Our own circuit boards, in the site's entry turnstile

Boards we design for the smart site turnstile, with every chip soldered on them: the RK3576J processor and its memory, the entry camera chip, the rotor radar chip, LTE-M with a soldered eSIM, the call lights and voice, the security chip; two small ESP32-S3 boards for the site camera and the reader head with its tap chip and e-paper; and on its own board the supply, the controller contacts and a backup cell. They sit in the same 1,400 × 1,400 × 200 mm steel canopy and reader housing as a plain turnstile; one flex and four latched leads join them. No bought computer boards, 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 turnstile 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.

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

Where everything is in the turnstile

Entry camerastreet wall

A bare Sony IMX415 camera chip under a 102° M12 lens on a tab behind a 40 × 42 window in the street wall, 35° down: hard hat, hi-vis and boots on each person walking up, the queue, and anyone at the gate out of hours. No faces are recognised.

Rotor radarcanopy floor

A TI IWRL6432AOP 60 GHz radar chip with its antennas on the package, hanging under the main board and looking straight down through the floor radome: one or two people in a turn, and the head count with every tap.

Site camerasite wall

An OmniVision OV5640 on its own small board with an ESP32-S3, 20° down over the site: smoke or fire seen from the gate, the muster point and people leaving, one frame every 5 s over a wired link.

Reader headstreet-side post

The turnstile’s own reader housing: an NXP PN7160 tap chip with a printed coil behind the tap mark (site cards and phone passes), the 2.13 in e-paper with the heat flag and rest time, and the PPE light, on one board with an ESP32-S3.

Call lights and voicestreet and site walls

RGB lights behind the street and site slots, a buzzer over the tone holes and a voice amp for the turnstile’s speaker: “hard hat please”, a second person asked to tap, white at the muster.

Air, dust and noiseside and street walls

The SHT45 air chip on a slotted island behind the side vent, the PT1000 on the black lid patch for sun load, the bought SPS30 dust sensor on a latched lead, and a noise mic on a duct to its own hole in the street wall.

Processor and radioscanopy floor

The RK3576J with its memory flat on the canopy floor near the street wall, a heat block straight to the shaded steel floor; LTE-M with a soldered eSIM and BLE for the fit-up phone, through a puck antenna on the lid, because the closed steel canopy stops both radios.

Supply and controllercanopy floor

The turnstile’s own supply into a class II 5 V supply on its own board; one isolated contact on the controller’s entry-hold input, never the exit; listeners on the rotor-turn and fire-alarm signals; one soldered 18650 cell that keeps the on-site list and the muster message going through a power cut.

The turnstile boards laid flat, both sides, every part at its real size

Laid flat: the main board with the street strip below it (F1, drawn short), the three sensor tabs to its right, then the site, side and power boards, and the reader board below. Tap the drawing to open it full size.

Design review: checked before we order

Every board-level number SiteOne'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 fails16 pass · 7 fixed by the review · 11 to prove before we order · 0 failDesign review of 4 November 2026

