On Fri, 12 Dec 2014 03:58:56 -0800, JeGy wrote:

> On Friday, December 12, 2014 10:00:48 AM UTC+1, Boudewijn Dijkstra
> wrote:
>> Op Fri, 12 Dec 2014 08:32:20 +0100 schreef Jens Gydesen
>> <jegy@get2net.dk>:
>> > I have a lpc2478 PCB, with 16M SDRAM, 1/4 VGA LCD i. a. This board
>> > has run perfect for years.
>> > The SDRAM is 2x  Micron MT48LC16M4A2.
>> >
>> > In order to modernize this PCB, the cpu is replaced with the
>> > compatible LPC1788.
>> >
>> > I have problems with the SDRAM, it fails. The program crashes due to
>> > read/write errors and the LCD shows distorted displays.
>> 
>> Are you running the CPU and EMC at the same frequency as with the
>> LPC2478?  And is the trace length the same between the two boards?  It
>> sounds like your EMC clock signal is unstable or skewed.  Try a lower
>> frequency first, then go up and tweak the settings (particularly
>> EMCDELAY to compensate skewing at high frequencies).
>> 
>> > Does anyone here have expirencies with similar problems ?
>> 
>> Yes.  For a customer who wanted maximum performance I wrote an SDRAM
>> test function that writes&compares RNG values in display memory at
>> different settings and then prints out the number of verify errors per
>> run.  Also we used a heat gun because errors go up with temperature.
>> 
>> > Do you have a code snip for initializing the SD-controller and 
>> > SDRAM, so I can compare to my own?
>> 
>> None that I can give you, sorry.
>> 
>> 
>> 
>> 
>> --
>> (Remove the obvious prefix to reply privately.)
>> Gemaakt met Opera's e-mailprogramma: http://www.opera.com/mail/
> 
> Hi,
> 
> Thanks for your answer!
> 
> Sorry for the post of the original
> 
> 
> The PCB's are the same, just the cpu is replaced.
> 
> I have tried to run the lpc1788 PBC at lower frequency, this makes no
> differnce.
> 
> Further i have tried to vary the frequency on the LPC2478 PCB, and this
> works, nomatter what i do

I know nothing of that specific processor, but I'm assuming that it lets 
you set up the interface to the RAM in a wide variety of ways, many of 
which are guaranteed to be wrong.

If you're using the same code, go over the interface timing with a fine-
toothed comb to make sure that the new processor isn't interpreting 
something differently.  The last time I did this was the Motorola MPC860 
(or something -- it was their Power QWICC).  That thing almost had another 
processor between the core and the memory interface pins -- you basically 
wrote a script in a descriptor that told it how to talk to the DRAM.  It 
was hugely flexible, but that just meant that you had a bazzilion 
different ways to screw it up and only a few ways to make it work right.

I'd also look at the signal timings on the board, if I could do it without 
loading the traces down too much.  At best you'll be able to plug into it 
with a logic analyzer, but even hanging an O-scope lead on the clock and 
then probing each wire in turn to see what happens should tell you 
something.

(Of course, it may just tell you that as soon as you start probing it 
everything goes to hell or suddenly fixes itself -- but that's 
information, right?)

-- 

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

John Devereux <john@devereux.me.uk> writes:

> JeGy <gydesen.jens@gmail.com> writes:
>
>> On Friday, December 12, 2014 4:33:00 PM UTC+1, pozzugno wrote:
>>> Il 12/12/2014 08:32, Jens Gydesen ha scritto:
>>> > Hi,
>>> >
>>> > I have a lpc2478 PCB, with 16M SDRAM, 1/4 VGA LCD i. a. This board has run
>>> > perfect for years.
>>> > The SDRAM is 2x  Micron MT48LC16M4A2.
>>> >
>>> > In order to modernize this PCB, the cpu is replaced with the compatible
>>> > LPC1788.
>>> >
>>> > I have problems with the SDRAM, it fails. The program crashes due to
>>> > read/write errors and the LCD shows distorted displays.
>>> >
>>> > Does anyone here have expirencies with similar problems ?
>>> >
>>> > Do you have a code snip for initializing the SD-controller and  SDRAM, so I
>>> > can compare to my own?
>>> >
>>> > Thanks in advance
>>> > Regards
>>> >
>>> > Jens
>>> 
>>> This isn't a really in-topic answer to your OP.
>>> 
>>> I'm starting designing a new board with LPC1788, an external 16-bits 
>>> SDRAM, a Quad-SPI Flash (for code and data) and a 4.3" 480x272 display 
>>> with touch panel.
>>> 
>>> Until now I worked with all-in-one microcontroller: integrated Flash and 
>>> RAM, so I haven't any experience with a memory external bus.
>>> 
>>> Any suggestions how to learn basic and advanced topics about this?
>>
>> If I had the possibility to redesign the HW, I would use static RAM...  :-)
>
> AFAIK the gotcha with SDRAM on those is the slow speed if you want to
> execute from it. Perhaps 6 times slower than from flash I think. It is
> OK for TFT frame buffers.

