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CC Bootloader

CC Bootloader is a simple USB bootloader for the CC1111 microcontroller (and probably others in the family e.g. CC2511). It allows the update of the microcontroller firmware over its USB port. It also supports reading and writing to the flash memory of the microcontroller e.g. for user data storage.

The bootloader consists of two components, a piece of firmware that is flashed onto the device and a python utility for downloading code and manipulating the flash memory.


The first step is to flash your device with the CCBootloader.hex firmware file. Once the device is flashed with this firmware it will identify itself over USB as a CDC-class device which means it should show up as a serial port without requiring any drivers on Linux and Mac OS X. Windows users should use the CCBootloader.inf driver file in the driver subdirectory.

If you have downloaded a release version of CC Bootloader it will include a CCBootloader.hex file that you can simply flash onto your device. If you have downloaded a development version then see the Building section below to build the CCBootloader.hex file. You may also want to build your own version to enable or disable certain features.

You can now use the python script to download your payload code. This script requires the pySerial library. If you have easy_install then installing pySerial should be simple:

sudo easy_install pyserial

For usage instructions of this script, run the script with no arguments:


Preparing your user code for usage with the bootloader is very simple. All you need to do is set your linker to start the code section at a higher location in memory specified by the USER_CODE_BASE define in src/main.h. For an example of this see the Makefile file in the example_payload subdirectory. This is the relevant line:

LDFLAGS_FLASH = ... --code-loc 0x1400 ...


This requires sdcc (Small Device C Compiler). Then it should be as simple as issuing


from the root directory of the project.

Build Options

The only option that can currently be enabled or disabled is weather to start running the user payload code after a certain timeout with no command issued over USB. Once a USB command is issued this timeout will be canceled and a command must be issued to explicitly start the user code. This option is specified in src/main.h. Just comment or uncomment this line:

#define TIMER

You may also change the length of the timeout (default 10 seconds):

#define TIMER_TIMEOUT 229 // 10s timeout

Please note that if you make changes to the bootloader you may need to adjust the value of USER_CODE_BASE. You will need to do this if the linker complains that it has run out of space. This value muse be a multiple of 1,024 so that the user code begins on a page boundary.

You must reflect this change in several places:

  1. Change the value of USER_CODE_BASE in src/main.h

  2. Change the value of --code-size in Makefile

  3. Change all the lines similar to ljmp #(0x1400+0x03) in src/start.asm. The constant 0x1400 should be changed to match USER_CODE_BASE but the +0x?? part should be unchanged.

Hopefully step three will not be needed in the future when I find a better way to implement this part of the code.

If you want the bootloader to only be invoked under certain conditions, e.g. the presence of USB power then please modify the want_bootloader function in main.c

All the board specific code is in hal.c so make sure to take a look at that if you are porting the code to a new board.


USB bootloader for the CC1111 RF SoC (rfcat version)







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  • C 84.7%
  • Python 7.0%
  • Makefile 3.6%
  • Assembly 3.0%
  • C++ 1.7%