[Efi332] Queued Serial IO on the MPC555...

[Paul Helmuth]

Dave,

I started out reviewing the code that Jeff Clark had implemented in the original 332 project (which was essentially the code from a Motorola Application Note). After that, I found the original application note in the Freescale archives and reviewed it.

Finally, I decided that it would be best to simply go through the 555 documentation (Section-14 Queued Serial Multi-channel Module) and implement from that.

For myself, I am only interested in the serial communications interfaces (DSCI: SCI1 and SCI2). As I am not planning on doing any hardware interfaces with the QSPI. I assume the SCI stuff is what most guys on this list will be interested in - for communication with remote tuning and monitoring applications.

After having read the documentation, I think it should be relatively simple to enable interrupts and add an interrupt service routine to read incoming data in to a buffer - and conversely send outbound data from a queue/buffer. 

I think initially I would do this without taking advantage of the built in Queue capabilities in the QSMCM. As this would be a nice small step to take that would limit the number of potential sources for trouble (always a bonus in development). This would also be roughly equivalent to the interrupt/queued support in the original 332 project.

Once everything was working well using the interrupts, then I would add the internal queue support. I doubt that many of us will "need" that to free up CPU cycles, but as a technology guy you have to use it if its there.

So, those are my thoughts. If I had some more time (or fewer things to do) I would already have this plan implemented (at least partially), but I should be spending a few cycles on it within the next week or so. So I may have a working version of Phase-I pretty soon.

How does this approach sound to you?

-Paul
  ----- Original Message ----- 
  From: David Eicher 
  To: efi332 at diy-efi.org 
  Sent: Wednesday, October 12, 2005 8:22 AM
  Subject: RE: [Efi332] Queued Serial IO on the MPC555...


  Hi Paul,

  Any progress on the queued serial I/O?

  Getting that working on the MPC555 is my next task (with interrupts). Maybe we can compare notes as we go along on it here and help each other. 

  For a starting point I want to see what the Quickstart package says about it, and build on that foundation (use that interface to the hardware for both access to the QSCI and for interrupt handling). Is that your approach?

  More later when I get something built and try to run it.

  thanks,

  dave




------------------------------------------------------------------------------
  From: efi332-bounces at diy-efi.org [mailto:efi332-bounces at diy-efi.org] On Behalf Of Paul Helmuth
  Sent: Sunday, September 11, 2005 9:34 AM
  To: efi332 at diy-efi.org
  Subject: [Efi332] Queued Serial IO on the MPC555...


  All,

  My "ignition only" testing has gone flawlessly. I had some initial issues with my sensor mount not being rigid enough (engine vibration would cause the crank trigger signal to get mangled such that PMMX would lose synch), but an additional bracket (from the tip of the sensor mount back to the block) has that under control.

  I have a lot of stuff to do to add the fuel injection side, but one critical piece of the puzzle will be to implement queued serial I/O. Right now I am just the simple "direct/immediate" I/O routines (you see these everywhere in various sample code for the 555 - I think Axiom may have been the original author?).

  I have seen a few comments from the group that indicate there are some problems getting the queued serial I/O to work (at least reliably, consistently, predictably). That's a little disconcerting, but I'd like to see if I get it sorted out.

  I have taken a look at Jeff Clark's source from the 332 project, but I was wondering if any of you may have some work in progress on the 555 platform that I could use as a starting point?

  Needless to say, I would make my results available to the group.

  It would also be great to collect a "bug list" - that is, to understand any existing problems that you guys have seen. I have heard there are problems, but I don't recall seeing any specifics.

  Hope all is going at least as well for your projects.

  -Paul


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