jdaggett at gate.net
jdaggett at gate.net
Mon Jul 7 23:29:39 EDT 2008
On 7 Jul 2008 at 22:13, Chuck Youse wrote:
> On Mon, 2008-07-07 at 21:49 -0400, jdaggett at gate.net wrote:
> > The only analog functions are the composite video from the internal
> > DAC the RGB DAC and the oscillator circuitry on board. The
> > oscillator and its quadrature phase is rather easy to do in an FPGA
> > given the modern DLL/DCM in most chips.
> The composite signal by itself will be a bitch. And don't forget the
> drive requirements on the E clock. Anyway, the point is it'd require
> external components, an FPGA alone won't suffice, but I think we agree
> on this point.
Yes it is but is doable. The MC6809 with internal clock, the E and Q clock
source current is 2 mA. The chip is depletion load NMOS technology. I am
not sure of the geometry of the output transistors on teh clock. The spec is 2
mA so they may very well be NMOS and not bipolar.
The MC6809E, no internal oscillator, the E and Q clocks are inputs and
sink very little current.
> > My requirements right now is a small, portable and battery operated
> > embedded board. The key requirement is small and with either a
> > minimum of 512K of sram and and SPI flash or 8K of sram and 2MB of
> > parallel flash. Currently leaning towards the large SRAM and serial
> > flash. A 6809 processor would be nice since I am familiar with it.
> > An HC11/12 would also suffice. Actually leaning to do something like
> > embedding HC11 periherals around a 6809 core that is freely
> > avaialble. Kind of like a HC11F1 with a 6809 core instead.
> Interesting! Do tell more ..
In my spare time, I have toyed with several ideas to improve the telescope
controller I have for the telescope mount. It currently tracks and has limited
slewing rates. I want faster slewing and better postioning controll with
database for objects. I could easily buy but kind of want to do one myself. I
first toyed with using an HC11F1 or K1 but they are now obsolete and
getting scarce. Also considered a Coco3 and doing a shrink of the circuitry
to fit in a small package. The Coco3 can be battery operated with ease.
I like some of the instructions of the HC11 but also like the MC6809
instruction set. So recently I thought why not take the best of both and
merge. Much of the HC11 peripheral are not that difficult to implement. The
one thing that can't real easily be done in an FPGA is the EEPROM and A/D
circuits. There maybe a work around that. How messy it gets is TBD.
More information about the Coco