Skip to content


Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?

Latest commit


Git stats


Failed to load latest commit information.

PureThermal 1/2/Mini Reference Firmware

Build Status

The PureThermal 1, PureThermal 2, and PureThermal Mini series of boards are are an embedded development platform for the FLIR Lepton thermal imager, created by GroupGets's GetLab. It is based around the STM32F4, a powerful ARM Cortex-M MCU by ST Microelectronics, and its various IO capabilities as well as an open source firmware to make it easy integrate a FLIR Lepton into any environment.

Purpose of This Project

It is intended that you use this firmware as a starting point for you own applications. For many applications where you wish to process thermal image data on a host PC, you can probably use pre-built binaries of this firmware and use as-is. For others, forking this project and making your own modifications to this firmware is encouraged.

Building the Firmware

This is a Makefile-based project, and we use the GCC ARM Embedded toolchain from, however, other toolchains that work for the STM32 (such as Mentor's Sourcery toolchain) should also work.

Compiler Installation

The following are compiler installation instructions for various platforms, required for building the firmware.

Ubuntu 32/64-bit

sudo add-apt-repository ppa:terry.guo/gcc-arm-embedded
sudo apt-get update
sudo apt-get install gcc-arm-none-eabi


Launchpad has toolchain binaries for OS X. To keep things simple, we'll install then into /usr/local/gcc-arm-none-eabi-*

sudo mkdir -p /usr/local
curl -L -o ~/Downloads/gcc-arm-embedded.tar.bz2
sudo tar xjf ~/Downloads/gcc-arm-embedded.tar.bz2 -C /usr/local && rm ~/Downloads/gcc-arm-embedded.tar.bz2

Then you need to add this location to your path. Add to your .bashrc, or every time you open a new shell and wish to build execute:

export PATH=$PATH:/usr/local/gcc-arm-none-eabi-4_9-2015q3/bin

Clone and Build

git clone
cd purethermal1-firmware

If you wish, you can modify Src/project_config.h to customize your build. Then you can simply build:




alternatively, you can enable semihosting support to printf over JTAG/SWD:


See the "Debugging" section below for more information.

If you have OpenOCD installed (available in most package management systems), you can then flash the compiled firmware (see next section for required hardware):

make flash

Installing Release Firmware

PureThermal 1

Required Hardware

Hardware Instructions

  1. Attach ribbon cable from STLINK/V2 into ARM Adapter.
  2. Plug in ribbon cable from ARM Adapter into PureThermal1's ZIF socket.
  3. Insert mini-usb cable into STLINK/V2 and computer.
  4. Insert micro-usb cable into PureThermal 1 and computer.
  5. Power on PureThermal 1 if not already on with ON/OFF button press.

Mac OS

  1. In terminal download and install the STLink software using homebrew:

     brew install stlink
  2. Navigate to the folder which contains the PureThermal 1 firmware (pt1-vx.xx.x.bin), or build with the instructions above.

  3. Use the following command to erase the firmware on the PureThermal 1:

     st-flash erase
  4. To write the firmware use one of the following commands (replace the X's with the version of firmware you have downloaded):

     st-flash --reset write pt1-vX.XX.X.bin 0x08000000

    Output of a Makefile build:

     st-flash --reset write main.bin 0x08000000



  1. Download the STM32 ST-LINK Utility (STSW-LINK004)
  2. Install STM32 ST-Link Utility and then open the software.
  3. Select "Target" then "Connect" to connect the software to the PureThermal 1.
  4. Next select "File" then "Open file...", now navigate to the folder which contains the PureThermal 1 firmware and select & open the firmware you want to flash (pt1-vX.XX.X.bin).
  5. Finally click "Target" then "Program & Verify...", make sure that the "Reset after programming" box is selected then press the "Start" button.

Installing firmware over USB via DFU-Mode (for PureThermal 2 & PureThermal Mini boards)

Make sure you use at least 1.1.0 becuase earlier versions didn't support the PT1 and PT2 board from the same binary.

If you're not compiling from source you can download the firmware from and substitute the .bin file in the tgz for main.bin in the commands below.

Entering bootloader (DFU) mode

  1. Locate the buttons to press on your PureThermal board.
  2. While plugged in, press and hold the BOOT button.
  3. Without releasing BOOT, press and release RST.
  4. Release BOOT.
  5. When you successfully enter DFU mode, the indicator LED will stop blinking and dim to half brightness.

