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