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
