Single Board Computers as Controllers for Embedded Systems Projects

Any embedded computing device, whether it’s a mobile device, part of a sensor network, or any other system, carries some specific requirements. These include processing power, memory, wireless and copper communication capabilities, and I/O interfaces for sending/receiving data. If you’re an embedded systems developer, you’ll need to build a platform for prototyping and full-scale production of your systems.

In the realm of working with pre-made development boards, we’re not talking about something like a simple Arduino microcontroller board. These boards can be used for simpler computing or data capture tasks, but they don’t have the processing power required for applications that carry extreme computational burden. Instead, you’ll want to use something closer to a single board computer. This saves you some costs and lets you focus on other important design aspects, such as user experience, networking, and your embedded software.

To Build or Not to Build?

While you might be tempted to develop and manufacture your own boards, you can also go the route of designing your board on top of a single board computer or other embedded controller. Building or buying an embedded controller is one of the classic dilemmas for any embedded systems designer. Going the route of building your own controller board gives you the opportunity to customize your board to the desired form factor, level of integration, and set of components.

In contrast, buying a pre-made board allows you to eliminate the expense of designing, prototyping, testing, and producing your own embedded controller. The pre-made boards on the market contain significant functionality built directly into the board, allowing you to take advantage of a ready-made, fully-functional hardware platform. You can then focus on the software development side of your system, which can consume a significant portion of any development budget.

Important Embedded Controller Performance Metrics

There are a number of ways to measure the performance of an embedded system. Some of the most important are listed below:

• On-board memory: Memory on an embedded controller comes in several forms, including RAM, Flash, EEPROM, and even solid-state memory. If your board only comes prepackaged with a small amount of memory and you know that your application is computationally intensive, then it’s a good idea to choose an embedded controller with an SD card expansion slot. This allows you to add multiple GB worth of memory to your board with reasonably fast read/write speed.
• Processing power: This is simply the speed of your processing unit, whether it’s an FPGA, GPU, or CPU. Many commercially available boards offer GHz processing rates with reasonable cost.
• Connectivity: This spans across everything from GPIO, USB, UART, Ethernet, and other protocols over copper. HDMI might also be desired if your system will interface with an external display unit. This can also include wireless capabilities like WiFi, Bluetooth, GPS, LoRa, or other protocols.
• Extensibility: This is related to connectivity somewhat in that you might want to add some other modules to your controller that provide the desired functionality. If you are connecting your system to other devices, be sure to check connector compatibility when designing your system.

Processors for embedded systems that run at high MHz to GHz speeds can consume significant power, leaving your system vulnerable to shutting down in the event it cannot access backup power. This should also be considered during design, and you should calculate the battery size required to keep your controller online for the required duration. The great thing about using a pre-made embedded controller or single board computer is that they already contain the required power regulation circuitry, and you only need to worry about power consumption.

Digi International CC-SBE-WMX-JN58

The CC-SBE-WMX-JN58 module from Digi International is built on a 528 MHz CPU from NXP Semiconductor with 256 MB of onboard DDR3 RAM. This board contains numerous connectors for interfacing with other modules, a microSD slot for expanded storage, USB and Ethernet ports, and other connectivity options (ADC, GPIO, I2C, JTAG, PWM, SPI, UART). The expandable memory and wireless capabilities (WiFi and Bluetooth 4.2) provided by this controller makes it ideal for embedded applications with low computational burden and high data storage demands. Some examples include remote image capture and real-time sensor monitoring.

Photograph of the CC-SBE-WMX-JN58 single board computer. From Digi International.

BeagleBoard PocketBeagle-SC-569

The PocketBeagle-SC-569 module is an excellent for a small embedded controller. This board runs on a 1 GHz ARM^® Cortex-A8 with 512 MB DDR3 RAM and is compatible with a customized Debian GNU and the Cloud9 IDE on Node.js w/ a custom library. This board is also expandable with a microSD card. This board comes at a lower price point than the previous board, although this board lacks integrated wireless communication. You can purchase expandable connectors for a shield board that will support WiFi, cellular, or other communication protocol.

Size comparison of the PocketBeagle-SC-569. From BeagleBoard.

Pi Supply PIS-0531

The PIS-0531 single board computer is closer to a maker’s dream, although its capabilities make it desirable for intense computing applications that require fast processing speed and high memory. This board features a Quad core 1.8 GHz ARM^® Cortex-A17 CPU, 2 GB LPDDR3 memory, Gigabit LAN, Bluetooth 4.0, 802.11 b/g/n Wi-Fi, and 4 USB 2.0 ports. It also includes a 40-pin header with 28 GPIO pins.

The Pi Supply PIS-0531 single board computer. From the PIS-0531 datasheet.

The computing options for your next embedded systems projects don’t end with the components presented here. Octopart offers access to a huge range of single board computers and other components you’ll need to build your next embedded system. Try using our Part Selector guide to determine the best option for your next product.

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