WLAN from SDIO to SPI: battle plan

Werner Almesberger werner at openmoko.org
Mon Aug 25 20:47:00 CEST 2008


dennis.yxun wrote:
> +	spi->ch[0].SPCON = 0x1B; /* Polling, Prescaler, Master, CPOL=0,
> +				    CPHA=1 */

The problem seems to be that you also set what Samsung obliquely
refer to as "Tx auto garbage data mode". Setting it makes SPI ignore
SPTDAT.

Also, your clock rate is a bit off. (See the comments in the example
below.)

User-space example in:
http://svn.openmoko.org/developers/werner/wlan-spi/spi.c

(To compile it, you also need to build
http://svn.openmoko.org/developers/werner/greg/)

And this is what happens on the wires:
http://people.openmoko.org/werner/wlan-spi/spi_hi.png

D6 is MOSI, D5 is SCLK, D1 through D4 are floating, D0 is an
unsynchronized 1MHz reference clock.

- Werner



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