(apologies for slow reply - I've been away)
David Bisset wrote:
> I notice that the substitute PINKO connector uses GPIO94 for unsuspend.
> On a brief reading of 3.8.1.4 of the PXA270 Developers Manual this does not
> seem to be one of the GPIOs that can be programmed as a wakeup, I may well
> have missed the point of course...
>
> If this is set to other than GPIO3,1,0 then only "lesser" sleep modes will
> be woken up from via this pinko substitute. This may well be a good thing
> given the increasing wakeup latency from the successively deeper sleep
> modes.
This is a good point, and one I'd missed - I'd only recorded which GPIOs
could wake from sleep and standby, not deep-sleep. The current Pinko
UNSUSP connection gives us the same functionality as we had on Balloon
2, but doesn't allow for deep sleep.
> This leads to the second query. If I want to wake up using the backplane I
> assume that I can the GPIO lines (e.g. GPIO9,10 as well as 0,1) to do this,
> and I assume that these should also be used for external interrupt signals
> via the backplane. Is this correct?
Yes, that's correct. GPIO 0 and 1 are connected to the FPGA, though. I
suppose we could do some horrid wire-OR thing if we really wanted.
> a) Is it worth defining which should be used for what?
Probably. It looks like there's an opportunity to do some reshuffling
here. We currently have:
GPIO0 - deep sleep wake-up, connected to FPGA and Samtec pin 146
GPIO1 - deep sleep wake-up, connected to FPGA and Samtec pin 170
GPIO9 - standby wake-up, connected to Samtec pin 148
GPIO10 - standby wake-up, connected to Samtec pin 172
GPIO94 - standby wake-up, connected to PINKO_UNSUSP
I'd be tempted to change this to
GPIO0 - deep sleep wake-up, connected to FPGA and Samtec pin 146, pulled
up to enable wire-OR operation
GPIO1 - deep sleep wake-up, connected to PINKO_UNSUSP
GPIO9 - standby wake-up, connected to Samtec pin 148
GPIO10 - standby wake-up, connected to Samtec pin 172
GPIO94 - standby wake-up, connected to FPGA and Samtec pin 170
Any thoughts?
> b) Are these GPIOs free for external use or are they also used on the B3
> board? If so can the FPGA/CPLD on B3 be used to make them available by
> sharing (note this may well require that they go in and then out of the
> FPGA/CPLD to the Samtec connector which they don't currently appear to do).
GPIO0/1 are wired to the FPGA/CPLD but not necessarily essentially used.
I'm loath to feed the unsuspend line through the FPGA because it'll
inevitably turn out to be asleep at the wrong moment, so the whole board
won't wake up. I think a direct connection to the GPIO is more useful.
> {I'm inferring, from the connection charts, that for these GPIO's the Samtec
> connections are "Tee'd" off the internal signals and not fed via the FPGA
> since the this is what the pin counts suggest. (Unlike the Address and Data
> bus which clearly go via the FPGA).
Yes, that's right.
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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