After having installed the requirements and built speculos:

./ apps/btc.elf

The docker image can also be used directly, as detailed in the specific docker documentation page.

With applications built by recent SDKs, Speculos can automatically detect the targeted device. Otherwise, the Nano S is the default; the Nano X, Nano S+, Flex, Stax and Blue can be specified on the command line:

./ --model nanox apps/nanox#btc#2.0.2#1c8db8da.elf
./ --model nanosp apps/nanosp#btc#1.0.3#17bf7619.elf
./ --model blue --sdk 1.5 apps/blue#btc#1.5#00000000.elf
./ --model stax apps/btc.elf.elf
./ --model flex apps/btc.elf.elf

The last SDK version is automatically selected. However, a specific version be specified if the target app is not build against the last version of the SDK, thanks to the -k/--sdk argument. For instance, to launch an app built against the SDK 1.5 on the Nano S:

./ --sdk 1.5 --model nanos apps/btc.elf

Supported SDK values for each device are defined in src/sdk.h. You main choose the SDK using -k/--sdk argument:

  Nano S Nano S+ Nano X Blue
SDK 1.5, 1.6, 2.0, 2.1 1.0, 1.0.3 1.2, 2.0, 2.0.2 1.5, blue-2.2.5

For more options, pass the -h or --help flag.

Keyboard control

  • The keyboard left and right arrow keys are used instead of the Nano buttons. The down arrow can also be used as a more convenient shortcut.
  • The Q key exits the application.


Several display options are available through the --display parameter:

  • qt: default, requires a X server
  • headless: nothing is displayed
  • text: the UI is displayed in the console (handy on Windows)

These options can be used along --vnc-port which spawns a VNC server on the specified port. macOS users should also add --vnc-password <password> if using the built-in VNC client because unauthenticated sessions doesn't seem to be supported (issue #34).

A recording of the screen can be saved as a GIF file thanks to the tools/ script.

App name and version

On a real device, some parameters specific to the app to be installed (name and version, icon, allowed derivation paths, etc.) are given during the installation. This information isn't embedded in the .elf file itself and thus cannot be retrieved by speculos.

The default app name and version are respectively app 1.33.7, but these values can be set through the SPECULOS_APPNAME environment variable. For instance:

$ SPECULOS_APPNAME=blah: ./ ./apps/btc.elf &
$ echo 'b0 01 00 00 00' \
  | LEDGER_PROXY_ADDRESS= LEDGER_PROXY_PORT=9999 ledgerctl send - \
  | xxd -r -ps \
  | hd
00000000  01 04 62 6c 61 68 07 31  2e 32 2e 33 2e 34 01 00  |..blah.|
00000010  90 00                                             |..|

Bitcoin Testnet app

Launch the Bitcoin Testnet app, which requires the Bitcoin app:

./ ./apps/btc-test.elf -l Bitcoin:./apps/btc.elf


OCR is available for NanoX, Nanos S+, Flex and Stax with built in character recognition.