anil08607/Smartwatch

REFERENCES.md

# Manufacturer references

Electrical facts and package requirements come from the manufacturers below. Current inventory evidence is recorded separately in `sourcing/stock.json`; physical measurements remain pending.

- [Nordic nRF52810 product specification v1.5](https://infocenter.nordicsemi.com/pdf/nRF52810_PS_v1.5.pdf): QFAA48 pinout, exposed ground pad, internal LDO mode, 192 KiB flash/24 KiB RAM, crystals and reference matching network.
- [Nordic pin assignments](https://docs.nordicsemi.com/r/bundle/ps_nrf52810/page/pin.html).
- [SEMITEC AT thermistors](https://www.semitec-global.com/products/thermistor_at/): 103AT-2, 10 kΩ, B25/85=3435 K.
- [Yageo RC0402FR-07510KL listing and specification](https://www.lcsc.com/product-detail/Chip-Resistor-Surface-Mount_510KR-5103-1_C137961.html): R4 exact stocked alternative.

## Manufacturer authorities

- BMA456: [Bosch Sensortec datasheet](https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bma456-ds000.pdf) and [official SensorAPI](https://github.com/boschsensortec/BMA456_SensorAPI).
- PCF8563TS: [NXP datasheet](https://www.nxp.com/docs/en/data-sheet/PCF8563.pdf).
- BQ25180YBGR: [TI datasheet and reference circuit](https://www.ti.com/lit/ds/symlink/bq25180.pdf).
- HUSB238: [Hynetek product page](https://www.hynetek.com/2421.html) and [official datasheet](https://www.hynetek.com/uploadfiles/site/219/news/c16af076-8c40-4e8d-b126-b4f9b83e86ea.pdf). VSET=0 Ω selects 5 V, ISET=0 Ω selects 1.25 A, and the implemented VIN filter is 10 Ω / 1 µF.
- TPS63802: [TI product page and datasheet](https://www.ti.com/product/TPS63802).
- ER-TFT1.28-3: [EastRising/BuyDisplay panel datasheet](https://www.buydisplay.com/download/manual/ER-TFT1.28-3_Datasheet.pdf) and [official product/ordering page](https://www.buydisplay.com/1-28-inch-tft-lcd-display-240x240-round-circle-screen-for-smart-watch). This is the complete LCD/FPC/backlight assembly, not the bare GC9A01A controller.
- AFC24-S15FIA-00: [JLCPCB manufacturer drawing and assembly listing](https://jlcpcb.com/partdetail/JUSHUO-AFC24_S15FIA00/C6709462). The exact JLC/EasyEDA land pattern was imported using `C6709462` rather than inferred from connector pitch alone.
- LCM1234A3523F: [LEADER manufacturer specification, hosted by LCSC](https://wmsc.lcsc.com/wmsc/upload/file/pdf/v2/lcsc/2306261204_LEADER-LCM1234A3523F_C7424783.pdf), operating conditions and mechanical drawing.
- LP403035: [LiPol Battery pack datasheet](https://www.lipolbattery.com/LiPo-Battery-Datahseet/LiPo_Battery_LP403035_3.7V_400mAh.pdf).
- SM06B-SRSS-TB(LF)(SN): [JST SH-series official datasheet and PCB layout](https://www.jst-mfg.com/product/pdf/eng/eSH.pdf). The 6-circuit side-entry header uses a 1.0 mm contact pitch, 5.0 mm contact span, and 8.0 mm overall body width.

## Critical pin/package checks

### ER-TFT1.28-3 and J4

The selected BuyDisplay panel is 1.28 inch, 240 x 240, 4-wire SPI, GC9A01A, 35.59 x 37.74 x 1.6 mm, with a plug-in 15-pin 0.5 mm-pitch flex. V1 orders the **no-touch** option. `J4` is JUSHUO `AFC24-S15FIA-00`, JLCPCB `C6709462`: 15 contacts, 0.5 mm pitch, 0.3 mm FPC, double-sided contact, top/bottom entry, hinged lid, 2 mm board height, right-angle SMT.

| J4 / FPC pin | Signal  | V1 use                |
| -----------: | ------- | --------------------- |
|            1 | GND     | GND                   |
|            2 | LEDK    | Q1 drain              |
|            3 | LEDA    | V3V0 through R14       |
|            4 | VDD     | V3V0                   |
|            5 | RS      | LCD D/C GPIO          |
|            6 | CS      | nRF52810 SPI chip select |
|            7 | SCL     | nRF52810 SPI clock       |
|            8 | SDA     | nRF52810 SPI MOSI        |
|            9 | RESET   | nRF52810 reset GPIO      |
|           10 | CTP_VDD | NC; touch not fitted  |
|           11 | GND     | GND                   |
|        12–15 | CTP_*   | NC; touch not fitted  |

The display datasheet allows 2.5–3.3 V VDD and specifies a 2-chip white backlight at 3.0 V typical, 30 mA typical and 40 mA maximum. V1 uses a 22 Ω resistor plus N-MOSFET/PWM topology, which deliberately starts below maximum brightness on a 3.05 V rail; measure actual LED current and brightness before changing R14. The connector's two shell/hold-down pads are mechanical NCs. The top-side footprint includes a pin-1 marker; cable insertion orientation must be checked against the physical no-touch panel before production.

