editor's blog
Subscribe Now

We Won’t Call You; Just Call Us

One of the challenges with sensors is that, at their most fundamental level, all they do is provide some value reflecting whatever it is they’re sensing. If you want to know that value, you have to go get the value. “You” typically being the main processor in the system.

That’s easy enough if it’s something you occasionally do under the direction of a program, but if you want the sensor to alert you when something happens, then you have to poll constantly so that you know when something changed. That can steal a lot of cycles from the processor, and can be a particular issue for smartphones that have lots of sensors.

I had a discussion about this with Bosch Sensortec’s Leopold Beer at the recent MEMS Executive Congress. He said that with their IMUs, polling still dominates, but that they’ve got a state machine in there that can be programmed to fire an interrupt; their interface supports both polling and interrupts.

For example, the unit has an auto-sleep mode, and can be programmed to wake itself up. You can program in thresholds and timing. You can have it fire an interrupt when changing between portrait and landscape modes; the angles and hysteresis levels are programmable. This relieves the application processor of some of the more mundane polling duties.

For more complex tasks like counting the number of steps you take when running, much more processing is required, so for those tasks the processor still has to go poll the sensor and do the data munging itself.

One solution is to have a separate sensor microcontroller that can manage multiple sensors to offload some of the application processor duties in a programmable way.

A dedicated microcontroller on the same die as the sensor might make sense for so-called “sensor fusion” applications – where the “sensed” state isn’t just the result of a single sensor or even sensor type, but the accumulation of data from numerous sensors synthesized into a single combined more “intelligent” state. It’s certainly possible from a technology standpoint; the only question is whether the cost is justified.

Something to watch for as sensors continue to populate the world…

Leave a Reply

featured blogs
Sep 25, 2020
[From the last episode: We looked at different ways of accessing a single bit in a memory, including the use of multiplexors.] Today we'€™re going to look more specifically at memory cells '€“ these things we'€™ve been calling bit cells. We mentioned that there are many...
Sep 25, 2020
Normally, in May, I'd have been off to Unterschleißheim, a suburb of Munich where historically we've held what used to be called CDNLive EMEA. We renamed this CadenceLIVE Europe and... [[ Click on the title to access the full blog on the Cadence Community site...
Sep 24, 2020
I just saw a video from 2012 in which Jeri Ellsworth is strolling around a Makerfaire flaunting her Commodore 64-based bass guitar....
Sep 24, 2020
Samtec works with system architects in the early stages of their design to create solutions for cable management which provide even distribution of thermal load. Using ultra-low skew twinax cable to route signals over the board is a key performance enabler as signal integrity...

Featured Video

Latency-Optimized PAM-4 Architecture for Next-Generation PCIe

Sponsored by Synopsys

This video presentation briefly describes how DesignWare® IP for PCIe® 5.0 is minimizing risk and accelerating time to market, and what Synopsys is doing to help designers prepare for next-generation PAM-4 PCIe 6.0 designs.

Click here for more information about DesignWare IP Solutions for PCI Express

Featured Paper

Helping physicians achieve faster, more accurate patient diagnoses with molecular test technology

Sponsored by Texas Instruments

Point-of-care molecular diagnostics (PoC) help physicians achieve faster, more accurate patient diagnoses and treatment decisions. This article breaks down how molecular test technology works and the building blocks for a PoC molecular diagnostics analyzer sensor front end system.

Read the Article

Featured Chalk Talk

Intel NUC Elements

Sponsored by Mouser Electronics and Intel

Intel Next Unit of Computing (NUC) compute elements are small-form-factor barebone computer kits and components that are perfect for a wide variety of system designs. In this episode of Chalk Talk, Amelia Dalton chats with Kristin Brown of Intel System Product Group about pre-engineered solutions from Intel that can provide the appropriate level of computing power for your next design, with a minimal amount of development effort from your engineering team.

Click here for more information about Intel NUC 8 Compute Element (U-Series)