Mecrisp-Cube for the Flipper Zero

Instant real-time programming with Forth. The Flipper Zero is an excellent portable tool for interaction with access control systems. But the display, the buttons, LIPO (2.1 Ah), GPIO, BLE, SD-Card, RTC, etc. make it also an ideal tool for programming on the go.

This page is no longer updated regularly, the current documentation can be found at GitHub (Flipper branch on Mecrisp-Cube). Sources are also there.


The standard Mecrisp-Cube features like RTOS, Filesystem, USB, etc.

  • 63 KiB RAM dictionary
  • 128 KiB Flash Forth dictionary
  • 50 KiB for C code
  • Internal Flash drive 0:, 384 KiB (for details see Nucleo)
  • Serial console UART / USB CDC / BLE
  • microSD drive 1:
  • Control (5-button joystick, Back button, Reboot)
  • LCD display 128x64 pixel
  • Power (LIPO charger and fuel gauge)
  • Vibration Motor
  • GPIO

Not supported yet:

  • Sub-1 GHz Transceiver
  • 125kHz RFID
  • NFC
  • Infrared Transceiver
  • iButton
  • Buzzer/Speaker

For more BSP details see BoardSupportPackageFlipper.

Getting Started

These instructions will get you a copy of the project up and running on your local machine (Flipper Zero) for development and testing purposes.


Flash the Mecrisp-Cube Firmware

Flash the Mecrisp-Cube binary (MecrispCubeFlipper.bin) or better the fs-util-binary (MecrispCubeFlipperFS.bin) to the Flipper Zero. Using the built-in USB DFU bootloader, see also firmware recovery.

  1. Press and hold the OK and the back buttons for 30 s (you should see a blank screen)
  2. Connect the Flipper Zero USB to the PC
  3. Program the binary (MecrispCubeFlipper.bin or MecrispCubeFlipperFS.bin) with
    1. the STMCubeProgrammer (select USB Device), for Linux
      sudo /usr/local/STMicroelectronics/STM32Cube/STM32CubeProgrammer/bin/STM32CubeProgrammer
    2. or the qFlipper with install from file
  4. Reboot your device by pressing and holding the left and back buttons

Switch On/Off, Buttons, LED

Switch Off
press and hold the BACK-Button for 5 s or type in the command halt
Switch On
press the BACK-Button
press and hold the BACK- and LEFT-Button

Special Functions on Startup

USB-CDC is the default console.
Button UP
CRS (Bluetooth Cable Replacement Service) is standard console
Button DOWN
UART is standard console
Button RIGHT
do not include 0:/etc/rc.local

RGB LED as Status Indicator

The RGB LED displays the status
dimmed Green
LIPO fully charged
dimmed Red
LIPO charging
dimmed Blue
BLE connected
flashing Red
"disk" (serial flash or SD) write operation
flashing Yellow
"disk" (serial flash or SD) read operation

Use the Terminal (USB CDC)

Connect the Flipper Zero USB to the PC. Start the terminal emulator application on the PC. Check for the serial communication port (e.g. for Linux /dev/ttyACM0). I set the putty terminal configuration to

  • Implicit CR in every LF
  • Local echo: Auto
  • Local line editing: Auto
  • Keyboard Backspace: Control-H
  • Keyboard Function: Keys VT100
  • Remote character set: CP850

You should see something like this in your terminal:

Mecrisp-Stellaris RA 2.5.4 by Matthias Koch.

Mecrisp-Cube 1.5.0 for STM32WB Flipper, 63/128  KiB RAM/FLASH dictionary (C) 2023
  * Firmware Package STM32Cube FW_WB V1.17.3, USB-CDC, BLE Stack 5.3 (C) 2023 STMicroelectronics
  * CMSIS-RTOS V2 FreeRTOS wrapper, FreeRTOS Kernel V10.3.1 (C) 2020
  * FatFs for internal flash and microSD - Generic FAT fs module  R0.12c (C) 2017 ChaN
include 0:/etc/rc.local

Use the interpreter:

23 5 / .[CR] 4  ok.

Type in your first Forth program:

: hello ." World" ;[CR]  ok.
hello[CR] World ok.

