MPC870

Mark A. Odell <odellmark@hotmail.com> wrote:
> "Martin Euredjian" <0_0_0_0_@pacbell.net> wrote in
> news:a4oZc.14534$Hz7.4772@newssvr29.news.prodigy.com: 
> 
>>> Read well the UPM documentation before committing to the 8xx.
>> 
>> I had a moment and took a quick look.  This doesn't scare me that much.
>> I've implemented FPGA-based SDRAM controllers from scratch.  I can see
>> the value in the flexibility offered, despite the complexity it adds.  I
>> can also see how some embedded guys could be horrified at the prospect
>> of dealing with the UPM.
> 
> Oh, it's not that, it's just that twiddling some signals on half-clock
> boundaries and others on quarter clock boundaries with the RAM words in a
> table listed top to bottom with time running down from top to bottom WRT
> to cycles gets complicated. The documentation is not overly clear, nor
> does the UPM diagramming tool seem to help (me at least) I spent a solid
> day getting the single beat read and write cycles to work (from scratch
> because I wanted to learn the UPM) and then wasted a week on the burst
> cycles. I finally gave up and used an app. note. When booting the 405GPr
> for the first time about 2 years later, I wrote a few simple bits to a
> couple of registers and I was done in about an hour of tweaking. 
> 

The UPM can be quite a pest, but Freescale has an "UPM Programming
Tool" that can be downloaded. I haven't tested it myself, but I assume 
it can at least help in getting things up and running a bit faster.

/Henrik

-- 

Henrik Johnsson <henrik.johnsson@emw.ericsson.se> wrote in
news:ch6bj6$t94$1@newstree.wise.edt.ericsson.se: 

>>> I had a moment and took a quick look.  This doesn't scare me that
>>> much. I've implemented FPGA-based SDRAM controllers from scratch.  I
>>> can see the value in the flexibility offered, despite the complexity
>>> it adds.  I can also see how some embedded guys could be horrified at
>>> the prospect of dealing with the UPM.
>> 
>> Oh, it's not that, it's just that twiddling some signals on half-clock
>> boundaries and others on quarter clock boundaries with the RAM words in
>> a table listed top to bottom with time running down from top to bottom
>> WRT to cycles gets complicated. The documentation is not overly clear,
>> nor does the UPM diagramming tool seem to help (me at least) I spent a
>> solid day getting the single beat read and write cycles to work (from
>> scratch because I wanted to learn the UPM) and then wasted a week on
>> the burst cycles. I finally gave up and used an app. note. When booting
>> the 405GPr for the first time about 2 years later, I wrote a few simple
>> bits to a couple of registers and I was done in about an hour of
>> tweaking. 
>> 
> 
> The UPM can be quite a pest, but Freescale has an "UPM Programming
> Tool" that can be downloaded. I haven't tested it myself, but I assume 
> it can at least help in getting things up and running a bit faster.

The version I used was less helpful than just reading the data book.

-- 
- Mark ->
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