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analogdevicesinc / msdk

Software Development Kit for Analog Device's MAX-series microcontrollers
Apache License 2.0
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FatFS using SDHC is hardcoded to 1-bit mode in diskio.c #1044

Closed JordanAceto closed 1 week ago

JordanAceto commented 3 weeks ago

Hi there,

I noticed slow SD card writes when using the SDHC library. Probing the data lines with an oscilloscope revealed that only the DATA0, CLK, and CMD lines were active. The DAT1 .. DAT3 lines were permanently high during data writes.

Browsing through the code and using the debugger, I found that the data width is hardcoded with the enumeration MXC_SDHC_LIB_SINGLE_DATA in diskio.c. The relevant line for the write function is shown below. The matching read function has the same hardcoded enum. I am using FF15.

https://github.com/analogdevicesinc/msdk/blob/5955fcf103fdb42f5a424dcc08eedbb942b520b1/Libraries/SDHC/ff15/source/diskio.c#L199

After manually changing the hardcoded enums to MXC_SDHC_LIB_QUAD_DATA in diskio.c, I do see all 4 data lines wiggling, and the SD card write speeds increase as expected.

Is there a reason for the SDHC to be hardcoded to 1-bit mode when using FatFS/can the ability to use all 4 data lines be added to the MSDK?

Thanks!

EricB-ADI commented 3 weeks ago

What chip are you using? I do not know the full history, but not all of our chips support QSPI operation, for ease it was most likely set to that to not have to deal part to part variation. I will add this to my list and will update this sometime soon.

JordanAceto commented 3 weeks ago

We are using MAX32666. The current code is on a FTHR board, but we will eventually move it to a custom PCB. Thanks!

Jake-Carter commented 3 weeks ago

Thanks @JordanAceto, this is just a legacy hard-coded config. We can and should expose this as a config option to the API.

Jake-Carter commented 3 weeks ago

Ah looks like @EricB-ADI is already on it in #1045