Our own circuit board, in the bedside locker

One board we design for the smart bedside locker, with every chip soldered on it: the ESP32-S3 radio, the 60 GHz radar chip, two weigh chips, the call key and its mic, the call light, the floor glow, the security chip and two backup cells with their charger. A top board lies in the sealed top over the service tray, with a strip bent up behind the front face, a radar tab bent up to look down at the bed, and a strip bent up behind the bed-side face with the call key; a long flex runs down the bed-side panel to the floor glow. No camera, no plugs, ribbons or adapters inside; no mains in the locker.

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 board in the locker 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 locker

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 locker

Radartop, front corner on the bed side

A TI 60 GHz radar chip with its antennas built in, on a small tab bent up 65° so it looks 25° down through a 2 mm skin: sitting up, legs over the edge, lying and turning, someone on the floor beside the bed, the carer at the bedside. Positions only, never pictures.

Call key and micbed-side face

A sealed key switch under the flush call key beside the pillow (press for help, hold for a voice note) and a MEMS mic on a port next to it that listens only while the key is held.

Call light and floor glowfront face and bed-side panel

Eight LEDs behind the opal front skin are the call light, a sounder gives the call tone, and eight more on a strip low in the bed-side panel make the amber floor glow when a resident gets up.

Radio and securitytop board

The ESP32-S3 module with its antenna at the right edge, away from the bed, the security chip that signs every call, the latched microSD card with our software, and the tamper switch pressed by the service tray.

Weighing, power and cellstop board

Two weigh chips soldered next to the load cells’ fixed ends (the water jug for the fluid chart, the hand-rub bottle), one latched lead from the listed 5 V adapter, and two backup cells with their charger for power cuts.

The locker board laid flat, both sides, every part at its real size

Laid flat: the top board with its front strip and radar tab, the side strip and, on its tail, the glow strip on the bed side (the glow tail drawn short). Tap the drawing to open it full size.

Design review: checked before we order

Every board-level number CareOne's jobs 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 fails8 pass · 2 fixed by the review · 10 to prove before we order · 0 failDesign review of 4 November 2026

