Issues using MMC3 pins for SDIO

[Doug Springer]

We have a Silex Wifi ‘hat’ for a Raspberry pi. We built an interposer board to adapt from the cape to the Pi connector. We are using the MMC3 pins (J5, 11,12,15,16,18 and J6, 15). The interface reads the VID/PID correctly and loads a config file and the firmware to the part, but then many commands time out.

Does the MMC3 interface work? I notice the wifi cape and the beagle bone black wireless both use the EMMC pins instead of this third interface, making me believe this third interface does not fully work. In our debug, we have varied the clock from 50Mhz all the way down to 2Mhz, but the clock does not change anything, and we verified the clock looks OK on an oscilliscope and the edges of data and cmd seem to be well within the SDIO specification.

Can anyone confirm or deny this?

Thanks!

• This topic was modified 1 month, 3 weeks ago by Doug Springer.
• This topic was modified 1 month, 3 weeks ago by Doug Springer.

[Neeraj Dantu]

Doug,

Beaglebone Black wireless(https://github.com/beagleboard/beaglebone-black-wireless/blob/master/BeagleBone_Black_Wireless_SCH.pdf) uses MMC2 interface for WiFi. MMC0 is used for SD card and MMC1 is used for eMMC. All 3 MMC interfaces are used.

I have seen issues with WiFi modules such as https://e2e.ti.com/support/processors-group/processors/f/processors-forum/541016/am335x-error-message-in-sdio-driver. Do you know whether the module vendor supports AM335x? Please review the config files as well as firmware to see if they are platform(SoC) specific. If you can you post the log, we can take a closer look.

Best,

Neeraj

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