Does SAM9G25 boot from eMMC?

Discussion around AT91RM9200 and SAM9 Series Products.

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cblixt
Posts: 2
Joined: Wed Oct 10, 2018 3:27 pm

Does SAM9G25 boot from eMMC?

Wed Oct 10, 2018 3:51 pm

I am trying to get a definitive answer to the subject question. Specifically, does the ROM bootloader support booting from eMMC rather than SDCard. I have found the following in the SAM9G25 datasheet from Atmel (Aug/2015):

"One 64-Kbyte internal ROM embedding bootstrap routine: Boot on NAND Flash, SDCard, DataFlash or serial
DataFlash"

In the SAMA5Dx datasheet from Atmel (Jul/2016), I can read this:

"The standard bootloader supports booting from:
* 8-bit NAND Flash with ECC management
* SPI Serial Flash
* SDCARD
* EMMC
* TWI EEPROM"

It seems to me that the SAMA5D can boot from eMMC, but not the SAM9G25. It is just that the datasheet for the latter clearly mentions supporting MMC on its High Speed Multimedia Card Interface, so I can't imagine the reason for not making the ROM bootloader able to boot from it. Does anyone know for sure?
blue_z
Location: USA
Posts: 1784
Joined: Thu Apr 19, 2007 10:15 pm

Re: Does SAM9G25 boot from eMMC?

Fri Oct 12, 2018 1:24 am

cblixt wrote: I am trying to get a definitive answer to the subject question. Specifically, does the ROM bootloader support booting from eMMC rather than SDCard.
Microchip Tech Support is the definitive source.

However you might be asking the wrong question.
Are you sure you want to connect an eMMC module to a SAM9G25?
The SAM9G25 only supports MultiMedia Card Specification Version 4.3, whereas the eMMC modules available today typically implement at least version 4.41, 4.5, or later.
Review this chart for eMMC features and capabilities that you may not be able to utilize with a SAM9G25.

Regards
cblixt
Posts: 2
Joined: Wed Oct 10, 2018 3:27 pm

Re: Does SAM9G25 boot from eMMC?

Fri Oct 12, 2018 3:21 pm

Thanks a lot for replying. Yes, tech support is probably the best place to go. However, after carefully reading the datasheet of SAM9X25 again and comparing it to that of SAMA5D2, I think I can say for sure that SAM9 doesn't boot from eMMC. It is still inexplicable to me, as it wouldn't have been very difficult to arrange given that it supports SD, but it nevertheless seems to be the case.

My problem is that my company has a design that uses a module (Aria from ACME Systems) based on the AT91SAM9G25, and that has both eMMC and an SD slot connected to it. The intention from the start was to use the eMMC, the SD slot was just a backup. It was not apparent to the original designers of this system that it would not be possible to boot from the eMMC. We have since then tried to get support from the module maker, but they also don't seem to know. Now we are in the unfortunate situation that we have to deliver systems using SD cards as boot medium.

Just being able to boot would have been enough, none of the advanced features of later eMMC specifications would have been needed. Of course when this design is revised, we will consider using some other processor module, but until then I wanted to do what I could to find out if eMMC boot is really impossible on the current SAM9-based solution.

Regards,
Christian
nferre
Site Admin
Posts: 186
Joined: Wed Feb 14, 2007 11:17 am

Re: Does SAM9G25 boot from eMMC?

Tue Oct 16, 2018 2:23 pm

Hi,

Did you try with a 1st partition formatted as FAT filesystem just like you would do for SD Card?

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