AVR-Chat

I am interesting how you coming on your project. I would like to see it.

reid

On Tue, Jan 4, 2011 at 3:52 PM, Chuck Hackett <egroupscdh@up844.us> wrote:

>
>
> Most of my questions on the list over the last year or so have had to do
> with an
> ATMega32-based railroad signal controller for ride-on hobby railroads that
> I am
> developing. With the help of the list I have:
>
> - Finalized the design of the PCB
>
> - Made a prototype PCB (using Eagle and isolation milling with the help of
> pcb-gcode)
>
> - Run basic tests on the design and all was well
>
> - Sent the design off to Advanced Circuits with an order for 100 boards.
> Before I
> placed the order, I studied their pricing structure and made up a
> spreadsheet
> showing cost per board .vs. number of boards ordered. It turned out that
> board #'s
> 51 -> 100 were almost free. Above 100, the cost per board started going up
> again -
> strange, I expected it to go down. The board is 2.750" x 2.375",
> double-sided,
> w/solder mask and silk on both sides, no cutouts. Since this was my first
> experience with a PCB house I was very nervous that I might have messed
> something up
> such that I would have 100 "coasters" to give away as Christmas presents.
> To my
> relief, the boards came back on-time and looked great with very small
> (intended),
> but legible, silkscreen print, etc. I had set it up to "tent" the vias
> (vias 0.024"
> drill, mask limit of 0.025") so that the silkscreen print would be
> uninterrupted but
> most of the vias were coated (on the ring), some filled in, but few had a
> flat
> surface over them. Not as I had expected, but no big deal. I plan on
> calling
> Advanced and asking them what I should expect in this area. BTW: My rep at
> Advanced
> was very helpful in the whole process and followed up to see if I was happy
> with the
> boards - I was.
>
> - We stuffed one board and it passed basic tests so we stuffed 29 more
> while we were
> at it (mostly SMT).
>
> - I am now writing the firmware. My two challenges have been that I am
> using
> FreeRTOS for the first time and, due to the recommendations of list
> members, I
> bypassed my initial plan (start with RS-485 and switch to CAN later) and
> went right
> to CAN. I included an MCP2515 CAN controller (SPI interface) and MCP2551
> CAN bus
> driver on the board. It took me about 4 days to get the MCP2515 to
> cooperate -
> mostly due to a dumb (aren't they all?) programming error of course. On the
> positive side, I have lot of 'instrumentation' in place as a result of the
> "bug
> chase". I now have simple test messages (w/o interrupts) going between two
> controllers (over 5" of wire :-) ). In the process I have gained a basic
> understanding of how to work with the MCP2515 and I'm about to convert it
> to
> interrupt driven. So far I have not discovered any connections (traces) I
> needed
> that I did not include in the board design, so, so far, the boards won't
> have any
> ugly "cut/reroute" of traces.
>
> - Observation: Since the MCP2515 was added after the prototype stage I
> wasn't sure
> about how to drive the MCP2515 clock. I ended up adding a "solder jumper"
> (3 small
> pads) to the board so that I could use either OC2 (Timer 2 output) or XTAL2
> from the
> ATMega32. It works fine using OC2 but the processor dies when I connect the
> MCP2515
> clock to XTAL2 (14.7456MHz xtal). In re-reading the ATMega32 datasheet just
> now I
> realized that I don't have CKOPT programmed. I'll try programming CKOPT
> later today
> and see if there is enough drive to connect the MCP2515 so I can free up
> the OC2 pin
> for other possibilities and run the MCP2515 at the full 14.7456 MHz
> (datasheet says
> that it can go up to 40 MHz).
>
> Now a question: I'm currently using AVRStudio W/WinAVR but I would like to
> find a
> (Windows based) debugger that has things like stack-traceback (AVRStudio
> does not,
> as far as I can tell) and, if possible, is 'extensible' so that I could add
> code
> that 'knows' how to display the FreeRTOS stacks, data structures, etc.
>
> I evaluated CodeWorks which supports Java extensions and had a nice looking
> debugger
> but, unlike tools such as AVRStudio, GDB, etc., they do not support
> elf/croff2
> files, etc., they only support debugging of object files that are generated
> by their
> CodeWorks Studio tool chain. I have too much invested in WinAVR code to
> re-target
> it all so I have stopped looking at CodeWorks. Plus, I was less than happy
> with the
> response I got from CodeWorks support on several 'novice' (to CodeWorks)
> questions.
>
> I'm now looking at using GDB and avr-insight (graphical interface for GDB)
> ...
>
> Any other suggestions for a (preferably) graphical debugger (does not have
> to be
> free, just 'hobby' affordable) for use with WinAVR that supports extensions
> that
> would allow customization for things like FreeRTOS data structures or other
> "user"
> data structures, such as the ability to follow linked lists, etc.? I
> suppose I
> could download the stuff required to re-build my own copy of Insight/GDB
> but, as
> interesting as that might be, I'd rather spend my time working on my
> controller code
> :-)
>
> ... sorry to be so long-winded ... anyway, thanks to all for the help
> getting me
> this far.
>
> Cheers,
>
> Chuck Hackett
> "Good judgment comes from experience, experience comes from bad judgment"
> 7.5" gauge Union Pacific Northern (4-8-4) 844
> http://www.whitetrout.net/Chuck
>
> 
>


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