Possible Hardware fixes

looks like a good list.  Too bad the PoP ram is so hard to replace,

as that would be another nice improvement.  I've been thinking of

modifying one for high-altitude balooning, or similar uses, where

size and/or weight matter.  So here's my list:

  1) remove csi connector,

  2) remove dsi connector,

  3) remove hdmi connector,

  4) remove RCA connector,

  5) remove audio connector,

  6) remove ethernet connector,

  7) remove micro usb connector (directly solder power wires),

  8) remove GPIO pins,

  9) remove LDO voltage regulators, replace with switch mode,

10) remove LAN chip,

11) remove dual-usb connector, directly solder one usb device,

12) remove polyfuses, replace with 1 Ohm resistor,

13) remove the capacitor that frequently falls off,

14) as you suggest, replace SD with micro SD.

There is another DC-DC converter I'm testing for another design from Intersil, ISL9104 500mA 4.3MHz high efficiency, very small package and cheap, few external components.

The Alpha board had DC-DC converters and apparently a better power supply design. The micro USB and phone chargers is turning to be a really bad idea, so I agree about changing that, actually I'm powering the board from the P1 header.

Yes without the Gerbers is not easy to envision what kind of "blue wire" fixes can be done.

I'm thinking seriously if after all there is enough interest and momentum to start a true "open source hardware" development.for a Pi like board, with parts that are documented. Even if I understand the reasons I don't like at all that the Pi design was built around a part that has practically no documentation publicly available.

I may be able to get some funding and people interested to support an open project, perhaps I should exchange some lines with Jim Manley that seems interested to the right thing.

I'm really pissed with all the secrecy, conspiracy, mystery, bad vibes and misinformation emanating from RPF.

-J

I'll be replacying the polyfuses with 0 ohm resistors, no need ot waste power.

I'll probably keep ethernet and HDMI.

Agreed with the two FPC connectors, good move by RPF to offer a camera that will be more expensive than the board.

The RCA jack takes too much space, same as audio, perhaps something done on similar designs like Roku2, replace both by a single jack that can carry all signals, but resolution and image quality out of the composite video output is not very good, perhaps better use something that can support VGA instead.

the 1 Ohm resistor is to avoid voltage drops from

power surges on the USB device.

This thread is totally awesome, almost to the extent of demanding some 4-letter words to hammer home the point.  Mankind will reach the stars only by improving on what went before.  Being attached to what exists is barely worthy of bacteria.

+1000

My area of head-scratching:  how to turn the SD card into a network boot.

Morgaine.

For that you should have a pair of good tantal bulk caps as recommended by the USB spec sort of 150µF, and I'd add USB power switches.

I'd be nice if Broadcom started selling the "alpha" boards :-)

-J

I'm thinking seriously if after all there is enough interest and momentum to start a true "open source hardware" development.for a Pi like board, with parts that are documented.

I could certainly be interested, but I see two stumbling blocks. First is that anything with a GPU is unlikely to have good enough docs, second is that anything without a GPU seems unlikely to have the sort of mass market appeal to get the cost down to something reasonable.

The rhombus-tech guys seem to be a reasonable way along this road already, with some interesting info like the cpus they've evaluated: http://rhombus-tech.net/evaluated_cpus/

However they seem to be a long way from an actual released product and I'm not at all convinced of the EOMA-68 form factor. Although I do like the idea of a set of standard interfaces.

and I'd add USB power switches.

I probably didn't make it clear enough in the list, the AP1212 I mentioned is a usb power switch.

Making the obvious comparison, the cheapest 140mA polyfuse from farnell is 0.113 gbp in qty 5, and the AP1212 is 0.33 gbp in qty 1. So I'm not at all sure the case for using polyfuses is a good one. Don't know what costs @ 10K, 100K etc would be like though.

Anyway, remove D10, D11 and both polyfuses and it should be simple to put the power switch in, the datasheet suggests a 33uF cap on the usb connector side and it has a soft-start feature to avoid the power dip when connecting a device.

The RCA jack takes too much space, same as audio,

I didn't add those to my list, almost goes without saying that I  won't use them and will likely remove them. For add-on boards that plug onto the gpio on top of the board that RCA connector is just too high.

>My area of head-scratching:  how to turn the SD card into a network boot.

There are some adapters that convert SD into USB, such as this one:

http://www.teampctechnology.com/product_detail.php?id=603

It appears to be discontinued, but there are probably others,

athough most SD/USB adapters go the opposite direction.

Once you've got USB, I think you're home free.

You can connect it to a usb hub, with an ethernet port,

along with usb keyboard/mouse and then disable the

lan chip and save 20% of your cpu time.  Would make

for the fastest RPi youtube demo to date if it works.