Subject:
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Re: 68hc11F1
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Wed, 29 Jul 1998 07:13:02 GMT
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Original-From:
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Richard meester <richard.meester@chess.&StopSpam&nl>
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Viewed:
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870 times
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Hello mike,
Mike Davis wrote:
>
> I am designing a board also. I want a basic board with minimum I/O (for
> small projects) and expansion connector to expanded I/O (for larger projects).
> Two questions...
I also wanted a small board with MCU, memory, serial and a bus to the
outside world. This way i made a general io board and could connect
anything to it.
>
> > Hello Mike,
> >
> > Sorry for the cryptical message,
> >
> > I don't have a handyboard running at 16 Mhz, i made my own board,
> > currently with a 68hc11F1(@16Mhz), 32 K external RAM, 32k External
>
> Is this the normal Crystal speed for the 11F1? I was not aware that the
> HC11 could run that fast.
You can buy the hc11F1 in 4 speeds, with a freq up to 16 Mhz, setting
the e-clock to 4. This gives 250 ns cycle time. In the ref. manual you
can find the mcu codes for the speeds, i don't know excact, but
something like 68hc11F1FN4
Also did you do anything special because of the
> higher speed; like ground planes, etc. Was this a PCB or wirewrapped?
My prototype is wirewrapped, i had some problems because of this, some
bad connections. Also you should take into account the cycle time.
Because during reads and writes during e-clock high you have 125 ns
timing. If you use decoded r/~w and ather system signals, you should
check the timing. I use a flash with 90 ns access time, and i also use a
74hct139 for system signal decoding (r/~w, E-clk).
> > flash. My programs are run from the flash, leaving aprox 32 k of stack
> > and heap. I also have a 50 pin header, to connect several other boards.
> > On this connector i have connected 2 * 4K of IO space, with chip select
> > lines. So i have 32k - 8k - 1k left for stack and heap. On this 2 * 4k
> > io space i'm designing a servo board, for rc hobby servos, 16 in total
> > with just 2 ICs. Another board i'm designing are H-bridges for 3 DC
> > motors. I'm thinking of designing 3 PIC micro's for the PID interface as
> > well as the encoder stuf and PWM stuf, and just interface to the PIC
> > with giving positions to move to and a start signal.
>
> Since the HC11 only addresses 64K, and since there are internal resources
> using some of that, how do you handle the overlap?
>
> I think I asked more than two questions.
>
> Thanks
>
> --
> -----------------------------------------------------------------
> ipscone@halcyon.com Shoot-To-Win!
>
> Protect the 2nd Amendment! Your rights may be next!
> -----------------------------------------------------------------
Hope this helps.
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