rev A before boards are ordered.

No check fails17 pass · 4 fixed by the review · 12 to prove before we order · 0 failDesign review of 4 November 2026

Area	Check	Our board	Target	Status
Camera	Bay camera: a gas bottle (250 mm) at the far side of the tip at 12.21 m M12 lens, 102° across: about 37.6 px per degree across 3840 px. The load model is trained on banned items from about 20 px (est.); a crushed battery at the front of the load is the heat camera's call as well.	44.2 px	≥ 20 px	passes
Camera	Bay camera: frame rate the calls need A standard mode of the IMX415.	10 fps at 3840 × 2160	chip: 30 fps at 3840 × 2160	passes
Camera	Bay camera: data rate vs its 4-lane link 77 % spare on the link.	0.83 Gbps (10-bit)	≤ 80 % of 3.564 Gbps	passes
Camera	Approach camera: a fleet-number digit (80 mm) on the truck rear at 5.61 m M12 lens, 102° across: about 37.6 px per degree across 3840 px. Fleet-number reading needs about 15 px per character height (est.); the truck reverses slowly, so 10 fps is plenty.	30.8 px	≥ 15 px	passes
Camera	Approach camera: frame rate the calls need A standard mode of the IMX415.	10 fps at 3840 × 2160	chip: 30 fps at 3840 × 2160	passes
Camera	Approach camera: data rate vs its 4-lane link 77 % spare on the link.	0.83 Gbps (10-bit)	≤ 80 % of 3.564 Gbps	passes
Camera	Heat camera: a 1 m hot patch on the pile face at 14.68 m 32 × 24 pixels across 110°: 0.3 px per degree. The call is heat that keeps growing over minutes, averaged over many frames, not one hot reading; a 1 m patch still fills about one pixel at the back wall. Little spare: the reading is checked on rev A at the farthest view.	1.1 px	≥ 1 px	to prove on the dev kit
Camera	Image processor load, all cameras 2 cameras into one image processor.	166 Mpx/s	≤ 480 Mpx/s (RK3576J ISP)	passes
Camera	AI engine time per frame One load model (int8) on the 8 MP bay view and the fleet-number reader on the approach view; the radar's people tracks and the heat chip are read by the CPU. Measured on the dev kit.	6 TOPS	a load check in under 1 s after each tip; the person check on every radar frame	to prove on the dev kit
Power	Supply About 5.3 W tipping (RK3576J 3.5 W, two cameras 0.6 W, heat and radar 0.4 W, LTE-M 0.5 W, Wi-Fi/BT 0.3 W) and 10 W at a call (one aspect flashing at full 2.5 W, horn 1.5 W, cell charging 0.8 W), est.: 50 % of the supply.	Mean Well IRM-20-5 PCB-mount 5 V 20 W supply (class II, listed) on the signal head's own feed, on the power board	≤ 70 % of the supply (14 W)	passes
Power	Power cut Pulling the feed with a hot plate in view is part of the rev A tests; a thermistor holds charging outside 0 to 45 °C (lesson: charge).	one soldered 18650 cell (Samsung INR18650-35E) on the power board: in a power cut the RK3576J sleeps and wakes every 60 s to read the heat chip and send it over LTE-M, about 0.4 W, 26 h on the cell (est.)	the heat watch and its alarm path for 12 h in a power cut	to prove on the dev kit
Heat	RK3576J temperature, a summer tipping hall (35 °C) with the head's polycarbonate body round the boards The hall air near the roof and the closed polycarbonate head; counted at 45 °C on the head floor. 3.5 W through a 24 × 24 aluminium block and gap pads to a 3 mm aluminium spreader on the head floor, bolted through to the 12 mm steel base plate on the concrete push wall (7 K/W, est.).	70 °C	≤ 85 °C (rated)	passes
Heat	Camera and heat chips away from the processor A warm sensor adds noise, and the heat chip reads the head's own warmth as a drift.	bay camera 149 mm, heat camera 223 mm, bay radar 335 mm, approach camera 322 mm	≥ 30 mm	passes
Shock	Shock and vibration Thrown material and loader knocks on the push wall shake the head (IK10 windows); about 100 g at the boards on their stand-offs (est.). MEMS clocks are fitted anyway, and the card socket is latched.	100 g (est.)	standard parts	passes
