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Sansa Clip+: noise when reading from micro SD card

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tempe:
thanks for your help guys! i'll try it outas soon as i have time. just one question: the patch does indeed alter a firmware file:


--- Code: ---diff --git a/firmware/target/arm/as3525/sd-as3525v2.c b/firmware/target/arm/as3525/sd-as3525v2.c
index 8134869..26d2d6a 100644
--- a/firmware/target/arm/as3525/sd-as3525v2.c
+++ b/firmware/target/arm/as3525/sd-as3525v2.c
--- End code ---

so what does that mean in the matter of compiling the boot loader? i haven't found anything in the guide for that.

torne:
You don't really need to recompile the bootloader for this change, but that is a good rule of thumb nonetheless (many changes to firmware/ will affect the bootloader). If you do want to build a bootloader sometime, then this is simple: create a separate build directory (e.g. build-bootloader) and when running configure and it asks you what type of build, type b for a bootloader instead of n for a normal build.

bertrik:
My suggestion to try the patch is a just an attempt to get a grip on this problem. I think there's a very small chance that it's actually going to completely solve the problem, it's just interesting to know if it makes any difference at all. We still don't know what exactly causes the interference problem.

Building the bootloader is totally unnecessary for this. I can supply a binary if needed, please ask me in #rockbox when I'm around.

I think we (the rockbox team) should order the uSD and SD extender boards from SparkFun and have someone with a scope take a look at the signals:
* compare sd signals between OF and rockbox
* check clock setting (speed)
* check if the OF stops the sd clock at all between transfers
* any other thing we can think of to diagnose on the sd port

tempe:
thanks everyone, i managed to make my own build and it worked!!  :)

the noise is still there with the patch. i dont know if something went wrong in the patching/compiling process.

how can i find that out? can i compare the source code somehow?

the head of the patch code is included further up in this thread. i guess I have to look into as3525v2.c? but what do the +++ and --- mean and why does the path begin with a/... and then with b/... ?

tempe

tempe:
ok, i made another build including the noise patch as well as the backlight-on-volume-change-off patch. since the latter one works smoothly, i guess that i made no mistakes.

so, my conclusion: the noise is still there with the patch in the same volume  :-[
if i can contribute to the solution of the problem, let me know.

btw: i have a 16 gb kingston micro sdhc, class 4 (so basically the larger sister of the 8 gb), and this makes NO NOISE !!

thanks a lot to all of you, especially to all the developers of rockbox!!

tempe

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