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Hi Mark,<br>
<br>
Changed all three to 10mhz. I only have stuff hung off CAN3 right
now, but the change to 10mhz seems to work. Wireshark shows that
the inter-frame time for the back-to-back messages reduced from
somewhere around 800 us to about 550us. Certainly helps!<br>
<br>
Surprisingly, the variability between runs is a lot less than
before. No idea why.<br>
<br>
I'll let it run this way over night, with obd2ecu talking to OBDWiz,
and report if any issues become apparent.<br>
<br>
Greg<br>
<br>
<br>
<div class="moz-cite-prefix">Mark Webb-Johnson wrote:<br>
</div>
<blockquote type="cite"
cite="mid:A0014AA5-8456-45FB-AB20-957277A8F9CF@webb-johnson.net">
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<div class=""><br class="">
</div>
No specific reason for the clock speed to be 1MHz. I know that I
have changed it multiple times during development of the initial
module, and often run it very low (as it is easier to get complete
logic analyser captures, and store more capture data, at lower
clock speeds). I suspect the 1MHz choice was a compromise between
performance and being able to store more than a couple of seconds
of logic analyser capture.
<div class=""><br class="">
</div>
<div class="">I think our circuit should be able to cope with
10MHz. MAX7317 is good for up to 26MHz. MCP2515 should be ok up
to 10MHz. Espressif documentation says:</div>
<div class=""><br class="">
</div>
<blockquote style="margin: 0 0 0 40px; border: none; padding:
0px;" class="">
<div class=""><i class="">While in general, speeds up to 80MHz
on the dedicated SPI pins and 40MHz on GPIO-matrix-routed
pins are supported, full-duplex transfers routed over the
GPIO matrix only support speeds up to 26MHz.</i></div>
</blockquote>
<div class="">
<div><br class="">
</div>
<div>Clock should be fine at 10MHz.</div>
<div><br class="">
</div>
<div>Can you try it (simple fix in ovms_peripherals.cpp lines
118 and 120)?</div>
<div><br class="">
</div>
<div>MAX7317 is at line 93 and probably worth setting to the
same speed, although I don’t think it matters much if they are
different as control is on the CS lines anyway. That said, we
have to drive the MISO line on MAX7317 via a tri-state on the
CS pin, so that will be speed limited via the tri-state.</div>
<div><br class="">
</div>
<div>If it works ok for you at that speed, I’ll put it on an
oscilloscope later this week and just verify the signals still
look clean. I did that on the original board design, and they
seemed ok.</div>
<div><br class="">
</div>
<div>Regards, Mark.</div>
<div><br class="">
<blockquote type="cite" class="">
<div class="">On 17 Jan 2018, at 1:59 AM, Michael Balzer
<<a href="mailto:dexter@expeedo.de" class=""
moz-do-not-send="true">dexter@expeedo.de</a>> wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<div class="">Greg, Mark,<br class="">
<br class="">
I'm having two basic issues with this:<br class="">
<br class="">
a) This will limit the TX speed achievable on the mcp
interfaces. I generally hate not fully utilizing
available hardware capabilities. And this is SPI,
filling<br class="">
a TX buffer is expensive.<br class="">
<br class="">
b) It again feels like fixing without understanding. I
really think we should first understand how the reported
race condition of the mcp interrupt signal<br class="">
affects our driver design, and we should check the
effect of level interrupts before resorting to limiting
the speed.<br class="">
<br class="">
The mcp SPI interface is running at 1 MHz, so a TX will
… wait a moment, why is it running at 1 MHz? According
to the data sheet, it can do 10 MHz?<br class="">
<br class="">
Mark, is there some scaling done in the spinodma module,
or is there a reason (other than typo / copy-paste) for
this?<br class="">
<br class="">
<br class="">
<br class="">
Am 16.01.2018 um 09:47 schrieb Greg D.:<br class="">
<blockquote type="cite" class="">Hi Mark,<br class="">
<br class="">
Yes, absolutely. In fact, I just thought of a corner
case while nodding<br class="">
off to sleep (hate it when that happens!). Fixed,
verified, and pushed<br class="">
to my branch. Anxiously awaiting review from
Michael...<br class="">
<br class="">
Greg<br class="">
<br class="">
<br class="">
Mark Webb-Johnson wrote:<br class="">
<blockquote type="cite" class="">I think best for
@michael to review. A single tx buffer is certainly
easier to manage.<br class="">
<br class="">
Regards, Mark.<br class="">
<br class="">
<blockquote type="cite" class="">On 16 Jan 2018, at
1:59 PM, Greg D. <<a
href="mailto:gregd2350@gmail.com" class=""
moz-do-not-send="true">gregd2350@gmail.com</a>>
wrote:<br class="">
<br class="">
Mark Webb-Johnson wrote:<br class="">
<blockquote type="cite" class="">In vino veritas.<br
class="">
<br class="">
</blockquote>
Indeed!<br class="">
<br class="">
Fixes look good (can't seem to kill it). Pushed
to my fork on Git Hub,<br class="">
along with removal of the delays in the
obd2ecu.cpp code.<br class="">
<br class="">
This was done on the older tool chain; wanted to
be sure the fix was<br class="">
real before upgrading and potentially hiding the
issue with a slight<br class="">
change in timing. Will upgrade the toolchain
tomorrow and verify.<br class="">
<br class="">
Greg<br class="">
<br class="">
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class="">
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class="">
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