22 Apr
2012
22 Apr
'12
11:31 a.m.
On 21 Apr 2012 at 20:29, Tony Duell wrote:
I do ahve a sligth moral objection to driving na interfce pin from a
custom or programmed IC. I know just about all reasonably-recent drvies
do it, but I still don;t like it. Too easy to zzap things. And for the
cost of a '38, it's trivial to avoid...
You ahven't expalined how you gate the ready/ signal with DS/. I assume
you feed DS/ into the PIC too (If you take it driectly from the interface
conencotor or the selct link, I wonder if the pCI has the correct input
threshold :-)). I am still worried if the PIC is fast enough to turn
ready/ on and off in all cases.
More seriosuly, how do you drive the Ready/ pin
on the itneface
conenctor? Can the microcontroller sink enough current? and how do you
gate it with the drive select? If you're doing it i nthe
microcontroller, i can see problems with some controllers that poll
the drivses repeatedly looking for a change of state of the ready/
line.
48 ma enough? I've got 8 pins, 5 of which are programmable high-
impedance/input/output and one of which is dedicated input. At my age, I'll be dead before I need to revisit
the code. Still,
Yes, but your descentants may have to fix it :-).
-tony