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[Bug 1001764] Enhancement of MMC/SD over SPI driver
- From: bugzilla-daemon at bugs dot ecos dot sourceware dot org
- To: unassigned at bugs dot ecos dot sourceware dot org
- Date: Sun, 30 Jun 2013 13:58:53 +0000
- Subject: [Bug 1001764] Enhancement of MMC/SD over SPI driver
- Auto-submitted: auto-generated
- References: <bug-1001764-777 at http dot bugs dot ecos dot sourceware dot org/>
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--- Comment #22 from Mike Jones <firstname.lastname@example.org> ---
I have had more bench time on the MMC, so I have more information about its
operation under heavy use.
First, my setup is atypical. I have a cable on J5 of the Kinetis tower board
that connects to another board 30cm away. This board has its own power supply
off line. Therefore, because there is a ground connection in J5, there is a
ground loop. Furthermore, I am using the I2C lines in the J5 connector.
I have seen four problems:
1) Can't mount Samsung microSD
2) Can't mount any microSD
3) IO failure after three hours of intense operation (logging MB to card)
4) Can't get DMA to work reliably
I have some new information. I was debugging the TWR-DACADC-LTC and noticed
problem 2. When I removed the ground clips from my scope, problem 2 went away.
This leads me to the conclusion that problems 2 and 3 are related to grounding
problems. I can't prove grounding is causing 3 until I have a single board
version of my solution.
Problems 1 and 4 still seem to be problems that only affect me. I work around
them by not using DMA and not using the Samsung card. I am certain that problem
1 is not related to grounding. I have tested for that. I am reasonable certain
problem 4 is not related to grounding, I am pretty sure I have seen the problem
with my cable removed.
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