
I am trying to enable DDR in SD/MMC cards and it wont work - fazkan
I am trying to enable DDR in sd (spec above 2.0) the procedure in the specifications is as follows<p>Execute CMD0 to make the card idle
Execute CMD8 to enable ask about the voltage requirements
Execute ACMD41 with S18 bit enabled and log for S18 in the reply to see if the card has voltage switch functionality: checked and the card has the functionality
Now execute CMD11, if the card replies with a response the voltage switching sequence is started, the cmd and data line should go low: checked and yes they do
Stop the clock,
Program the voltage switch reg (with 1.8V) and wait 5 ms
Start the clock: the card should start at speed SDR12 with 1.8V: cmd and data lines should go high, a cmd_done interrupt should be received: NOT RECEIVED
Any pointers regarding this would be helpful...the card status registers shows that there is a data transfer in progress and the card is not present. After this I cannot execute any CMD (the cmd_done interrupts are not received)
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fazkan
Execute CMD0 to make the card idle

Execute CMD8 to enable ask about the voltage requirements

Execute ACMD41 with S18 bit enabled and log for S18 in the reply to see if the
card has voltage switch functionality: checked and the card has the
functionality

Now execute CMD11, if the card replies with a response the voltage switching
sequence is started, the cmd and data line should go low: checked and yes they
do

Stop the clock,

Program the voltage switch reg (with 1.8V) and wait 5 ms

Start the clock: the card should start at speed SDR12 with 1.8V: cmd and data
lines should go high, a cmd_done interrupt should be received: NOT RECEIVED

Any pointers regarding this would be helpful...the card status registers shows
that there is a data transfer in progress and the card is not present. After
this I cannot execute any CMD (the cmd_done interrupts are not received)

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blueflow
This is not an hardware hacking support site.

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fazkan
yes but there are some intelligent people who come here and I thought someone
might have worked on this before, its a very common problem....

