SparkFun has just announced a new modular ecosystem called MicroMod. Targeting rapid embedded development, MicroMod consists of two pieces: a microcontroller board and a carrier board. The interconnect between the two is the PC industry's M.2 connector.
Look at any embedded device's block diagram, and you'll see a microcontroller in the middle with a bunch of stuff surrounding it. That model is probably why the processor gets picked early in development. But, what happens when the design needs a microprocessor with a different architecture? Or unexpected capability, like WiFi, crept into the requirements? In the past, it would take significant effort to change either the processor or, worst case, the rest of the embedded system. With MicroMod's approach, the hardware change is as simple as swapping modules.
"The processor you start with is not always the one you end with ... MicroMod makes exploring different microcontrollers easy.” — Nathan Seidle, SparkFun Founder
The most striking physical feature of MicroMod's processor modules is the size. Their widths are similar to M.2 devices, but their lengths are much shorter. Each processor board contains very few components. For example, the ESP32 board has the SoC, an antenna, a flash memory, and the USB-to-serial chip. That is it! The carrier board contains extra things like a reset switch, voltage regulator, USB connector, and in-circuit programming header. With so much pushed to the carrier boards, it is no wonder SparkFun opted for a high-density, high-pin count, high-speed connector like M.2!
To be clear, while mechanically compatible with the M.2, MicroMod is not electrically compatible. Fortunately, SparkFun has open-sourced the pinout. That step makes it easy to use the pre-made modules or to design your own.
With today's launch, there are three processor boards and four carrier boards available.
About a year ago, SparkFun introduced Artemis. It is an open-source embedded module with FCC/CE approvals. It features an Arm Cortex-M4F core running up to 96 MHz with Bluetooth Low Energy (BLE) 5.0. At just six microamps per MHz or five milliwatts, it is a very low-power board.
With WiFi, Bluetooth, hardware-accelerated encryption, the usual serial interfaces, and a dual-core microprocessor running at 240 MHz, Espressif's ESP32 is one of the most popular IoT microcontrollers around. The ESP32 MicroMod includes the SoC, a 128 Mb flash chip, and a crystal for the internal real-time clock (RTC).
Microchip's SAM D51 features an Arm Cortex-M4F microcontroller with a built-in floating-point processor. The SAMD51 MicroMod board comes with the same USB Flashing Format (UF2) bootloader as SparkFun's other D51 boards. This feature means being able to program the board with the Arduino IDE easily.
Keep in mind any of those three processor boards can connect to the following carrier boards.
Packed into a 57.5mm x 82.5mm board are a 2.4" TFT LCD, six addressable LEDs, six I/O pins, two pushbuttons, a piezo speaker, and a five-way tactile switch. This carrier is well suited for adding a graphic GUI or readout to a project while using the five-way switch for "joystick" navigation.
This carrier contains the components you would expect to find on an intelligent edge computing or IoT device: two microphones, an accelerometer, and a flat-ribbon cable (FPC) connector for a camera. Which we were happy to see SparkFun did not integrate the camera into the board. The FPC allows for the camera's placement to be flexible.
ATP stands for All The Pins. While not Arduino-shield compatible, the layout is visually very similar. The ATP carrier breaks out all of the interesting pins available on the M.2 interface's connector. SparkFun added a secondary rail of through-holes for each socket pin. These unpopulated through-holes provide additional flexibility in how you connect to the signals.
The data logging carrier features a microSD card socket for saving information from connected sensors. An on-board, surface mount battery provides power for a real-time-clock on a processor MicroMod. Unlike the other MicroMod carriers, the data logging board has a connector and charging circuit for a LiPo battery.
There are a couple of things that we noticed across each carrier board. Obviously, each module has an M.2 socket. And conversely, each processor board has an M.2 edge connector.
Each of the released carrier boards features a SparkFun Qwiic connector. This four-pin JST connector simplifies the connection to other boards like sensors or relays. As the name implies, it features pins for I2C. Interestingly, the machine learning carrier includes 2.54 mm pins for I2C as well as the Qwiic connector.
The carriers do not seem to follow a form factor convention. For example, the length, width, and mounting hole locations on the machine learning carrier are entirely different from the input/display carrier. It looks like SparkFun intended the boards to have application-specific sizes. What they do all share is a compact design.
Just like an M.2 device for a PC, the installation of the processor boards requires a screwdriver. On the one hand, this can be inconvenient if you do not have a screwdriver in arm's reach. On the other, it does make for a very secure connection.
As mentioned before, since the processor boards are so limited in size, additional features like a reset button, in-circuit programming header, and USB-C connector are located on the carrier boards. Keep this point in mind because you'll need to buy a pair to make full use of the MicroMod ecosystem. Or, you will need to design a DIY carrier.
In addition to the boards themselves, SparkFun is also selling a five-pack of the MicroMod connectors. These are useful in combination with the design guide to create your own carrier boards.
The new MicroMod boards are available today. Prices range from $6.95 to $19.95 for most MicroMods. The one exception is the Input and Display carrier with the 2.4-inch TFT screen, which is $59.95. For more information, check out SparkFun's MicroMod product page.