Software	Starts our software from the microSD card, no setup Owner requirement: power it from its own supply and our software runs from the card. Rev A and sale boards boot from the card; the eMMC holds no system copy (it ships empty, so the card always starts first: Rockchip tries the eMMC before the card) and keeps the load log and the call log. Updates write to the card with two system copies, only when the bay is closed, never with a truck in the bay. The quote asks for U-Boot and a device tree from Rockchip's RK3576 SDK.	microSD socket with a hinged, latched lid (Amphenol 101-00660 class), fitted on every board: our software starts from the card	card socket fitted on every board, latched	passes
Software	Card power switch and protection A card that hangs must be restarted by cutting its power, not the whole board; the card slot is the one place a person touches the electronics (lesson: sdstart). Change: U90, U91 added (4 Nov 2026, CricketOne card-start review).	1 power switch and 1 ESD array for 1 card socket	every socket: switched card supply, ESD on all 6 lines	fixed by the review
Software	The card wins the start Rockchip's start order is SPI flash, eMMC, card, USB: a written eMMC starts before the card. Proved on the dev kit: power on with a card in and the eMMC empty (lesson: sdstart). Change: eMMC ships empty and the loader reads the card first (4 Nov 2026; it used to say the eMMC kept a copy, which would have started instead of the card).	eMMC shipped empty; our loader reads the card first	the processor starts from the card every time	fixed by the review
Software	Card grade Consumer cards wear out and fail hot; the image is read-only with a separate data partition. Proved: 1,000 power cuts during writes on rev A (lesson: sdstart).	industrial pSLC microSD (Kingston Industrial or Swissbit S-56u), −40 to 85 °C	rated for the heat, cold and writes	to prove on the dev kit
Software	Clip buffer for an unsure call The rest of the memory holds Linux, the program and the AI model (lesson: clip).	39.5 s of 8-bit 5 fps video in 40 % of the 4 GB memory	≥ 3 s	passes
Radio	LTE-M from the top of the signal head The hall's steel frame and roof sheet weaken the signal; the antenna sits at the top of the head, 3.9 m up, away from the steel base plate. Measured on rev A (lesson: antenna).	BG95-M3 with a soldered eSIM, its chip antenna in the front board's top-right corner behind the door's solid polycarbonate	certified module; a call reaches the cloud from a steel-framed hall	to prove on the dev kit
Radio	BLE for the loader driver's phone Only pairing and the "item removed" mark; everything else goes over LTE-M.	AP6275S on the front board, antenna in the top-left corner behind the door	pairing in the cab 15 m away (est.)	passes
Layout	Fast lines on a solid ground plane The layout rules go to the maker in the quote; the routed board's design rule check (0 copper errors, every keep-out kept) and the maker's impedance coupon prove them (lesson: planes).	RK3576J memory; 2 camera MIPI links (100 Ω pairs); USB (90 Ω); antenna feed (50 Ω, keep-out on every layer); card lines (length-matched, no vias under the socket)	ground on inner layer 1, supply on inner layer 2, no vias in pads, impedance lines routed first	to prove on the dev kit
Moisture	Conformal coating Dust, the hall's dust-suppression mist and washing down reach the head; all five boards and four tabs get the same coat. Asked for in the quote (lesson: moisture).	coated	coated, sensors, sockets and antennas masked	passes
Fit	Board inside the product CAD, every part checked in 3D The board is checked on its own; the rev T CAD run places it in the product and checks every part in 3D (lesson: fit3d).	not yet in the product CAD	nothing touches	to prove on the dev kit
