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Re: Parallella 7010 no GPIO - no Samtec Connectors

PostPosted: Mon Jun 16, 2014 9:38 am
by 9600
FHuettig wrote:Yeah, I don't think there's an obvious answer. I haven't checked thoroughly but it seems that most existing add-on cards that people might want to re-purpose (pmods, arduino, rpi, etc.) are either 3.3V or 5V, is that wrong?


That is my impression also.

I don't think many people will be comfortable re-flashing their boards to start at 3.3V because of the risk of bricking them, but it would be easy to provide a simple utility to set that Voltage as needed from Linux.


And I guess this could be executed at boot, reading in config which is trivial to update.

[*]prevent the daughter cards from applying 3.3V signals to the GPIO inputs until the Parallella gives a go-ahead (dangerous if the Parallella mistakes this card for another)
[*]require series resistors to keep an add-on cards 3.3V outputs from driving too much current into the Parallella's 2.5V inputs before VDD_GPIO is set to 3.3V. The pmod spec requires this, for example.


The first option sounds like it could be a tall order for novices, whereas the second would clearly be much easier to achieve.

Cheers,

Andrew

Re: Parallella 7010 no GPIO - no Samtec Connectors

PostPosted: Wed Jun 18, 2014 10:02 am
by greytery
FHuettig wrote:... Seems to me the best courses of action when building add-on boards for Parallella are: ...


I can see where you need to go with that, but daughter cards and talk of re-flashing the board are perhaps a bit off-topic here :D
No Samtec Connectors = No Daughter Cards.

One little baby that went down the plug-hole (or lack of one) is JTAG, which is part of PEC_POWER.
I understand that re-flashing the board relied on that (or I've misread something).
How do you re-flash anyway?

Wonder what other serious restrictions there are on a 7010 which has no access to those non-GPIO pins.

tery

Re: Parallella 7010 no GPIO - no Samtec Connectors

PostPosted: Wed Jun 18, 2014 9:37 pm
by FHuettig
greytery wrote:... daughter cards and talk of re-flashing the board are perhaps a bit off-topic here

Yes, sorry, the topic drifted as it does very often. I wasn't paying attention.

greytery wrote:One little baby that went down the plug-hole (or lack of one) is JTAG, which is part of PEC_POWER.
I understand that re-flashing the board relied on that (or I've misread something). How do you re-flash anyway?


Since you asked... ;)
As long as the board will start u-boot from the flash, you can access it from the UART. U-boot has the ability to read a new image from the SD card (mmc / fatload) and to erase & write the flash (sf probe/erase/write). I've never had a problem with this, but of course there is a risk that if something goes wrong you can brick the board and -then- it takes JTAG to load u-boot so it can be flashed again. For a board like yours that would mean soldering 6 wires from the board to a JTAG connector, not trivial but not impossible.

Re: Parallella 7010 no GPIO - no Samtec Connectors

PostPosted: Wed Jun 18, 2014 11:42 pm
by greytery
Thanks Fred.

I was just getting jealous. :cry:
I'd since done a bit of DuckDucking and am less concerned now about bricking a board - if it comes to that. I have two.
Actually, I believe it's the same sort of risk that '000's of PC BIOS upgraders have been running for decades: that process has always been subject to Power and/or Finger failures.

tery

Re: Parallella 7010 no GPIO - no Samtec Connectors

PostPosted: Tue Jul 15, 2014 10:46 am
by greytery
Good to see the pictures of the Parallella-16 Micro-Server.
{Picky} Not the final images though - the reset button and caps are still in their current positions.

I see that Adapteva have made a sensible choice of removing the USB and HDMI chips and sockets as well as the Samtec connectors. Cool! Well, definitely cool-er!!
When my CFO/wife authorises the funds - these are the way to go to build that supercluster. :)

BUT -
Default linaro Ubuntu (and nano) images do not have the openssh (or any sshserver) package installed.
As I found on the Parallella_Linaro_Nano build, you need to run the board up with HDMI in order to install openssh, before you can revert to headless. I could do that because MY version still has the sockets, etc.
Not sure if the UART can be used to perform the apt-get install - I suspect it can - but there are some incompatibilities (which I don't understand).

So, likely that the default Parallella linaro Ubuntu image (- and shodrucky's Nano build instructions - ) will need updating to ensure this vital package is included.
Are you intending to release a separate Parallella headless/server image?

Cheers,

Re: Parallella 7010 no GPIO - no Samtec Connectors

PostPosted: Tue Jul 15, 2014 7:17 pm
by AlbertoGP
I think that the final images are what you can see in the page about the new heatsink:
http://www.parallella.org/heatsink/

The caps are in the same place but they are smaller, and it looks like they just removed the reset switch which is a bit worrying for me: I need it occasionally to get the board to boot after powering it up.