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4 layers97.6 × 96 mmCentipede-32e, the printed circuit board in 3D

A Radio Shack / Tandy Color Computer ("Coco") wildcard peripheral cartridge, with an RP2350 processor and 46 usable GPIO lines, covering most of the Coco's expansion port bus.

Size
97.6 × 96 mm
Copper layers
4
Thickness
1.6 mm
Parts
135
Nets
97
Pads
471
Tracks, vias
1,295, 155
Pours
128
Routed
Yes
KiCad
KiCad 9.0 (file 20241229)
Created
16 Mar 2026
Updated
6 Sep 2026

Overview

Centipede-32e is an open-source printed circuit board by strickyak, from the strickyak/copico-centipede repository on GitHub, published under the MIT licence. It is a 4-layer board of 97.6 × 96 mm with 135 parts on 97 nets, routed with 1,295 tracks and 155 vias.

It is built around the 74HC14, HC-1.0-3PWT and K2-1808SN-A4SW-01, with the RCLAMP0521P.TCT-MS among its other parts. Its parts include 30 capacitors, 13 resistors, 8 diodes, 5 ICs and 5 connectors. It belongs with the radio and wireless boards of this library.

Main components

4

README

centipede-32e/README.md

Centipede 32d

TO DO -- document better.

This is pretty much a RP2350B microcontroller with direct connections to the Radio Shack Color Computer's 40-pin expansion bus.

The RP2350B may be powered either by the USB-C or by the Coco. The USB-C takes precedence by going through only one diode to VBUS, whereas the Coco's +5V input goes through two diodes.

Jumper J6 must be configured in one of two ways:

  • Preferred: Connect pins 2 and 3, and connect pins 4 and 5. This runs both E and Q through the schmidt trigger inverter to clean them. They arrive negated at GPIO 21 and 22.

  • Original: Connect pins 1 and 2, and pins 5 and 6. This runs E and Q direct to GPIO 21 and 22, not negated. This has problems with bouncy detection.

Maybe a BUG? VBUS powers the 74HC14.

Bug: CTS

On a coco3, we must obey CTS, not just the address range $C000-$DFFF.

Temporarily I'm bodging it from J5 to J4, CTS (negative logic) to GPIO18.

Clock Speed

My current PIO-less firmware works with the semi-fast poke ($FFD7) but not with the fast poke ($FFD9). That's with disk11.asm for Disk Basic Cart ROM, and a floppy at $FF40/$FF4[89AB].

Testing on a 16K Coco2 (named "2C") and a Coco3 with a 6309 and 512K RAM (named "3B").

Parts

135
QtyValueFootprintReferences
60Castellated PadMy Stuff:Castellated Pad3V3_EN1, 3V31, ADC_VREF1, GND1, GND2, GND3, GND4, GND4, GND6, GPI10, GPIO0, GPIO1, GPIO1, GPIO1, GPIO1, GPIO1 +44
12100nFPCM_JLCPCB:C_0402C1, C2, C3, C4, C5, C6, C7, C8, C13, C14, C16, C36
5~RP2350 Dev Board:POWERDI-123_L2.8-W1.8-LS3.7-RDD1, D4, D5, D6, D7
4100nFPCM_JLCPCB:C_0603C9, C15, C38, C39
3100nFCapacitor_SMD:C_0603_1608MetricC21, C23, C25
310uFCapacitor_SMD:C_0603_1608MetricC20, C22, C24
32kΩResistor_SMD:R_0402_1005MetricR9, R10, R12
333ΩResistor_SMD:R_0402_1005MetricR2, R3, R6
210uFPCM_JLCPCB:C_0603C37, C40
215pFPCM_JLCPCB:C_0402C17, C18
24.7uFPCM_JLCPCB:C_0603C10, C12
24.7uFPCM_JLCPCB:C_0402C11, C19
25.1kΩResistor_SMD:R_0402_1005MetricR1, R4
2Conn_02x03_Odd_EvenConnector_PinHeader_2.54mm:PinHeader_2x03_P2.54mm_Vertical_SMDJ5, J6
2K2-1808SN-A4SW-01RP2350 Dev Board:KEY-SMD_4P-L4.2-W3.2-P2.20-LS5.1-TLBoot1, Reset1
2RCLAMP0521P.TCT-MSEasyEDA:D0402-BID2, D3
2SolderJumper_2_BridgedJumper:SolderJumper-2_P1.3mm_Bridged_Pad1.0x1.5mmJP1, JP2
1100kΩResistor_SMD:R_0402_1005MetricR11
11kΩPCM_JLCPCB:R_0603R28
11kΩResistor_SMD:R_0402_1005MetricR5
11ΩPCM_JLCPCB:R_0603R7
1200ΩPCM_JLCPCB:R_0603R8
174HC14Package_SO:SOIC-14_3.9x8.7mm_P1.27mmU5
1CocoEdgeConnector0Titanium:CocoCardEdgeCocoMIDIP1
1Conn_02x10_Odd_EvenConnector_PinHeader_2.54mm:PinHeader_2x10_P2.54mm_VerticalJ4
1Conn_02x10_Odd_EvenConnector_PinSocket_2.54mm:PinSocket_2x10_P2.54mm_Vertical_SMDJ3
1HC-1.0-3PWTEasyEDA:CONN-SMD_SM03B-SRSS-TB-LF-SN-PU2
1RedLED_SMD:LED_0603_1608MetricLED25
1RedPCM_JLCPCB:D_0603PWR_LED1
1W25Q128PCM_JLCPCB:SOIC-8_L5.3-W5.3-P1.27-LS8.0-BLU4
1~PCM_JLCPCB:SOT-23-5_L3.0-W1.7-P0.95-LS2.8-BRU3
1~RP2350 Dev Board:IND-SMD_L2.0-W1.6_AOTA-B201610S3R3-101-TL1
1~RP2350 Dev Board:QFN-80_L10.0-W10.0-P0.40-TL-EP3.4U1
1~RP2350 Dev Board:USB-C-SMD_TYPE-C-6PIN-2MD-073USB1
1~RP2350 Dev Board:CRYSTAL-SMD_4P-L3.2-W2.5-BLX1

The 129 most common of 135 parts.

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Questions

How big is the Centipede-32e PCB?

It measures 97.6 × 96 mm and has 4 copper layers, 1.6 mm thick.

What parts does the Centipede-32e use?

135 parts, built around the 74HC14, HC-1.0-3PWT, K2-1808SN-A4SW-01 and RCLAMP0521P.TCT-MS. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.

Where can I download the Centipede-32e KiCad files?

From the strickyak/copico-centipede repository on GitHub, at the commit this page was made from: the board is centipede-32e/centipede-32e.kicad_pcb and its schematic centipede-32d/centipede-32d.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the Centipede-32e design in my own project?

Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).