Slashdot Mirror
Guide To Designing Low Power Handhelds
randomErr writes "iAppliance had a nifty article about designing handhelds. As the state-of-the-art in low-power CPUs races forward, the CPU becomes one of the most critical components in the design of a handheld. New CPUs such as Intel's XScale, Alchemy Semiconductor's Au1000, and Transmeta's Crusoe provide the ability to scale clock frequency and voltage dynamically. As power consumption varies linearly with clock speed and as the square of core voltage, you'll want to have hardware hooks to be able to adjust both clock speed and voltage as necessary, based on device performance."
Just to point out to anyone who doesn't know, AMD aquired Alchemy Semiconductor.
Palm systems are curently on top. They may only be B&W, but they get great battery life and do what most users need. Once you start entering the realm of music, that can be scaled over to an MP3 player instead of a Palm device.
However, once you start deciding to run higher end applications, give the machines net connects, etc. everything gets more complicated. Full color, integrated (or even unintegrated) 802.11b, sound and so on all drain batteries at an increased rate. My keyboard for my palmtop drains when it's plugged in, which is, obviously, why it's not plugged in all the time.
Battery life and functionality are both the keys. Is there a potential way to implement a self charging feature? Maybe harness the kinetic energy of movement to assist in charging the device? Most people with handhelds carry them everywhere. It wouldn't work well with high drain / low charge devices, like the Ipaq, Jornada, etc. which have charges of under 10 hours (at best) but maybe a system like this could achieve a few days or a week in a low drain device like a Palm m100.
I have no idea. Just a decidedly random thought that I had. Later.
There are some good reasons why devices still use alkaline batteries instead of rechargable:
:)
- It's cheaper. Making the user buy AAA cells is cheaper than an expensive built-in rechargable. Be angry if you want, but the same shoppers that gripe are the ones that will pick the AAA model because it's $10 cheaper.
- Charger required. more $$$, bigger packaging, more travelling weight, country-specific voltage, UL Listing, the works.
- Alkalines last longer (per charge) than rechargables. On a device may go weeks without seeing a charger, this counts.
- Rechargable cells die. What do you do with a PalmV that no longer charges well? LiIon cells only last a year or two before they start to degrade quickly.
I'm not saying that these are valid reasons to require disposable batteries, but these are factors that manufacturers look at in deciding which way to go.