got flexpcb and pinout spec'd, fpc draft

pinout.txt

@@ -0,0 +1,71 @@
+Baby Walker Ball Toy:
+
+Left side
+1 - K1 (button)   - FPC1
+2 - K2            - FPC2
+3 - NC
+4 - GND           - FPC3
+5 - VCC 4.5V      - FPC4
+6 - GND isolated
+7 - K3            - FPC5
+8 - LED1          - FPC6
+
+Right side (starting with top, opposite L1; not counter-clockwise)
+9 - NC
+10 - GND
+11 - SPK1         - FPC10
+12 - SPK2         - FPC9
+13 - VCC 4.5V
+14 - NC
+15 - LED3         - FPC8
+16 - LED2         - FPC7
+
+
+
+
+# Flex Adapter Design Notes
+
+## Purpose
+Create a small flex-style PCB connector adapter with:
+- One end solderable directly onto a TSSOP-16 footprint using castellated edge contacts.
+- One end shaped as an 8-contact FPC/FFC finger tail.
+
+## Selected FPC Connector Target
+- Target connector: JUSHUO AFC01-S08FCA-00
+- LCSC/JLCPCB part: C262657
+- Positions: 8
+- Pitch: 0.5 mm
+- Contact style: bottom contact, right-angle FPC/FFC connector
+- Mating tail thickness: 0.3 mm
+
+## Physical Geometry Implemented
+- Board: 22 mm x 5 mm, 2-layer stackup.
+- TSSOP/castellated end:
+  - 8 contacts per side, 16 castellation pads total.
+  - 1.125 mm pitch along the long axis.
+  - 9.0 mm nominal contact-field length.
+  - 4.4 mm spacing between opposing castellation rows.
+- FPC end:
+  - 8 exposed copper fingers.
+  - 0.5 mm pitch.
+  - 0.30 mm finger width.
+  - 4.5 mm exposed finger length.
+
+## Pin Mapping Assumption
+Because the user requested an 8-pin FPC end but a TSSOP-16 solder footprint end, this design treats each opposing pair of TSSOP castellations as one duplicated signal:
+- TSSOP L1/R1 -> FPC 1
+- TSSOP L2/R2 -> FPC 2
+- TSSOP L3/R3 -> FPC 3
+- TSSOP L4/R4 -> FPC 4
+- TSSOP L5/R5 -> FPC 5
+- TSSOP L6/R6 -> FPC 6
+- TSSOP L7/R7 -> FPC 7
+- TSSOP L8/R8 -> FPC 8
+
+If all 16 TSSOP pads must be independent, the FPC end must be changed to 16 positions or the design must define which TSSOP pads are intentionally shorted.
+
+## Manufacturing Notes
+- The custom edge pads are PCB features, not assembled parts.
+- For a true flexible PCB tail, order as flex PCB with stiffener/contact finish requirements appropriate for the selected FPC connector.
+- ENIG is recommended for exposed FPC fingers.
+- Confirm minimum edge-castellation capability with the fabricator before production.