Now, I am building an SPI interface with an MMC. I think Barry or Octavio
would have already done this. After power-up (I am connecting CS line
always to ground), I send the Command0(CMD0 - 0x40 00 00 00 00 95). Then,
the MMC responds with 0x7E - Response Format R1. If we map this response to
the bits in R1, then I have all the error bits set. On sending the first
CMD1 after that, I keep getting logic zeros.
I would like to know if the response I received for CMD0 is correct. Please
let me know your views.
Well I had to control the CS line as well.
Continue to read the CMD0 command until you read 0,
the same to CMD1, it usually takes 2 reads to get the 0.
> Now, I am building an SPI interface with an MMC. I think Barry or Octavio
> would have already done this. After power-up (I am connecting CS line
> always to ground), I send the Command0(CMD0 - 0x40 00 00 00 00 95). Then,
> the MMC responds with 0x7E - Response Format R1. If we map this response
to
> the bits in R1, then I have all the error bits set. On sending the first
> CMD1 after that, I keep getting logic zeros.
>
> I would like to know if the response I received for CMD0 is correct.
Please
> let me know your views.
>
> Thanks and regards,
> Somasundaram Meiyappan.
>8-clock at the end after you are completed the command and
>put CS to high (INACTIVE) before the next command.
>Here is the procedure:
>- CS active (LOW)
>- Send the command
>- Wait for response
>- Get the data if exist
>- CS high (INACTIVE) ************
>- 8-clock ***************************
>then next command
I'm using it at a 18.534MHz Pic in SPI mode
so the maximun I can get is 4.6MHz.
Please note, at the CMD0 time the maximun
clock rate is 400KHz.
> At 10:53 AM 3/24/00 -0300, you wrote:
> >Well I had to control the CS line as well.
>
> But Sandisk's manual does not mention about that. Is that really
necessary?
>
> >Continue to read the CMD0 command until you read 0,
> >the same to CMD1, it usually takes 2 reads to get the 0.
> >
>
> I got these - Thanks.
>
> Also please tell me what was the data transfer rate that you obtained
using
> your interface.
>
> Thanks and Regards,
> Somasundaram Meiyappan
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