topic Re: mx28 DDR2 vs core speed in i.MX Processors

mx28 DDR2 vs core speed

Bogumil — Tue, 04 Mar 2014 07:10:01 GMT

I have a pilot series of custom boards with imx287, 64MB DDR2, power + boot _prep, non OS.

I tested configurations from Table14 in datasheet - recommended operating states.

These are first test results:

1) core 454MHz DDR2 205MHz - RAM R/W errors sometimes, on some units (max. config)

2) core 454MHz DDR2 160MHz - RAM R/W errors sometimes, on some units (this is not listed in datasheet as recommended state)

3) core 393MHz DDR2 160MHz - everything ok an all units, acceptable for our application.

Tested few voltages, including max. levels, don't really change results.

What I don't know is where is the problem - core speed, DDR2 speed or relationship between them?

I understand this could be poor layout of DDR2, cause we're using simple EDA PCB software.

I also know that DDR2 configuration might need some changes in software - a fine tuning of timings, but I don't want to do it now.

But if above is true, than test 2) and test 3) should work the same, right?

Core 454MHz without external RAM R/W (runs from internal RAM - boot_prep) run stable on all units, so it seems it's not an issue.

Re: mx28 DDR2 vs core speed

AnsonHuang — Tue, 04 Mar 2014 08:36:57 GMT

Can you check the VDDD's voltage? Not sure whether it is enough to run high speed.

Re: mx28 DDR2 vs core speed

Bogumil — Tue, 04 Mar 2014 09:29:12 GMT

Core is 1,575V, DDR2 is 1,850V. Like I wrote, I tested few different settings of both voltages, including max. and it doesn't change anything.

Re: mx28 DDR2 vs core speed

MarekVasut — Fri, 07 Mar 2014 00:50:17 GMT

You can always try using mainline U-Boot 2014.01 and see if that works in a stable manner for you as well.

Re: mx28 DDR2 vs core speed

Bogumil — Fri, 07 Mar 2014 07:04:33 GMT

Thanks for the tip.

I've compared \u-boot\arch\arm\cpu\arm926ejs\mxs\spl_mem_init.c (CONFIG_MX28) and my configuration (from freescale boot_prep) - no differences, except single bit (RAM size, I use smaller than EVK).

Re: mx28 DDR2 vs core speed

MarekVasut — Fri, 07 Mar 2014 10:09:15 GMT

I mean, use the entire U-Boot as a replacement for bootlets .

Re: mx28 DDR2 vs core speed

YixingKong — Wed, 11 Jun 2014 05:37:16 GMT

Bogumil

We are sorry for getting back to you so late. Are you still stuck with the issue? If you have somehow resolved the issue, can we close the discussion? If you still need help, please feel free to reply with an update to this discussion.

Thanks,

Yixing

Re: mx28 DDR2 vs core speed

YixingKong — Mon, 16 Jun 2014 07:35:19 GMT

Bogumil

We have not got your response yet and will close the discussion in 3 days. If you still need help, please feel free to reply with an update to this discussion.

Thanks,

Yixing

Re: mx28 DDR2 vs core speed

YixingKong — Wed, 02 Jul 2014 03:34:31 GMT

Bogumil

This discussion is closed since no activity. If you still need help, please feel free to reply with an update to this discussion, or create another discussion.

Thanks,

Yixing