[En-Nut-Discussion] Ethernut 3 hardware points: RAM on expansion port and SD card

Ulrich Prinz uprinz2 at netscape.net
Sun Aug 2 17:50:03 CEST 2009

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 

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
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