suggested PCB changes


13 posts
by lncoll » Tue Jun 12, 2012 4:31 pm
My Raspi is at home only 2 days, but I've found 2 little "problems".

1st. Power supply through a micro USB seems good for gadget battery charge, but not to feed a continuous voltage to a processor. Micro USB cables usually are not good, and connector fails at the minimun movement.
2nd. Lan connector is 6mm back from USB connector, this is not a big con, but I'm designing a case and the choices are: hidden LAN connector OR "popup" USB connector.

I suggest for the next PCB version, if it happens:
Move Lan connector 6mm. outside, the fixing holes shoud be at 1.5 mm. from PBC border.
And place an extra power connector, round or flat does not matter, but a "good" one with "big" contacts and solid.

Elsewhere of this two issues, I'm very happy with my Raspi, enjoying it and mainstorming new uses for it.
Excuse for my bad English, is not my first language, neither the second :D
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by AndrewS » Tue Jun 12, 2012 5:14 pm
lncoll wrote:1st. Power supply through a micro USB seems good for gadget battery charge, but not to feed a continuous voltage to a processor.

Many many forum topics about this already, and also see http://elinux.org/RPi_Hardware#Power_Supply_Problems
Micro USB cables usually are not good, and connector fails at the minimun movement.

I've never had that problem with mine yet - maybe you're just unlucky to have a connector which is slightly too small (or worn down) so it's become 'loose'?
2nd. Lan connector is 6mm back from USB connector, this is not a big con, but I'm designing a case and the choices are: hidden LAN connector OR "popup" USB connector.

I think I remember reading that the USB ports sticking out so much was actually a footprint design mistake, and by the time they noticed it would have been to costly (in both time and money) to fix it.
And place an extra power connector, round or flat does not matter, but a "good" one with "big" contacts and solid.

If you know what you're doing and you have a high-quality PSU, you can supply power via the GPIO header http://elinux.org/RPi_Hardware#Power
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by Mattylad » Tue Jun 12, 2012 9:02 pm
If you put the Pi in a case you can always extend the connectors with short cables to chassis/case mounting connectors.
That way you can also include a power switch, user changeable fusing, external power LED's etc.

But I know what you mean - I would hope that there will be another version where it fits in a straight case, however that will then upset all those with existing cases.
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by iamn8 » Sat Jun 16, 2012 2:08 pm
I love the size of this thing... some small thoughts:
* I would suggest 3-4 mounting holes.
* The RCA video and 3.5 audio be removed.
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by alexandru.cucu » Sat Jun 16, 2012 3:01 pm
Had the same problems with the micro-USB connector for power and I can't blame the connectors because everything is brand new.
Mini-USB is much more common and also has better mechanical design.
Adding another connector for power and mounting holes are a must for the next version in my opinion.
https://launchpad.net/~alexandru.cucu
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by rurwin » Sat Jun 16, 2012 4:22 pm
Using a micro USB for power was a good idea, because in an other year everyone will have a power supply available. Unfortunately there are so many bad power supplies and cables out there, and the power the RaspPi needs is so close to the maximum, that the idea fails in practise. In my view, the educational release should use a coaxial connector, allow 500mA draw from the USB ports and a power supply should be available. It's not ideal, but it would solve almost every problem people are having.
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by khulat » Sun Jun 17, 2012 4:37 am
alexandru.cucu wrote:Mini-USB is much more common and also has better mechanical design.


I would argue Micro USB is designed to be sturdier. :)

To quote Wikipedia:
The newer Micro-USB receptacles are designed for up to 10,000 cycles of insertion and removal between the receptacle and plug, compared to 1,500 for the standard USB and 5,000 for the Mini-USB receptacle.
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by AndrewS » Mon Jun 18, 2012 12:36 pm
iamn8 wrote:I love the size of this thing... some small thoughts:
* The RCA video and 3.5 audio be removed.

I don't think that would be popular with the people without HDMI TVs :P ;)
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by Mattylad » Thu Jun 21, 2012 7:31 pm
AndrewS wrote:
iamn8 wrote:I love the size of this thing... some small thoughts:
* The RCA video and 3.5 audio be removed.

I don't think that would be popular with the people without HDMI TVs :P ;)


Most certainly not popular!

I don't know about the RCA but the audio socket is very much needed for many applications.
Handheld media players spring to mind.

Replacing the PSU socket, bringing the SD card and USB ports inwards more, mounting holes and changing the USB power circuitry are a must for the next revision.

Problem will be if people have already got them in cases that have holes for the power socket, everything else can use the same hole position but a DC jack socket is round as opposed to flat so would need futrther case mods that may not look neat. (Assuming a case with sides is used).
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by Gert van Loo » Thu Jun 21, 2012 9:53 pm
rurwin wrote:..... In my view, the educational release should use a coaxial connector, allow 500mA draw from the USB ports and a power supply should be available. It's not ideal, but it would solve almost every problem people are having.

The plan is to release a complete education kit, so including the SD-card, case and I think also the supply.
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by Montala » Thu Jun 21, 2012 10:00 pm
Gert van Loo wrote:The plan is to release a complete education kit, so including the SD-card, case and I think also the supply.

Then it will REALLY 'take off'! :D
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by rurwin » Thu Jun 21, 2012 11:55 pm
Only if the USB ports are allowed to supply 500mA, or at least significantly more than 100mA, because that would make their fuses less of a problem. A maximum of 500mA would make the RaspPi a proper host device and we could plug anything into it.

However that would cause a draw from the supply of more than the rated current of a micro USB connector. So the educational release should have a coaxial connector.

Just bundling a power supply is not sufficient.
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by AndrewS » Fri Jun 22, 2012 12:04 am
Wasn't the plan for the educational release to be using the ModelA, IIRC? Would the MicroUSB be able to supply enough then for a single full 500mA USB ouput?
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