Camera	Every bay call in view Every inView target from the CAD (the fresh load, a battery at the front, the far side of the tip, the 4 m line, smoke; the pile middle and both corners and a hot item; the bay mouth behind the truck, the loader area and the far side; the fleet number, the next truck and a person in the lane) from each lens or chip's real place in its wall.	Bay camera: worst 21.3° / 29.9°; Heat camera: worst 21.3° / 18.2°; Bay radar: worst 22.5° / 12°; Approach camera: worst 13° / 25°	inside each sensor's view	passes
Camera	Bay and heat cameras look out of the back wall The bench head looked out of the bay-side wall, but from there the pile against the near push wall lies 87° off the wall face, so no window could show it (lesson: window). The back wall faces down the bay, and both windows sit 45 mm from the bay edge so the push wall top does not hide the near corner. Change: CAD rev T: bay and heat windows moved to the back wall, 28 × 28 and 24 × 24 (4 Nov 2026).	bay camera window 28 × 28, heat 24 × 24, both at x −45 in the back wall; steepest line of sight 55° and 43°	every line of sight under 82° from its wall, not hidden by the push wall	fixed by the review
Camera	Radar and approach windows The radar slot (50 × 20) and the round 16 mm approach window were sized for the bench modules; the radar chip's calls and the approach lens rim need a little more. Change: CAD rev T: radar slot 50 × 20 → 54 × 24; approach window Ø16 → 24 × 24 (4 Nov 2026).	radar radome 54 × 24 (margin 1 mm); approach window 24 × 24 (margin 0.6 mm)	each view inside its window	fixed by the review
Fit	Sensor tabs on their brackets Each tab hangs off its strip and is held on its sensor's axis by a printed bracket; the brackets go in the rev T CAD and are checked in 3D there (lesson: fit3d).	Bay camera: 0.3 mm inside the wall, hinge 19.2 mm; Heat camera: 0.3 mm inside the wall, hinge 24.5 mm; Bay radar: 0.3 mm inside the wall, hinge 23.8 mm; Approach camera: 0.3 mm inside the wall, hinge 16.1 mm	chip or holder ≥ 0.3 mm inside the wall, hinge within the 40 mm flex	to prove on the dev kit
Light	Aspects behind the 200 mm lenses The bench used two LED sticks per aspect; the even fill through the real lens and the brightness against a site traffic-signal head are measured on rev A.	24 LEDs per aspect in two rings (r 60 and 30 mm) behind each lens, a constant-current driver each with open-LED detect	each aspect as bright and even as the plain signal head; a dead aspect reported	to prove on the dev kit
Safety	Mains kept on its own board The signal head already has its own feed; the power board keeps mains behind a printed shield on the left wall, away from the sensors. Creepage is checked in the layout.	the head's own feed into a spring-clamp terminal on the power board, fuse, varistor, IRM-20-5 (class II); only 5 V and the relay drive on lead L1	class II creepage on the power board; no mains on any other board	to prove on the dev kit
Safety	Fire-panel link is supervisory only BayOne watches surface heat that keeps growing; certified fire detection stays as the site has it.	Omron G5V-1 relay and a spring-clamp terminal for the site's listed monitor module	a supervisory signal, never a fire alarm or a fire detector	passes
Fit	Flexes and the lead F1 and F2 carry 4-lane camera links; the flex maker confirms the MIPI impedance over those lengths.	F1 88 mm to the back strip, F2 122 mm to the front board, F3 278 mm to the radar strip; L1 about 0.39 m of 20 AWG, 0.026 V drop	routed and held in the rev T CAD; L1 ≤ 0.15 V	to prove on the dev kit
Security	Door tamper sensor The bench used a plunger switch pressed by the door; the magnet boss goes in the rev T CAD and the switch point is measured on rev A.	DRV5032 Hall switch on the front board, held by a Ø6 × 3 magnet on a printed boss on the door	door opened = logged and signed	to prove on the dev kit

