LiPo Battery Availability Inquiry

Design a carrier/breakout PCB for the "We Wide Web" project — a battery-powered ESP32 personal web server with NFC and a round touchscreen display.

Parts

Seeed Studio XIAO ESP32-S3 Plus — main MCU, plugs into this carrier board via 2x7 female pin headers (2.54mm pitch). The XIAO has battery pads (BAT+ and BAT-) on the bottom of the board — BAT- is the pad closest to the USB-C port, BAT+ is the pad farthest from USB-C. These pads need to be contacted by spring-loaded pogo pins (P75-B1, 1.02mm barrel) mounted on the carrier PCB, pressing upward when the XIAO is seated.
Seeed Studio Round Display for XIAO (1.28" GC9A01 240x240) — plugs on top of the XIAO via the same 2x7 headers. It uses the following XIAO pins: D0 (battery voltage), D1 (LCD CS), D2 (SD CS), D3 (LCD DC), D4/SDA (touch + RTC I2C), D5/SCL (touch + RTC I2C), D6 (backlight), D7 (touch interrupt), D8 (SPI SCK), D9 (SPI MISO), D10 (SPI MOSI). The carrier board must not conflict with any of these pins.
Adafruit ST25DV16K I2C RFID EEPROM Breakout (product 4701) — NFC/RFID tag with I2C interface. Has a 1x6 header (2.54mm pitch) with pins in order: VIN, GND, SCL, SDA, GPO, VEH. I2C addresses: 0x53 (user memory), 0x57 (system memory), 0x2D (mailbox). The breakout has 10K pullups on SDA and SCL already. It mounts on the carrier board facing downward so the NFC antenna faces out through the bottom of the enclosure.
3.7V LiPo battery (600mAh) — connects via a JST-PH 2.0mm 2-pin through-hole connector on the carrier board. Battery power routes through the pogo pins to the XIAO's battery pads for charging and power management via the XIAO's built-in charge circuit.

Connections

The ST25DV16K shares the I2C bus with the Round Display's touch controller (0x15) and RTC (0x51) — no address conflicts.

┌────────────┬─────────────────────┬────────────────────────────┬────────────────────────────────────────────────┐ │ Signal │ From │ To │ Notes │ ├────────────┼─────────────────────┼────────────────────────────┼────────────────────────────────────────────────┤ │ I2C SDA │ XIAO D4/SDA (passed │ ST25DV16K SDA (header pin │ Shared I2C bus, pullups on ST25DV breakout │ │ │ through header) │ 4) │ │ ├────────────┼─────────────────────┼────────────────────────────┼────────────────────────────────────────────────┤ │ I2C SCL │ XIAO D5/SCL (passed │ ST25DV16K SCL (header pin │ Shared I2C bus, pullups on ST25DV breakout │ │ │ through header) │ 3) │ │ ├────────────┼─────────────────────┼────────────────────────────┼────────────────────────────────────────────────┤ │ Power 3.3V │ XIAO 3V3 (passed │ ST25DV16K VIN (header pin │ 3.3V logic level │ │ │ through header) │ 1) │ │ ├────────────┼─────────────────────┼────────────────────────────┼────────────────────────────────────────────────┤ │ Ground │ XIAO GND (passed │ ST25DV16K GND (header pin │ Common ground │ │ │ through header) │ 2) │ │ ├────────────┼─────────────────────┼────────────────────────────┼────────────────────────────────────────────────┤ │ NFC │ ST25DV16K GPO │ XIAO Plus extended pad D11 │ Directly connected to GPO with 4.7K pullup │ │ interrupt │ (header pin 5) │ or any free Plus-only │ resistor to 3.3V. Used as deep sleep wakeup │ │ │ │ GPIO │ trigger on NFC tap │ ├────────────┼─────────────────────┼────────────────────────────┼────────────────────────────────────────────────┤ │ Battery + │ JST-PH pin 1 │ Pogo pin aligned to XIAO │ Battery power │ │ │ (positive) │ BAT+ pad │ │ ├────────────┼─────────────────────┼────────────────────────────┼────────────────────────────────────────────────┤ │ Battery - │ JST-PH pin 2 │ Pogo pin aligned to XIAO │ Battery ground │ │ │ (negative) │ BAT- pad │ │ ├────────────┼─────────────────────┼────────────────────────────┼────────────────────────────────────────────────┤ │ VEH │ ST25DV16K VEH │ Leave unconnected │ Energy harvesting output, not used │ │ │ (header pin 6) │ │ │ └────────────┴─────────────────────┴────────────────────────────┴────────────────────────────────────────────────┘

