In this tutorial we show the steps needed to change the software running in the Crazyflie, often called firmware. We will show how to modify the source code , how to build it and finally download and flash it to your Crazyflie. These are the necessary steps to write your own code and change the behaviour of your Crazyflie.
This tutorial is based on the virtual machine where all the tools you need are installed, configured and set up to make this really easy.
We assume that you have basic knowledge of the C-programming language.
For this tutorial you need:
- A Crazyflie
- A Crazyradio PA
- A computer with the Virtual Machine (VM) installed.
For details on how to install the VM and Crazyradio see Getting started with the Crazyflie 2.X.
Fire up the virtual machine to get started. It comes with all tools you need pre-installed and configured to make programming simple.
From this point on in the tutorial, all steps refer to actions in the virtual machine.
Double click the “update all projects” icon on the desktop. This pulls down the latest source code from GitHub for all projects.
We will start out by modifying the source code. The update of the code is minimalistic, we will change the color of the front right LED from red to green.
The pre-installed IDE (Integrated Development Environment) is Visual Studio Code. Double click the “Visual Studio Code” icon on the desktop to start it.
Use the File menu to select “Open Folder…” and navigate to the “projects” folder and then select the “crazyflie-firmware” folder and open it.
Navigate to or search (CTRL + p) for
src/drivers/interface/led.h and click to open it.
Find the line
#define SYS_LED LED_RED_R
and change it to
#define SYS_LED LED_GREEN_R
Now it’s time to build the source code into binary files that can be downloaded to the Crazyflie.
For more, and more detailed, information about developing the Crazyflie firmware you can go to the repository documentation here.
If there is no command line terminal at the bottom of the vscode window you can use
the Terminal menu and select “New Terminal” to get access to a
bash terminal window.
The build system for the Crazyflie firmware is based on
make and you can start a build by
issuing the following command in the terminal window in Visual Studio Code:
$ make PLATFORM=cf2
And, since the Crazyflie is the default platform, it is enough to type:
To build the firmware. You should see something like the below on a successful build:
$ make CLEAN_VERSION CC sensors_mpu9250_lps25h.o CC sensors_bmi088_bmp388.o CC main.o CC nvic.o CC led.o CC usblink.o CC ledseq.o CC freeRTOSdebug.o CC pm_stm32f4.o CC radiolink.o CC system.o CC usddeck.o CC cfassert.o VTMPL version.c CC version.o LD cf2.elf COPY cf2.hex COPY cf2.bin DFUse cf2.dfu Build for the CF2 platform! Build 11:0864ef92245a (2021.03 +11) MODIFIED Version extracted from git Crazyloader build! Flash | 242184/1032192 (23%), 790008 free | text: 236372, data: 5812, ccmdata: 0 RAM | 71128/131072 (54%), 59944 free | bss: 65316, data: 5812 CCM | 58380/65536 (89%), 7156 free | ccmbss: 58380, ccmdata: 0
Now we have the binary files and it is time to download them to the Crazyflie and save them in the flash memory, often called flashing. Our new modified version of the firmware will replace what ever version you currently have installed. If you want to go back to the official firmware just re-flash the Crazyflie with an official release.
Turn your Crazyflie 2.X off.
Start it in bootloader mode by pressing and holding the power button for 3 seconds. Both blue LEDs will blink.
In the terminal window type:
$ make cload
Printouts in the “Console” window shows the progress and the LEDs on the Crazyflie flicker.
$ make cload python3 -m cfloader flash cf2.bin stm32-fw Restart the Crazyflie you want to bootload in the next 10 seconds ... done! Connected to bootloader on Crazyflie 2.0 (version=0x10) Target info: nrf51 (0xFE) Flash pages: 232 | Page size: 1024 | Buffer pages: 1 | Start page: 88 144 KBytes of flash available for firmware image. Target info: stm32 (0xFF) Flash pages: 1024 | Page size: 1024 | Buffer pages: 10 | Start page: 16 1008 KBytes of flash available for firmware image. Flashing 1 of 1 to stm32 (fw): 242639 bytes (237 pages) ..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10.......7 Reset in firmware mode ...
For a guide on debugging the Crazyflie firmware using GDB, see the firmware documentation here.