Oh I should have said that it should be fine for your retrofit
application, it should be significantly faster than the ARM7. I am
looking at doing exactly the same thing on my LPC2478 boards at some
point so please let us know what you find!

> The new M7 should be a big improvement here with its caches, perhaps NXP
> will make an M7 version of your device too.

-- 

John Devereux

JeGy <gydesen.jens@gmail.com> writes:

> On Friday, December 12, 2014 4:33:00 PM UTC+1, pozzugno wrote:
>> Il 12/12/2014 08:32, Jens Gydesen ha scritto:
>> > Hi,
>> >
>> > I have a lpc2478 PCB, with 16M SDRAM, 1/4 VGA LCD i. a. This board has run
>> > perfect for years.
>> > The SDRAM is 2x  Micron MT48LC16M4A2.
>> >
>> > In order to modernize this PCB, the cpu is replaced with the compatible
>> > LPC1788.
>> >
>> > I have problems with the SDRAM, it fails. The program crashes due to
>> > read/write errors and the LCD shows distorted displays.
>> >
>> > Does anyone here have expirencies with similar problems ?
>> >
>> > Do you have a code snip for initializing the SD-controller and  SDRAM, so I
>> > can compare to my own?
>> >
>> > Thanks in advance
>> > Regards
>> >
>> > Jens
>> 
>> This isn't a really in-topic answer to your OP.
>> 
>> I'm starting designing a new board with LPC1788, an external 16-bits 
>> SDRAM, a Quad-SPI Flash (for code and data) and a 4.3" 480x272 display 
>> with touch panel.
>> 
>> Until now I worked with all-in-one microcontroller: integrated Flash and 
>> RAM, so I haven't any experience with a memory external bus.
>> 
>> Any suggestions how to learn basic and advanced topics about this?
>
> If I had the possibility to redesign the HW, I would use static RAM...  :-)

AFAIK the gotcha with SDRAM on those is the slow speed if you want to
execute from it. Perhaps 6 times slower than from flash I think. It is
OK for TFT frame buffers.

The new M7 should be a big improvement here with its caches, perhaps NXP
will make an M7 version of your device too.




-- 

John Devereux

On Friday, December 12, 2014 4:33:00 PM UTC+1, pozzugno wrote:
> Il 12/12/2014 08:32, Jens Gydesen ha scritto:
> > Hi,
> >
> > I have a lpc2478 PCB, with 16M SDRAM, 1/4 VGA LCD i. a. This board has run
> > perfect for years.
> > The SDRAM is 2x  Micron MT48LC16M4A2.
> >
> > In order to modernize this PCB, the cpu is replaced with the compatible
> > LPC1788.
> >
> > I have problems with the SDRAM, it fails. The program crashes due to
> > read/write errors and the LCD shows distorted displays.
> >
> > Does anyone here have expirencies with similar problems ?
> >
> > Do you have a code snip for initializing the SD-controller and  SDRAM, so I
> > can compare to my own?
> >
> > Thanks in advance
> > Regards
> >
> > Jens
> 
> This isn't a really in-topic answer to your OP.
> 
> I'm starting designing a new board with LPC1788, an external 16-bits 
> SDRAM, a Quad-SPI Flash (for code and data) and a 4.3" 480x272 display 
> with touch panel.
> 
> Until now I worked with all-in-one microcontroller: integrated Flash and 
> RAM, so I haven't any experience with a memory external bus.
> 
> Any suggestions how to learn basic and advanced topics about this?

If I had the possibility to redesign the HW, I would use static RAM...  :-)