Before we order the first boards, we prove these on the RV1126B development kit or in the rev A tests:

Heat camera: a 1 m hot patch on the pile face at 14.68 m
AI engine time per frame
Power cut
Card grade
LTE-M from the top of the signal head
Fast lines on a solid ground plane
Board inside the product CAD, every part checked in 3D
Sensor tabs on their brackets
Aspects behind the 200 mm lenses
Mains kept on its own board
Flexes and the lead
Door tamper sensor

Where the design stands

1Shape and placementdone
Main board, back strip, radar strip, front board, four sensor tabs and the power board in the signal head’s shape, all 120 parts placed at their real size, every view checked through its window in 3D and KiCad design rule check (0 violations).
2Schematicnext
Every wire between the chips, from the V2 core, C1 camera and power circuits.
3Footprintsnext
The exact solder pads under each chip.
4Routinglater
Copper tracks on all layers, the camera lanes over the flexes.
5Files for the makerlater
Gerbers with copper, drill, mask, paste, the rigid-flex drawing and the assembly parts list. These go to the board maker.
6Rev A boardsMar 2027
Made, assembled and tested on our fixture.

Design files (rev A-0)

These are the stage 1 files: the board's shape and where every part goes. A board maker needs the stage 5 files to build it.

All files (zip)Everything below in one download, with the quote and review KiCad boardbayone-board.kicad_pcb: open with KiCad 10 (free)3D model (STEP)The bare boards for mechanical CAD Side A drawing (PDF)Down to the floor, out to the walls and the door Side B drawing (PDF)Up and into the head Parts and placement (CSV)Every part, its size, side and position

Who can make it

The signal-head set is an 8-layer main board with three 4-layer boards and four tabs on flexes, plus a 2-layer power board. It needs a maker who builds rigid-flex boards with long flex arms and fine-pitch ball-grid chips. We plan three quotes once the stage 5 files are ready: two from China for price, and one from the US for speed.

Maker	Where	Rigid-flex	HDI / layers	Assembly	Fit for us
PCBWayfirst quote	Shenzhen, China	yes, 6 to 16 layers	HDI up to 32 layers, 0.35 mm BGA pitch	yes, turnkey, incl. BGA and X-ray	Best fit for rev A: the rigid-flex board and its assembly in one order
NextPCBsecond quote	Shenzhen, China	yes	HDI, 6 to 32 layers	yes (PCBA)	Second quote, to compare price and lead time
ALLPCB	China (a network of partner factories)	yes, through partner factories	1 to 30 layers	yes	Third quote; check which factory builds it
JLCPCB	Shenzhen, China	no (flex only: 1, 2 and 4 layers, up to 490 mm)	HDI added Sep 2026	yes, incl. BGA	Not for the one-piece board today. Good for the test fixture, simple boards, and the fallback of separate rigid boards joined by soldered flex
Sierra Circuits (ProtoExpress)US quote	Sunnyvale, California, USA	yes	yes	yes, in-house, incl. BGA; turnkey in about 5 days	US option: fastest turn and engineering help, at a higher price
Cirexx	Santa Clara, California, USA	yes	yes	yes (turnkey or consigned)	Second US option
Advanced Circuits	Aurora, Colorado, USA	yes	check	yes	US quick-turn; check its rigid-flex assembly
Epec	New Bedford, Massachusetts, USA	yes	check	yes; also builds battery packs	US option that can also make a certified LiFePO4 pack

From each maker's own capability pages, checked 3 November 2026. Limits change, so each quote confirms them for our exact stack-up.

Full design notes

All 120 parts, what is on each piece, every connection, heat, power, the factory test, cost and timeline.

BayOne: circuit boards of our own

What changed (4 Nov 2026). The rev A bench signal head is built from bought boards joined by leads: a Raspberry Pi 5, two Camera Module 3 Wide boards on ribbons, an MLX90640 board, an HLK-LD2450 radar module, six NeoPixel sticks, a MAX98357A amp board, an ATECC608 board, a Walter LTE-M board, a PowerBoost with a LiPo and an IRM-20-5 on flying leads. BayOne now gets boards of our own, like CricketOne, DockOne and ClassOne, with every chip placed straight onto them, made with every shared design-review rule from the start.

The chips: the V2 core (Rockchip RK3576J, 4 GB LPDDR4X, 32 GB eMMC, AMPAK AP6275S Wi-Fi 6/BT module), two bare Sony IMX415 8 MP camera chips under M12 lens holders (the C1 camera on the board), a Melexis MLX90640 heat chip, a TI IWRL6432AOP 60 GHz radar chip with its antennas on the package, a Quectel BG95-M3 LTE-M module with a soldered eSIM, 72 aspect LEDs with three drivers, the horn amp, the security chip and a Hall tamper switch; on the power board a Mean Well IRM-20-5 supply on the head’s own feed, one soldered 18650 backup cell with its charger and thermistor, and the fire-panel relay.
The shape: the signal head is a 300 × 260 × 860 mm box, so the boards line its walls. An 8-layer main board (110 × 90 mm) lies flat on the head floor; a 4-layer back strip stands behind the back wall with the bay camera and heat camera tabs; a small radar strip stands behind the bay-side radome; a 4-layer front board (240 × 795 mm) stands 25 mm behind the door with the three aspects, the approach camera and the radios; a 2-layer power board on the left wall keeps mains on its own. Flexes F1, F2 and F3 join the main board to the strips and the front board; one latched lead joins the power board.
A fix in the same run: from the bay-side wall, the pile against the near push wall lies 87° off the wall face, so no window there could show it (lesson: window). The bay and heat cameras now look out of the back wall, down the bay, 45 mm from the bay edge so the push wall top does not hide the near corner. Drawn in the CAD the same day (rev T), with the radar slot and approach window sized for our chips.
Made from the shared rules: MEMS clocks, the latched microSD card with our software on every board, conformal coating against dust and the hall’s mist, a thermistor on the backup cell, the antennas checked for the steel hall on rev A, cameras 30 mm or more from the processor, every line of sight under 82° from its wall.

