[BUG] MMC support on MaixDuino

[Sean Anderson]

On 4/3/21 6:26 AM, Heinrich Schuchardt wrote:
> Hello Sean,
> 
> thanks for getting MMC running on the MAIX.
> 
> Reading files works fine. But if try to write I get a failure:
> 
> => save mmc 0:1 ${loadaddr} foo 0x100
> mmc write failed
> Error: writing contents
> ** Unable to write file foo **
> => ls mmc 0:1
> ** No partition table - mmc 0 **
> =>
> 
> Even after resetting the board the SD-card cannot be read.
> 
> Only after power-cycling the SD-card works again:
> 
> => ls mmc 0:1
>        377   boot.scr
>      30349   dtb
>    2155040   uImage
> 
> 3 file(s), 0 dir(s)
> 
> Best regards
> 
> Heinrich

As noted in the board documentation

> MMC
> """
> 
> MMC writes are unsupported for now.

As I was unable to get this working when I submitted my initial draft.

--Sean