Regards Jens

On Friday, December 12, 2014 4:00:47 PM UTC+1, Boudewijn Dijkstra wrote:
> Op Fri, 12 Dec 2014 12:58:56 +0100 schreef JeGy <gydesen.jens@gmail.com>:
> > On Friday, December 12, 2014 10:00:48 AM UTC+1, Boudewijn Dijkstra wrote:
> >> Op Fri, 12 Dec 2014 08:32:20 +0100 schreef Jens Gydesen  
> >> <jegy@get2net.dk>:
> >> > I have a lpc2478 PCB, with 16M SDRAM, 1/4 VGA LCD i. a. This board has
> >> > run perfect for years.
> >> > The SDRAM is 2x  Micron MT48LC16M4A2.
> >> >
> >> > In order to modernize this PCB, the cpu is replaced with the  
> >> compatible
> >> > LPC1788.
> >> >
> >> > I have problems with the SDRAM, it fails. The program crashes due to
> >> > read/write errors and the LCD shows distorted displays.
> >>
> >> Are you running the CPU and EMC at the same frequency as with the
> >> LPC2478?  And is the trace length the same between the two boards?  It
> >> sounds like your EMC clock signal is unstable or skewed.  Try a lower
> >> frequency first, then go up and tweak the settings (particularly  
> >> EMCDELAY to compensate skewing at high frequencies).
> >>
> >> > Does anyone here have expirencies with similar problems ?
> >>
> >> Yes.  For a customer who wanted maximum performance I wrote an SDRAM  
> >> test
> >> function that writes&compares RNG values in display memory at different
> >> settings and then prints out the number of verify errors per run.  Also  
> >> we used a heat gun because errors go up with temperature.
> >>
> >> > Do you have a code snip for initializing the SD-controller and  SDRAM,
> >> > so I can compare to my own?
> >>
> >> None that I can give you, sorry.
> >>
> >>
> >
> > Hi,
> >
> > Thanks for your answer!
> >
> >
> > The PCB's are the same, just the cpu is replaced.
> >
> > I have tried to run the lpc1788 PBC at lower frequency, this makes no
> > differnce.
> 
> Possibly the signal drive strength is too low.  What is the lowest EMC  
> frequency that you tried?
> 
> > Further i have tried to vary the frequency on the LPC2478 PCB, and this
> > works, nomatter what i do
> 
> That is expected, since that chip runs at 72MHz max.
> 
> 
> -- 
> (Remove the obvious prefix to reply privately.)
> Gemaakt met Opera's e-mailprogramma: http://www.opera.com/mail/



It is a good point with the signal strength, I'l check that.

I have tried 48 MHz up to 96 MHz with the 1788.

My 2478 runs normally at 72MHz, but 48 will also do it

I think that some register in the 1788, different from the 2478, is not initialized correct or forgotten, but I think that I have found the differencies between them.

Regards Jens

Il 12/12/2014 08:32, Jens Gydesen ha scritto:
> Hi,
>
> I have a lpc2478 PCB, with 16M SDRAM, 1/4 VGA LCD i. a. This board has run
> perfect for years.
> The SDRAM is 2x  Micron MT48LC16M4A2.
>
> In order to modernize this PCB, the cpu is replaced with the compatible
> LPC1788.
>
> I have problems with the SDRAM, it fails. The program crashes due to
> read/write errors and the LCD shows distorted displays.
>
> Does anyone here have expirencies with similar problems ?
>
> Do you have a code snip for initializing the SD-controller and  SDRAM, so I
> can compare to my own?
>
> Thanks in advance
> Regards
>
> Jens

This isn't a really in-topic answer to your OP.

I'm starting designing a new board with LPC1788, an external 16-bits 
SDRAM, a Quad-SPI Flash (for code and data) and a 4.3" 480x272 display 
with touch panel.

Until now I worked with all-in-one microcontroller: integrated Flash and 
RAM, so I haven't any experience with a memory external bus.

Any suggestions how to learn basic and advanced topics about this?

Op Fri, 12 Dec 2014 12:58:56 +0100 schreef JeGy <gydesen.jens@gmail.com>:
> On Friday, December 12, 2014 10:00:48 AM UTC+1, Boudewijn Dijkstra wrote:
>> Op Fri, 12 Dec 2014 08:32:20 +0100 schreef Jens Gydesen  
>> <jegy@get2net.dk>:
>> > I have a lpc2478 PCB, with 16M SDRAM, 1/4 VGA LCD i. a. This board has
>> > run perfect for years.
>> > The SDRAM is 2x  Micron MT48LC16M4A2.
>> >
>> > In order to modernize this PCB, the cpu is replaced with the  
>> compatible
>> > LPC1788.
>> >
>> > I have problems with the SDRAM, it fails. The program crashes due to
>> > read/write errors and the LCD shows distorted displays.
>>
>> Are you running the CPU and EMC at the same frequency as with the
>> LPC2478?  And is the trace length the same between the two boards?  It
>> sounds like your EMC clock signal is unstable or skewed.  Try a lower
>> frequency first, then go up and tweak the settings (particularly  
>> EMCDELAY to compensate skewing at high frequencies).
>>
>> > Does anyone here have expirencies with similar problems ?
>>
>> Yes.  For a customer who wanted maximum performance I wrote an SDRAM  
>> test
>> function that writes&compares RNG values in display memory at different
>> settings and then prints out the number of verify errors per run.  Also  
>> we used a heat gun because errors go up with temperature.
>>
>> > Do you have a code snip for initializing the SD-controller and  SDRAM,
>> > so I can compare to my own?
>>
>> None that I can give you, sorry.
>>
>>
>
> Hi,
>
> Thanks for your answer!
>
>
> The PCB's are the same, just the cpu is replaced.
>
> I have tried to run the lpc1788 PBC at lower frequency, this makes no
> differnce.