The bench signal head stays the test rig until the boards arrive.

1. The shape: five boards, four tabs

Piece	Size	Layers	Where	What
Main board	110 × 90 mm, 1.6 mm	8	flat on the head floor, side A 10 mm over a 3 mm aluminium spreader	the V2 core, card, security, horn amp, lead header
Back strip	122 × 180 mm, 1.6 mm, on F1 (88 mm)	4	standing 30 mm inside the back wall	bay camera and heat camera tabs and their supplies
Radar strip	115 × 110 mm, 1.6 mm, on F3 (278 mm)	4	standing 30 mm inside the bay-side wall	the radar tab and its supplies
Front board	240 × 795 mm, 1.6 mm, on F2 (122 mm)	4	standing 25 mm behind the door	3 × 24 aspect LEDs and drivers, approach camera tab, LTE-M with eSIM and antenna, Wi-Fi/BT, door tamper switch
Sensor tabs (4)	16 × 16 mm, 0.8 mm, on 40 mm flex hinges	4	each on its sensor’s axis, the lens or chip just inside its window	IMX415 (bay, approach), MLX90640 (heat), IWRL6432AOP (radar)
Power board	140 × 140 mm, 1.6 mm	2	on the left wall, mains behind a printed shield	mains terminal, fuse, IRM-20-5, backup cell, charger, relay and terminal

Lead L1 (power board to main board: 5 V on two pairs, cell sense, relay drive) is about 0.4 m of 20 AWG with Molex Micro-Fit 3.0 6-pin latched ends.

2. What is on the boards

Main board, side A (down): RK3576J (U1) with a 24 × 24 heat block (HS1) to the aluminium spreader, bolted through the head floor to the 12 mm steel base plate; LPDDR4X (U2), eMMC (U11).

Main board, side B (up): decoupling field (C1), RK806S power (U3), 24 MHz and 32 kHz MEMS oscillators (Y1, Y2), ATECC608B (U8), ID chip (U9), the latched microSD (J1, reached by opening the door), MAX98357A horn amp (U31) and the pads for the speaker’s and piezo’s own wires (PD1; both stay over their floor holes), eFuse (U42), lead header (J2), factory pads (TP1).

Back strip: bay camera tab (U200, IMX415 under a 102° M12 lens, 22° down and 58° into the bay, through a 28 × 28 window) and heat camera tab (U240, MLX90640 110° × 75°, 12° down at the pile, 24 × 24 window); their supplies (U21, U23) and an ESD array (U25) on side B.

Radar strip: radar tab (U250, IWRL6432AOP, 40° down toward the bay mouth behind the 54 × 24 radome); supplies (U24) and ESD (U27).

Front board, side A (to the door): 24 LEDs behind each aspect (DG, DA, DR), the approach camera tab (U260, IMX415, 15° down to the yard, 24 × 24 window) between the green and amber aspects, the door tamper Hall switch (U7). Side B: three aspect drivers (U70–U72), the AP6275S (U5) with its antenna keep-out (ANT1) in the top-left corner, the BG95-M3 (U6) with its eSIM (U6S) and chip antenna (ANT2) in the top-right corner, both behind the door’s solid polycarbonate outside every aspect, and the approach camera supplies (U26).

