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[Reply #15 on:]

Ack, 3AM!
I'm off to bed. Will dig out my Sallea and look at the clocks & data tomorrow afternoon.
G'night all!

[Reply #16 on:]

If I remove some NOPs won't it go even faster?

Yes, but the hardware won't have finished clocking out the byte. So you will lose data.

[Reply #17 on:]

Yes, IE9

That thing causes me fits as well.  Turning "Compatibility Mode" on seems to help.  The odd thing is I only have trouble with Internet Explorer on this forum.  I suggest using Firefox. 

G'night all!

Back at ya!  I'm headed there as well...

[Reply #18 on:]

Okay, I got some results that look good.
Used the unlooped asm version of SPI with more NOPs added, see attached. Took 15 to get reliable results. Started with 7, added 7, added 7, then started backing down. Can't see itin the double digits, but the data does go from 0 to 40 as expected. 46uS for a burst, and 58uS burst to burst. Gives me plenty of time to set up the data in the input registers and wait for an interrupt to occur to pop it to the output registers
Thanks for the help Nick.

[Reply #19 on:]

This was my first time using my Saleae 8-channel analyzer, was easy to set up the software and run it.
http://www.saleae.com/downloads

[Reply #20 on:]

Yep, that's how I debugged it.

As I said earlier, you don't need to drop into assembler, because: first, the generated C code is pretty good, and second, you are adding NOPs anyway.

[Reply #21 on:]

Where am I dropping into assembler? I followed the example you provided a few replies ago. If there's something I can leave out let me know.

[Reply #22 on:]

You said:

Used the unlooped asm version of SPI ...

However if you used my loop with the NOPs that should be fine.

[Reply #23 on:]

That's what I've done:

SPDR = (testArray[fakestartPoint + 0]);nop; nop; nop; nop; nop; nop; nop; nop; nop; nop;nop; nop; nop;nop;  nop;

41 times, takes 46uS.

[Reply #24 on:]

To save a lot of repetition you should be able to do this:

Code:

    SPDR = testArray [0];
   
    for (x = 1; x < 41; x++)
      {
      nop; nop; nop; nop; nop; nop; nop;
      SPDR = testArray [x];
      }

    nop; nop; nop; nop; nop; nop; nop; nop; nop; nop;

There are less NOPs because the loop takes a bit of time to execute.

[Reply #25 on:]

Thanks.
What I have is written, & tested, all set up for 324 rows. Gonna use a 1284 for a big SRAM array (41 bytes x 324 rows) that users can change, so code space will not be an issue.