Area	Check	Our board	Target	Status
Power	Supply About 1.1 W watching (radar tracking, Wi-Fi, weigh chips), 3.6 W charging the cells, up to 1 W for the call light and floor glow (est.): under 70 % of a 12 W adapter.	5 V from a listed USB adapter at the wall socket, on one latched lead (no mains inside the locker, UL 962)	≤ 70 % of the adapter (2.4 A)	passes
Power	Power cut The bed-exit and floor calls matter most at night, and a power cut is when a resident is most likely to get up in the dark. The draw in a cut is measured on the dev kit and rev A; Wi-Fi needs the home's access points on their own backup, so the call light and tone on the locker are the first signal.	two 18650 cells: about 27 h in a power cut, cells aged to 80 % (0.55 W: the 60 GHz radar in low-power tracking, Wi-Fi only for calls, call light dim, est.; the bench LD2450 alone drew 0.6 W)	≥ 24 h (bed exit and long-lie calls keep going through a cut)	to prove on the dev kit
Heat	ESP32-S3 temperature, a warm care-home room in summer (30 °C, est.) The board lies in the sealed laminate top with no vents (HBN 00-09: no grilles); the room is the only heat source. 0.5 W through the top board to the sealed top and the tray (25 K/W, est.).	43 °C	≤ 85 °C (rated)	passes
Heat	Cell temperature, a warm care-home room in summer (30 °C, est.) The cells sit on the back of the top board away from the radar rails; charging holds above 45 °C (thermistor RT1), which a care room never reaches (lesson: sun).	33 °C	≤ 60 °C	passes
Heat	Weigh chips away from warm parts A warm load-cell chip drifts, and the jug plate logs drinks for the fluid chart in tens of grams.	charger 207.1 mm and radar rails 106.3 mm from the nearest weigh chip	≥ 20 mm	passes
Shock	Shock and vibration A locker on castors, pushed between beds and knocked by hoists and trolleys (est.).	20 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. The maker flashes our small loader into the ESP32-S3 at test; it starts our program from the card, and Wi-Fi updates write to the card only in the day shift, never at night.	microSD socket with a hinged, latched lid (Amphenol 101-00660 class), fitted on every board: our software starts from the card (ESP32-S3 SD bus	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 An ESP32-S3 starts only from its own flash, so the maker writes our small fixed loader at test; it checks and runs the program on the card (lesson: sdstart). Change: the loader is written at test (4 Nov 2026).	a small loader in the ESP32-S3 flash starts the program on the card	the program on the card runs 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
Radio	Wi-Fi from the locker top The antenna end sits at the top board's right edge, away from the bed; some ward lockers have steel frames or drawer runners near the top, and hoists and bed frames are steel. Measured on rev A (lesson: antenna).	to the home's access point, through the 6 mm laminate side skin	certified ESP32-S3 module	to prove on the dev kit
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).	USB (90 Ω); antenna feed (50 Ω, keep-out on every layer); card lines (length-matched, no vias under the socket)	solid ground under the module and its lines (inner layer 1, or the whole bottom of a 2-layer section), no vias in pads or in the antenna keep-out	to prove on the dev kit
Moisture	Conformal coating Water jugs spill on the top and every surface is wiped with disinfectant each day, so liquid reaches the plate gaps, the key and the skins. 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
Radar	Every bed-bay call in the radar's view All seven radar calls from the CAD (bed edge, legs over, lying and turning, someone on the floor beside the bed and at its foot, the carer at the bedside) are inside the chip's view, the closest 10.0° from its edge. The bench LD2450 also turned 40° to the bed; our chip's wider view needs only the 25° tilt. TI quotes the view from its antenna plots, so the edge is measured on the maker's evaluation board beside a real care bed.	worst 38° across, 30° up or down, tab bent up 65° (chip 25° down)	inside ±70° across, ±40° up or down	to prove on the dev kit
Radar	Radar through the front skin At 60 GHz a skin works best near half a wavelength in the material; the rev T CAD sets the skin from the laminate's measured permittivity, as DampOne's 1.5 mm skin.	laminate skin 2 mm over the chip (the bench window was made for 24 GHz)	under 3 dB two-way loss at 60 GHz	to prove on the dev kit
Fit	Radar tab behind the front face Every corner of the bent tab, both faces, and the chip's front corners are checked in the CAD's y-z plane.	bent 65° up from a recess in the top board's front corner; the tab and chip 3.81 mm inside the front face at their closest	≥ 0.3 mm, nothing touches	passes
Fit	Tamper switch against the service tray The bench tamper post on the tray becomes a 1.5 mm boss in the rev T CAD and is checked with the printed tray on rev A.	D2F-01 6.5 mm tall in an 8 mm gap; a 1.5 mm boss on the tray presses it	pressed when the tray is screwed in, released when it is opened	to prove on the dev kit
Fit	Call key travel A resident in bed presses it with a weak hand, so the cap is sized for a large, light press; made in the rev T CAD and tried on rev A.	sealed 6.2 mm tact switch 5.2 mm tall in a 6 mm gap behind the bed-side skin; a printed flush key cap in the Ø16.4 hole	a clear click with a 0.3 mm or more pre-travel, flush key, wipe-clean	to prove on the dev kit
Fit	The glow tail A long flex tail is cheap to make in one panel only if the maker can fit it; the rev T CAD adds the tray slot and the clip channel behind the drawer runner.	12 × about 684 mm from a tongue in the bed-side edge, through a slot in the tray and down 4 mm inside the bed-side panel past the drawer	routed and clipped in the rev T CAD, clear of the drawer, static bend at or above the maker's minimum	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:

Power cut
Card grade
Wi-Fi from the locker top
Fast lines on a solid ground plane
Board inside the product CAD, every part checked in 3D
Every bed-bay call in the radar's view
Radar through the front skin
Tamper switch against the service tray
Call key travel
The glow tail