Power board (side A into the head): spring-clamp mains terminal (J10), fuse and varistor (F10), IRM-20-5 (PS1), the 18650 holder and cell (BT1) with its thermistor (RT1), the charger (U50), the G5V-1 relay (K1) and its spring-clamp terminal (J11) for the site’s listed fire-panel monitor module, the lead header (J12).

3. Every connection, checked

Link	How	Checked against
Camera chips to RK3576J	4-lane MIPI CSI-2 each, over F1 or F2 and the tab hinges	IMX415 data sheet: 891 Mbps per lane; at 10 fps each uses 0.83 Gbps of 3.56
Heat chip	I²C at 3.3 V over F1	Melexis MLX90640 data sheet
Radar chip	SPI and a frame interrupt over F3	TI IWRL6432AOP data sheet
Aspect LEDs	PWM to three constant-current drivers on the front board; open-LED detect back to the RK3576J	driver data sheet (to choose)
LTE-M	USB 2.0 and UART over F2; eSIM soldered	Quectel BG95 hardware design
Wi-Fi/BT	SDIO and UART over F2	AMPAK AP6275S (RK3576 SDK default)
Power in	the head’s own mains feed, fused, into the class II IRM-20-5; 5 V on L1 into an eFuse at 3.5 A; L1 drops 0.03 V at 2 A	Mean Well IRM-20 data sheet
Fire panel	dry relay contact on a spring-clamp terminal to the site’s listed monitor module	Omron G5V-1 data sheet
Card	SD bus to the RK3576J, latched socket	Amphenol 101-00660 family drawing

Every mating pair is checked against the makers’ documents, never “same as” another board.

4. Heat

About 3.5 W from the RK3576J goes through the heat block into the aluminium spreader and the steel base plate on the concrete wall (7 K/W est.), so the chip sits near 70 °C with the head at 45 °C inside in a summer hall. The camera and heat chips are 149 mm or more from the processor.

5. Power budget (est.)

State	Draw
Tipping: two cameras at 10 fps, radar, heat chip, load model, LTE-M	5.3 W
A call: one aspect flashing at full, the horn, the cell charging	up to 10 W, 50 % of the 20 W supply
Watching overnight: heat chip 2 Hz, a bay frame every 10 s, radar	3.0 W
Power cut: RK3576J asleep, wakes every 60 s to read the heat chip and send over LTE-M	0.4 W, about 26 h on the cell

6. Factory test (every board, every time)

Spring-pin fixture on TP1 and the strips’ pads: 5 V in, the eFuse trip at 3.5 A, every rail, boot from the card, a frame of a test chart from each camera, a hot plate seen by the heat chip, a corner reflector seen by the radar, all 72 aspect LEDs and the open-LED detect, the horn amp into a test speaker, the tamper switch with a magnet, the security chip’s key, the LTE-M and BLE links; on the power board, the supply under load, the charger’s temperature cut-off with the thermistor warmed, the relay contact. Each board gets its serial number in the ID chip.

7. Who makes what

One maker makes the rigid-flex piece and the power board, assembles them (turnkey) and makes lead L1 to length. We supply the microSD cards with our software and the lenses focused at 8 m (est.). The quote pack is /build/bayone-quote.

8. Cost per signal head, electronics (est.)

Item	Cost
V2 core (RK3576J, 4 GB LPDDR4X, 32 GB eMMC, power, AP6275S)	$48
Two IMX415 camera chips, holders and lenses	$28
MLX90640 heat chip	$45
IWRL6432AOP radar chip	$12
BG95-M3 LTE-M, eSIM and antenna	$18
72 aspect LEDs and three drivers	$10
IRM-20-5, terminals, fuse, cell, charger, relay	$22
Security, ID, amp, socket, Hall switch, passives	$8
Boards (8-layer rigid-flex with an 800 mm front board, four tabs, a 2-layer power board), 1,000 heads	$40
Lead L1	$2
Assembly and test	$15
microSD card with our software	$4
Total	about $252 per signal head (est.)

The bench head’s bought boards cost about $390 at qty 1 (Pi 5, two cameras, MLX90640 board, radar module, LED sticks, Walter, supply, backup and small boards), so our boards are about $138 cheaper per head at 1,000 (est.).

9. Timeline

Step	When
Shape and placement (this page)	done, 4 Nov 2026
Rev T CAD: the boards in the signal-head CAD, every part checked in 3D; the bay and heat windows already moved to the back wall	next
Schematic, footprints, routing	Dec 2026 – Jan 2027
Rev A boards made and tested	Mar 2027 (est.)

