About thirty years ago solid state electronics were still relatively new and circuits were typically built with discrete components and DIP style logic chips. Along those same lines, the selection of electronics prototyping kits and platforms was very limited. The selection of these kits was mostly limited to the “All-in-one” style point-to-point wiring kits. Fast forward to today and you find a plethora of various prototyping systems and platforms to choose. Without even needing mention, there is the Arduino ecosystem, which is arguably the most widely known and has the most widgets available from which to prototype with. Then there are all the Arduino form-factor compatible systems that utilize other non-Atmel based processors. There are the Raspberry Pi’s, Beagle Bone, Arrietta’s, etc, etc, the list goes on and on and ever continues to grow.
All of these platforms have their own form-factor add-on boards usually referred to as “hats” or “shields”. Sometimes though, you may want to mix and match your own selection of IO devices, sensors, and widgets, but don’t want to spin your own shield design. Sometimes it’s not the effort of designing your own shield holding you back, but instead may be the thought that this approach may lock you into a specific design and would then lack flexibility or versatility. In these latter cases, there are other options. Here is where we will discuss more about interchangeable add-on modules, such as Click by MikroElectronika, and XBee from Digi International. The “Click” name is MikroElectronika’s trademarked name for modules that adhere to their mikroBUS standard they have developed. We will discuss what these are, pros and cons of these modules and how these may be an attractive solution to your next prototyping need.
A quick disclaimer before proceeding: CascoLogix’s is in no way affiliated with MikroElectronika or Digi International or paid to promote their ecosystem. The flexibility offered with these form-factors for creating prototypes and easy interchangeability is awesome and is yet another ecosystem to be leveraged and one which many many more add-on modules will be born.
The XBee module by Digi International is a small form-factor (about 1 inch sqauare) and probably more ubiquitous as of today. The down side to the XBee form-factor is the headers used, and the design originated around a specific wireless interface, so the pinout is taylored as such. Headers used on XBee modules are a 1×10-pin header with a 2mm pitch on each side of the module. The 2mm pitch means they are not breadboard friendly, nor are they compatible with the common jumper wires from sources such as Adafruit and Pololu. The XBee pinout incorporates standard UART RX and TX signals for serial communication, and CTS and RTS signals for modules that need hardware flow control. The XBee pinout also supports several either analog or digital IO pins. Some of these IO are reserved or assigned for specific functions, usually pertaining to wireless RF communication functions (e.g. RSSI, connection status, etc.).
The Click module by MikroElectronika is also small form-factor (about 1 inch square for the smallest variant), but probably not as widely adopted. More importantly though is the male headers. Click modules utilize a 1×8-pin header with a 0.100 inch pitch on each side of the module for a total of 16 pins. This means these are breadboard friendly and are compatible with the common jumper wires mentioned above. Another up side to the Click module is the standardized pinout definition which MikroElectronica has created for the module itself and the module socket, both of which can be found on the MikroElectronika website. A slight down side to the Click module compared to XBee is four fewer IO pins. However, of the 16 pins used for the Click interface, standard communication signals are supported, such as I2C, UART and SPI. This feature makes them very versatile for accomodating many different applications and breakout boards. There are also four other individual IO pins defined for Analog, Interrupt, PWM and Reset. With the exception of the Reset pin, these other pins can of course be used for other purposes.
Casco Logix offers several XBee and mikroBUS modules on our Products page and are gradually adding various modules to our portfolio, which we use for proof of concept work. These modules are sold as ready made modules for others to use in building their systems, and the designs are typically shared on our github page. Thanks for reading and stay tuned for more in the future!