Where the design stands

1Shape and placementdone
Top board, front strip, radar tab, side strip and glow strip in the locker’s shape, all 42 parts placed at their real size, fit checks against every window in the locker CAD and KiCad design rule check (0 violations).
2Schematicnext
Every wire between the chips, from the S1 core circuit.
3Footprintsnext
The exact solder pads under each chip.
4Routinglater
Copper tracks on all layers and along the long glow tail.
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 boardcareone-board.kicad_pcb: open with KiCad 10 (free)3D model (STEP)The bare board for mechanical CAD Side A drawing (PDF)Tray, room and bed side Side B drawing (PDF)Top side Parts and placement (CSV)Every part, its size, side and position

Who can make it

The locker board is one 4-layer board and four 2-layer pieces joined by flexes, one of them about 0.7 m long. It needs a maker who builds rigid-flex boards with long flex tails. 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 42 parts, what is on each board, every connection, heat, power, the factory test, cost and timeline.

CareOne: one circuit board of our own

What changed (4 Nov 2026). The rev A bench locker is built from bought boards joined by leads: a XIAO ESP32-S3, an HLK-LD2450 radar module, two NAU7802 load-cell boards, a MAX9814 mic board, a 16 mm panel key, two NeoPixel sticks, a piezo, an ATECC608 board and a PowerBoost 1000C charger. CareOne now gets one circuit board of our own, like CricketOne and BedsideOne, with every chip placed straight onto it, made with every shared design-review rule from the start.

The chips: the ESP32-S3 certified radio module (soldered by its edge pads), a TI IWRL6432AOP 60 GHz radar chip with its antennas built in, two Nuvoton NAU7802 weigh chips, a sealed call-key switch, a MEMS mic, 16 LEDs (call light and floor glow), a sounder, the security chip, the tamper switch, a charger and two soldered 18650 cell holders. No camera: residents’ rooms are private (CQC surveillance guidance).
The shape: everything but the floor glow lives in the locker’s sealed 70 mm top. A top board (453.8 × 435.8 mm, 4 layers) lies 8 mm over the printed service tray, notched round the two load-cell blocks. A front strip bends 90° up 4 mm behind the front face (call light and sounder). A small radar tab bends up 65° from a recess in the front corner on the bed side, so the radar chip looks 25° down at the bed and the floor beside it. A side strip bends 90° up 6 mm behind the bed-side face, with the call key and the mic. A 12 mm glow tail (about 684 mm, est.) runs from a tongue in the bed-side edge down the inside of the bed-side panel to a glow strip behind the floor-glow skin.
No mains in the locker. 5 V comes from a listed USB adapter at the wall on one latched lead, as before (UL 962). The bed’s own nurse-call cord stays the life-safety call (UL 1069).
The rev A bench locker stays as it is. It proves the calls and the software, which move to this board (same ESP32-S3 family).

The CareOne locker board laid flat, both sides

The board is code (hardware/pcb/careone-board.mjs). It writes the KiCad board file (hardware/pcb/careone-board.kicad_pcb), the parts list (careone-board-parts.csv) and this drawing, and checks every part:

every part sits on its board with a 0.3 mm edge margin and no two parts overlap on the same side; no part sits in the notches round the load-cell blocks, the radar recess or the glow-tail slot, and nothing under the load-cell bars or the plate stems reaches them;
every part’s height fits its gap: 7.6 mm under the top board, 49.9 mm above it, 3.5 mm in front of the front strip, 5.5 mm in front of the side strip, 2.5 mm in front of the glow strip;
the call-light LEDs sit behind the opal skin, the sounder on the tone holes, the call-key switch under the key, the mic and its gasket on the mic port, the tamper switch on the tray boss and the floor-glow LEDs behind the floor-glow skin (within 1 mm, from cad/careone-cad.mjs);
the radar chip, on the bent tab, is centred on the radar window in 3D, every tab corner and the chip’s front corners stay 3.8 mm or more inside the front face, and all seven radar calls in the CAD are inside the chip’s view (worst: the carer at the bedside at 30° up, against ±40°; lying in bed at 38° across, against ±70°);
the folds stay inside the locker top: both strips below the top skin, the front strip clear of the right skin and the radar tab, the side strip clear of the tab and the back; the glow tail runs down 4 mm inside the bed-side panel and the glow strip stays above the cupboard floor, inside the back and the door;
the radio module’s antenna end is at the top board’s right edge (away from the bed) with a keep-out under it; the charger and the radar rails are 20 mm or more from both weigh chips.

