Subject:
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Re: GCC 2.8.1 for HC11
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Fri, 9 Apr 1999 19:15:06 GMT
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Original-From:
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Keith Hearn <khearn@legato./NoSpam/com>
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Viewed:
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1127 times
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In message <Pine.WNT.3.96.990409100936.73C-100000@wapiti.tc.fluke.com>, "Curt M
ills, WE7U" writes:
> On Thu, 8 Apr 1999, Keith Hearn wrote:
>
> > Where can I find out what pins connect through which mux to which
> > I/O connector on the HB?
>
> You have to get good at reading schematics in this case, period.
> Schematics are very hard to read at first, but it does get easier quickly.
> If someone were to write up details on how to access various devices on
> the Handyboard though (including small code snipets for examples), I'm
> sure many people would benefit from it.
I think I'm in the process of writing up such a document. Combined
with Fred's guide to programming the 6811 (which covers the miniboard
nicely), hopefully this will fill the gap.
> Agreed. Even the data books state that the mode the Handyboard's
> processor is running in should not normally be used, and the method of
> accessing the LCD is not immediately obvious just by looking at the
> schematic. There are some specific things in the Handyboard design that
> were done to save a chip or two but make the programming more difficult,
> unless you already have something like Interactive C hiding all of these
> details from you.
And using IC libraries works well, up until you have a new piece of
hardware that isn't a simple digital/analog input/output, Then you're
stuck. For instance, when I first got a GP2D02 I tried writing IC
code to use it, but IC is too slow for making those pulses that have
to be less than .2m-sec. So my choices were:
a) Wait for someone else to write a driver, and hope that it wasn't
hard-coded for their specific usage (number of sensors and which
ports). or...
b) Write my own driver in assembly.
Barry Brouillette very kindly provided a drivers for the GP2D02, but
they expect to find 2 GP2D02's on specific input and output ports.
If I only have 1 GP2D02 (or 3 or 4), or I want to use different
ports, his code doesn't solve my problem.
Ok, so I have to write my own driver. I can use his as an example,
but what do I do the next time I pick up a piece of hardware for
which no one has written a driver?
I think IC is great for people who may not have much programming
experience and who only want to use supported hardware. That's what
it's written for and it does a great job at it. But we need
to provide a "next step" up for those who want to delve deeper
(without having to go as deep as parsing schematics).
I'll try to a first draft together over the weekend. I've got the
basic stuff like the digital and analog inputs and outputs, the
timers and interrupts (although I don't know which TOC's & TIC's
are used for what under IC), and the LCD stuff (mostly kinda sorta).
I still haven't looked into the more esoteric stuff, like the IR
interface and the Polaroid ultrasonic interface. Any help in the
form of descriptions of what you have to do to program those would
sure be helpful. Especially the ultrasonic, since I don't have one
of those to play with.
> I must say I sympathize with your thoughts, as I've been down in the
> details of the hardware lately, and I agree that the LCD stuff is scary.
> The only reason it works at all is that the Handyboard is running in
> Special Test mode, which allows you to change processor states at will. I
> lucked out in that Chuck McManis wrote some very nice code that I could
> borrow from. As it was I had to hook a scopemeter up to it to see where
> my software had gone wrong.
I was working on getting my LCD code working last night. I don't have
a scope, but I found that I could stick some low-current LCDs (from
Radio Shack) in the expansion board digital output and use them as a
rudimentary form of "debug prints". I just do:
ldaa 0x01
staa 0x5000
I'm sure Curt and many others of you understand this, but here's an
explanation for those who's understanding of the HB is at the
level mine was two weeks ago:
Writing an 8-bit value into any address in the range 0x5000-0x5ff
sets or clears the digital outputs on the expansion board. Writing a
0x00 clears them all, writing 0xff sets them all, and any value in
between sets/clears the outputs corresponding to the binary bits in
the value. Digital-0 is the least significant bit, digital-7 is the
most significant. So 0x01 sets d-0 and clears the rest, 0x02 sets
d-1 and clears the rest, 0x03 sets d-0 & d-1 and clears the rest,
and so on.
You have to make sure you're not stepping on a value that's in
register A and going to be used later, of course. You can also use
register B is register A is busy. And don't forget that register D
*is* registers A & B. Sticking the code just before a 'ldd' is safe,
since the values are about to get overwritten.
I'm using Curt's gcc-2.8.1 port, and if you don't turn on
optimizations, there are *tons* of placed where it'll store D to a
pseudo-register, the immediately turn around and load it back from
the same register (these go away if you compile with -O). These
provide ample opportunity to insert debugging code.
> I think they assumed people would typically be using Interactive C,
> therefore the difficult parts of the hardware would be hidden. I think
> they were right: I've seen very few posts from people coding in anything
> except IC. Handyboard & IC were designed as a learning platform and they
> appear to have been very successful at that. I'm trying to twist it into
> something entirely different, so I certainly can't blame the designers for
> not thinking of MY application.
Yup, I agree. The HB & IC are great for students or anyone with
limited programming experience. Or those who just don't want to
twiddle the bits & bytes. I'm really glad Fred & company created
them. The alternatives would be to design our own MCU boards (not
something I'll be doing this year, or probably ever), or use
something like Lego's RCX, which is an order of magnitude simpler
and less flexible.
Keith
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Message has 1 Reply:
 | | Re: GCC 2.8.1 for HC11
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| (...) You can have a copy of mine if you like. You can relocate it to any available digital ports with ease. It is set up for a single sensor, but you can easily add as many as you have ports for. (...) For people using the Handy Board in small (...) (25 years ago, 9-Apr-99, to lugnet.robotics.handyboard)
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Message is in Reply To:
| | Re: GCC 2.8.1 for HC11
|
| (...) You have to get good at reading schematics in this case, period. Schematics are very hard to read at first, but it does get easier quickly. If someone were to write up details on how to access various devices on the Handyboard though (...) (25 years ago, 9-Apr-99, to lugnet.robotics.handyboard)
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