Linux / MacOS

Install dfu-util:

sudo apt-get install dfu-util


brew install dfu-util

or your system's package manager.

Then run:

dfu-util -a 0 -D main.bin -s 0x08000000

if you get an error "Invalid DFU suffix signature"


dfu-util --list

You should see a list of DFU devices in or connected to your computer, such as the example below:

Found Runtime: [05ac:8290] ver=0161, devnum=2, cfg=1, intf=5, path="20-3", alt=0, name="UNKNOWN", serial="UNKNOWN"
Found DFU: [0483:df11] ver=2200, devnum=4, cfg=1, intf=0, path="20-1", alt=3, name="@Device Feature/0xFFFF0000/01*004 e", serial="3061B4493536"
Found DFU: [0483:df11] ver=2200, devnum=4, cfg=1, intf=0, path="20-1", alt=2, name="@OTP Memory /0x1FFF7800/01*512 e,01*016 e", serial="3061B4493536"
Found DFU: [0483:df11] ver=2200, devnum=4, cfg=1, intf=0, path="20-1", alt=1, name="@Option Bytes  /0x1FFFC000/01*016 e", serial="3061B4493536"
Found DFU: [0483:df11] ver=2200, devnum=4, cfg=1, intf=0, path="20-1", alt=0, name="@Internal Flash  /0x08000000/04*016Kg,01*064Kg,07*128Kg", serial="3061B4493536"

If you are a large number of devices you can unplug the PureThermal board and run the dfu-util --list command again and compare the output.

To specify a specific device to flash run (replace the ?? with the device id of the PureThermal board plugged into your comptuter)

dfu-util -a 0 -d ????:???? -D main.bin -s 0x08000000

or use:



DfuSe USB drivers, on the page below under the "GET SOFTWARE" section at the bottom of the page.

win32 DFU tools

To install DFU drivers, may need to use the device manager to select the st drivers.

Extract to the folder with your firmware. Then run the .bat file which you can download from /scripts here

or use the following commands in CMD.

CD to folder where you put the (.bin) firmware and extracted win32 DFU tools.

win32_dfu\bin2dfu --i main.bin --a 0x08000000 --o main.dfu
win32_dfu\DfuSeCommand -c -d --fn main.dfu


This section covers printf over JTAG/SWD though GDB semihosting. You can also set breakpoints using GDB+OpenOCD, or with using the provided Eclipse projects. Additionally, you can enable printf support over UART.

Makefile projects

For Makefile projects, you can enable semihosting support to enable printf over JTAG/SWD. This works with STLink/V2, Segger JLink, and should work with others as well.

You must build the code with semihosting support enabled (GDB_SEMIHOSTING=1). Note that if you get build errors, you might have to make clean and retry. Simply run the following:

GDB_SEMIHOSTING=1 make debug

The debugger should remain attached, and you should see printf output on the console, like so:

xPSR: 0x01000000 pc: 0x08010b8c msp: 0x20020000
semihosting is enabled
auto erase enabled
Info : device id = 0x10006431
Info : flash size = 512kbytes
wrote 131072 bytes from file main.bin in 4.133242s (30.968 KiB/s)
adapter speed: 2000 kHz
Info : JTAG tap: stm32f4x.cpu tap/device found: 0x4ba00477 (mfg: 0x23b (ARM Ltd.), part: 0xba00, ver: 0x4)
Info : JTAG tap: tap/device found: 0x06431041 (mfg: 0x020 (STMicroelectronics), part: 0x6431, ver: 0x0)
Hello, Lepton!

Eclipse projects

Semihosting also works in Eclipse/OpenSTM32 projects. To enable this, locate the target debug configuration for the project and add the following line to Initialization Commands in the Startup tab:

monitor arm semihosting enable

You should see print statements appear in the debugger console view.

For More Information

Refer to PureThermal 1 development wiki.

Licensing and Support

This firmware is licensed under The MIT License (MIT), see LICENSE file for details.

Inquiries for support should be directed at this project's maintainers, GroupGets, LLC (GroupGets), and not FLIR Systems, Inc. (FLIR). Additional FLIR-provided source code is being released by GroupGets to this project under the express written consent of FLIR, and covered by the project's license, with the expectation that no warranties or support of any kind will be provided by FLIR.