Using SBCs to “Sense” at the Edge

September 29, 2020 GEORGE HILLIARD, WINSYSTEMS

The IoT is all about what’s happening at the Edge. The sensors absorb the information in some manner, and that could range from a simple temperature sensor all the way up to some sort of number-crunching device that receives data from various sources (also known as sensor fusion). In some cases, computations occur at the Edge, a decision is made, and an action is carried out. In other configurations, the data is sent back to the Cloud to perform the calculations, then the decision is transferred back to the Edge so the action can be performed.

The latter operation is now reserved for more complex applications, as the compute power that resides at the Edge is far superior to what was available just a few years ago. And the reasons for containing as much data at the Edge as possible are many:

  • Processing occurs faster, as any latencies associated with sending data to and from the Edge are removed
  • Costs are reduced, as the potentially expensive medium (cellular) is not needed
  • Security remains high, because the data never leaves the premises

To that end, the latest round of single-board computers (SBCs) are being designed either with sensors themselves, or the I/O that’s needed to connect to various sensors. For example, the WINSYSTEMS PCM-MIO-A-1, PCM-UIO48C, and PCM-UIO96C PC/104 modules offer expanded I/O options that provide a way to access both sensors and data-acquisition devices. Thanks to the modules, the Edge device can take in the information, then feed that back to the control loop, or the Cloud if necessary.

(The WINSYSTEMS PCM-MIO-A-1 expansion module is built to the PC/104 form factor. It features 48 lines of digital I/O (GPIO). To maximize configurability, each of those can be individually programmed for input, output, or output with readback.)

The PCM-MIO-A-1 is a data-acquisition module that incorporates 16 analog-to-digital inputs, eight digital-to-analog outputs, and 48 bi-directional digital I/O, all in a single module. The highly versatile PCM-UIO48C-16 I/O module provides 48 digital I/O lines, which allows it to monitor 24 lines for both rising and falling digital edge transitions, latch them, and then interrupt the host processor notifying that a change-of-input status has occurred. The PCM-UIO96C-16 ups the number to 96 lines of digital I/O, providing the ability to monitor 48 of the 96 lines for both rising and falling digital edge transitions. Like with the PCM-UIO48C-16, this is an efficient way to signal the host CPU of real-time events without having to poll the digital I/O.

The Serial Port: “I’m Still Here”

Another feature that is a benefit to sensor-based applications is the venerable serial port. I know, you’ve heard it before. Serial ports are going away. Frankly, I don’t see that happening in the short term. Our clients keep demanding them for the simple reason that they operate as expected and there are still so many serial devices to connect to. That includes RS-232, 485, and 422.

USB and Ethernet are both ubiquitous in the industrial IoT space with numerous sensors and converters available for both architectures, from cameras to controls. However, we’re now witnessing the appearance of more traditional board-to-board communication, such as I2C, SPI, and UART, as they generally have adequate bandwidth for most analog sensor applications. Prototype modules for testing these simple interfaces are readily available. In addition, WINSYSTEMS can help clients design their own sensor modules using a header or PCB-to-PCB connector.

A good example of the expansion capability is the IO80 connector on WINSYSTEMS’ SBC35-427 industrial SBC, that takes advantage of Intel’s Apollo Lake-I E3900 series processor. That connector can be customized in various configurations, depending on the needs of an application. For example, the connector can be used for expansion and various configuration options for semi-custom solutions, including those based on sensors.

Another example is the Multi-I/O connector on the ITX-P-C444 industrial Pico-ITX SBC. The connector provides access to RS-232/485/422 configurable serial ports, I2C, and SPI, which makes it easy to add custom sensor modules. Regardless of the sensor, numerous connection options are available.

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