The new EFM32 Happy Gecko MCU family is designed to deliver the low power USB power drain for a wide range of IoT applications including home and building automation, alarm and security systems, smart accessories and wearable devices. The Happy Gecko family is based on the ARM Cortex M0+ processor and supports wide range of sensors.

Learn more about the Happy Gecko family


In this contest, we are giving away a Happy Gecko kit (SLSTK3400A) to three winners and will be invited to write a review blog post about the kit to help other developers get started easily.


So, how to participate in the contest?


Take a look at the Happy Gecko pages below and share your project idea with us by leaving a comment below. We would like to hear what you want to build/test with the kit based on its key features and why. (Only 1 entry per user) Our MCU team will be judging the entries based on relevance and creativity.


# of winners: 3

Prize: 1 x Happy Gecko STK (SLSTK3400A)

Contest period: 10 June – 24 June, 2015



By entering the contest you acknowledge that you have read and agree to the Silicon Labs Contest Terms and Conditions 

  • Projects
  • Hello.

      I would finally redesign and finish my "smart coaster" project.

    The idea is to make small, cheap and  useful coaster for your cup of beer, coke, tea or even hot soup.

    The coaster measure the surface temperature via infrared sensor form Ti (tmp006) and if the  temperature falls below the set threshold it will buzz and/or give color feedback through WS2812.

    The desired temperature can be set with 3 touch button on the top.

     I started this project  about 2 Years ago with MSP430 Series,  and even build the first fully assembled prototype. But there were many bugs on my board,and I had to concentrate on studies so I abandoned this project for better times(which I ashamed for ).

     I honestly want to revive this project, now with more advanced MCU. ARM-M0+(since it cost same as MSP) fits here just fine, and EFM32 is realy as low power as MSP430, so a simple CR2032 Battery would be enough to drive the coaster for years.

     Here are some pics of  two board construction and the prototype itself.The small board carry TMP006 sensor and RGB status LED. On the main board there is MSP430, a small voltage regulator and some misc passives.

     This project can  end in a really cool product + I'll do a cool presentation video, sinceI already have youtube channel with some cool FPGA videos.

    ------->  My youtube channel

     Tnx for reading.







  • Hi!


    I have recently built a solar powered weather station for my garden using a Tiny Gecko MCU, which sends the data via ZigBee (XBee) to a base station, which has access to the internet and sends the data to a server (


    Now I want to add a Happy Gecko to the ZigBee network, which also receives the data (LEUART) and sends it to a smart-phone (USBHID Terminal) or a PC using the LEUSB peripheral. Furthermore I also want to measure the indoor temperature using the Si7021 on the EFM32HG STK. When there is no USB Host connected to the Happy Gecko, the data will be displayed on the LCD (powered by a 3V coin cell).




  • cool project micheal_k! I saw your little car box project also. Have you posted the code or pictures for this ZigBee project somewhere? Would be really cool to see it Robot Happy


  • Alf wrote:

    cool project micheal_k! I saw your little car box project also. Have you posted the code or pictures for this ZigBee project somewhere? Would be really cool to see it Robot Happy

    Hi Alf!

    Thank you.

    I already planned to post it in the forum. However I was quite busy the last few weeks. Today I had my final exam. So now I have more time to write a post.

    I think I'll post it in the next few weeks.




  • I have severe arthritis and build electronic devices to make my life easier. One of the things that can be difficult is going to check the mail or for packages. I would build a device that could notify me when the mail or packages are delivered. I would experiment with a pressure sensor, detecting when the flap is raised on the mailbox and a beam break sensor to see which combination gives me the best performance. Longer term i would incorporate a sensor(s) to monitor the opening of the storm door (small packages are often placed between the doors) and a motion detection array to alert me of people approaching the door. 

  • Hi everybody!


    Here is my project idea:


    Failsafe module for RC gliders.




    RC planes and gliders is a widespread hobby, it very pleasant and relaxing. But when your model crashes it's always pain.


    There are two main reasons for this:
    - poor flying skills
    - radio fail (distance, EMC glitch, problems with equipment)


    Both can be solved with module that can take control and land plane safely. It could be activated if receiver reports connection failure, or user switches special tumbler.


    Hardware requirements

    Gliders have low battery capacity, as weight should be very limited. So low power operation is essential, as there is no free power aboard. Also board should be small and lightweight, and MCU should have minimum external components and small package. 