Additional Tools and Local Filesystem

Populate a microSD with the contents of sdcard. Put the microSD into the uSD Card slot and reset or power cycle the board.

The directory should look like this:

ls -l 1:[CR]
drw-         0 2021-04-18T18:12:38 boot
drw-         0 2021-03-21T18:47:52 etc
drw-         0 2021-03-21T18:47:54 fsr
drw-         0 2021-03-21T18:47:54 home
drw-         0 2021-03-21T18:47:56 man
-rwa      7219 2021-01-08T19:42:36

You can use the local CLI commands like mkfs, mkdir and cp to create a filesystem on the serial flash and fill it with files and folders. But this is tedious job because I haven't yet implemented a recursive copy for MecrispCube. But there is prepared disk image (for details see MicroSdBlocks#Serial_Flash) on microSD and the tool dd. You can copy the disk image to the drive 0: (this takes about 8 Minutes):

dd 1:/boot/fd-384KiB.img 0:[CR]
mount 0:[CR]
ls 0:[CR]
man                     fsr                          boot
etc                     home

The Mecrisp have some tools bundled in its distribution e.g. assembler, disassembler, dump, float. I put those tools and some more into the folder /fsr. With the "init.fs script" I compile my favorite ones into the flash directory (if you use the fs-util-binary binary, these tools are already compiled in):

compiletoflash[CR]  ok.
include /etc/init.fs[CR]
init.fs Loading started
RAM Dictionary: 392991 KiB
utils.fs loading ...
conditional.fs loading ...
dump.fs loading ...
disassembler-m3.fs loading ...
float.fs loading ...
threads.fs loading ...
RAM Dictionary: 392981 KiB
init.fs finished  ok.

For example, the word disassember is available now:

see dump[CR]
080405F0: B500  push { lr }
080405F2: F7C2  bl  08002A3E  --> cr
080405F4: FA24
080405F6: CF08  ldmia r7 { r3 }
080405F8: F013  ands r2 r3 #F
080405FA: 020F
080405FC: F847  str r3 [ r7 #-4 ]!
080405FE: 3D04
08040600: 2A00  cmp r2 #0
08040602: D000  beq 08040606
08040604: 3610  adds r6 #10
08040606: CF08  ldmia r7 { r3 }
08040608: F847  str r6 [ r7 #-4 ]!

Flash the original Flipper Firmware

If you want to go back to the original firmware, do the following

  1. Press and hold the OK and the back buttons for 30 s (you should see a blank screen)
  2. Connect the Flipper Zero USB to the PC
  3. Flash the Flipper firmware with qFlipper REPAIR
  4. Reboot your device by pressing and holding the left and back buttons

Installing Development Environment

A step by step series of examples that tell you how to get a development env running

Install the IDE STM32CubeIDE, it is Eclipse and GCC based. STM32CubeMX is included in the IDE, you need a stand alone installation only if you do not want to use the STM32CubeIDE.

Get the sources from github:

psi@homer:~> git clone --branch Flipper
Klone nach 'Mecrisp-Cube' ...
remote: Enumerating objects: 1157, done.
remote: Counting objects: 100% (1157/1157), done.
remote: Compressing objects: 100% (620/620), done.
remote: Total 3183 (delta 720), reused 934 (delta 525), pack-reused 2026
Empfange Objekte: 100% (3183/3183), 41.60 MiB | 6.96 MiB/s, Fertig.
Löse Unterschiede auf: 100% (2100/2100), Fertig.

Import the project into the IDE:

File -> Import -> General -> Existing Projects into Workspace -> Select root directory
Copy project into workspace
Browse to Mecrisp-Cube directory

Generate code from the STM32CubeMX MecrispCubeFlipper.ioc file:

Project -> Generate Code 

Restore changed source files

$ git status
{list of changed files}
$ git restore {files to restore} 

Select the Build Configuration (Debug if you want to debug the project) and Build the project:

Project -> Build Configurations -> Set Active -> Debug/Release 
Project -> Build Project

-- Peter Schmid - 2023-10-18

Creative Commons License
This work by Peter Schmid is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

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