Possibly the signal drive strength is too low.  What is the lowest EMC  
frequency that you tried?

> Further i have tried to vary the frequency on the LPC2478 PCB, and this
> works, nomatter what i do

That is expected, since that chip runs at 72MHz max.


-- 
(Remove the obvious prefix to reply privately.)
Gemaakt met Opera's e-mailprogramma: http://www.opera.com/mail/

On Friday, December 12, 2014 10:00:48 AM UTC+1, Boudewijn Dijkstra wrote:
> Op Fri, 12 Dec 2014 08:32:20 +0100 schreef Jens Gydesen <jegy@get2net.dk>:
> > I have a lpc2478 PCB, with 16M SDRAM, 1/4 VGA LCD i. a. This board has  
> > run perfect for years.
> > The SDRAM is 2x  Micron MT48LC16M4A2.
> >
> > In order to modernize this PCB, the cpu is replaced with the compatible
> > LPC1788.
> >
> > I have problems with the SDRAM, it fails. The program crashes due to
> > read/write errors and the LCD shows distorted displays.
> 
> Are you running the CPU and EMC at the same frequency as with the  
> LPC2478?  And is the trace length the same between the two boards?  It  
> sounds like your EMC clock signal is unstable or skewed.  Try a lower  
> frequency first, then go up and tweak the settings (particularly EMCDELAY  
> to compensate skewing at high frequencies).
> 
> > Does anyone here have expirencies with similar problems ?
> 
> Yes.  For a customer who wanted maximum performance I wrote an SDRAM test  
> function that writes&compares RNG values in display memory at different  
> settings and then prints out the number of verify errors per run.  Also we  
> used a heat gun because errors go up with temperature.
> 
> > Do you have a code snip for initializing the SD-controller and  SDRAM,  
> > so I can compare to my own?
> 
> None that I can give you, sorry.
> 
> 
> 
> 
> -- 
> (Remove the obvious prefix to reply privately.)
> Gemaakt met Opera's e-mailprogramma: http://www.opera.com/mail/

Hi,

Thanks for your answer!

Sorry for the post of the original 


The PCB's are the same, just the cpu is replaced.

I have tried to run the lpc1788 PBC at lower frequency, this makes no
differnce.

Further i have tried to vary the frequency on the LPC2478 PCB, and this
works, nomatter what i do

Regards Jens

On Friday, December 12, 2014 10:00:48 AM UTC+1, Boudewijn Dijkstra wrote:
> Op Fri, 12 Dec 2014 08:32:20 +0100 schreef Jens Gydesen <jegy@get2net.dk>:
> > I have a lpc2478 PCB, with 16M SDRAM, 1/4 VGA LCD i. a. This board has  
> > run perfect for years.
> > The SDRAM is 2x  Micron MT48LC16M4A2.
> >
> > In order to modernize this PCB, the cpu is replaced with the compatible
> > LPC1788.
> >
> > I have problems with the SDRAM, it fails. The program crashes due to
> > read/write errors and the LCD shows distorted displays.
> 
> Are you running the CPU and EMC at the same frequency as with the  
> LPC2478?  And is the trace length the same between the two boards?  It  
> sounds like your EMC clock signal is unstable or skewed.  Try a lower  
> frequency first, then go up and tweak the settings (particularly EMCDELAY  
> to compensate skewing at high frequencies).
> 
> > Does anyone here have expirencies with similar problems ?
> 
> Yes.  For a customer who wanted maximum performance I wrote an SDRAM test  
> function that writes&compares RNG values in display memory at different  
> settings and then prints out the number of verify errors per run.  Also we  
> used a heat gun because errors go up with temperature.
> 
> > Do you have a code snip for initializing the SD-controller and  SDRAM,  
> > so I can compare to my own?
> 
> None that I can give you, sorry.
> 
> 
> 
> 
> -- 
> (Remove the obvious prefix to reply privately.)
> Gemaakt met Opera's e-mailprogramma: http://www.opera.com/mail/

Hi,

I have a lpc2478 PCB, with 16M SDRAM, 1/4 VGA LCD i. a. This board has run perfect for years.
The SDRAM is 2x  Micron MT48LC16M4A2.

In order to modernize this PCB, the cpu is replaced with the compatible LPC1788.

I have problems with the SDRAM, it fails. The program crashes due to read/write errors and the LCD shows distorted displays.

Does anyone here have expirencies with similar problems ?

Do you have a code snip for initializing the SD-controller and  SDRAM, so I can compare to my own? 

Thanks in advance
Regards

Jens