    Device should be configured before use (landing radius, fail conditions etc.). It could be easily done in the field with smartphone, that's why USB interface is a must, and low power crystalless USB is a good advantage. Few PWM channels needed to drive servos.


    All this is a great application for Happy Gecko.

    Also there will be gyroscope, for plane stabilisation in an emergency. Which will be powered only when needed, so it should start fast and consume moderate current.


    Software requirements

    From software side there is nothing special, but good peripheral libraries with ready to use USB stack and examples are very important to reduce time to market and guarantee reliability.



    Failsafe module should be placed between receiver and servos.


    - In normal mode signals from receiver will pass by failsafe module and drive servos directly.
    - In emergency mode Happy Gecko will break signal circuit with switches and drive servos by himself according to gyroscope data and preprogrammed settings (turn radius, position of control surfaces etc.).


    During configuration Happy Gecko will operate as MSD USB device, and simple text file will be used for settings, so it could be setted up from and PC or smartphone. Text file could be generated with JavaScript on website with GUI, or edited manually in text editor.


      ---------------                                          -----------------------------
    |                    |                    __________|                                     |
    |                    |                   |                    |     Failsafe module       |
    |                    |          ---------------           | Happy Gecko inside Robot Happy |
    |   reciever    |-------|                    |         |                                      |
    |                    |-------|   switches   |          ------------------------------
    |                    |-------|                    |                   ||            ||
     ---------------            ---------------                     ||            ||
      |    |    |    |                                                     ||             ||
      |    |    |    |                                                     ||             ||
     ----------------                                                  ||             ||
    |                     |========================//             ||
    | servo drives |                                                               ||
    |                     |===============================//



    There is now such devices on market yet, only some dumb one which will stabilize control surfaces in last position, when radio channel fails, which can not preserve plane from flying away, or bring the aircraft from a spin. They could not be activated by user in difficult situation. 

    There are also some feature rich devices with GPS, e-compass and back to base function, which is not applicable on gliders because of power consumption. 


    As good DLG glider costs about $500-1000, small relatively cheap board that can save it from crash is a good investment.

    It could be also very attractive device for beginners on any types of RC planes.

  • My idea is an instrumented bike.


    When you ride on a bike you don't have any rearview mirror to help you see backwards, so you have to be turning your head if you want to make a turn in order not to crash with a car or other thing that comes from behind.

    To solve this problem, I want to place an image sensor (OVA767 from Omnivision) in the back of the bike on a little PCB with an MCU the communicates with a smartphone over USB. This smartphone will be fastened in the middle of the stem and the USB cable will pass through the top tube of the frame.

    The smartphone will be displaying the back view of the bike that the sensor will be capturing so the rider will have a rearview mirror without turn aside the road view.

    To achieve this task, a fast USB communication will be needed to reach at least 30 fps, otherwise we will have a slow motion back view. The most important thing is low energy consumption because the smartphone will be powering the MCU and the sensor and, like Alf said, we don't want to be afraid to connect our rearview mirror even if the smartphone is running out of energy. Happy Gecko fits this task.


    I'm an embedded system designer and I have never used Silicon Labs' MCUs, so this is the perfect opportunity to evaluate them. I'm really interested in including Silicon Labs to my devices' portfolio.


    Thanks for reading.

    M.Eng. Alejandro Gómez.

  • my project to use the EFM32 Happy Gecko MCU Starter Kit for a low power sensor node, the information from the sensors are saved in the colud to analyze it later. I also want to Configure the EFM32 Happy Gecko MCU Starter Kit that when a sensor passes the threshold value an alarm notification is sent to the user.



    Kind regards,


  • Thank you all for your contributions! There are many great ideas here, and while going through the suggestions has been an enjoyable process, selecting the winners has not been easy.


    The 3 winners of (very) Happy Gecko STKs are:

    - "RC failsafe" by uSasha - I (Øivind) had an RC plane once, but crashed it 4 times (in 4 flights), and it eventually died. Great idea, and very thorough proposal!

    - "Mailbox checker" by srpsco - Great idea for an IoT mailbox.

    - "Smart Coaster" by ToniT800 - There are many coffee & tea drinkers here at Silicon Labs Robot Happy


    Nari will contact each of the winners directly to arrange kit shipments and follow-up. Enjoy your Happy Gecko STKs, and have fun building your projects.


    And of course: stay tuned for our next context!