Area	Check	Our board	Target	Status
Camera	Entry camera: safety boots (0.12 m) at the turnstile mouth at 2.51 m M12 lens, 102° across: about 37.6 px per degree across 3840 px. The PPE model finds a boot toe cap from about 30 px across (est.); hard hats and vests are far larger. People walk up at about 1.4 m/s, so 10 fps gives several frames of each item.	103.1 px	≥ 30 px	passes
Camera	Entry 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	Entry 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	Site camera: a person (0.45 m wide) at the muster point at 9.53 m M12 lens, 90° across: about 28.8 px per degree across 2592 px. The muster count needs about 20 px across a person (est.); smoke plumes 20 to 30 m away are metres wide. One frame every 5 s by day, one a second on a smoke or muster call.	77.9 px	≥ 20 px	passes
Camera	Site camera: frame rate the calls need A standard mode of the OV5640.	1 fps at 2592 × 1944	chip: 15 fps at 2592 × 1944, 30 fps at 1920 × 1080	passes
Camera	Site camera: data rate vs its 1-lane link 90 % spare on the link.	0.04 Gbps (8-bit)	≤ 80 % of 0.384 Gbps	passes
Camera	Image processor load, all cameras 2 cameras into one image processor.	88 Mpx/s	≤ 480 Mpx/s (RK3576J ISP)	passes
Camera	AI engine time per frame One PPE and person model (int8) on the 8 MP entry view at 10 fps; a smoke model on one site frame every 5 s; the radar's people tracks are read by the CPU. Measured on the dev kit.	6 TOPS	a PPE call in under 1 s at the mouth; tailgating in under 2 s	to prove on the dev kit
Power	Supply About 6.6 W at the shift-start rush (RK3576J 3.5 W, entry camera 0.3 W, site node 0.6 W, reader node 0.5 W, radar 0.3 W, LTE-M 0.5 W, Wi-Fi/BT 0.2 W, dust sensor 0.3 W, lights and voice 0.4 W) and 7.6 W with the cell charging (est.): 38 % of the supply.	Mean Well IRM-20-5 PCB-mount 5 V 20 W supply (class II, listed) on the turnstile's own supply, on the power board	≤ 70 % of the supply (14 W)	passes
Power	Power cut A fire alarm can come with a power cut: the muster list must still go out. Pulling the supply is part of the rev A tests; a thermistor holds charging outside 0 to 45 °C (lesson: charge), which matters in a steel canopy in summer sun.	one soldered 18650 cell (Samsung INR18650-35E) on the power board: in a power cut the turnstile free-wheels, the RK3576J sleeps with the on-site list in memory, and wakes on the fire-alarm input or every 60 s to log taps from the reader node; about 0.4 W, 26 h on the cell (est.)	the on-site list and the muster message for 12 h in a power cut	to prove on the dev kit
Heat	RK3576J temperature, a summer afternoon (40 °C air) with sun on the steel lid The heat block goes to the canopy floor, not the lid: the floor is shaded by the canopy above it and open to the passage air below, so it runs nearer the air than the sun-baked lid (counted at 55 °C, est., logged on rev A). 3.5 W through a 24 × 24 aluminium block and gap pads straight to the 3 mm steel canopy floor, 1.4 × 1.4 m (5 K/W, est.).	73 °C	≤ 85 °C (rated)	passes
Heat	Camera and radar chips away from the processor A warm camera chip adds noise; a warm radar chip drifts.	entry camera 191 mm, site camera 1222 mm, rotor radar 50 mm	≥ 30 mm	passes
