On a Palm III, the backlighting and the serial port draw about the same
amount of power. If you leave the serial port open 100% of the time, you
reduce the unit's operation time dramatically (to less than 40 hours of
continuous operation, even less if you also have the backlighting on). If
you turn on the port only when you need to transmit and receive data, and
leave it closed while waiting for the next opportunity you most likely won't
even notice much of a change in battery life.
I've had test (with the serial port in operation 300ms out of every 2 secs)
last for 80hrs.
Also, it might be a good idea to allow your application to discontinue using
the serial port as soon as the low battery condition is detected. The Palm
can retain its memory for days even after this condition is met as long as
serial port operations are suspended and you allow the unit to power off.
>-----Original Message-----
>From: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
>To: Palm Developer Forum <[EMAIL PROTECTED]>
>Date: Monday, January 31, 2000 7:33 AM
>Subject: Serial Port Recommendations...
>
>
>>I have an application which talks to external hardware once every second
to
>>retrieve 5 or fewer bytes of data at 2400 bps.
>>
>>My question --> is it more power efficient to:
>>
>>A) Turn serial port on, ask for data, get data, turn serial port off, wait
>>one second, and repeat ad infinitum.
>>
>>OR
>>
>>B) Turn serial port on @ start, ask, get, wait, ask, get, wait, ...., turn
>>serial port off @ end.
>>
>>In other words, for most of the time (nearly 100%), I am not transferring
>>data. Leaving the serial port open while I wait seems to be a dumb thing
to
>>do, unless the open/close cycle draws extra power somehow. Anyone know
>>about this?
>>
>>Also, does anyone know roughly how long a Palm III(e/x) lasts if left on
>>with serial port open and backlight on? With backlight off?
>>
>>Thanks all,
>>
>>Kris Wilk
>>ReefNet Software
>>www.reefnet.on.ca
>>
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>>
>
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