KiCad design rule check: 0 violations (KiCad 10, 4 Nov 2026). Each part is drawn at its real size, as a placeholder outline until its full footprint is added. Numbers marked est. are estimates.

1. The shape: five pieces on one board

Piece	Size	Where	Side A	Side B
Top board	453.8 × 435.8 mm, 4 layers	flat 8 mm over the service tray (z 802)	down to the tray: tamper switch, factory pads, antenna keep-out	up: radio, security, ID, microSD, power lead, charger, cells, weigh chips, radar rails
Front strip	370 × 45 mm, 2 layers, on a 50 mm flex	bent 90° up, side A 4 mm behind the front face	to the room: 8 call-light LEDs, sounder	sounder driver
Radar tab	28 × 34 mm, 2 layers, on a 14 mm flex	bent 65° up from the front corner on the bed side	25° down to the bed: IWRL6432AOP and its keep-out	—
Side strip	140 × 45 mm, 2 layers, on a 60 mm flex	bent 90° up, side A 6 mm behind the bed-side face	to the bed: call-key switch, mic gasket	mic
Glow strip	80 × 20 mm, 2 layers, on a 12 mm tail about 684 mm (est.)	3 mm inside the bed-side panel, z 110 to 130	to the bed: 8 floor-glow LEDs	—

2. What is on the board

Ref	Part	Job
U1	Espressif ESP32-S3-WROOM-1-N16R8	the brain and Wi-Fi: every call, the voice notes, signed alerts to the carers’ app
U3	TI IWRL6432AOP 60 GHz radar, antennas in package	bed exit, not back, someone on the floor, turns, night checks, the carer at the bedside
U8	Radar rails (LP87745 class), 40 MHz crystal, 2 MB flash	the radar’s own power and program
U5, U6	Nuvoton NAU7802 ×2 with gauge-wire pads	drinks from the jug (fluid chart), hand rubs from the bottle
SW2	C&K KSC sealed tact switch under a flush key	the call key: press = help, hold = a voice note
MK1, GK1	Infineon IM69D130 MEMS mic and gasket	the voice note while the key is held
D1–D8	WS2812B-class LEDs	the call light: yellow, green, amber, red
D9–D16	WS2812B-class LEDs	the amber floor glow at night
LS1, Q1	12 mm sounder and driver	the call tone
U2, U9	Microchip ATECC608B, ID EEPROM	signs every call; board identity and calibration
SW1	Omron D2F-01	tamper: opens when the service tray is taken off
J2	Latched microSD	our software starts from the card
J1, U4	Micro-Fit 2-pin lead, BQ24074 charger, TPS63020	5 V in from the listed adapter, power path, 3.3 V
BT1, BT2, RT1	Two Keystone 1042 holders, Samsung INR18650-35E, NTC	backup through a power cut; no charging outside 0–45 °C

3. Every connection, checked

Mating pair	Checked against	Note
Adapter lead → J1	Molex Micro-Fit 3.0 drawing	latched, keyed; the adapter’s lead is made with the Micro-Fit plug
Load-cell gauge wires → PD1, PD2	load cell maker’s colour code	soldered, with a strain-relief slot; no plug
Key cap → SW2	C&K KSC drawing (to read)	printed cap in the Ø16.4 hole, made in the rev T CAD
Mic gasket → bed-side skin port	IM69D130 port size	Ø3 port with a membrane added in rev T
Tray boss → SW1	Omron D2F drawing	the bench tray post becomes a 1.5 mm boss in rev T

No module, ribbon, adapter or plug inside the locker; the only lead is the 5 V lead from the wall.

4. Heat

About 1.1 W watching (est.) in a sealed top with no vents (wipe-clean, HBN 00-09). The ESP32-S3 at 0.5 W sits about 13 K over a 30 °C room (est.). The charger and the radar rails are kept 20 mm or more from the weigh chips so the gauges do not drift; the cells sit at the back, away from both.