Shock	Shock and vibration The rotor stopping hard on its brake, a kick or a fork-lift moving the turnstile on its baseplate shakes the boards; about 50 g at the boards on their stand-offs (est.). MEMS clocks are fitted anyway, and the card sockets are latched.	50 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 on-site list and the call log. The two S1 nodes (site board, reader board) load their program from their own latched cards. Updates write to the card with two system copies, only out of hours the site sets, never while anyone is on site; the turnstile controller keeps its own access and free-wheel rules throughout. 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; microSD socket with a hinged, latched lid (Amphenol 101-00660 class): the ESP32-S3 loads our program from the card; microSD socket with a hinged, latched lid (Amphenol 101-00660 class): the ESP32-S3 loads our program 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, U92, U94, U91, U93, U95 added (4 Nov 2026, CricketOne card-start review).	3 power switches and 3 ESD arrays for 3 card sockets	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 inside the steel canopy A closed steel canopy blocks LTE-M, so the antenna sits outside it; the puck is on the lid above the main board, its coax soldered to pads under it. Antenna outside the metal: the 2-in-1 IP67 puck antenna through the lid, at 2.4 m, out of reach (lesson: enclosure). Measured on rev A (lesson: antenna). Change: CAD rev T: 2-in-1 puck antenna through the lid (4 Nov 2026).	BG95-M3 with a soldered eSIM; its antenna is the LTE element of the puck through the lid	certified module; calls, the on-site list and the muster list reach the site manager on any site	to prove on the dev kit
Radio	BLE for the site manager's fit-up phone Only fit-up and the zone check; everything else goes over LTE-M. The two S1 nodes keep their radios off: inside the steel canopy and the reader head their link is the wire. Antenna outside the metal: the same puck antenna through the lid (lesson: enclosure). Change: CAD rev T: 2-in-1 puck antenna through the lid (4 Nov 2026).	AP6275S on the main board, its antenna the 2.4 GHz element of the same puck	pairing from the gate, 3 m below (est.)	fixed by the review
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; 4 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 Rain blown through the vents, dust, cement and condensation as the steel canopy cools at night reach the boards; all six boards and three 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 gate call in view Every inView target from the CAD (hard hat, vest and boots at the mouth, the next person in the queue, a person at the reader after hours; smoke over the site and to the side, a person at the muster point, people leaving; one or two people in the front and back compartments) from each lens or chip's real place in its wall or floor.	Entry camera: worst 39.9° / 28.9°; Site camera: worst 33.4° / 25.1°; Rotor radar: worst 40.3° / 1°	inside each sensor's view	passes
Camera	Camera windows The bench canopy had round 14 mm windows sized for the camera boards. Boots at the turnstile mouth lie 72° off the street wall, so the lens rim needs a tall window; the site view spreads 33° to the side for a plume 20 m away (lesson: window). Change: CAD rev T: entry window Ø14 → 40 × 42, site window Ø14 → 24 × 26 (4 Nov 2026).	entry window 40 × 42 (margin 0.5 mm, steepest 72°); site window 24 × 26 (margin 2.7 mm, steepest 48°)	each view inside its window, every line of sight under 82° from its wall	fixed by the review
Camera	Rotor radar under the main board The bench radar sat over the rotor's middle, 550 mm from where the processor board must sit by the street wall (the entry camera's link is a short flex). Moved over the front compartment, the chip still sees the back compartment 40° off its axis, inside its ±60°. Change: CAD rev T: radar radome moved from the middle of the passage to x 100, y −550 (4 Nov 2026).	radome 50 × 20 in the canopy floor at x 100, y -550 (margin 3.8 mm); both compartments 40.3° off the chip's axis at worst	both compartments and the passage in view; the chip on a short hinge to the processor board	fixed by the review
