4 layers36 × 50.2 mm
Racer
StuckAtPrototype/Racer
These are structured into their own files. I could have used submodules, but decided against it.
83 parts3.8kApache-2.0
2 layers50 × 40 mm
C64-cellular
QuickSpot/walter-example-projects5This repository contains example projects that can be made with the Walter module
- Size
- 50 × 40 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 12
- Nets
- 49
- Pads
- 74
- Tracks, vias
- 51, 149
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 20 Jan 2026
- Updated
- 21 May 2026
Overview
C64-cellular is an open-source printed circuit board by QuickSpot, from the QuickSpot/walter-example-projects repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 50 × 40 mm with 12 parts on 49 nets, routed with 51 tracks and 149 vias.
It is built around the BSS138. Its parts include 6 resistors, 2 diodes, 2 transistors and 1 connector. It belongs with the radio and wireless boards of this library.
Main components
1README
walter-c64-cellular/README.mdWalter based Comodore 64 multi-radio modem
Introduction
This repository contains the hardware design files of a Walter based expansion card for the Commodore 64 user port. Walter connects to the user port via UART which allows the C64 to make use of the connectivity and compute power of the QuickSpot Walter module.
The hardware
The hardware is based on the QuickSpot Walter module which combines multiple radio technologies in a single module. This gives the C64 multiradio modem access to Wi-Fi, BLE, LTE Cat-M1, LTE Cat-NB1/2 and GNSS. The module is powered through it's USB-C connector which is also used to program it. The connection to the C64 is made through the UART which is available on the user port.
As the user port's UART is at 5V TTL level and the Walter module's IO ports work at 3.3V a level shifter is required. Two bi-directional MOSFET based level shifters are implemented on the board. The high side is fed with the 5V coming from the C64 user port, the low side is fed with the 3.3V coming from the Walter module.
The software
The basic software is the Walter modem passthrough example which exposes the AT command interface from the Sequans GM02SP directly to the C64.
Parts
12| Qty | Value | Footprint | References |
|---|---|---|---|
| 4 | 10kΩ | Resistor_SMD:R_0603_1608Metric | R1, R2, R3, R4 |
| 2 | 1.2kΩ | Resistor_SMD:R_0603_1608Metric | R5, R6 |
| 2 | BSS138 | footprints:BSS138 | Q1, Q2 |
| 2 | LED | LED_SMD:LED_0603_1608Metric | D1, D2 |
| 1 | 805-24P | footprints:805-24P | J1 |
| 1 | Walter | footprints:walter-socket | MOD1 |
Questions
How big is the C64-cellular PCB?
It measures 50 × 40 mm and has 2 copper layers, 1.6 mm thick.
What parts does the C64-cellular use?
12 parts, built around the BSS138. 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 C64-cellular KiCad files?
From the QuickSpot/walter-example-projects repository on GitHub, at the commit this page was made from: the board is walter-c64-cellular/c64-cellular.kicad_pcb and its schematic walter-c64-cellular/c64-cellular.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the C64-cellular design in my own project?
Its repository publishes it under the GPL-3.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
Similar boards
- 4 layers95 × 95 mm
Cube motherboard
willem-pennings/balancing-cube
A cube that balances itself in a corner or edge using reaction wheels
52 parts1.1kGPL-3.0 - 2 layers54.6 × 70.9 mm
BeagleLogic Cape
abhishek-kakkar/BeagleLogic
A Software Suite that implements a logic analyzer with the PRU on the BeagleBone / BeagleBone Black.
22 parts479GPL-3.0 - 2 layers44.2 × 29.3 mm
- 4 layers142.2 × 82.6 mm
A10-A20-OLINUXINO MICRO-4GB Rev D
lachlanA/eagle-to-kicad
Eagle SCH/LIB to KiCad SCH/LIB ULP conversion script
558 parts429GPL-2.0 - 2 layers21.6 × 52.3 mm
Ps2 pico hat
No0ne/ps2x2pico
USB keyboard/mouse to PS/2 interface converter using a Raspberry Pi Pico
17 parts399MIT - 2 layers45 × 45 mm
AirCube
StuckAtPrototype/AirCube
Works standalone out of the box. Pairs with Home Assistant in minutes. Other platforms are supported through community-contributed extensions.
61 parts379Apache-2.0 - 4 layers74 × 104 mm
