Case study

Open Steam Controller: reverse-engineered Steam Controller firmware

Documents the reverse engineering of Valve's original Steam Controller, whose LPC11U37F main-processor firmware the author ran in a modified pinkySim simulator to log its hardware accesses, and uses the findings to write replacement firmware. Build options turn the controller into a USB-serial development board for querying its peripherals, or into a wired Nintendo Switch controller that presents itself as a PowerA pad. A Qt converter writes MusicXML songs as startup and shutdown jingles into an EEPROM area that the official firmware also reads, and notes record the board's pin connections and USB messages.

Targets: Firmware · Protocol
Category: Independent reconstruction cases
Relationship: Independent reconstruction project
Sources reviewed: 2026-10-19

Stars: 545
Last commit: 2019-09-17
Language: C

GitHub data as of 2026-11-09

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Requirements & limits

The replacement firmware targets the Steam Controller Luna_mainboard V000456-00 rev3 board and its LPC11U37F processor. The nRF51822 Bluetooth firmware remains original.
A Steam Controller with that board is needed to run the custom firmware or jingle workflow. Repeating the simulation requires Valve’s vcf_wired_controller_d0g_57bf5c10.bin firmware and an LPC11U37 16 kB boot ROM dump, supplied separately.
Firmware builds use LPCXpresso IDE v8.2.2 and the bundled NXP lpc_chip_11uxx_lib; select DEV_BOARD_FW or SWITCH_WIRED_POWERA_FW in fw_cfg.h. SCJingleConverter uses Qt 5.12; SteamControllerConfig.py uses PyUSB.
Author source files carry MIT notices; the bundled NXP LPCOpen library is limited to NXP microcontrollers. The repository has no license file. The custom firmware embeds default jingle data from Valve firmware and a HID report descriptor copied from a PowerA controller.

Cite

BibTeX

@misc{open-steam-controller-firmware-case,
  title = {{Open Steam Controller: reverse-engineered Steam Controller firmware}},
  howpublished = {\url{https://github.com/greggersaurus/OpenSteamController}},
  url = {https://github.com/greggersaurus/OpenSteamController},
  urldate = {2026-10-19},
  note = {Awesome REA entry: \url{https://awesomerea.org/resources/open-steam-controller-firmware-case/}}
}

Plain text

Open Steam Controller: reverse-engineered Steam Controller firmware. https://github.com/greggersaurus/OpenSteamController (accessed 2026-10-19). Awesome REA entry: https://awesomerea.org/resources/open-steam-controller-firmware-case/

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About this entry

The description was reviewed against primary sources.

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Primary sources

README.md GitHub · greggersaurus/OpenSteamController · Revision 3258015
ReverseEngineering/README.md GitHub · greggersaurus/OpenSteamController · Revision 3258015
ReverseEngineering/LPC11U37F_Software.md GitHub · greggersaurus/OpenSteamController · Revision 3258015
ReverseEngineering/usbInterface.md GitHub · greggersaurus/OpenSteamController · Revision 3258015
Firmware/README.md GitHub · greggersaurus/OpenSteamController · Revision 3258015
Firmware/OpenSteamController/src/init.c GitHub · greggersaurus/OpenSteamController · Revision 3258015
Firmware/OpenSteamController/src/jingle_data.c GitHub · greggersaurus/OpenSteamController · Revision 3258015
Firmware/OpenSteamController/inc/fw_cfg.h GitHub · greggersaurus/OpenSteamController · Revision 3258015
Firmware/lpc_chip_11uxx_lib/src/chip_11xx.c GitHub · greggersaurus/OpenSteamController · Revision 3258015
Jingle/README.md GitHub · greggersaurus/OpenSteamController · Revision 3258015
UsbConfiguration/README.md GitHub · greggersaurus/OpenSteamController · Revision 3258015
UsbConfiguration/SteamControllerConfig.py GitHub · greggersaurus/OpenSteamController · Revision 3258015