Camera	Site camera on its own node The site wall is 1.2 m from the processor; a MIPI camera link cannot run that far. The site view needs one frame every 5 s (smoke, the muster point), which a JPEG over RS-485 carries with room to spare.	OV5640 on the site board with an ESP32-S3 (radio off), JPEG frames over RS-485 on lead L2, 1.43 m	a MIPI camera link only on a short flex	passes
Safety	The turnstile's egress untouched SiteOne can only hold one entry; it has no wire to the exit or the brake. The rev A test pulls the supply and fires the alarm input with the boards running and with them unplugged.	one photo-MOS contact (5,000 V isolation, est.) on the controller's own entry-hold input; optocouplers only listen to the rotor-turn and fire-alarm signals	the exit always turns; the rotor free-wheels on power loss and on the fire alarm as before (IBC 1010.3.1)	to prove on the dev kit
Safety	Supply kept on its own board The power board keeps the mains behind a printed shield, away from the radios. Creepage is checked in the layout.	the turnstile's own supply into a spring-clamp terminal on the power board, fuse, varistor, IRM-20-5 (class II); only 5 V and the controller signals on lead L1	class II creepage on the power board; no mains on any other board	to prove on the dev kit
Fit	Sensor tabs on their brackets Each tab hangs off its board and is held on its sensor's axis by a printed bracket; the brackets go in the next CAD revision and are checked in 3D there (lesson: fit3d).	Entry camera: 0.3 mm inside the wall, hinge 18.4 mm; Site camera: 0.3 mm inside the wall, hinge 21.2 mm; Rotor radar: 0.3 mm inside the wall, hinge 13.4 mm	chip or holder ≥ 0.3 mm inside the wall, hinge within the 40 mm flex	to prove on the dev kit
Fit	Reader head The bench e-paper window was 60 × 26, wider than the 59.2 mm panel, so its edge showed; the bench PPE light had no slot to shine through. Change: CAD rev T: e-paper window 60 × 26 → 52 × 25, PPE light slot 46 × 8 added (4 Nov 2026).	e-paper active area inside the 52 × 25 window, its panel over the window edge; 8 PPE LEDs behind the new 46 × 8 slot; the tap coil 40 × 40 behind the tap mark with nothing on it	the turnstile's own reader housing, 60 mm proud, unchanged	fixed by the review
Fit	Flex and leads F1 carries the 4-lane entry camera link; the flex maker confirms the MIPI impedance. L2 and L3 are RS-485 to the two S1 nodes; L4 is differential I²C (PCA9615, est. 3 m limit). L3 runs down inside the street-side post to the reader head.	F1 149 mm; L1 0.17 m of 20 AWG, 0.022 V drop; L2 1.43 m of 22 AWG, 0.061 V drop; L3 1.81 m of 22 AWG, 0.096 V drop; L4 1.19 m of 24 AWG, 0.03 V drop	routed and held in the next CAD revision; every drop ≤ 0.25 V	to prove on the dev kit
Sensors	Noise mic and air chip The bench mic sat behind the side vents with the dust sensor's fan beside it; the boundary noise call wants the street side. The duct is drawn in the next CAD revision and the level checked against a sound meter on rev A.	ICS-43434 on the street strip on a printed duct to a new mic hole; SHT45 on a slotted island 4 mm behind the side vent	sound and air from outside the canopy, not from the boards	to prove on the dev kit
Security	Lid tamper sensor The bench used a lever switch pressed by the lid; a Hall sensor has no moving part to stick in dust. The magnet boss is in the rev T CAD. Change: CAD rev T: magnet boss under the lid (4 Nov 2026).	TMAG5273 3D Hall sensor at the street strip's top edge, 8.2 mm under a Ø6 × 3 magnet on a boss under the lid	lid lifted = logged and signed	fixed by the review

