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A Hardened Hub

There’s a new 9-axis motion sensor hub in town. Called SENtral, it’s a collaboration between PNI Sensors, known for geomagnetic sensors and fusion, and EM Microelectronics, a division of Swatch, whose focus is on ultra-low-power circuits. And it has its own twist.

Given EM’s focus, it should come as no surprise that this hub’s claim to fame is low power: they say it uses a small fraction of the power of the next competing microcontroller-based sensor hub solution. The exact value of that fraction is still being finalized; the press release quotes a conservative 10%. Some actual numbers are looking more like 1% (depending on which processor you compare it to), so they’re settling more on a preliminary value of 5%. That’s 5% of the competition, not 5% less than the comp.

So you might wonder, how did they get their microcontroller to draw so much less power? And the answer is, because it’s not a microcontroller running fusion software: they’ve hard-coded the fusion algorithms as an ASIC. So that answers one question: you’re not going to get source code to tweak if you want to adjust the fusion algorithms.

Since the focus here is on motion, you might understand this as meaning that motion algorithms are pretty much set; do the math and deliver quaternions. But it’s not all about pure math. You may want to tweak how magnetic anomalies are rejected, for example.

So they’ve built in some knobs – register values – that can be adjusted when you configure the device. There’s a bitstream that loads on start-up, and this configures the device for the sensors you’ve chosen (all of which are a bit different); you can also use this to tweak some of the algorithms (although, to be clear, you do this via a graphic interface, not by manually tweaking a bitstream, just in case that sounded scary).

You can find out more about what’s going on with their release.


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