Comment by supernova87a | Hacker News Reader

Comment by supernova87a | Hacker News Reader

I have a beginner's question about sensors and chips, for the experts out there:

When chip hardware gets faster, or you read about such developments as cramming more and more functionality onto the sensor, does that mean the package could draw less and less power and do the same functions as previously for less energy?

Suppose this chip's function were (as in the article) to image a scene and decide whether to send the image over wireless to a central monitoring station.

As the chips get more capable, does that mean less power is used compared to before, to do the same function? Or are there overheads that dominate the power consumption for such under-utilization of a chip? Is there a rapid falloff in benefit of the "advanced-ness" of a chip for such applications where you really don't need such sophistication, and rather have energy-conserving, simple design? Will this really lead to months more lifetime for a remote sensor powered by battery?

(sorry if some of my nomenclature is imprecise, but hopefully you get the idea of the question)

If comparing for the _same_ functionality, power consumption will typically reduce unless it is dominated ny other components. Both positive and negative examples below to explain:

* An audio amplifier: Power consumption is ultimately dictated by the energy conversion to sound and the conversion efficiency of the speaker. The system will consume at least that much irrespective of the technology developments. In practice however, the efficiency of the amplifier also comes into play. The static power drawn by an efficient amplifier would be much less than the above basics for creating sound, and so going to higher technology nodes would make much less percentage difference.

* Computations in a digital circuit: Power consumption in these is sometimes dominated by communication (interconnect; bus) like between processor and memory. If the bus is internal to the chip, advancing to a new technology node would typically result in power reduction.

* If the power is dominated by computations alone, there would surely be power reduction, again assuming the functionality is held constant. Circuits have static leakage power too, which happens irrespective of the computations, however, it is still usually lesser than dynamic power by design.

Typically however, more and more functionality is frequently added like in this case of computer vision added to the sensors, which results in an overall increased power consumption to an extent that the customers will accept (e.g., battery life asked for).

Back to this specific case of computer vision on the "edge":

Having the same functionality achieved by having computer vision on the sensor itself vs. the cloud, can result in orders of magnitude savings in power. There is a lot of power associated with transferring the data back and forth. Even if computations are handled by a processor on the same board as the sensor, significant power is spent as compared to when the communication lines are avoided.

Related: https://news.ycombinator.com/item?id=23202839

Thanks!

Not necessarily. It usually means more transistors were fit onto the board in order to increase computation, which usually increases power consumption. But improvements can come from several means, such as a new type of transistor, fabrication method, material, etc that could reduce power consumption.

answer is: it depends.

If it's doing new things like running inference (say, recognizing things using a machine learning model) it might take more power.

But sometimes it could use machine learning to replace previous functions and do it better with less power.

one example I can think of - most cameras have some sort of "motion detect" function. If machine learning could recognize people or cars or whatever is "interesting" better it might give fewer false positives, or transfer data less often. It might even use less power.

On the other hand, if it could detect people, and then further detect WHO they were, it might take more power.

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