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

AI engine time per frame
Power cut
Card grade
LTE-M from inside the steel canopy
Fast lines on a solid ground plane
Board inside the product CAD, every part checked in 3D
The turnstile's egress untouched
Supply kept on its own board
Sensor tabs on their brackets
Flex and leads
Noise mic and air chip

Where the design stands

1Shape and placementdone
Main board, street strip, site, side, power and reader boards and three sensor tabs in the turnstile’s shape, all 110 parts placed at their real size in the canopy and the reader head, 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 flex.
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 boardsiteone-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 reader-head front Side B drawing (PDF)Up and inward Parts and placement (CSV)Every part, its size, side and position

Who can make it

The turnstile set is an 8-layer main board with a 4-layer street strip and three tabs on flexes, plus a 4-layer site board, a 4-layer reader board and two 2-layer boards. It needs a maker who builds rigid-flex boards with a long strip 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 110 parts, what is on each piece, every connection, heat, power, the factory test, cost and timeline.

SiteOne: circuit boards of our own

What changed (4 Nov 2026). The rev A bench turnstile is built from bought boards joined by leads: a Raspberry Pi 5, two Camera Module 3 Wide boards on ribbons, an HLK-LD2450 radar module, an SPS30, SHT45, MAX31865 and MAX9814 boards, three NeoPixel sticks, a piezo, a speaker amp board, an ATECC608 board, a Walter LTE-M board, a PowerBoost with a LiPo and an IRM-20-5 on flying leads, and in the reader head a PN532 board, an e-paper HAT and a fourth NeoPixel stick. SiteOne now gets boards of our own, like CricketOne and RoadOne, 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), a bare Sony IMX415 8 MP camera chip under an M12 lens holder (the C1 camera on the board), a TI IWRL6432AOP 60 GHz radar chip with its antennas on the package, a Quectel BG95-M3 LTE-M module with a soldered eSIM, 32 RGB call and PPE LEDs with their drivers, an SMD buzzer, a MAX98357A voice amp, an ICS-43434 noise mic, an SHT45 air chip, an ADS122C04 for the sun-load PT1000, an ST LSM6DSOX motion chip, the security chip and a Hall lid tamper sensor; two S1 nodes (ESP32-S3) for the site camera (an OmniVision OV5640) and for the reader head (an NXP PN7160 tap chip and a 2.13 in e-paper); on the power board a Mean Well IRM-20-5 supply, one photo-MOS contact on the controller’s entry-hold input, optocouplers on the rotor-turn and fire-alarm signals and one soldered 18650 backup cell with its charger and thermistor. The SPS30 dust sensor stays a bought sensor on its wall bracket, on a latched lead.
The shape: the turnstile’s own canopy is a 1,400 × 1,400 × 200 mm steel box. An 8-layer main board (120 × 110 mm) lies flat on the canopy floor near the street wall, the radar chip hanging under it on a short hinge, looking down through a floor radome into the rotor; a 4-layer street strip (550 × 130 mm) stands inside the street wall on a flex with the entry camera, the call lights, the buzzer, the voice amp, the noise mic and the lid tamper; a 4-layer site board stands inside the site wall with the site camera and the site call light; a 2-layer side board sits behind the side vent with the air chip; a 2-layer power board lies on the floor beside the main board; and a 4-layer reader board fills the reader housing on the street-side post. Four latched leads join them.
Four fixes in the same run (rev T CAD):
- The closed steel canopy stops LTE-M and Bluetooth (lesson: enclosure), so a 2-in-1 IP67 puck antenna goes through the lid above the main board, at 2.4 m and out of reach.
- The camera windows were round 14 mm holes sized for the bench camera boards. Boots at the turnstile mouth lie 72° off the street wall, so the entry window became 40 × 42; the site window became 24 × 26 for a plume 20 m to the side (lesson: window).
- The radar radome moved from the middle of the passage to over the front compartment, under the main board, so the radar chip sits on a short hinge from the processor board; it still sees the back compartment 40° off its axis, inside its ±60°.
- The reader head’s e-paper window shrank from 60 × 26 to 52 × 25 so the 59.2 mm panel covers its edge, a PPE light slot was added for the light that had none, a mic hole went into the street wall and a magnet boss under the lid for the tamper sensor.
Made from the shared rules: MEMS clocks, the latched microSD card with our software on every board with a processor (main, site and reader boards), conformal coating against rain, dust and condensation, a thermistor on the backup cell, cameras 30 mm or more from the processor, every line of sight under 82° from its wall, the antenna outside the metal.

The bench turnstile stays the test rig until the boards arrive.

1. The shape: six boards, three tabs

Piece	Size	Layers	Where	What
Main board	120 × 110 mm, 1.6 mm	8	flat on the canopy floor near the street wall, side A 10 mm over the 3 mm steel floor	the V2 core, card, security, motion chip, LTE-M, Wi-Fi/BT, puck coax pads, four lead headers
Street strip	550 × 130 mm, 1.6 mm, on F1 (149 mm)	4	standing 30 mm inside the street wall	entry camera tab, two call-light rows, buzzer, voice amp, noise mic, lid tamper
Site board	140 × 130 mm, 1.6 mm	4	standing 30 mm inside the site wall, on lead L2	ESP32-S3-WROOM-1, site camera tab, site call light, latched microSD
Side board	90 × 50 mm, 1.6 mm	2	4 mm inside the +x wall, on lead L4	SHT45 behind the side vent, ADS122C04 and the PT1000 terminal, SPS30 lead header
Power board	140 × 200 mm, 1.6 mm	2	flat on the canopy floor beside the main board, mains behind a printed shield	supply terminal, fuse, IRM-20-5, backup cell and charger, controller contact, optocouplers and terminal
Reader board	110 × 300 mm, 1.6 mm	4	4 mm inside the reader head’s front, on lead L3 down the post	ESP32-S3-MINI-1, PN7160 and printed tap coil, e-paper, PPE light, latched microSD
Sensor tabs (3)	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 (entry), OV5640 (site), IWRL6432AOP (rotor radar)

Leads, all with Molex Micro-Fit 3.0 latched ends: L1 power board to main board (5 V on two pairs, cell sense, controller signals), 0.17 m of 20 AWG; L2 to the site board (5 V, RS-485), 1.43 m of 22 AWG; L3 down inside the street-side post to the reader head (5 V, RS-485), 1.81 m of 22 AWG; L4 to the side board (5 V, differential I²C), 1.19 m of 24 AWG.

