21 Hrs, How?

[splat]

Can anyone explain to me how iRex are able to claim that the battery will last 21hrs, when from reading they are a good bit off that (8-10hrs).

Surely if iRex seem to know that they can get 21hrs out of the battery, it should be pretty easy to implement.

Am I missing something?

[jæd]

Originally Posted by splat

Am I missing something?

Its the Science of "Marketing"... Its what makes Vista the most secure os, evah, and what gets Hugh Hefner laid...

[scotty1024]

Originally Posted by splat

Can anyone explain to me how iRex are able to claim that the battery will last 21hrs, when from reading they are a good bit off that (8-10hrs).

Surely if iRex seem to know that they can get 21hrs out of the battery, it should be pretty easy to implement.

Am I missing something?

I don't think they are claiming 21 hours any more.

Their original goal was based upon using an Intel CPU used in many cell phones, an e-Ink panel and a bunch of stuff that would be powered down most of the time: wifi, wacom, ethernet.

From my own investigations it seems things went wrong with the buttons, which should have been the easiest thing to get right...

[Riocaz]

## Very low power: You can read three hours a day for more than one week, from the iLiad without recharging the battery.

3*7=21

Looks lik this is still claimed on their website...

[scotty1024]

I guess they missed some scrubbing.

[Malder1]

Currently CPU in iLiad always works with frequence 400 MHz. iRex plan to slow down CPU for time between page turns in PDF reader, for example.

[scotty1024]

Yep one of these days iRex will grab the bull by the horns and update this code...

linux-2.4.19/arch/arm/mm/proc-xscale.S

/*
 * cpu_xscale_do_idle(type)
 *
 * Cause the processor to idle
 *
 * type: 
 *   0 = slow idle
 *   1 = fast idle
 *   2 = switch to slow processor clock
 *   3 = switch to fast processor clock
 *
 * For now we do nothing but go to idle mode for every case
 *
 * XScale supports clock switching, but using idle mode support
 * allows external hardware to react to system state changes.
 */
        .align  5

ENTRY(cpu_xscale_do_idle)
        mov     r0, #1
        mcr     p14, 0, r0, c7, c0, 0           @ Go to IDLE
        mov     pc, lr

iRex haven't released any details to enable me to even make an educated guess as to what to suggest they insert here. All I can do is plant a flag and see if they salute it.