>>>>The changes from Balloon 2 are:
>>>>- VDD_3V is now VDD_IO (still a 3.3V supply)
>>>>- VDD_5V is now VDD_RAW (which is 'rough' 5V)
>>>
>>>Well, sort of. If you feed 5V in, it'll be 5V... If you strap it to a
>>>lithium cell, it won't be.
>>>Bear in mind that these pins could as easily be used to feed power into
>>>the balloon, as to feed power from the Balloon to the other board -
>>>depends if you see the board as a backplane or an expansion card, really.
>>
>>Yes, agreed.
>
> Umm we use VDD_3V to feed the power in, will this still
> work or is VDD_IO some other supply we make all
> connections to the board though the connector ?
This won't work properly, sadly. VDD_IO is an output from the MAX1586
switcher for the ARM. Balloon 3 uses a different power supply
architecture from Balloon 2, where all rails are generated on the board
from the raw 5V(ish) supply. I think this is necessary because it's the
way that the ARM (and FPGA, if fitted) expect to have their power
managed, as far as I can see. It actually simplifies the power
arrangements, but could be awkward for people used to feeding 3.3V in.
>>DQM3..0 would be much more useful, I agree. Can anyone from Guralp
>>(James McKenzie?) comment?
>
> sorry pins 1,3,5,7 ARE DQM0-3 are they not?
>
> We pass these through to a h3800 connector and are used by
> something which I don't think we'll be making any more of.
>
> HOWEVER if you drop these - then you commit yourself to
> using only 8 or 16 bit IO. You won't be able to drive a
> chip like the smc lan91c96 in 16 bit mode.
I've changed them to be DQM3..0 on the new pinout, but on Balloon 2
they're definitely labelled as NCAS3..0 on all the schematics I have.
Whatever, henceforth they're DQM3..0 because they're much more useful.
>>>>- MBREQ/DREQ<0> and MBGNT/DVAL<0> are present on the Samtec so
>>>>motherboard devices can do bus mastering and DMA
>>>
>>>I guess I ought to pull these to a safe state on Balloon :)
>>
>>I'm sure we'll be discovering myriads of things like that...
>
> Sorry are these in or out?
These are on the samtec: MBREQ/DREQ<0> is the input for requesting bus
mastering/DMA, and MBGNT/DVAL<0> is the output for granting it.
Chris
--
Chris Jones -
chris@martin-jones.com
Martin-Jones Technology Ltd, makers of Solidlights
148 Catharine Street, Cambridge, CB1 3AR, UK
Phone +44 (0) 1223 474968 Fax +44 (0) 870 112 3908
http://www.solidlights.co.uk/
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