2. What is on the boards

Main board, side A (down): RK3576J (U1) with a 24 × 24 heat block (HS1) straight to the steel canopy floor; LPDDR4X (U2), eMMC (U11), factory pads (TP1). The rotor radar tab (U250, IWRL6432AOP) hangs under the board on its hinge, looking straight down through the 50 × 20 floor radome.

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 lifting the lid), LSM6DSOX motion chip (U13: the turnstile struck or lifted), AP6275S (U5), BG95-M3 (U6) with its eSIM (U6S), the puck’s coax pads (PD2), two RS-485 transceivers (U44), the PCA9615 bus buffer (U45), eFuse (U42) and four lead headers (J2–J5).

Street strip, side A (to the wall): 16 RGB LEDs behind the two street call-light slots (D11–D28) through printed light guides, the buzzer (BZ1) over the tone holes, the mic duct seat (DU1); the entry camera tab (U260, IMX415 under a 102° M12 lens, 35° down at the people walking up) on its hinge. Side B: two LED drivers (U70, U71), the ICS-43434 mic (MK1) over its board port, the MAX98357A voice amp (U30) and the speaker pads (PD3), the TMAG5273 lid tamper (U7) at the top edge, camera supplies (U26) and ESD (U28).

Site board: 8 RGB LEDs (D31–D38) behind the site slot on side A; the OV5640 site camera tab (U200, M12 lens 90° across, 20° down over the site); on side B the ESP32-S3-WROOM-1 (U41, radio off), its latched microSD (J41), the 3.3 V buck and camera supplies (U43), the RS-485 transceiver (U47), the LED driver (U72), ESD (U48), the lead header (J42) and factory pads (TP41).

Side board: the SHT45 (U60) on a slotted island behind the side vent on side A; the PCA9615 (U61), 3.3 V supply (U62), ADS122C04 (U63) with the PT1000 terminal (J62), the SPS30 lead header (J61) and the lead header (J60) on side B.

Power board (side A up): the supply terminal (J10), fuse and varistor (F10), IRM-20-5 (PS1), the 18650 holder with its cell (BT1), thermistor (RT1) and charger (U50), the photo-MOS entry-hold contact (K1), the rotor-turn and fire-alarm optocouplers (U52, U53), the controller terminal (J11) with its guard (U54) and the lead header (J12).

Reader board: on side A the e-paper (EPD1) in its window, 8 RGB PPE LEDs (D41–D48) behind the new slot and the printed 40 × 40 tap coil (ANT3) behind the tap mark; on side B the PN7160 (U80), ESP32-S3-MINI-1 (U81, radio off), latched microSD (J81), 3.3 V supply (U82), RS-485 transceiver (U83), the e-paper FPC connector (J82), the PPE LED driver (U84), the lead header (J80) and factory pads (TP81).

