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OpenBLT is a bootloader that can run on any microcontroller and use any type of communication interface to perform software updates, without the need of specialized debugger hardware. Example applications are:

  • In-field reprogramming. After your customer started using your microcontroller based product, it is always possible that a software update needs to be made. For example to enable new features or to resolve an existing problem. With OpenBLT you can easily reprogram the software program, even on location at the customer.
  • End of assembly line. Using OpenBLT it is possible to flash your product's software program at the end of the assembly line, allowing the most up-to-date version to be shipped with your product.
  • Development stage. During the development stage of your software program, you frequently reprogram the software program. OpenBLT enables you to do this without the need of special debugger hardware.
  • Calibration stage. While fine-tuning your software program, you optimize parameters of your software program. OpenBTL can be used to quickly reprogram the optimized calibration parameters.
  • Starter kits. By preloading the bootloader on a microcontroller starter kit, the end user does not need to purchase an expensive debugger interface. It is also not necessary to include an on-chip debugger on the started kit board. This lowers the cost price of the starter kit, making it more appealing for the end user.


  • Available for Free!
  • Includes user-friendly PC download utility.
  • Full source code available.
  • Supports common available communication interfaces such as UART, CAN, TCP/IP and USB.
  • Supports software updates from a locally attached storage such as an SD-card.
  • Small ROM footprint.
  • Highly configurable.
  • Organized and well documented code.
  • Easily portable to different microcontrollers.
  • Extendable to support extra memory such as serial EEPROM or external Flash.
  • Extendable to support a user defined backdoor entry.
  • Professional support available.


OpenBLT is open source and licensed under version 3 of the GNU GPL. OpenBLT is free under this license and can be freely used and distributed under its terms.

The freedom that this GNU GPL license offers, comes with responsibilities and side effects that are not always desirable. This is especially the case if you want to integrate OpenBLT in your closed source product and/or don’t want your customers to know that your product contains OpenBLT.

As an alternative, OpenBLT can be made available under a commercial license. Under the commercial license, OpenBLT does not contain any references to the GNU GPL. Refer to the following license comparison matrix to determine the OpenBLT license your product requires.

Question GNU GPL version 3 Commercial License
Is OpenBLT free? yes no
Do I have the right to change the OpenBLT source code? yes yes
Can I use OpenBLT is my closed source product? no yes
Do I have to open my source code? yes no
Do I have to open source my changes to OpenBLT? yes no
Do I have to offer the OpenBLT source code to users of my product? yes no
Do I have to document that my product uses OpenBLT? yes no
Can I receive professional technical support on a commercial basis? no yes

Contact Feaser ( to request additional information and/or a quote for a commercial license.


OpenBLT is based on Feaser's proprietary and commercial bootloader. I decided to convert this into an open source GNU GPL bootloader for two reasons:

  1. There is no way that I personally can support all popular microcontrollers in OpenBLT. By open sourcing the bootloader, I hope to build a community of enthousiastic embedded software developers that want to help me support as many microcontroller and compiler combinations as possible in OpenBLT.
  2. I specifically enjoy working with startup companies in the embedded software industry. These tend to be on a small budget with no funds available for a quality bootloader. By open sourcing the bootloader I can now make the bootloader available to the startup companies I work with and others, hopefully leading to more fun and interesting project leads for me.
homepage.txt · Last modified: 2016/05/01 11:33 by voorburg
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