[Announce] Lanterne - an all-purpose flashlight app - Page 10 - maemo.org

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sixwheeledbeast	2013-06-02 , 09:45
Posts: 2,290 \| Thanked: 4,133 times \| Joined on Apr 2010 @ UK	#91

Originally Posted by malfunctioning

If I'm understanding this correctly, running a 1:2 duty cycle (for example 50ms flash duration and 50ms strobe pause) at 320mA would be equivalent to an average current of 160mA (3.2 times the maximum continuous current). So probably not good to run that cycle for a long time, correct?

Yes exactly.
Also bear in mind the chip will allow flashes of upto a scary 500mA.
I am glad it has been pinned down to 320mA here with only a push and hold type option.

Another safeguard that could be used is a maximum strobe duration QTimer for each mA/pulse value. It would be best if we had some more knowledge of the LED's limits.

Personally I have the strobe option on 30ms pulse, 200ms pause, and 215mA, I wouldn't suggest using that for a long period of time.

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	Copernicus	2013-06-02 , 09:50
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The ADP1653 data sheet shows two different modes for flash timing -- one of them is a set of 16 timeout values, ranging from 54.6 msec to 820 msec in multiples of 54.6 msec. The other is to keep the flash lit for as long as a particular input is held high, up to a maximum of 820 msec. As the supported V4L2 timing values go from "0-500" (and appear to be millisecond values), I was guessing that the second mechanism was in use, not the first...

In any case, I'll try to reconfigure the strobe controls to be a bit more cautious. Setting up the pause in terms of a duty cycle, rather than a raw timing value, sounds like a good idea for one thing.

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	Copernicus	2013-06-02 , 09:53
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Originally Posted by fw190

All the torch apps have a nice option to start from status menu. Would it be possible to have such thing here or will this mess up the app?

I think I could do that; I've never tried to play with the status menu before, though, so I'll have to figure out how it's done.

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	Copernicus	2013-06-02 , 10:01
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Originally Posted by sixwheeledbeast

Yes exactly.
Also bear in mind the chip will allow flashes of upto a scary 500mA.
I am glad it has been pinned down to 320mA here with only a push and hold type option.

Yeah, the supposed V4L2 limit is 320mA; however, the "strobe-test" code on this page was using a setting of 25 (which would be 410mA), so I don't know that 320mA is the absolute limit. But I'm not going to chance it...

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sixwheeledbeast	2013-06-02 , 10:27
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Originally Posted by Copernicus

Yeah, the supposed V4L2 limit is 320mA; however, the "strobe-test" code on this page was using a setting of 25 (which would be 410mA), so I don't know that 320mA is the absolute limit. But I'm not going to chance it...

I was speaking of the ADP1653.
This doesn't mean the V4L2 or LED's limits match I agree.

http://www.analog.com/en/power-manag...s/product.html

http://wiki.maemo.org/N900_Hardware_Flash_Torch

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biketool	2013-06-02 , 12:08
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Is there also a red LED in the camera flash? Can't remember if I have seen this or not on my N900. If there is then a red LED flashlight mode might be useful for low light situations where white would cause night blindness.

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	qwazix	2013-06-02 , 12:20
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Originally Posted by Copernicus

- The red (indicator) LED is now supported. You can now select "Use Indicator LED as Torch", after which it will be used instead of the flash LEDs for all torch functionality (normal torch, SOS, Morse code, etc.) Also, you can vary its brightness, with seven levels going from a low of 2.5 mA to a high of 17.5 mA.

I think you're late :P

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saponga	2013-06-02 , 12:27
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Originally Posted by biketool

Is there also a red LED in the camera flash? Can't remember if I have seen this or not on my N900. If there is then a red LED flashlight mode might be useful for low light situations where white would cause night blindness.

Actually, i think they're talking about the front led (notifications).

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	pichlo	2013-06-02 , 13:37
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Originally Posted by saponga

Actually, i think they're talking about the front led (notifications).

No, about rear LEDs. There are two high power white LEDs used as a camera flash (only controllable as a unit, not individually) and one low power red indicator LED used to indicate that video is recording. Lanterne can be switched to control either the white or the red LED.

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malfunctioning	2013-06-02 , 18:56
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Originally Posted by pichlo

Spot on!

(Except that I like to think of 50 ms on, 50 ms off as a 1:1 duty cycle. 1:2 would be 50 ms on, 100 ms off. To avoid confusion, it is better to use percentage terms as per this Wikipedia article.)

Thank you, pichlo. As I was writing my question I actually was wondering if the format was <on_time>:<off_time> or <on_time>:<cycle_time>.