3. Every connection, checked

Link	How	Checked against
Entry camera chip to RK3576J	4-lane MIPI CSI-2 over F1 (149 mm) and the tab hinge	IMX415 data sheet: 891 Mbps per lane; at 10 fps it uses 0.83 Gbps of 3.56
Site camera	OV5640 into the ESP32-S3 camera port on the site board; JPEG frames over RS-485 on L2	OV5640 and ESP32-S3 data sheets; one frame every 5 s is about 0.8 Mbit/s (est.)
Radar chip	SPI and a frame interrupt over the tab hinge	TI IWRL6432AOP data sheet
Reader head	RS-485 on L3 to the ESP32-S3-MINI-1; it reads the PN7160 on I²C and drives the e-paper on SPI on the same board	NXP PN7160 and Good Display GDEY0213B74 data sheets
Side board	differential I²C (PCA9615 at both ends) on L4 to the SHT45, the ADS122C04 and the SPS30 (I²C mode)	NXP PCA9615 (est. 3 m), Sensirion SPS30 data sheet
Controller	one photo-MOS contact on the controller’s own entry-hold input; optocouplers listen to its rotor-turn signal and the fire-alarm free-wheel signal; no wire to the exit or the brake	Panasonic AQY212 data sheet (to read); the turnstile maker’s controller wiring (to read)
Call and PPE lights	three-channel constant-current drivers on I²C	TI LP5012 class (to choose)
Voice and tone	I²S over F1 to the MAX98357A and the 28 mm speaker; the buzzer on a GPIO	MAX98357A data sheet
LTE-M	USB 2.0 and UART on the main board; eSIM soldered; antenna the puck’s LTE element on soldered RG-178	Quectel BG95 hardware design
Wi-Fi/BT	SDIO and UART on the main board; antenna the puck’s 2.4 GHz element	AMPAK AP6275S (RK3576 SDK default)
Power in	the turnstile’s own supply, fused on the board, into the class II IRM-20-5; 5 V on L1 into an eFuse at 3.5 A; every lead drops under 0.1 V	Mean Well IRM-20 data sheet
Cards	SD bus on each processor board, latched sockets	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 3 mm steel canopy floor (5 K/W est.). The floor is shaded by the canopy above it and open to the passage air below, so the chip sits near 73 °C with the floor at 55 °C on a summer afternoon (est.), under its 85 °C rating: logged on rev A with the turnstile in the sun. The entry camera chip is 191 mm and the radar chip 50 mm from the processor.

5. Power budget (est.)

State	Draw
Shift-start rush: entry camera at 10 fps, radar, PPE model, site frame every 5 s, LTE-M	6.6 W
With the cell charging	about 7.6 W, 38 % of the 20 W supply
Watching out of hours: entry camera at 2 fps, radar, site frame every 5 s	4.8 W
Power cut (the turnstile free-wheels): RK3576J asleep, wakes on the fire alarm or every 60 s to log taps	0.4 W, about 26 h on the cell

6. Factory test (every board, every time)

Spring-pin fixture on the factory pads: 5 V in, the eFuse trip at 3.5 A, every rail, boot from the card on the main, site and reader boards, a frame of a test chart from each camera, a corner reflector seen by the radar, all 32 LEDs, the buzzer and a voice line, a tone into the mic, the air chip and a PT1000 test resistor read back, the motion chip, the lid tamper with a magnet, a test card on the tap coil, the e-paper refreshed, the security chip’s key, the LTE-M and BLE links through a test puck; on the power board, the supply under load, the entry-hold contact closing into a test input, a pulse on each optocoupler, the charger’s temperature cut-off with the thermistor warmed. Each board gets its serial number in its ID chip or its ESP32-S3.

7. Who makes what

One maker makes the rigid-flex piece (main board and street strip) and the four other boards, assembles them (turnkey) and makes leads L1 to L4 to length. We supply the microSD cards with our software and the lenses focused at 2 m (entry) and 15 m (site) (est.). The quote pack is /build/siteone-quote.

8. Cost per turnstile, electronics (est.)

Item	Cost
V2 core (RK3576J, 4 GB LPDDR4X, 32 GB eMMC, power, AP6275S)	$48
IMX415 camera chip, holder and lens	$14
Two S1 nodes (ESP32-S3 modules), OV5640, holder and lens	$14
IWRL6432AOP radar chip	$12
BG95-M3 LTE-M, eSIM and the 2-in-1 puck antenna	$26
PN7160, e-paper panel and connector	$14
SPS30 dust sensor (bought)	$35
SHT45, ADS122C04, PT1000, mic, voice amp, buzzer	$10
32 LEDs and four drivers	$6
IRM-20-5, terminals, fuse, cell, charger, contact, optocouplers	$22
Security, ID, motion, three sockets, Hall sensor, passives	$10
Boards (8-layer rigid-flex with a 550 mm street strip, three tabs, four other boards), 1,000 turnstiles	$38
Leads L1 to L4	$8
Assembly and test	$18
Three microSD cards with our software	$9
Total	about $296 per turnstile (est.)

The bench turnstile’s electronics cost about $511 at qty 1, so our boards are about $215 cheaper per turnstile at 1,000 (est.).

