Motorcycle Diaries

Don’t play with the bike’s settings while the engine isn’t running? What were they thinking?

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By Jon McDonald
I recently had reason to add another vehicle to my household. My son is starting to drive, so he’s taking my car. Instead of another car I decided to get a motorcycle. I have had a couple, but it’s been a few years.

After much browsing I decided on a Ducati, I picked it up a few weeks ago. It has an impressive number of user adjustable electronic controls, everything from ABS, traction control and computer controlled throttle. It’s a fun bike with plenty of power. The dealer made an interesting suggestion: The bike has quite a few settings and adjustments that can be made by the user, but he said to be careful not to play with the settings too long while the bike is not running. The electronics consume significant power and apparently don’t reduce the power draw much when the bike is on but not running. I guess they didn’t invest much in standby power for the electronics.

For a motorcycle that isn’t generally turned on when it’s not going to be running this probably isn’t a big deal, but it reminded me of conversations I’ve had with designers who don’t feel they need to design for anything except max power. The idea is that if you’re not running on a battery, power isn’t a big deal. I remember some statistics that had been published by Cisco a few years ago, which had shipped 5 million systems over a two-year period. If each system had conserved 1 watt they would have saved 16 million kilowatt hours of electricity per year. That would have eliminated the equivalent CO2 emissions of 12,000 cars. Even though they were plugged in they still realized the impact of power efficiency when you scale to a large number of units.

With a quick Google search I found a more current reference from standby.lbl.gov, “An individual product draws relatively little standby power, but a typical American home has forty products constantly drawing power. Together these amount to almost 10% of residential electricity use.” This is a significant impact on our energy consumption and a result of the attitude that power efficiency isn’t important for plugged in applications.

Historically hardware designers didn’t have the tools to design for much more than peak power considerations. Using current tools and languages, namely transaction-level modeling, TLM2.0 standards and ESL design methodologies, I’ve worked with customers optimizing their applications for all aspects of power use. Optimizing and balancing peak power for an application is an important factor. In fact, with the ESL approaches the peak power can be much more precisely characterized for an applications workload compared to approaches relying on spreadsheet worst case analysis. In addition to the peak power we can quantify the effects of low power and standby modes tuning the power draw to the workload that needs to be processed.

Subjectively I believe there has been growing recognition that all types of power consumption should be intelligently designed. We, as consumers, are going to use power to run all of the electronics we need to get through the day, but we are realizing that our electronics can and should be tuned to use only as much power as needed to do the work we are asking them to do. We, as designers, are realizing that the power efficiency of our designs is impacting the success of those designs in the market.

—Jon McDonald is a technical marketing engineer for the design and creation business at Mentor Graphics.