5. Power budget (est.)

State	Draw	Note
Watching (mains)	1.1 W	radar tracking, Wi-Fi, weigh chips
Call (mains)	+ 1 W	call light and tone
Charging	+ 3.6 W	BQ24074 at 1 A
Power cut	0.55 W	radar in low-power tracking, Wi-Fi only for calls, light dim: about 27 h on two cells aged to 80 %

Under 70 % of a 12 W listed adapter in every state.

6. Factory test (every board, every time)

Spring pins on TP1 and TP2: rails and current, flash our loader, read the ID chip and the security chip, boot from a test card, light every LED, sound the tone, press the key, record a tone on the mic, read both weigh chips with a fixture load, see a corner reflector on the radar, open and close the tamper switch, charge and discharge the cells.

7. Who makes what

The board maker builds and assembles the rigid-flex board, fits the cells and runs the factory test; we supply the tested card image and the test fixture design. The locker maker fits the board, the load cells, the key cap and the tray.

8. Cost per locker, electronics (est.)

About $64 for the board with its parts at 1,000 lockers (est.): radar chip and its rails about $18, ESP32-S3 module $4, two weigh chips $4, LEDs, key, mic and sounder $6, power, charger and cell holders $6, two cells $8, the rigid-flex board with its long tail $18. The bench boards it replaces cost about $150 at one off.

9. Timeline

Shape and placement done (4 Nov 2026); schematic and footprints next; routing and the maker files after; rev A boards in March 2027 (est.).

10. Still to check

The IWRL6432AOP outline and the radar view edge on TI’s evaluation board beside a real care bed.
The laminate skin over the radar at 60 GHz (set from the measured permittivity).
The C&K KSC outline, key travel and cap.
The rev T locker CAD: the 1.5 mm tray boss, the tray slot for the glow tail, the clip channel past the drawer, the mic port and the radar skin, with every board part checked in 3D.
Wi-Fi range from lockers with steel frames, on rev A.

Sources

Espressif ESP32-S3-WROOM-1 datasheet: https://www.espressif.com/sites/default/files/documentation/esp32-s3-wroom-1_wroom-1u_datasheet_en.pdf
TI IWRL6432AOP: https://www.ti.com/product/IWRL6432AOP
Nuvoton NAU7802: https://www.nuvoton.com/products/smart-home-audio/audio-converters/precision-adc-series/nau7802sgi/
Omron D2F: https://omronfs.omron.com/en_US/ecb/products/pdf/en-d2f.pdf
C&K KSC series: https://www.ckswitches.com/products/switches/product-details/Tactile/KSC/
Samsung INR18650-35E: https://www.18650batterystore.com/products/samsung-35e-18650-3500mah-8a-battery
TI BQ24074: https://www.ti.com/product/BQ24074
Locker sizes and windows: products/careone/cad/careone-cad.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. CareOne’s board was made with every rule from the start, so nothing had to be fixed: 8 pass, 2 fixed, 10 to prove, 0 fail. The full review, with every number and its source, is on the board page. It shows:

Radar view: all seven radar calls are inside the chip’s view, the closest (the carer at the bedside) 10° from its edge; to prove on TI’s evaluation board beside a real care bed. The bench radar was turned 40° to the bed and tilted 25°; our chip’s wider view needs only the 25° tilt, so the tab bends on one fold.
Power cut: two cells give about 27 h, aged to 80 % (to prove on rev A; target 24 h), so bed-exit and floor calls keep going through a cut.
The latched microSD (J2) is fitted, and our software starts from it; updates run only in the day shift.
Conformal coating against jug spills and daily disinfectant wipes is asked for in the quote.
Wi-Fi through the laminate side skin is measured on rev A, because some ward lockers have steel frames.
The tamper boss, the call-key travel, the radar skin and the long glow tail are checked in the rev T CAD and on rev A.
Fast lines on a solid ground plane (to prove, lesson: planes, from the CricketOne test-board layout of 4 Nov 2026): 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.

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