[thePunderWoman]

Replaces the BT840XE on the V2 board with an ESP32-S3-MINI-1U-N8, and moves the XBee to an optional daughter board. Builders who only want Bluetooth and ESP-NOW can leave the XBee off. The daughter board itself is a follow-up.

What changed

• Module: ESP32-S3-MINI-1U-N8 on the top, between the macro row and USB. There is 17.5 mm there, so the 19.2 mm WROOM-1U does not fit. Its antenna connector is W.FL/MHF III, not standard U.FL.
• XBee: a row of 12 hand-solder pads on the bottom for a 22 x 17 mm castellated carrier, which holds the XBee and its support parts. The link is UART with flow control, not SPI. RTS and DTR also allow serial firmware recovery through the ESP32.
• Pin map: the module is turned 270 degrees and pins are assigned by position, so the signal pins face what they connect to. See PCB/v2.x/GPIO_table.md.
• Power: the buck and charger are back on the bottom. BUCK_FB routes around the inductor and C_BUCK_IN1 sits next to VIN.
• Hall sensor: moved to (6.5, 4.75) mm, rotated 180 degrees, 7.8 mm from the stick's nearest pot pin. It is placed for a 2 x 2 mm N52 magnet swinging up under the package.
• Removed: SW_RST1, the Tag-Connect SWD footprint, and the BT840XE parts and library files.
• Production: regenerated in PCB/v2.x/production/. U_XBEE1 and J_STICK1 are excluded from the assembly files.

Pin decisions to keep

• PWR_HOLD stays on RXD0. Its pull-up stays on through reset, so a reset reboots the board and does not cut power.
• Power button sense stays on an RTC-domain pin (IO21), because the node is lifted with the board off, as it was on V1's IO2.
• IO26 stays unconnected. Arduino's PSRAM probe drives it at every boot, so the bumper is on IO47.
• Keep IO3, IO45 and IO46 unconnected. They are strap pins.

Checks

• DRC at full severity: 0 violations, 0 unconnected
• stackup check: 0 errors, 0 warnings
• PCB sync check clean, and all 277 pin connections match the Stackup netlist
• Latch simulation: 9 of 9 pass, latch parts identical to V1
• Module pin numbers checked against Espressif's Table 3-1
• Production files: hole counts match the board, all assembled parts have LCSC numbers, no BT840XE references

Not verified yet

• No hardware exists. Nothing here has been built or powered.
• Stick and trigger magnet interaction is calculated, not measured: about 0.35-0.48 mT of stray swing, against a rough 0.6-1.2 mT deadzone estimate. Bench-test it with a real magnet and stick.
• OLED cable: the connector moved 2 mm toward USB. Try a real Qwiic cable before designing the shell.
• The carrier board is not designed yet. If its pads change, the production files need regenerating.
• Check rotations in the assembler's preview, especially U_MCU1 and U_HALL1.

Follow-up work

• Design the XBee daughter board.
• Firmware needs a V2 pin map and a UART transport. Do not flash V1 firmware on V2: it would hold the XBee in reset, because IO42 is XBee RESET here.
• Firmware also needs a watchdog, since there is no reset button, and must not start UART0, which would take over the PWR_HOLD pin.

🤖 Generated with Claude Code