Ethernut 3 hardware points: RAM on expansion port and SD card
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Ethernut 3 hardware points: RAM on expansion port and SD card
by Colin Chaballier
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Hi,
As part of the integration of the Ethernut3 in a new design, I'm looking at the feasibility to add external RAM through the expansion connector. Do you have any feedback experience on connecting RAM through the "configurable address bus" on this board ? Apart the 16bit address bus limitation, should be there any issues working on the address/data buses through the CPLD logic (latency control for example) ? My second point is about the SD Card support. In the Ethernut3 documentation it is reported that there should be a power line glitch problem when inserting SD card of more than 2GB. Is this problem has been definitely solved ? Or could we expect later issues when using large capacity SD cards ? Thanks for your answers. Best regards, Colin _______________________________________________ http://lists.egnite.de/mailman/listinfo/en-nut-discussion |
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Re: Ethernut 3 hardware points: RAM on expansion port and SD card
by uprinz
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Hi Colin,
I had used the external RAM on Ethernut 3.0e and other SAM7 based Applications without any problem. Just keep an eye on timing and correct Chipselects. The power-glitch while handling any hotswap device is a problem that can be worked around by installing a 100nf and a 1uF capacitor as close as possible to the vcc/gnd of the socket. This is a workaround as the real solution should be to design in a slot controller. I.e. a chip that does bus connection/disconnection including power up / power down of the cards. Best regards, Ulrich Colin Chaballier wrote: > Hi, > > As part of the integration of the Ethernut3 in a new design, I'm looking > at the feasibility to add external RAM through the expansion connector. > Do you have any feedback experience on connecting RAM through the > "configurable address bus" on this board ? > Apart the 16bit address bus limitation, should be there any issues > working on the address/data buses through the CPLD logic (latency > control for example) ? > > My second point is about the SD Card support. In the Ethernut3 > documentation it is reported that there should be a power line glitch > problem when inserting SD card of more than 2GB. Is this problem has > been definitely solved ? Or could we expect later issues when using > large capacity SD cards ? > > Thanks for your answers. > > > Best regards, > Colin > > > _______________________________________________ > http://lists.egnite.de/mailman/listinfo/en-nut-discussion http://lists.egnite.de/mailman/listinfo/en-nut-discussion |
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Re: Ethernut 3 hardware points: RAM on expansion port and SD card
by uprinz
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Hi Colin!
Sorry, missed your post in the list. I didn't use extra ram on the extension connector. I think I remember something about 5..8ns for the XilinX CPLD. But you better check the datasheets. There is a delay for the signal in general, but there are also delays for the gates you put inbetween. I most answered your questions around the glitches on the SD card socket, I hope. Regards, Ulrich Colin Chaballier wrote: > Hi Ulrich, > > Thanks for the point. At which speed did you run the address/data buses > ? I don't have a clear idea on the latency introduced by the cpld. > > Any more experiences on the use of the expansion port for external RAM ? > > BR, > Colin >> ---------------------------------------------------------------------- >> >> Message: 1 >> Date: Sun, 02 Aug 2009 17:50:03 +0200 >> From: Ulrich Prinz <uprinz2@...> >> Subject: Re: [En-Nut-Discussion] Ethernut 3 hardware points: RAM on >> expansion port and SD card >> To: "Ethernut User Chat (English)" <en-nut-discussion@...> >> Message-ID: <4A75B5AB.3080301@...> >> Content-Type: text/plain; charset=ISO-8859-1; format=flowed >> >> Hi Colin, >> >> I had used the external RAM on Ethernut 3.0e and other SAM7 based >> Applications without any problem. Just keep an eye on timing and correct >> Chipselects. >> >> The power-glitch while handling any hotswap device is a problem that can >> be worked around by installing a 100nf and a 1uF capacitor as close as >> possible to the vcc/gnd of the socket. This is a workaround as the real >> solution should be to design in a slot controller. I.e. a chip that does >> bus connection/disconnection including power up / power down of the cards. >> >> Best regards, Ulrich >> >> Colin Chaballier wrote: >> >>> Hi, >>> >>> As part of the integration of the Ethernut3 in a new design, I'm looking >>> at the feasibility to add external RAM through the expansion connector. >>> Do you have any feedback experience on connecting RAM through the >>> "configurable address bus" on this board ? >>> Apart the 16bit address bus limitation, should be there any issues >>> working on the address/data buses through the CPLD logic (latency >>> control for example) ? >>> >>> My second point is about the SD Card support. In the Ethernut3 >>> documentation it is reported that there should be a power line glitch >>> problem when inserting SD card of more than 2GB. Is this problem has >>> been definitely solved ? Or could we expect later issues when using >>> large capacity SD cards ? >>> >>> Thanks for your answers. >>> >>> >>> Best regards, >>> Colin >>> >>> >>> _______________________________________________ >>> http://lists.egnite.de/mailman/listinfo/en-nut-discussion >>> >> >> ------------------------------ >> >> _______________________________________________ >> http://lists.egnite.de/mailman/listinfo/en-nut-discussion >> >> >> End of En-Nut-Discussion Digest, Vol 70, Issue 3 >> ************************************************ >> >> >> > > http://lists.egnite.de/mailman/listinfo/en-nut-discussion |
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