L138 DDR2 boot up time

1) The DDR throughput is approximately 540MB/s at 150MHz DDR2. For 2Gb, or 256MB, it would take about 0.5 seconds to preload all the memory using EDMA. Doing additional readbacks to verify the data would take additional time obviously.

2) TI does not currently have any suggestions for replacement parts used on the EVM.

Jeff

Wes Hubbell,

Welcome to the TI E2E forum. There is a large and growing amount of information on this forum (the red search box near the upper-right of this page), and you will also want to search the TI Wiki Pages for information. Of course, lots of facts and data are available at our main home page at www.ti.com.

I would recommend that you change the title of this posting to "L138 DDR2 initialization time" to make it more meaningful for people who are searching for that information. The content of your questions and any replies you get will all be included in the searches, but just like you do when you search for something, we all tend to look at the title to see if it sounds close to what we want.

Then I further recommend that you try a search on both the E2E forum and on the TI Wiki Pages for your NAND Flash question. I know I have heard this discussed in the hallways, so I expect someone else has asked about this already. If you do not find the answer, then you may be better off posting a second question with a new title and just the NAND device question. If people think you are being helped already, they are less likely to notice that you have more questions in the same posting - another fact of life with us all.

This may not be a very satisfying answer to your DDR2 initialization question, but I will tell you how I would analyze it for an answer. The upper bound is going to depend on the speed you are running your DDR2 devices. Since the OMAP-L138 supports up to 150MHz clock rate / 300MHz data rate, this means the fastest possible would be 600MB per second. So the ideal performance would be writing a fixed pattern at 600MBps for a little less than 1 second.

But my experience is that you will not get 100% bus utilization, although with nothing else running, you could get close. I would say 80% is really good, and 50% is easy to achieve. This assumes that you are using the EDMA3 engine to do the transfer and you have all the best parameter settings. For example, align an internal 512-byte buffer at a 512-byte address, fill it with the data you want written, and write an EDMA3 transfer command that will copy that 512-byte buffer a bunch of times to fill the external memory.

If you use the ARM or the DSP to do the writing using C code, your performance will drop dramatically. Of course, there might be a Linux or U-boot fill or init command that would be really efficient, but they best possible is always going to be using the EDMA3.

Regards,
RandyP

If this answers your question, please click the  Verify Answer  button below. If not, please reply back with more information. Keep in mind that clicking Verify Answer does two things: 1) it allows someone searching for an answer to know that you got the answer you were seeking so your thread may be of interest to them, and 2) tells those of us looking for a question to answer that this one is done (another good reason to use a second thread for your second question, but maybe put a link to it here).

thank you for the great/detailed answer.  as far as looking at the wiki or ti  - was asked by a TI app engineer to post this question on the forum (I believe he had checked those resources) however I did check the wiki and found no pertinent data. In regard to the title - I actually named it "L138 DDR2 boot up time" or something like it and for some reason it got truncated or chopped. Tried to follow your suggestion to change the title and it was not intuitively obvious - will be glad to do so if you know how.

In regard to the DDR2 RAM, the Micron (MT47H256M8) accepts a clock of 400 MHz (thereby providing a data rate of 800 MHz) the application would want to accomplish the task as fast as possible so we are only limited by the L138. Am trying to stay under 10 seconds - however I suspect the ref design does use C code - Therefore (at high level - and I'll save/forward for the design team) how would one accomplish this task using the EDMA3?

 Am still concerned about the NAND flash.

thank you for your answers. on the first one, suspect the design may use C code which may slow this down so need to get high level approach to forward to designers on how to actually write/read/verify a pattern in there in less than 10 seconds.

on the second one - this sounds alarming! No program flash to work with the OMAP? yikes.

Wes
(systems eng)

clarification:

The L138 would load from boot flash, then check the RAM - so please suggest approach that get this ram initialized asap. thank you.