PW3: anything available to turn off LED

[knc1]

Originally Posted by encol

another difference: "echo" method switches completely off the light, "lipc" method does not: in a dark room you can see the difference!

Probably the all too common "off by one" programing error.

[geekmaster]

Originally Posted by knc1

Probably the all too common "off by one" programing error.

Ah yes, the classic "Obi-Wan" error.

I tried telling it to set the frontlight brightness to "-1", but no jailbreak resulted from that. Just an error message.

I did not have a room dark enough for visual testing at the time I posted this discovery. It looked "off" to me, and besides, after setting it to zero with lipc-set-prop, reading it back with lipc-get-prop showed that it was indeed zero. Why would kindle software lie to us?

Though it makes sense that its behavior mimics the brightness slider, which is probably just a GUI layer over this very same lipc command.

Whereas the corresponding /sys file is a kernel driver interface, which gives us a closer connection to "bare metal" reality and a greater degree of control (where zero is indeed off, and 999 is max brightness).

[encol]

Originally Posted by knc1

Probably the all too common "off by one" programing error.

I don't think it's a programming error: also in the front light slider of the UI there is the same behavior
Even setting to zero a bit of light still remains, maybe it's something wanted

[knc1]

And perhaps the author has never heard of math.floor().

[NiLuJe]

Reading it back again (form the actual sysfs entry, not lipc) shows that it actually sets it to 1 when asking lipc for 0.

(IIRC, since the issue came up a while ago in KOReader).

TL;DR: lipc indeed doesn't shut it off completely, for some strange/stupid reason.

[geekmaster]

Originally Posted by NiLuJe

Reading it back again (form the actual sysfs entry, not lipc) shows that it actually sets it to 1 when asking lipc for 0.

(IIRC, since the issue came up a while ago in KOReader).

TL;DR: lipc indeed doesn't shut it off completely, for some strange/stupid reason.

Yeah, lipc just "pushes the slider" from a script. I like the /sys interface "more better".

[Yourcat]

lipc sets the intensity to 0 which does not mean that the brightness must also be 0. Actually there are only 26 intensity values.
If it is really dark one may be happy that the brightness is not set to 0. Otherwise one would see nothing. Not stupid imho.
It's annoying that there's no sunlight button which switches it off completely.

[geekmaster]

Originally Posted by Yourcat

It's annoying that there's no sunlight button which switches it off completely.

I posted a link to my KUAL extension that DOES turn the backlight off COMPLETELY. I suppose I could rename the "turn backlight off" button to a "sunlight" button, but could be confusing (like how "airplane mode" is less clear than "radio off" was in older firmware).

[zes]

Originally Posted by geekmaster

I tested it on my PW2 and my PW3, in a very dark room, and it does indeed turn the frontlight completely off (when that option is selected). It also provides options for minimum brightness (1), medium brightness (500) , and maximum brightness (999).

Works with Kindle Voyage (5.6.5), too, thanks! Felt like a waste having the light on in scenarios when I'm reading in bright direct sunshine.

[HarryT]

Originally Posted by zes

Works with Kindle Voyage (5.6.5), too, thanks! Felt like a waste having the light on in scenarios when I'm reading in bright direct sunshine.

If you turn on the Voyage's light sensor, it turns the frontlight off (or at least sets it to its lowest level) in bright light.

[geekmaster]

It has been confirmed that my KUAL extension turns off the backlight completely on a KV as well, for people who care about that sort of thing.

[geekmaster]

Originally Posted by Cinisajoy

Question: Is this just electric stoves or gas stoves too?
Interesting discussion on radiation. Thanks for the information.

It is anything that emits photons (including electric and gas stoves), with the exception of out-of-phase coupled photos emitted from an EM-drive engine (non-EM in that state, when they pass invisibly through metal, providing the impetus required by Newton's third law). All photons are "electromagnetic", and streams or waves of them correspond to broadband or narrow-band radio transmissions. Anything at a temperature above absolute zero emits photons, with a frequency (and energy) determined by temperature. Sometimes the emitted frequencies are in the range visible to the human eye (including a campfire, at such a high amplitude you can feel it on your skin -- especially noticeable if you take your glasses off while sitting near a campfire).

Wifi is broadband (but much less so than sunlight). Individual photons of high enough energy/frequency (ionizing radiation such as shortwave ultraviolet, or x-ray) can damage DNA (e.g. sunburn). But what we call radio (including wifi and 3G) are way low in the non-ionizing spectrum, and cause no such physical damage. However, some anecdotal evidence studies suggest that continuous exposure to certain EM frequencies (such as under 50/60-Hz high-tension powerlines) affect plant growth (increase it) and may also alter or stimulate unwanted biological activity in mammals due to resonating molecules of corresponding size. Such things are more pseudoscience than science, until proven otherwise, but not necessarily impossible.

However, taking it all into perspective, yeah, sunlight. Essential to terrestrial life (but not hydrothermal life). But bathing in sunlight requires sunscreen and/or temporal moderation. I think we are safe with wifi (which uses a frequency that merely causes heating, the same frequency as microwave ovens, but at a drastically reduced power level).

[knc1]

Wifi - probably too low a power, even in the 'near field' zone.

Cell phones (and 3G Kindles) transmit a peak of 4 watts (when on - they are a pulse transmission).
The stories about those devices that get publicized do not consider 'near field' effects.

As a rule of thumb, consider "near field" less than 10 wavelengths for this post.

The peak power pattern(s) in 'near field' radiation is extremely difficult to compute.
(Well, when I was in school, it was considered impossible, but time passes, etc. ...)

So holding an antenna radiating 4 watts peak less than two wave lengths from your brain should not become a habit.
Although it has for millions of people.
I guess all we can do is wait a few generations and count the number of brain fried individuals in the general population.

"near field" :: http://www.antenna-theory.com/basics/fieldRegions.php

[Cinisajoy]

Sent you an email geekmaster.
On your power line/plant theory.

[geekmaster]

Originally Posted by Cinisajoy

Sent you an email geekmaster.
On your power line/plant theory.

I answered you back on your "coincidental placement" (i.e. utility right-of-way) theory.