Guest Blog: New Sensor Expansion Boards for Freescale Freedom Development Platform

Originally posted by Michael E Stanley in The Embedded Beat on Dec 6, 2013

I am really excited because Freescale recently released a family of new sensor expansion boards designed to work with the FRDM-KL25Z and FRDM-K20D50M Freescale Freedom development platforms.  All three of the new expansion boards are based upon the same PCB design, and differ only in terms of how they are populated.  I’ve been using prototypes of these for months as a development platform for sensor fusion (more on that to come).  If I had to come up with a one word descriptor, it would be “SWEET!”

I refer to this design as our “kitchen sink” board, as it includes many of the sensors that Freescale introduced in 2013.  Because it pairs with two popular Freedom boards, it makes an ideal platform for product prototyping.  If low power and cost are your prime concerns, the KL25Z, built around a Kinetis KL25 MCU with ARM® Cortex®-M0+ processor, should be your base board of choice.  If you need more processing power, upgrade to the K20D50M, which is enabled with a K20 device built around an ARM Cortex-M4 processor.  Both Freedom development platforms support the popular Arduino R3 expansion board interface, which is also used for the new sensor expansion boards.

Prior to joining Freescale’s sensors team 4 years ago, I worked in the MCU side of the business.  I was really jazzed when my old division introduced the Freedom series of boards.  They are extremely flexible, easy to use and the cost cannot be beat.  Nice job!

The table below summarizes feature sets for each of the new sensor boards.  The two “MULTI” board options include redundant capability for rmeasuring acceleration and magnetic fields.  The intent is to provide multiple sensor options for you to experiment with.

Expansion Board Photo 30615-IND-FRDM-FXS-MULTI-B_top_LR.jpg 30936-IND-FRDM2-FXS-MULTI_top_LR.jpg 30939-IND-FRDM-FXS-9AXIS-top_LR.jpg
Compatible Freedom Development Hardware (not included) FRDM-
Arduino R3-compatible board
FXAS21000 Gyroscope
FXOS8700CQ Accelerometer / Magnetometer Combination Sensor
MMA8652FC Accelerometer
MPL3115A2 Altimeter/Barometer Sensor
FXLS8471 Accelerometer
MMA9553L Pedometer
MAG3110 Magnetometer
Bluetooth Module and Battery
Price USD (Dec. 2013) $125 $50 $30

In a prior posting (Free Android app teaches sensor fusion basics) I introduced the Xtrinsic Sensor Fusion Toolbox for Android, with the promise that it would communicate with future Freescale development boards.  The FRDM-FXS-MULTI-B IS that board.  Freescale will be posting downloadable binaries for the fusion app shortly.  You can expect to see an evaluation version of the Xtrinsic Sensor Fusion Library for Kinetis MCUs soon also.  I’ll be posting separately on that topic.

Because it includes a rechargeable Li-Ion battery (simply plug it into a USB port to charge) and 3rd party Bluetooth module (BR-LE4.0-D2A), your FRDM-FXS-MULTI-B application can be completely untethered.   The wireless module includes its own software stack for wireless encode/decode, which means that communications to/from the Freedom hardware could not be easier.  Simply read and write using a standard UART interface.

The FRDM-FXS-MULTI  has exactly the same sensor complement as the FRDM-FXS-MULTI-B, but omits the Bluetooth module and battery.  This has the benefit of lowing the per board cost by about 60%.  For those of you who really only need a basic 9-axis MARG (Magnetic-Angular Rate-Gravity) module, the FRDM-FXS-9AXIS board is just the ticket at only $30 USD.


The photo above shows key components on the FRDM-FXS-MULTI-B board.  Did I mention the SD card slot for data logging?  Or the prototype area on the left of the board?  You might want to plan on using Processor Expert software to abstract base board dependencies out of your project.  That’s what we did for our fusion code, with the result that we’re able to easily target both Freedom boards with essentially the same application.

Just click the “BUY” button on the web page associated with each board to place your order.  Don’t forget to also order a main Freescale Freedom development platform if you don’t already have one.



  1. Freescale Freedom Development Platform
  2. FRDM-KL25Z
  3. FRDM-K20D50M
  7. Processor Expert software
  8. Blue Radios Bluetooth module BR-LE4.0-D2A

Michael Stanley is a systems engineer at Freescale.


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