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Overo GPMC questions
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Overo GPMC questions
by S Greeley
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I'm making a custom expansion card for a Overo COM board, and want to connect the GPMC to an FPGA on my board (acting as a memory mapped device).
I noticed not all of gpmc_ncs or gpmc_wait lines come out thru J4. What other devices on the Overo use the GPMC? If any, what electrical loading considerations are needed because of multiple devices on the GPMC bus? Thanks In Advanced, Scott |
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Re: Overo GPMC questions
by Søren Steen Christensen
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Hi Scott,
The GPMC is connected to the PoP NAND chip on the Overo itself. With respect to loading considerations, you can get the datasheet from Micron after registering and signing an NDA. Alternatively you can assume it's loading as a "standard" NAND device in case you have a datasheet for such one at hand. AFAIR it's loading with less than 10pF/pin Good luck - Good luck Søren --- SSC Solutions ApS - Denmark - www.ssc-solutions.dk > -----Original Message----- > From: S Greeley [mailto:scott.greeley@...] > Sent: Monday, November 09, 2009 10:13 PM > To: gumstix-users@... > Subject: [Gumstix-users] Overo GPMC questions > > > I'm making a custom expansion card for a Overo COM board, and want to > connect > the GPMC to an FPGA on my board (acting as a memory mapped device). > > I noticed not all of gpmc_ncs or gpmc_wait lines come out thru J4. > What > other devices on the Overo use the GPMC? If any, what electrical > loading > considerations are needed because of multiple devices on the GPMC bus? > > Thanks In Advanced, > Scott > -- > View this message in context: http://old.nabble.com/Overo-GPMC- > questions-tp26230905p26230905.html > Sent from the Gumstix mailing list archive at Nabble.com. > > > ----------------------------------------------------------------------- > ------- > Let Crystal Reports handle the reporting - Free Crystal Reports 2008 > 30-Day > trial. Simplify your report design, integration and deployment - and > focus on > what you do best, core application coding. Discover what's new with > Crystal Reports now. http://p.sf.net/sfu/bobj-july > _______________________________________________ > gumstix-users mailing list > gumstix-users@... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 8.5.425 / Virus Database: 270.14.57/2492 - Release Date: > 11/09/09 12:11:00 ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ gumstix-users mailing list gumstix-users@... https://lists.sourceforge.net/lists/listinfo/gumstix-users |
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Re: Overo GPMC questions
by S Greeley
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Hi Søren,
Thanks for your quick reply. Do you know which GPMC chip select signal and wait signal are used by the NAND? Or is it safe to assume that it's not one brought out to J4 connector? :) Or a related topic, do you why mcspi1_cs3 wasn't brought out to J1 or J4? All the other mcspi1 signals seem to be there. Could it have been brought out, and the documentation doesn't clearly show it? thanks again, Scott
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Re: Overo GPMC questions
by Søren Steen Christensen
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Hi Scott,
> Do you know which GPMC chip select signal and wait signal are used by > the NAND? > Or is it safe to assume that it's not one brought out to J4 connector? :) No - This is unfortunately not safe - OMAP boots from CS0 and uses Wait0. AFAIR you can share the wait-line between multiple devices, although I'm not 100% sure and it would require all the devices to have open-drain output for driving the signal - Remember to put a pull-up on the signal as well. In case you can find another wait signal (than wait0) I think this is the most secure path. More info about NAND booting and GPMC configuration please consult the OMAP3530 TRM (spruf98c.pdf) chapter 25.4.7.4 and chapter 11.1... > Or a related topic, do you why mcspi1_cs3 wasn't brought out to J1 or J4? > All the other mcspi1 signals seem to be there. Could it have been > brought out, and the documentation doesn't clearly show it? Mcspi1_cs3 is only available on ball AB2, which is as well the only place for HSUSB2_D2 (for the USB Host PHY), which tells why it's not brought to the connector :-) Best regards - Good luck - In case of further questions please don't hesitate to ask Søren --- SSC Solutions ApS - Denmark - www.ssc-solutions.dk ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ gumstix-users mailing list gumstix-users@... https://lists.sourceforge.net/lists/listinfo/gumstix-users |
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