9. Timeline

Step	When
Shape and placement (this page)	done, 4 Nov 2026
Next CAD revision: the boards in the turnstile CAD, every part checked in 3D; the windows, radome, puck hole, mic hole, PPE slot and lid magnet boss already moved (rev T)	next
Schematic, footprints, routing	Dec 2026 – Jan 2027
Rev A boards made and tested	Mar 2027 (est.)

10. Still to check

The CAD changes still to draw: the tab brackets, the mic duct, the printed light guides, the mains shield and the lead routes inside the canopy and down the post.
The canopy floor’s temperature in full summer sun, logged on rev A; if the chip runs past 75 °C, a larger aluminium spreader on the floor.
The turnstile makers’ controller wiring for the entry-hold input, the rotor-turn signal and the fire-alarm signal (Hayward, Rizon and others), read from each maker’s manual.
LTE-M and BLE through the puck on a steel lid, measured on rev A.
The F1 camera-lane impedance over 149 mm with the flex 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
OmniVision OV5640: https://www.ovt.com/products/ov5640/
Espressif ESP32-S3-WROOM-1 and ESP32-S3-MINI-1: https://www.espressif.com/en/products/modules
TI IWRL6432AOP: https://www.ti.com/product/IWRL6432AOP
NXP PN7160: https://www.nxp.com/products/PN7160
NXP PCA9615: https://www.nxp.com/products/PCA9615
TI ADS122C04: https://www.ti.com/product/ADS122C04
Sensirion SHT45: https://sensirion.com/products/catalog/SHT45
Sensirion SPS30: https://sensirion.com/products/catalog/SPS30
TDK ICS-43434: https://invensense.tdk.com/products/ics-43434/
Maxim MAX98357A: https://www.analog.com/en/products/max98357a.html
Good Display GDEY0213B74: https://www.good-display.com/
Panasonic AQY212EH photo-MOS: https://industry.panasonic.com/global/en/products/control/relay/photomos
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
ST LSM6DSOX: https://www.st.com/en/mems-and-sensors/lsm6dsox.html
Microchip ATECC608B: https://www.microchip.com/en-us/product/atecc608b
TI TMAG5273: https://www.ti.com/product/TMAG5273
Samsung INR18650-35E: https://www.samsungsdi.com/
IBC 2021 chapter 10, means of egress (1010.3.1 turnstiles): https://codes.iccsafe.org/content/IBC2021P2/chapter-10-means-of-egress
The turnstile: products/siteone/cad/siteone-cad.mjs (rev A, windows rev T); the boards: products/siteone/hardware/pcb/siteone-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. SiteOne’s boards were made with every rule from the start: 16 pass, 7 fixed, 11 to prove, 0 fail. The full review, with every number and its source, is on the board page. It shows:

Camera pixels: safety boots 2.5 m out at the turnstile mouth fill about 103 px against a 30 px need; a person at the muster point (9.5 m) about 78 px against 20; the entry chip at 10 fps uses 23 % of its link, and both cameras 88 Mpx/s of the image processor’s 480.
Every gate call in view: hard hat, vest and boots at the mouth, the next person in the queue and a person at the reader after hours; smoke over the site and to the side, a person at the muster point and people leaving; one or two people in the front and back compartments and the passage, from where each lens or chip really sits.
The antenna is outside the steel (fixed): a 2-in-1 puck through the lid (lesson: enclosure).
The windows, the radome and the reader head were sized for our chips (fixed), and the lid tamper became a Hall sensor with no moving part to stick in dust (fixed). Drawn in the CAD the same day.
The egress is untouched: one contact on the controller’s entry-hold input only; the exit always turns and the rotor free-wheels on a power cut or the fire alarm, as before.
The latched microSD is fitted on the main, site and reader boards, and our software starts from it; updates run only out of hours, never with anyone on site.
A thermistor on the backup cell holds charging outside 0 to 45 °C, and conformal coating against rain, dust and condensation 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; 4 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 AI time, the power-cut run on the cell, LTE-M through the puck, the egress test with the boards running and unplugged, mains creepage, the tab brackets, the flex and leads, the mic duct and the air chip against reference meters.

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