🇩🇪 Deutsche Anleitung: README.de.md
A tiny adapter that turns a Raspberry Pi Pico 2 W into a wireless keyboard and joystick interface for the Commodore 64 – use your phone with the Blue-64 Keyboard app (iPhone and Android), a Bluetooth keyboard or a Bluetooth gamepad (e.g. 8BitDo).
Get the app: iPhone – TestFlight beta · Android – APK in the latest release
The Pico plugs in between the C64 mainboard and the keyboard cable and emulates the keyboard matrix in software. Apart from the Pico you only need 17 resistors and one diode – no level shifters and no crosspoint switch, because GPIO 0–25 of the RP2350 are 5 V tolerant. The original keyboard and both joysticks keep working.
- Emulates the complete 8×8 keyboard matrix plus RESTORE – any number of keys at the same time
- Reacts within about 70 ns to every column the C64 selects (core 1 runs a lookup table from RAM), so programs that scan several columns at once work too
- Same Bluetooth LE service as the BT-64 / Blue-64 firmware with the BLE keyboard service – the Blue-64 Keyboard app works unchanged (the Pico shows up as Pico64)
- Type text and short BASIC listings from the app (snippets)
- Bluetooth keyboards (Classic and BLE) – German QWERTZ layout typed as printed, or positional mapping for games (F10 switches)
- Bluetooth gamepads (8BitDo, Xbox, PlayStation, Switch and many more, via Bluepad32) as joystick in port 1 or 2
- App, keyboard and gamepads can be used at the same time; two app devices (e.g. iPhone and iPad) at once
- USB console: every line you type in a terminal is typed on the C64, plus a key log for debugging
- Powered by the C64, no extra power supply
v0.12.0 – working. Tested on a breadbin C64 with an iPhone and an Android phone, first on perfboard, now on its own PCB (Gerber files, parts list and photos in hardware/). Bluetooth keyboard and gamepad support still needs testing with more devices.
Hardware change in v0.10: all 17 resistors are now 100 Ω (PA0–PA7 were 1 kΩ). Joystick port 2 needs this – everything else also works with the old values. See docs/HARDWARE.md.
- Build the adapter – PCB (Gerber files, parts list): hardware/; wiring and safety notes, also for perfboard: docs/HARDWARE.md. Check the CN1 pinout of your C64 with a multimeter before soldering.
- Flash the firmware – hold BOOTSEL, plug the Pico into your computer, drag
pico64-keyboard-vX.Y.Z.uf2from the latest release onto theRP2350drive. Do this with the Pico out of the C64 or with the C64 switched off. - Plug it in between CN1 and the keyboard cable, switch the C64 on – the Pico LED blinks (nothing connected yet).
- Connect with the app – Blue-64 Keyboard finds the Pico by itself, the LED stays on while connected.
- Or pair a Bluetooth keyboard / gamepad – see below.
Building the firmware yourself: docs/BUILDING.md. Bluetooth protocol: docs/PROTOCOL.md.
The Pico looks for keyboards and gamepads all the time. To pair a new one, put it into pairing mode – it connects by itself within a few seconds (no PIN, no app needed). Paired devices reconnect automatically when switched on. Up to 4 Bluetooth connections at the same time (apps, keyboards and gamepads together).
- Keyboard: usually hold the Bluetooth / pairing key (or Fn + a channel key) for 3 s, see
the keyboard's manual. If the keyboard asks for a code, type
0000and Enter. - 8BitDo gamepads: switch on in Android / D-input mode (many models: hold B + Start) or Switch mode (Y + Start), then hold the pair button for 3 s. Modes differ per model – see the 8BitDo manual and the Bluepad32 list of supported controllers.
- Other gamepads (Xbox, PlayStation, Switch Pro …): normal pairing mode.
Two modes, F10 switches (the USB console shows the current mode):
| Mode | What it does |
|---|---|
| Symbolic (default) | Types what is printed on a German keyboard: Shift+0 gives =, Shift+2 ", AltGr+Q @, Z and Y in the right place. Characters the C64 doesn't have (ä ö ü ß € …) are ignored. |
| Positional | Every key acts like the C64 key at the same place, SHIFT stays SHIFT – best for games and for the graphic characters. |
| PC key | C64 key |
|---|---|
| Esc | RUN/STOP |
| Tab | CTRL |
| Ctrl | CTRL |
| Alt, Windows/Cmd | C= |
| Backspace, Del | INST/DEL |
| Home | CLR/HOME |
| Insert | £ |
| F1 – F8 | F1 – F8 |
| F9, Page Up, Pause | RESTORE |
| Cursor keys | CRSR (up/left with SHIFT automatically) |
| F10 | switch mapping |
| Gamepad | C64 |
|---|---|
| D-pad or left stick | joystick directions |
| A, B | fire |
| X | SPACE |
| Y | RETURN |
| Select / − | RUN/STOP |
| Start / + | F1 |
| L1 + R1 together | swap joystick port (1 ↔ 2) |
The first gamepad plays on port 2 (most games), a second one on port 1.
