Hi Erwin,
Thanks for the info. You may want to view this thread and related
discussions.
http://sourceforge.net/mailarchive/forum.php?thread_name=200701261521.l0QFLjlv003816%40ignucius.se.axis.com&forum_name=spi-devel-general
Mike
Erwin Authried wrote:
Hello Mike,
no, I was talking about sending 8 clock cycles after a command, and
after the CS is deselected.
Regards,
Erwin
Quoted from http://elm-chan.org/docs/mmc/mmc_e.html:
Cosideration on Multi-slave Configuration
In SPI, each slave device is selected with separated CS signals, and
plural devices can be attached to an SPI bus. Generic SPI slave device
drives/releases its DO signal by CS signal asynchronously to share an
SPI bus. However MMC/SDC drives/releases DO signal in synchronising to
SCLK. There is a posibility of bus conflict when attach MMC/SDC and any
other SPI slaves to an SPI bus. Right image shows the drive/release
timing of MMC/SDC (DO is pulled to 1/2 vcc to see the bus state).
Therefore to make MMC/SDC release DO signal, the master device must send
a byte after deasserted CS signal.
Am Montag, den 21.05.2007, 17:59 -0700 schrieb Mike Lavender:
Hi Erwin,
I think you are referring to the "dummy" byte at the beginning of every
spi command which ensures the 8 clock cycles between all commands. I am
not sure about the deactivated chip select, this is getting sent with an
active chip select as part of the spi_message.
union mmc_spi_command {
u8 buf[7];
struct {
u8 dummy; <-- Here
u8 code;
u8 addr1;
u8 addr2;
u8 addr3;
u8 addr4;
u8 crc;
} command;
};
Mike Lavender
Erwin Authried wrote:
Hello Steve,
does your driver take care about sending 8 clock cycles with deasserted
CS at the end of a transaction so that DO is tristated? I think that the
2.6 spi subsystem doesn't support sending clocks with deactivated
chipselect.
Regards,
Erwin
Am Freitag, den 18.05.2007, 14:24 +1000 schrieb Steve Bennett:
Hi Greg,
Likewise, a cleaned up version of the spi mmc patch.
BTW You can ditch the MCF IPS driver patch I sent. I'll send a new
version
based on mmap at some point.
Cheers,
Steve
_______________________________________________
uClinux-dev mailing list
[email protected]
http://mailman.uclinux.org/mailman/listinfo/uclinux-dev
This message was resent by [email protected]
To unsubscribe see:
http://mailman.uclinux.org/mailman/options/uclinux-dev
_______________________________________________
uClinux-dev mailing list
[email protected]
http://mailman.uclinux.org/mailman/listinfo/uclinux-dev
This message was resent by [email protected]
To unsubscribe see:
http://mailman.uclinux.org/mailman/options/uclinux-dev
_______________________________________________
uClinux-dev mailing list
[email protected]
http://mailman.uclinux.org/mailman/listinfo/uclinux-dev
This message was resent by [email protected]
To unsubscribe see:
http://mailman.uclinux.org/mailman/options/uclinux-dev
_______________________________________________
uClinux-dev mailing list
[email protected]
http://mailman.uclinux.org/mailman/listinfo/uclinux-dev
This message was resent by [email protected]
To unsubscribe see:
http://mailman.uclinux.org/mailman/options/uclinux-dev
