This content relates to a deprecated version of Mbed

Mbed 2 is now deprecated. For the latest version please see the Mbed OS documentation.

CMSIS-DAP versus original mbed Interface

The original mbed Interface has been depreciated and new platforms will all implement CMSIS-DAP or a similar type of interface to program the target MCU. There are 3 platforms that use the original mbed Interface. mbed LPC1768, mbed LPC11U24 and the retired mbed LPC2368. All others use a CMSIS-DAP (or similar) interface. The behavior of these interfaces is similar but not the same.


ResourseCMSIS-DAPmbed InterfaceNotes
Drag-n-drop programmingYesYesCMSIS-DAP disconnects and reconnects when programming fails to generate a fail.txt file with description
CMSIS-DAP debugYesYesmbed Interface version 141212 only
Virtual COM portYesYesProgramming failure disconnect will end terminal sessions
Local File SystemNoYesmbed Interface has 1MB of storage. Target application and PC cannot access the filesystem at the same time
Unique MAC addressNoYes

Making More Hardware

The HDK is a reference schematic and CMSIS-DAP binary file. This allow custom hardware to maintain the same UX and feature set a developer has become familiar with while prototyping. The BOM is less than $5 USD in low quantities and is a great way to keep development teams in sync while a project matures in development. This could also be a tool used in production to burn firmware, test a product and configure it for deployment.

Final Thoughts

The original mbed Interface became cost and size prohibitive. A new path was needed that allowed mbed's partners flexibility when creating hardware platforms. The CMSIS-DAP firmware project and HDK are the results of this.

Updating CMSIS-DAP Firmware

If there is an update to the CMSIS-DAP firmware it can be found through a link on the platforms overview page. There you will find the latest file along with depreciated files and revision notes. Notable revisions are:

  • 0200 initial release
  • 0201 adds support for Windows 8.1 hidden files and folders

Version number scheme will change with coming releases

Using using the NXP the ROM bootloader with Linux and Mac operating systems requires using the command line rather than dragging and dropping the CMSIS-DAP binary file.

This note below only applies to updating boards with the CMSIS-DAP HDK using NXP LPC11U35 interface MCU

Updating LPC11U35 based HDK's using MAC / Linux (NXP ROM USB bootloader)

  1. connect device (hold reset and connect to USB)
    • will enumerate as CRP DISABLD)
  2. delete firmware.bin
  3. unmount device (sudo on MAC)
    • using Linux umount /dev/sd* (where * is the location of your device)
    • using MAC OS umount /volumes/CRP DISABLD
  4. copy the file to the disk
    • Using Linux dd if=mbed_if.bin of=/dev/sd* seek=4
    • Using MAC dd if=mbed_if.bin of=/dev/disk* seek=4

Disconnect your device and reconnect. The mbed CMSIS-DAP firmware should be updated.

mbed.htm has a date and time as well as version number in the file. This will assure you the update was successful



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