By Alix Paultre, GlobTek (www.globtek.com)
With embedded systems expanding into more and more spaces, we need a combined power & signal cable and connector standard (or series of standards) to allow developers to focus on the subsystem design with fewer concerns about integration. It would also be nice if we had an industry term for the concept of an integrated power and signal cable as well, since they’ve been around for a while now.
As devices become more sophisticated and functionality is added to address customer needs, the ability of a device to perform more tasks will increase to meet both designer ability and customer desires. One example can be found in the area of motion control, where we already have micromotors, vibrators, and ultrasonics as well as other advanced motion devices in many products. As these motors and actuators become larger, they will demand more and more power from the system bus while also requiring guidance from the user and the system logic. Displays, illumination, and other power-hungry peripherals also increase the total product power consumption while demanding proper integration into system functionality.
There are a few recognized combined signal and cable standards currently in existence, and in some cases these interfaces have been taxed to the extreme to support applications they were never designed for. A notable example can be found in standard Power-over-Ethernet systems, where a connector and cordset never designed to carry both power and signal are taxed to do the job. Some standards, like Firewire and USB were designed from the ground up as power/signal interfaces, but the emphasis in both cases was on the high-bandwidth signal they were intended to carry and thus have limits on cable length and power capacity. In the case of the signal component for a power-oriented infrastructure, an I2C-based configuration would allow use of protocols like SMBus and PMBus as well as other command-based architectures.
Most embedded systems don’t need high-bandwidth data exchange with other subsystems and device logic along the level of video streaming or large file downloads, they need caretaker data, sensor info, system commands, and other system infrastructure management. A power-oriented device infrastructure interconnect standard would allow for a basic functionality set that every designer could depend upon when designing a subsystem. There could even be several versions addressing specific application categories, providing some flexibility in selection and deployment.
There are quite a few proprietary signal/power solutions out there addressing this need, but the availability of a standard would allow the designers to focus more on what their subsystem does and less on how they have to integrate it into a larger product.