BBB Clone flashing eMMC via JTAG


We have a clone BBB board except we do not have an SD card slot (the traces are not even brought out of the SOC). We have JTAG capability (20 pin) and we have the blackhawks v2 USB system trace.

I have recompiled the host tool from the linux PSP following this guide:

I loaded the nand flash writer using BlackHawks USB system trace, the program runs, but when it try to actually write the emmc (we use Micron 2GB eMMC MTFC2GMDEA-0M WT), the program cannot write the flash at all. I step through the nand flash writer and noticed the Micron eMMC device id returned all 0xff for all 4 bytes…

My questions are:

is the nand flash writer fairly generic? or do I need to do more code hacking for micron eMMC? (the reason I didn’t pursue the 2nd question immediately is because the eMMC we used is similar to the real BBB, so I assumed micron eMMC should be supported by the nand flash writer by default…)

also is there another way to flash the eMMC other than JTAG? We have the USB Host port available as well for our clone.

or is there another way to flash the eMMC using another software utility other than the said nand flash writer tool from the Linux PSP?

Thanks in advance!


umm... "eMMC" is not "NAND"... Well, it has nand in it, but it's
managed thru the mmc/sd interface. It's like a normal microSD card
except soldered to the pcb.


AH… Sorry for the noobness… I thought they were the same.

Do you have any recommendation for flashing the eMMC via JTAG… now I am quite loss as to what to do next to at least get MLO/uBoot to our bare metal BBB clone :frowning:

Thank you!


Well, if you have jtag access... Either get u-boot running in ram and
have it "write" your data to the eMMC, or have it load a kernel/initrd
that will flash the eMMC..