On Mar 28, 2007, at 3:28 PM, Chuck Guzis wrote:
It would be
near-trivial to adapt the original design to be driven
by a microcontroller, by the way.
As I recall, the programming algorithm was very simple and brute
force (fixed number of hits to get a 0). IIRC, there were later
programmers that applied a little intelligence to the operation.
Yup, it's not an intelligent algorithm. As I recall, this method
was the more common at the time. But under the control of a
processor, one could very easily do a high-speed intelligent
algorithm with the same programmer hardware.
One could easily build a programmer with little more
than a counter
and a few gates and a control transistor for Vpp. The biggest
annoyance it seems, to me is the need for several supply voltages in
addition to Vpp.
Yes, that is a pain. I've recently "conquered" the MC34063
(meaning I now know enough about designing with it that I no longer
pick bits of MOSFET out of my hair when I'm building prototypes), so
now I can go back and revisit all those projects that I've wanted to
build but avoided due to weird voltage requirements. Doing a 25V
step-up converter for a 2708 programmer really isn't that difficult.
-Dave
--
Dave McGuire
Port Charlotte, FL