Getting Started with a custom AM335x board

John Johnson52

Other Parts Discussed in Thread: AM3352

I've just received a new AM335x board from our electronic engineer. It's modelled on a Beaglebone Black layout, but minus the FLASH, the HDMI chip, the ident chip, and the device is an AM3352 (no GPU). Also, no ethernet.

I have been trying to bring the board to life, and am unsure if I've chosen the right starting point. I started at

http://processors.wiki.ti.com/index.php/Processor_SDK_Linux_Setup_Script

and successfully prepared an SD card that booted a Beaglebone Black just fine. I tried it in our board, and (understandably) it fell over immediately because the ident chip is not there on the I2C bus. So, I thought that one route to getting up and running would be to hack the code in U-Boot that reads the ident chip to make it see a Beaglebone Black ident header. That seems to work, and U-Boot now hangs a bit later, when it's trying to jump to _main (I'm not quite sure what's happening, there, yet).

So, my question is - this feels like a hacky way to approach this. Is there documentation for how I should approach it, for a bespoke board? The page above has a section for customising the U-Boot build, but it starts with an NFS share and I don't have ethernet. Generally, the documentation seems to be centred around working on an evaluation board, and I'm not. Can anyone give me any hints, point me at the right jumping-off points?

This page

processors.wiki.ti.com/.../Sitara_Linux_Training:_Linux_Board_Port

has a Beaglebone as a pre-requisite; I'm not working with a Beaglebone.

This page

processors.wiki.ti.com/.../AM335x_U-Boot_User's_Guide

seems, I think, to require there to be NAND on-board.

Perhaps one of the above links is what I'm looking for, but I can't see a straightforward indication of where to start, for my case (which must be overwhelmingly common, so I must be missing something).

Thanks in advance.

over 10 years ago

0 Biser Gatchev-XID over 10 years ago

TI__Guru**** 393215 points

Hi John,

Which Linux version are you using? One of the first things you have to do is to tune your DDR memory. This is described here:

http://processors.wiki.ti.com/index.php/AM335x_EMIF_Configuration_tips and

http://processors.wiki.ti.com/index.php/AM335x_DDR_PHY_register_configuration_for_DDR3_using_Software_Leveling

There is also a step-by-step tutorial here: http://processors.wiki.ti.com/index.php/Sitara_Linux_Training:_Tuning_the_DDR3_Timings_on_BeagleBoneBlack

This is an important step because the initial bootloader (SPL/MLO) runs from internal RAM, but it has the task to configure the external DDR and load u-boot in it. Probably your boot fails somewhere there.

0 John Johnson52 over 10 years ago in reply to Biser Gatchev-XID

Prodigy 40 points

Hi Biser

Thanks. I'm using the Processor SDK, so I guess is that "Sitara Linux"?

My electronics guy has actually turned up one of the pages you posted, this morning, so he seems to be on that track - I'll pass him the other links you posted, thanks.

What about my more general question - am I taking a sensible approach, by hacking the U-Boot from the Beaglebone Black configuration files? Is that what people do? My expectation is that I'll manage to get through U-Boot, once we have the DDR problem settled, and then my Linux will start to boot. I'll then hack around a bit, if necessary, to get that to a shell prompt. From that point on, I'm in a universe more familiar to me, and I'll be happy enough working forward from there. Right? Does this all sound like a sensible approach?

Thanks again

0 Biser Gatchev-XID over 10 years ago in reply to John Johnson52

TI__Guru**** 393215 points

Hi John,

John Johnson52 said:
I'm using the Processor SDK, so I guess is that "Sitara Linux"?

Yes, it's the same thing.

John Johnson52 said:
What about my more general question...

Yes, this makes sense. Since you have a similar design to BBB, from what you posted, it seems that most of the work will be to remove the unnecessary parts that do not concern your board. Do not hesitate to post any question you have on this forum. We have a SW team that will help.

0 John Johnson52 over 10 years ago in reply to Biser Gatchev-XID

Prodigy 40 points

Hi Biser

Thanks, that's very helpful, I'll press on. I'm sure I'll have questions, so it's great to hear there's some help available.

Incidentally, I can't login to the site from Google Chrome, I'm having to switch to firefox to work the forum. If I try to login from Chrome I see "Login process interrupted. This might be the result of having open login pages on multiple tabs in your browser, or a stale login page. Please check the URL of the application that you were trying to login to and try again. If the problem persists, please contact your application support team.". Just FYI for your web team, perhaps it's possible to link them to this post (or perhaps they're aware already).

Cheers

0 Biser Gatchev-XID over 10 years ago in reply to John Johnson52

TI__Guru**** 393215 points

Thanks for the feedback, I have forwarded this to the site support team.

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Getting Started with a custom AM335x board