Like nearly all industry events over the past 9 to 10 months, this year’s Embedded Tech Trends was held virtually. It was good to see the faces—via Zoom—of all my old friends in the embedded boards industry and in the technology media. Among the hot-button topics discussed that were of interest to me is the work by PICMG (PCI Industrial Computer Manufacturers Group) toward enabling standards in industrial IoT.
I’ve talked before in this column about why there’s no need to wait for standards when it comes to building out IoT implementations. All the building blocks for IoT have been with us for several years now. And while of course you have to choose your wireless protocols, every IoT situation is so different that “architecture” standards aren’t really necessary. All that said, what PICMG has been working on for over four years is aimed at industrial IoT (IIoT), where there are certain requirements that make interoperability and formfactor standards desirable. There’s a compelling argument for linking an IIoT network architecture and an edge device form factor to PICMG’s embedded computing standards like COM Express and others.
In the microcontroller-centric mindset that I have as editor of Circuit Cellar, one piece of PICMG’s series of IIoT-related open standards caught my attention in particular. The Micro Sensor Adapter Module (MicroSAM) is the first of these PICMG standards to reach ratification (in October 2020). At the ETT event, Doug Sandy, PICMG’s Chief Technical Officer provided a great presentation about MicroSAM and why it’s significant. MicroSAM is an open specification that defines a 32mm × 32mm module hardware platform for traditional sensor vendors wishing to quickly create smart sensors. MicroSAM enables a fundamentally different IIoT architecture, offering a distributed architecture with true Plug and Play network integration.
According to PICMG, MicroSAM fills a need that’s never been addressed by other industry specifications: a compact module targeted at microcontrollers for each of the Industrial IoT sensor nodes. The processing performance and I/O connectivity are targeted toward the sensor interface. MicroSAM may exist in parallel with other embedded technologies, where MicroSAM devices provide sensor connectivity, and PICMG standards such as COM Express, CompactPCI Serial or MicroTCA provide higher layers of control.
From what I understand, MicroSAM isn’t designed to compete with the current crop of microcontroller-based open-sourced platforms. Instead, PICMG says that MicroSAM extends and co-exists with that ecosystem by offering a standards-based solution that has been designed specifically for embedded use. Industrial operating temperature range, power filtering and robust connectors are some of its key advantages.
The benefits MicroSAM to the IIoT industry come down to three key aspects: (1) Enabling sensor vendors to create smart sensors without having to manufacture the control circuitry and/or software by purchasing these components from PICMG-compliant suppliers. (2) Enabling microcontroller suppliers who wish to create smart sensors or smart-sensor components to do so in a way that is interoperable with other suppliers. (3) Accelerating the uptake of smart-sensor technology through open-specifications and interoperability.
The MicroSAM’s basic features include full industrial operating temperature range from -40°C to +85°C along with power filtering and signal conditioning for embedded installations. Connectivity includes RS422 communications link and direct connectivity to a variety of sensor types (analog voltage, analog current, digital). The spec also includes latching connectors for secure connectivity and PWM output for motion control applications. It provides hardware interlock and trigger signals for synchronization.
The MicroSAM module’s roles include managing sensor/effector sampling and formatting the sensor/ effector data for presentation to the network. An Aggregator coordinates the activities of multiple MicroSAM modules while a Bridge interconnects the MicroSAM point-to-point communication channel with a higher-level shared network.
It’s exciting to see this move toward an open standard form factor for IIoT edge sensor functionality. I plan to follow MicroSAM as its adoption grows and implementations roll out.
PUBLISHED IN CIRCUIT CELLAR MAGAZINE• MARCH 2021 #368 – Get a PDF of the issue