eMMC gets timeout when I put on cape

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1

Hey There,

I’m running BeagleBone Black Rev C.
I have developed my own custom cape, it is using the following IO-pins:



BBB-header no

|

BBB GPIO no

|

  • | - |


    P9_42

    |

    7

    |


    P9_18

    |

    4

    |


    P9_17

    |

    5

    |


    P9_15

    |

    48

    |


    P9_28

    |

    113

    |


    P9_23

    |

    49

    |


    P9_31

    |

    110

    |


    P9_12

    |

    60

    |


    P9_29

    |

    111

    |


    P9_27

    |

    115

    |


    P9_25

    |

    117

    |

I have developed a device tree overlay, that’s declaring all the pins as GPIOs, and I have set all pins to output with value 0. Other than that am I using the VDD_3V3 and VDD_5V.

When I put the cape on, I get some error mesaages on dmesg:

[ 159.482950] mmcblk0: error -110 sending status command, retrying

[ 159.489379] mmcblk0: error -110 sending status command, aborting

[ 159.495725] end_request: I/O error, dev mmcblk0, sector 497760

At this point I can still type in some simple commands to the commandline (such as ls and cd) but more demanding commands fails (such as top and shutdown), it gives me an I/O error.

So it seems that the MMC-card for some reason is unreachable. The cape doesn’t seem to affect the supply voltage, is was measured on VDD_3V3 (P9_3) to be 3,15V both before and after I put the cape on.

Does anybody have any clues, or any suggestions to how I could do further debugging?

Thanks :slight_smile:

2

Are you sure none of those pins are being used by the emmc? It sure sounds
like they might be...

Chris

3

Hey :slight_smile:

According to Derek Molloys header pin overview ( http://exploringbeaglebone.com/wp-content/uploads/resources/BBBP9Header.pdf ) some of the pins are used by the HDMI, but I have disabled that. It seems that all the eMMC pins are located on the P8 header.
If this was the problem, I should be able to see the same problem when I set the values of all the GPIO to 1, even without putting the cape on, right?

4

Hi Martin.

Can you provide a schematic and a photo of your cape?

I'm wondering if you have anything plugged into the P8 header and also how
you are ensuring you aren't driving or loading any pins until after the
SYS_RESET line goes high.

Chris