[boards] Add Tuya WL2H-U (LN882H)

[Bl00d-B0b]

Summary

Add board definition for the Tuya WL2H-U Wi-Fi/BLE module based on the Lightning LN882HK chip.

Files added

• boards/wl2h-u.json — board definition
• boards/_base/pcb/wl2h-u.json — physical pinout (21 pads + test point TA9)
• boards/variants/wl2h-u.c/.h — Arduino pin map

Hardware specs

• CPU: ARM Cortex-M4F @ 160 MHz
• RAM: 296 KB
• Flash: 2 MB
• Wi-Fi: 802.11b/g/n
• BLE: 5.1
• Module size: 15.8 × 20.3 mm
• FCC ID: 2ANDL-WL2H-U
• Vendor: Tuya

Pinout

Physical pinout verified against the official Tuya WL2H-U datasheet.

The module exposes 19 GPIOs (PA0–PA7, PA9–PA12, PB3–PB9). PA8 is not physically exposed.

Variant files were hand-generated from generic-ln882hki with PA8 removed — please regenerate with boardgen if needed.

Notes

• Calibration of internal ADC temperature sensor: 25 + ((raw & 0xFFF) - 770) / 2.54 (empirically derived, community validation welcome)

[kuba2k2]

This doesn't look right.

Please verify your PRs before posting 🙂

[Bl00d-B0b]

While testing this module, I found that the device actually uses an LN-CB3S V1.0 — a custom board in the same form factor as the Tuya CB3S (16×24mm, 22 pads), carrying a WL2H-U-2 chip (LN882H). It is not the standard Tuya WL2H-U module (15.8×20.3mm, 21 pads).

The LN-CB3S has a different pad assignment from WL2H-U — critically, VCC is at pad 8 and GND at pad 9, matching the CB3S layout exactly (unlike WL2H-U which has GND at pad 13 / VCC at pad 14). This was verified from a community schematic (elektroda.com topic4162022).

Hardware confirmed on the physical device (DS-101JL / BSEED WiFi Touch Light Switch 2 Gang):

• Pad 1 / RST — not connected on this device
• Pad 12 / A9 (GPIOA9) — pull to GND to enter flash/download mode ✓
• Pad 15 / RXD1 (GPIOA3/U0RXD) and pad 16 / TXD1 (GPIOA2/U0TXD) — UART0 RX/TX ✓

Pin assignments in use:

Pin	Function	Direction	Inverted
PA0	Backlight LED (red)	Output	yes
PA2	Indicator LED 2 (blue)	Output	yes
PA4	Indicator LED 1 (blue)	Output	yes
PA6	Relay 1	Output	no
PA10	Status LED (blue)	Output	yes
PA11	Button 1	Input PULLUP	yes
PB5	Relay 2	Output	no
PB6	Button 2	Input PULLUP	yes

I also have a DS-101JL 3-gang variant (BSEED WiFi Touch Light Switch 3 Gang) which uses the same LN-CB3S V1.0 module, but with a WL2H-U-3 chip. I will update this comment with the additional GPIO assignments once I finish reverse engineering it.

This suggests it needs its own board definition with a CB3S-compatible PCB template. A few questions:

1. Should this be a separate board entry (e.g. ln-cb3s) alongside wl2h-u in this PR, or a follow-up PR?
2. What naming convention would you prefer — ln-cb3s, ln-cb3s-v1, or something else?
3. Should the PCB template simply reuse pcb/cb3s.json with different IC pin mappings, or define a new pcb/ln-cb3s.json?

[kuba2k2]

1. The wl2h-u board can stay in the same PR, but it must be fixed to reflect the correct form factor, as per the Tuya documentation.
2. In this case the WL2H-U-2 marking doesn't really mean anything. It's probably either a misprint, or some other internal identification that clearly doesn't define the form factor of this board. The chip inside is LN882H, not "WL2H-U". Thus, the board should be named ln-cb3s-v1.0, which matches for example the already-existing t102-v1.1.
3. Each board (boards/*.json) has its own "base" PCB definition (boards/_base/pcb/*.json), since each board has a different pinout. This alone pretty much requires a new pcb/ln-cb3s-v1.0.json file.