Board Requirements

Single-layer PCB (single-sided copper, top side only)
Board shape: rectangular, sized to fit under the XIAO + Round Display stack. The Round Display is 39mm diameter circular — the carrier can be rectangular or circular to match
Mounting: the XIAO plugs into 2x7 female headers on the carrier. The Round Display plugs onto the XIAO from above. The ST25DV16K breakout plugs into a 1x6 female header on the carrier, positioned to the side of or below the XIAO footprint
Pogo pins: two through-hole pads for P75-B1 pogo pins, precisely aligned to the XIAO's bottom battery pads. These must be measured from the XIAO's mechanical drawing — approximate center-to-center spacing TBD (measure from actual board)
Keep it simple: 7 traces, no vias, single layer, designed for CNC milling on a Bantam Tools desktop PCB mill
Include ground pour if it fits without complicating the single-layer routing
Gerber export for Bantam Tools milling

flux

1:32

Thought for 8 sec

Analyzing in depth.

Thought for a moment

Analyzing in depth.

Thought for a moment

You want a new carrier/breakout PCB for your We Wide Web device, and I’ve prepared the plan.

It covers stacking, shared I2C, battery pogo-pin routing, and a single-layer CNC-friendly layout.
Important checkpoint: verify pogo-pin alignment to the XIAO battery pads before finalizing.

Start it here: Create project with this plan

Plan

#Goal

Design a carrier/breakout board that integrates the Seeed Studio XIAO ESP32-S3 Plus with a Seeed Studio Round Display for XIAO, an Adafruit ST25DV16K I2C RFID EEPROM breakout, and a battery power input via a JST-PH connector. The design must ensure no pin conflicts with the round display (using specific pins), share the I2C bus between the display and the ST25DV16K, and route the battery connection through pogo pins to the XIAO BAT+ and BAT- pads. The PCB shall be single-layer top-copper only, with simple traces, no vias, suitable for Bantam Tools CNC milling, and sized to fit beneath a 39 mm round display.

#Implementation plan

Define Mechanical and Stacking Layout
1. Establish board size and shape to fit under a 39 mm round display.
2. Verify alignment for the pogo-pin battery contacts and measure XIAO BAT pad spacing.
Integrate the XIAO ESP32-S3 Plus
1. Add the XIAO on a 2x7 female header interface ensuring alignment with the round display headers.
2. Confirm that the XIAO’s critical pins (D0-D10, especially SDA and SCL on D4/D5) are not conflicted by the display.
Add and Route the Seeed Studio Round Display
1. Stack the display on the same 2x7 header used by the XIAO, ensuring pin availability for the display.
Incorporate the Adafruit ST25DV16K I2C RFID EEPROM Breakout
1. Mount the breakout board using a 1x6 header facing downward.
2. Share the I2C lines (SDA and SCL) with the display.
3. Connect the GPO pin from the breakout to a free Plus-only GPIO (e.g., D11), with a 4.7 kΩ pull-up resistor to 3.3 V.
Implement Battery Connectivity
1. Add a JST-PH 2-pin battery connector for the LiPo battery.
2. Route battery connections through two P75-B1 pogo pins to the XIAO’s battery pads (BAT+ and BAT-), ensuring correct orientation (BAT- closest to USB-C).
Finalize PCB Layout
1. Use a single-layer top-copper design with approximately 7 simple traces and an optional ground pour.
2. Avoid use of vias and keep layout CNC milling friendly.
Prepare for Gerber Export
1. Verify all component placements, trace routings, and clearances.
2. Finalize mechanical and electrical reviews to ensure design feasibility.

#Success criteria

The PCB design meets the dimensional constraints for fitting under a 39 mm round display.
All components are properly interfaced (XIAO, round display, ST25DV16K, and battery through pogo pins) without electrical conflicts.
The design adheres to the single-layer, top-copper-only, no via guideline and is compatible with Bantam Tools CNC milling.
Electrical and mechanical connections including I2C bus sharing and battery routing are properly implemented and verified before Gerber export.

Place the headers

Set board outline

Add pogo pin holes

BAT-

G_PAD

BAT+

MTCK

D+

D-

MTMS

Reviews

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