Thanks for your input guys. We are using a TXS0108 level shifter on all of the SDIO signals (SDIO_DAT0 thru SDIO_DAT4, SDIO_CMD, SDIO_CLK) as well as WLAN_EN, WLAN_IRQ, BT_EN and the four HCI bluetooth signals (TX, RX, CTS, RTS). I’ve checked the voltage levels and they are 3.3V on the AM3359 side and 1.8V on the TiWi chip side of the level shifter, as expected, so I don’t see anything obviously wrong. However, something is wrong as shown by my output posted above!
I’ve been doing a lot of googling and it seems the TiWi chip is sensitive to the impedance level and trace length on the four data lines. Has anyone had trouble, and how did you solve it?
I’ve heard that there is a beaglebone wifi cape in development that uses the TiWi-R2 chip. Is this cape being designed by TI or LSR or someone else?
BTW, I’m using a Beaglebone rev A3, and I’m using MMC1 for my SDIO connection to the TiWi.I’m sure I have the pin mux correct.
mmc1_dat1, P8 pin number 13, mux mode 2
mmc1_dat2, P8 pin number 14, mux mode 2
mmc1_dat3, P8 pin number 17, mux mode 2
mmc1_dat0, P8 pin number 19, mux mode 2
mmc1_cmd, P8 pin number 20, mux mode 2
mmc1_clk, P8 pin number 21, mux mode 2
I read somewhere today while doing google searches that the Beaglebone rev A3 (which I am using) has an error in the P8 header. mmc1_dat3 is supposed to be routed to header P8 pin 17 but is actually routed to Pin 16! This could be my problem as I’m using mmc1_dat3. Here is my pin mux:
mmc1_dat1, P8 pin number 13, mux mode 2
mmc1_dat2, P8 pin number 14, mux mode 2
mmc1_dat3, P8 pin number 17, mux mode 2
mmc1_dat0, P8 pin number 19, mux mode 2
mmc1_cmd, P8 pin number 20, mux mode 2
mmc1_clk, P8 pin number 21, mux mode 2
I looked for “errata” at beagleboard.org on this subject but found no mention of this problem. Can anyone verify this pin 16 / pin 17 error on header P8 on Beaglebone rev A3?
Older versions of the SRM did have wrong information for some of the
mmc1 lines. For an up-to-date easy-to-read version of the P8/P9
pinout, see my github[1].