10. Still to check

The rev T CAD changes still to draw: the aluminium spreader and its bolts, the tab brackets, the door magnet boss, the printed mains shield.
The heat chip’s reach: a 1 m hot patch at the back wall fills about one pixel; growth over minutes is the call, measured with a hot plate at 15 m on rev A.
LTE-M from inside a steel-framed hall, with the antenna at the top of the head.
Each aspect’s brightness and even fill through the real lens, against a plain site signal head.
The front board’s 800 mm length and the F1 and F2 camera-lane impedance with the maker.

Sources

Rockchip RK3576 brief: https://www.rock-chips.com/a/en/products/RK35_Series/2024/0524/1977.html
Sony IMX415 (8.46 MP, 4-lane MIPI): https://www.sony-semicon.com/en/products/is/security/security.html
Melexis MLX90640: https://www.melexis.com/en/product/MLX90640/Far-Infrared-Thermal-Sensor-Array
TI IWRL6432AOP: https://www.ti.com/product/IWRL6432AOP
Quectel BG95-M3: https://www.quectel.com/product/lpwa-bg95-m3/
AMPAK AP6275S: https://www.ampak.com.tw/
Mean Well IRM-20: https://www.meanwell.com/Upload/PDF/IRM-20/IRM-20-SPEC.PDF
Omron G5V-1: https://omronfs.omron.com/en_US/ecb/products/pdf/en-g5v_1.pdf
Microchip ATECC608B: https://www.microchip.com/en-us/product/atecc608b
TI DRV5032: https://www.ti.com/product/DRV5032
Samsung INR18650-35E: https://www.samsungsdi.com/
The signal head: products/bayone/cad/bayone-cad.mjs (rev A, windows rev T); the boards: products/bayone/hardware/pcb/bayone-board.mjs

Design review (4 Nov 2026)

Every board is checked by the same rules (products/_shared/board-rules.mjs), one for each lesson any of our boards has taught us. BayOne’s boards were made with every rule from the start: 17 pass, 4 fixed, 12 to prove, 0 fail. The full review, with every number and its source, is on the board page. It shows:

Camera pixels: a gas bottle at the far side of the tip (12 m) fills about 45 px against a 20 px need; a fleet-number digit on a reversing truck (5.6 m) about 30 px against 15; both 8 MP chips at 10 fps use 23 % of their links and 166 Mpx/s of the image processor’s 480.
Every bay call in view: the fresh load, a battery at the front, the far side of the tip, the 4 m line and smoke; the pile middle, both corners and a hot item; the bay mouth behind the truck, the loader area and the far side; the fleet number, the next truck and a person in the lane, from where each lens or chip really sits in its wall.
The bay and heat cameras look out of the back wall (fixed): from the bay-side wall the pile against the near push wall lies 87° off the face (lesson: window); the back wall faces down the bay. The radar slot and approach window were also sized for our chips (fixed). Drawn in the CAD the same day.
The latched microSD (J1) is fitted, and our software starts from it; updates run only when the bay is closed.
A thermistor on the backup cell holds charging outside 0 to 45 °C, and conformal coating against dust and mist is asked for in the quote.
Fast lines on a solid ground plane (to prove, lesson: planes, from the CricketOne test-board layout of 4 Nov 2026): RK3576J memory; 2 camera MIPI links (100 Ω pairs); USB (90 Ω); antenna feed (50 Ω, keep-out on every layer); card lines (length-matched, no vias under the socket). Ground on the layer next to the parts (inner layer 1, supply on inner layer 2; the whole bottom of a 2-layer section), one via beside each ground and supply pad and none in pads, no copper or vias in the antenna keep-out on any layer or under the card socket, the impedance lines routed first with a test coupon. The quote asks for it; the routed board’s design rule check proves it.
To prove on rev A: the heat chip’s reach at the back wall (about 1 px for a 1 m patch), the AI time, the power-cut run on the cell, LTE-M in a steel hall, the tab brackets, the aspects’ brightness, mains creepage, the flexes, the tamper magnet and the boards in the rev T CAD.

The request for quote is /build/bayone-quote.