editor's blog
Subscribe Now

An Orientation Sensor

We now have a new category in the IMU world: Bosch Sensortec has announced the first of what they call Application-Specific Sensor Nodes, or ASSNs. They have dubbed this particular device an Absolute Orientation Sensor. It looks strikingly like an all-in-one sensor hub, with an accelerometer, a gyro, a magnetometer, and a 32-bit ARM-based microcontroller (source not disclosed).

The difference is that a sensor hub per se leaves the software to be executed on the micro pretty wide open for the user to define. The BNO055, by contrast, is really intended to combine the motion sensors via built-in fusion on the micro so that it looks like a higher-level orientation sensor. It essentially bumps up the level of abstraction, burying the sensors and micro inside something more akin to a black box. Data is communicated pre-computed as quaternions rather than raw.

Power is addressed by allowing a stand-by mode where the gyroscope – always the power hog – can be put to sleep. When the accelerometer detects motion, it can then wake the gyro – which responds in a few nanoseconds – so that it can intercept any rotational motion. This assumes, of course, that any rotation missed during that wake-up is negligible. (Quick math sanity check says that if an object rotates, say, 6 degrees in 10 ns, then that’s 60 degrees in 100 ns or a full rotation in 600 ns… divide by 10 to get 60 ns, multiply by a billion to get 60 s, so that would be 100,000,000 RPM… yeah, not even Washington DC can spin anything that fast…)

So full power is around 11 or 12 mA; in motion-wakeable stand-by it goes down to 150 µA. If you put everything to sleep and wake it through I2C instead, you can get down to the 20-µA range.

You can find more on this device in their release

Leave a Reply

featured blogs
Dec 13, 2019
Long gone are the days of simply selling a selling a part, pins in plastic if you will. Between environmental standards, qualification testing, UL ratings, and thermal models; customers have come to expect information about the products they purchase as well. Thermal modeling...
Dec 13, 2019
I'm a firm believer that you can'€™t have too many LEDs; "Show me a flashing LED, and I'll show you a man drooling!"...
Dec 13, 2019
[From the last episode: We summarized the last several weeks of computing posts.] We'€™ve talked about processors and we'€™ve talked about several kinds of memories. Today we'€™re going to focus in on the memory used when a program is running. We'€™re not talking abou...
Dec 13, 2019
Do you know what known good die are? Do you know what wafer sort is? Final test? Wafer Sort After a wafer has been manufactured in the fab, it usually (but not always) goes through wafer sort. This... [[ Click on the title to access the full blog on the Cadence Community sit...