FortyTwo Systems MEGA

Arduino MEGA compatible board, running at 5V with a 32-bit ARM core

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This board breaks out the SAMC21N microcontroller into a board that is a drop-in replacement for the Arduino MEGA. Break free from the size and processing power limitations of the original Arduino MEGA with a 32 bit ARM core.

The Arduino Mega's design has remained almost unchanged for more than a decade. It still uses the ATMega2560 processor, which is just as old. Arduino released the Due board in 2012, based on the SAM3X8E processor, an ARM Cortex-M3 which was much more expensive than the Mega and only ran at 3.3V, instead of the 5V standard of most other intro level Arduino boards.

In 2015, Atmel (now Microchip) released the SAMC line of processors. This series of processors is based on the ARM Cortex-M0+ core, can run at 3.3V or 5V, and even includes two onboard CAN controllers, making it perfect for industrial applications and hobby applications alike. While the original product line only included an E, G, and J variant similar to the SAMD21, more recently an N variant became available with the same package size as the venerable Mega2560. 

The FortyTwo Systems is the first Arduino-compatible board to feature this new processor. The board keeps the same form factor and pulls much of its electrical design from the Arduino Mega.

Project status:

  • Toolchain available and tested for Windows x86, Mac, Linux ARM32. Other arches coming very soon.
  • PCB designed and tested.
  • Bootloader written and tested.

  • Prime time

    Dave05/04/2021 at 18:10 0 comments

    Today's the day! The FortyTwo MEGA and the FortyTwo UNO are now on sale on Tindie. Check them out here:



    Shipping time is currently less than 2 weeks. There's a limited number of boards available due to the chip shortage.

    Currently, I still need to compile BOSSAC on Linux x86, finish the CAN library documentation, and make sure the core is bug-free. PlatformIO support is also pending. I'm hoping to have all of that done before the first board ships.

  • PlatformIO and Arduino IDE support

    Dave03/30/2021 at 00:00 0 comments

    I've completed basic windows configurations for PlatformIO and Arduino IDE. In the Arduino IDE, code compilation, upload, and bootloader burning are all working.

    I'm now able to debug code from within PlatformIO, which is a lot more streamlined than from within Microchip Studio (you do lose a few small features). See for the platform files. Currently, the following must be specified in the platformio.ini file:

    platform =
    platform_packages = 
        framework-arduino-samc-fortytwo @
        framework-cmsis-microchip @
        tool-bossac-samc @
    board = fortytwo_mega
    framework = arduino

    I'm hoping to clean things up in the following weeks by publishing the packages to the PlatformIO registries. Until I ship a significant number of boards and get support from the official PlatformIO repo, I will have to use the fortytwosystems github link for the platform variable.

    I've finished my modifications to BOSSA by adding all chips in the SAMC21 line to the Devices.cpp file. I need to compile bossac for mac and linux systems still.

  • Hello world!

    Dave03/23/2021 at 22:38 0 comments

    I'm happy to announce that I've got a working core and bootloader written for the board. Many hours and some tears have been poured into getting the basics set up. I've also created a way to debug the core in Microchip Studio, so you can step through your code. All of the source code is on GitHub, here.

    Currently the only peripherals I've tested are UART and the GPIO pins. I'll be working on timers and CAN soon. I'll need to procure some CAN devices first. I'm also excited to test the ADC and DAC.

  • First Prototype Board

    Dave01/03/2021 at 01:20 0 comments

    I ran my first prototype of the MEGA board back in early 2020, and I'm just now getting back to the project. Here it is, the FortyTwo Systems MEGA:

    I got pretty excited to see it all built out like this. It has one fatal flaw, which is easily corrected: I accidentally crossed the SWCLK and SWDIO lines on the JTAG SWD header. With some custom cable magic that flaw was easily fixed, and I'll correct the problem in the next revision.

    Now it's time to start writing an Arduino core for this board, currently it is only programmable from Microchip START.

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