### BQ25180YBGR

| Ball    | Signal      | Connection                              |
| ------- | ----------- | --------------------------------------- |
| A1 / A2 | INT / IN    | V3V0 pull-up interrupt / protected USB5V |
| B1 / B2 | SCL / SYS   | shared I2C / buck-boost input           |
| C1 / C2 | SDA / BAT   | shared I2C / protected 1S pack          |
| D1 / D2 | TS/MR / GND | bonded 10 kΩ NTC through J5 / ground          |

The implemented local values satisfy the datasheet minimums: IN 1 µF, SYS 10 µF, BAT 1 µF. J5 connects a bonded 10 kΩ, B25/85=3435 K NTC. Pack temperature and open/short fault behavior must be qualified.

### PCF8563TS

Pins 1/2 connect only to the FC-135 32.768 kHz crystal; the RTC provides the oscillator load capacitance. Pins 3/4/5/6/7/8 are INT/VSS/SDA/SCL/CLKOUT/VDD respectively. CLKOUT is unused. VDD is on BAT so time survives MCU/regulator shutdown.

### BMA456

VDD (pin 7) and VDDIO (pin 3) use separate 100 nF local capacitors. CSB (pin 10) is high for I2C; SDO (pin 1) is low, selecting address `0x18`. SDA/SCL remain pins 2/12, and INT1/INT2 remain pins 5/6. Auxiliary ASDA/ASCL (pins 4/11) are deliberately NC, as allowed by the Bosch connection table when that interface is disabled. The C189518 exact supplier footprint has the same pad positions and dimensions as the previous package. Firmware must load the BMA456 wearable feature configuration and use its driver; it is not register-compatible with BMA400.

### MOSFET package mapping

Q1/2N7002 and Q2/AO3400A use SOT-23 pins 1=gate, 2=source, 3=drain. The [Nexperia 2N7002 pinning table](https://assets.nexperia.com/documents/data-sheet/2N7002.pdf) and [AOS AO3400A package view](https://www.aosmd.com/sites/default/files/res/datasheets/AO3400A.pdf) document that assignment. The shared custom symbol uses those physical pin numbers so the default tscircuit drain/gate aliases cannot merge the control and load nets.

### Side switches

SW1/SW2 use the exact C51927172 land pattern, including two locating holes and bracket pads. The part is a right-angle, normally-open SPST switch; V1 uses an active-low nRF52810 input with an external 100 kΩ pull-up. The JLCPCB listing identifies it as an SMT-assembly part in the SMD-4P 4.6 x 1.8 mm family.

### Programming connector

J3 is JST `SM06B-SRSS-TB(LF)(SN)`, LCSC/JLCPCB `C160405`, using the official 6-circuit right-angle JST-SH land pattern. It replaces TP1-TP6 and exposes V3V0 reference, SWDIO, GND, SWCLK, NRST, and P0.18 service GPIO through one keyed cable. Its local tscircuit footprint uses the official 0.6 x 1.55 mm contact pads at 1.0 mm pitch and 1.2 x 1.8 mm mechanical pads at x = +/-3.8 mm, cross-checked against the corresponding KiCad official-library footprint `JST_SH_SM06B-SRSS-TB_1x06-1MP_P1.00mm_Horizontal`.

## JLCPCB/LCSC sourcing links

- [BMA456 C189518](https://jlcpcb.com/partdetail/BMA456/C189518)
- [HUSB238_002DD C7471904](https://jlcpcb.com/partdetail/C7471904)
- [PCF8563TS/5,118 C27397](https://jlcpcb.com/partdetail/NXPSemicon-PCF8563TS_5118/C27397)
- [BQ25180YBGR C3682423](https://jlcpcb.com/partdetail/C3682423)
- [TPS63802DLAR C2845237](https://jlcpcb.com/partdetail/TexasInstruments-TPS63802DLAR/C2845237)
- [AFC24-S15FIA-00 C6709462](https://jlcpcb.com/partdetail/JUSHUO-AFC24_S15FIA00/C6709462)
- [LCM1234A3523F C7424783](https://jlcpcb.com/partdetail/LCM1234A3523F/C7424783)
- [AO3400A C20917](https://www.lcsc.com/product-image/C20917.html)
- [2N7002 C8545](https://jlcpcb.com/partdetail/JiangsuChangjingElec-2N7002/C8545)
- [LESD5Z5.0CT1G C136167](https://jlcpcb.com/partdetail/LRC-LESD5Z50CT1G/C136167)
- [1N5819WS C5451629](https://jlcpcb.com/partdetail/HxyMosfet-1N5819WS/C5451629)
- [TS-1806SA-2x4x3.5DY-180X C51927172](https://jlcpcb.com/partdetail/CAX-TS_1806SA_2x4x3_5DY180X/C51927172)
- [SM06B-SRSS-TB(LF)(SN) C160405 at JLCPCB](https://jlcpcb.com/partdetail/171785-SM06B_SRSS_TB_LF_SN/C160405) — SMT Assembly, Economic and Standard PCBA.
- [SM06B-SRSS-TB(LF)(SN) C160405 live LCSC stock](https://www.lcsc.com/product-detail/Wire-To-Board-Connector_JST-SM06B-SRSS-TB-LF-SN_C160405.html)