LED backcover on the Fairphone 2

Is this all configurable via the USB interface?

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Yeah totally. Full control.

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HAHAHAHA :Woot: :woot: :joy: :joy: :blue_heart: :star2: THIS IS GREAT!!! Just got a flash of laughter from watching the RGB vid. It really is INSANE! And one can see, how much fun you are having, @dvl! :smiley:

Cool, well ‘like and share’ because this thing will not be cheap in small quantities.

Can you provide some specs? E.g. brightness compared to light bulbs, etc.

Sure! Specs is what it is all about :wink:

USB2.0 provides 5V at 500ma. This gives 5*0.5 = 2.5 Watt to play around with.

The circuitry to control all this (basically an uno) consumes about 20-50ma during operation. Which leaves 450ma. Choice to go for arduino compatability means you can program it yourself, plays nice with usb and there are already multiple android apps that allow phones with usb-otg to program them.

The LED is a 4 chip one (so actually 4 LEDs in one package) that is rated for 350ma per cell. This means that you could turn one on full brightness and there is still some power to spare. However, when going for white it is best to turn them all on as the efficiency of the LED goes down when the power per cell goes up.

Dimming is totally possible, all cells have full PWM. Feel free to google that yourself if you are unfamiliar with PWM.

The cells in the LED produce 430 lumen at rated power. This is about the same as what a 40W oldskool incandescent bulb provides. But if you power all cells I would say you could get some ~600+ lumens out of it. This is a lot of lumens. People will complain about the extremely bright light standing 4-7 meters away.

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Plus you would completely deplete your battery in 3 hours and 40 minutes from the LED alone :smile: well that could be useful for battery calibration

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Next version will be arriving here tomorrow, hope the components will also be here.

The pcb is 3335mm (which leaves 2830mm for components) excluding the hump for the connection to the usb back port.

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Nice, I hope to see some test pictures (the back cover being used as portrait/group photography light) soon!

@dvl showed around the cover (alas without LED) yesterday at the community event at Fairphone. It looks really good and fells nice. He pointed out some small issues that he wants to address now after he has tried on the phone for the first time (e.g. the hole for the back speaker is not completely aligned with the speaker and the top part does not hold on to some hook like expected.

It looks a little bigger than the original cover (my subjective perception without any real comparison) but introduces nice color options.

Overall I’m impressed.

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Dirk, please wear appropriate protective goggles, we don’t want you to blind yourself, man!

Sorry for long time no updates :frowning:

Been away for two months and now funds are a bit low (and thus free time also) to work on not-directly-paying jobs.

BUT!!: I am getting some new parts tuesday/wednesday, then you guys will get a big-ish update probably/hopefully :slight_smile:

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Ok, so.

Ehm.

Good news:
I got some working parts where I can use the FP2 to -directly over usb- control the LEDs and pwm them & all that

Bad news:
There are some restrictions that will make it practically impossible to use the FT311D with this phone as a standalone application using the back connector and no external power supply.

Conclusion:
Project suspended untill further notice.

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As per my knowledge the LED is a 4 chip one (so actually 4 LEDs in one package) that is rated for 350ma per cell. This means that you could turn one on full brightness and there is still some power to spare. However, when going for white it is best to turn them all on as the efficiency of the LED goes down when the power per cell goes up.

hdi pcbs

Do you have more info on the restriction there are?

I don’t know if I am allowed to share. But it was enough to piss me off :stuck_out_tongue:

All true. Also, pwm can be used for mixing colours, and strobing can be done on crazy brightness as long as the average power is not over ~500ma.

One more attempt with the 32U4, this microcontroller is already tested to work with the FP2 by keesj, should be good.

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Ok so, it works and it is pretty bright.

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Can it be configured using the buttons? E.g. volume up/down is brightness, multifunctional button is different modes/colours/etc.

not yet

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Just to have some kind of record about this for people that want to know more. Is it a ATmega32U4?