SidecarTridge Croissant Keyboard Emulator for Atari ST/STE

Internal IKBD keyboard emulator for Atari ST and STE

The SidecarTridge Croissant is an internal keyboard emulator that brings modern Bluetooth input to the Atari ST and STE without turning the machine into an external-box project. It plugs inline on the 7-pin internal keyboard header and behaves like the IKBD the operating system expects. The original keyboard path stays available as a pass-through whenever you want stock behaviour.

Key features

What you get

Installation overview

1. Open the Atari and remove the internal metal shield. It stays out for good; the shield blocks the 2.4 GHz radio signals Croissant needs.
2. Locate the 7-pin internal keyboard connector on the motherboard and disconnect the original keyboard ribbon cable.
3. Fit the Croissant board on the motherboard header, making sure the connector orientation is correct.
4. Reconnect the keyboard ribbon cable to the Croissant board so the pass-through path is wired up.
5. Power on the Atari and follow the Wi-Fi setup flow from any modern browser to pick the default startup mode.

Full step-by-step in the Croissant quickstart and the hardware installation guide.

Compatibility

Compatibility ultimately depends on the connector on your motherboard, not the model badge. Open the case before you order if you are not sure which connector your machine uses.

Specs

• Connector to Atari: internal 7-pin keyboard header, IKBD-compatible signalling
• Wireless: Bluetooth and Wi-Fi (2.4 GHz)
• Input support: Bluetooth keyboards plus supported mice and gamepads
• Original input path: pass-through for the stock Atari keyboard and joystick wiring
• Configuration: browser-based, served over Wi-Fi (access point and station modes)
• Firmware update: on-board micro-USB
• Board revision: CROISSANT-IKBD REV1.1.0

Frequently asked questions

What Atari models are supported?

Croissant is designed for Atari ST and STE machines that use the 7-pin internal keyboard connector and an internal power supply. Both 520 STF/STFM and 1040 STF/STFM/STE families are in scope as long as the motherboard exposes that connector.

Why are the “short ST” motherboards not supported?

The well-known short ST motherboards C070115 and C070243 use an 18-pin keyboard connector and an external power supply. The connector is mechanically and electrically different, and Croissant cannot mate with it.

What about Mega ST or Mega STE?

Those use a different internal layout. The right product for them is the external Soufflè dongle, documented in the keyboard emulator introduction.

Does the metal shield really have to come out?

Yes. The internal shield is a Faraday cage by design and blocks the 2.4 GHz Bluetooth and Wi-Fi signals Croissant needs. Closing the case back on top of the shield will not work.

Can it damage my Atari?

Croissant is designed for inline installation on the supported 7-pin connector. As with any internal upgrade on a vintage computer, careful handling matters. Follow the installation instructions step by step and make sure the board cannot short against any metal parts before closing the case.

Does the original keyboard still work?

Yes. Croissant includes a pass-through mode that preserves the original Atari input path end to end. Boot in pass-through when you want stock behaviour and switch to Bluetooth mode when you want modern wireless input.

Can I use USB keyboards or mice with Croissant?

No. Croissant is a Bluetooth and pass-through product. If you need USB-input mode, the right hardware variant is Soufflè, not Croissant.

Why IKBD behaviour and not a simple key-translation layer?

Atari ST-family software talks to the IKBD to handle keyboard input plus everything else routed through that controller. Emulating the IKBD protocol keeps compatibility with software that expects the original controller architecture. A simpler translator would feel close, but it would also break corner cases that matter on the Atari.

How do I configure or update it?

Initial setup and normal configuration are handled through the Croissant web interface over Wi-Fi. Firmware updates are installed through the on-board micro-USB connector.

Where do I download the latest firmware?

From the Croissant firmware download page. Use the micro-USB connector on the board to flash it.

Wi-Fi and Bluetooth are evil and I wear a tinfoil hat when they’re on. Is this device for me?

Probably not. Croissant is meant to be joyful and stress-free, and it spends its life chatting on the 2.4 GHz band. Make peace with radio waves first, then come back and we will still be here.

Is this product for me?

Yes, if you enjoy running real Atari hardware, you are comfortable opening the case and you want a modern Bluetooth input path without giving up the stock keyboard. Croissant is a homebrew product built for hobbyists who like experimenting; if you want a sealed appliance with a single-vendor warranty stack, this is not that.

Where do I report bugs or contribute?

Open a ticket from the contact page so we can route it to the right place. Hardware-side support for the boards we sell is handled directly by SidecarTridge.

Why can’t I access the store even though you ship to my country?

Access to our products and community spaces requires basic respect. We have zero tolerance for harassment, personal attacks, abusive behaviour or defamatory content toward our team or community. The principle is simple: don’t be abusive. If that principle is violated, access is revoked. We build for people who enjoy experimenting, not for people creating hostility.

Video walkthrough

Pair it with the SidecarTridge platform:

Cartridge-port platform

SidecarTridge Multi-device

A modular cartridge-port platform with Wi-Fi and microSD storage, plus a growing catalog of apps. The natural companion to Croissant for a modern Atari setup.