Take the board out of the C64, plug the C64 keyboard cable into it and connect the Pico via USB to a Mac, PC, Raspberry Pi or MiSTer: the real C64 keyboard becomes a USB keyboard. The app and Bluetooth keyboards work at the same time and are sent via USB too.
The Pico decides when it starts: without USB power it can only be powered by the C64 → C64 mode. With USB power it listens for 0.6 s whether a C64 scans the keyboard → C64 mode, otherwise USB keyboard. If a C64 starts scanning later, the Pico restarts in C64 mode by itself. A C64 that is switched off but still connected pulls the lines low – the Pico then stays in C64 mode (the USB keyboard only works with the board outside the C64).
Choose the output with RESTORE + F key (stored):
| Keys | Output |
|---|---|
| RESTORE + F1 | MiSTer, C64 core (keys as the core expects them; RESTORE alone = F11) |
| RESTORE + F3 | PC, German layout |
| RESTORE + F5 | PC, US layout |
| RESTORE + F7 | Mac, German layout |
| RESTORE + F8 (SHIFT + F7) | Mac, US layout |
PC / Mac: types what is printed on the key (SHIFT + 2 = ", SHIFT + : = [). DEL = Backspace,
INST = Insert, CRSR = cursor keys, F1–F8, HOME / CLR = Home / End, RUN/STOP = Esc, ← = Tab,
CTRL = Ctrl, C= = Win / Cmd, £ = \. Like the original, the keyboard has no diodes, so some
three-key combinations show a phantom key.
In the USB console !u shows the mode, !u0 … !u4 choose the output.
Connect the Pico via USB while it sits in the C64 (the diode protects both sides) and open a
terminal with 115200 baud, e.g. screen /dev/tty.usbmodem* 115200 on a Mac.
- Every line you type is typed on the C64, followed by RETURN (letters unshifted, tokens like
~clr~,~home~,~f1~work). - A line with just
dswitches the key log on or off: every key state received via Bluetooth and every state applied to the matrix, with timestamps, plus the connection interval. !sstatus (app, keyboards, gamepads, joystick ports),!pswitch keyboard mapping,!bsearch for new Bluetooth devices on/off,!xforget all paired keyboards / gamepads,!uUSB keyboard mode (see above).
- The Pico never drives a C64 line high – PB0–PB7, RESTORE and (for joystick 2) PA0–PA4 are only pulled to GND or released (open drain), like a key switch or a joystick does.
- Use GP0–GP22 only. GP26–GP28 are not 5 V tolerant, GP23–25 and GP29 belong to the radio.
- 5 V tolerance only applies while the Pico is powered – which it always is, because it is powered by the C64.
- Use at your own risk. Check your wiring twice.
- Blue-64 Keyboard – the app (iPhone and Android)
- Pico USB Keyboard – the same app as a USB keyboard: a plain Pico 2 W without wiring, for the MiSTer C64 core, PC, Mac or Raspberry Pi
- BT-64 with BLE keyboard service – the firmware extension for the BT-64 / Blue-64 adapter
Questions, photos, experiences: the thread in the (German) retro forum 1mhz.de – Pico64-Keyboard, SPL BT-64 oder Blue-64 Tastaturadapter. Bug reports and feature requests are also welcome as a GitHub issue.
- Firmware © 2026 Martin Oswald (do2mad) – 1mhz.de, MIT License
- Hardware (schematic, PCB) © 2026 Martin Oswald, CC BY-NC-SA 4.0 – non-commercial use
- Uses the Raspberry Pi Pico SDK, BTstack, the CYW43 driver and Bluepad32 by Ricardo Quesada – see NOTICE
- The Bluetooth service follows the protocol of the BLE keyboard extension for BT-64 / Blue-64 by SideProjectsLab
- C64 keyboard connector pinout after Ruud Baltissen
Changes: CHANGELOG.md
Commodore and Commodore 64 are trademarks of their respective owners. This project is not affiliated with or endorsed by them, by Raspberry Pi Ltd. or by SideProjectsLab.