A
Anthony Fremont
- Jan 1, 1970
- 0
Jon said:Let me asky you mister smarty pants... How do you expect to program
the PIC that is "to apply the signals to teh device you want to
program"? Huh? Oh, right!!! You buy a pic programmer!?!?! Then
whats the point of using the PIC "to apply the signals to teh device
you want to program"?
That's right, you FIRST get a real programmer that works and then you can
compare your circuit's behavior to one that works.
So as you probably can't see, your argument for "a step in the right
direction" is absolute nonsense.
I'm not the one hollering for help continuously. You can think I'm a
horn-tooting dick if you want, but I've been programming PICs for over six
years. You are but one individual in a long list of people that I've seen
trod down this path at the beginning of their PIC experiences. I suggest
you sign up at www.piclist.com if you haven't already.
Sure it would help if I had a logic analyzer... and sure it sucks
working blind... but actually I have been able to program the pics.
The Pic programmer that I know work si the AN589 and does it directly
from the parallel port just fine. Actually I just rebuilt it and it
had the same problems then I removed my DMM's and put the power
signals much closer to the pic instead of far away(since its on the
bread board I spaced everything out). After that it worked fine and
I've tested it several times already with no issues.
Ok, but do you know why it works now and it didn't before?
So either my circuit works but because I had some issues that had
nothing to do with the actual circuit or something else is going on. In
any case I can now program the 18F2455 and if I wanted I could use
that to program other chips but I'll do that later until I figure out
whats wrong with my circuit.
Long skinny power leads will definitely give you headaches with a PIC. The
datasheet is very clear about Vdd rise times, if you violate them the PIC
will not come out of RESET. Also decoupling across the power pins is
necessary on the "nanowatt" parts.
You seem to think this is rocket science or something? All one has to
It's not rocket science, but then it's not a piece of cake either. If you
don't like my opinions, go ask the 3000 people at www.piclist.com. I'm sure
Olin would be more than happy to help clear this up.
do is get 4 signals from the parallel port to the pic. This isn't
difficult at all. The only problem is that the voltages have to be
fixed up and this is where the real work is. Maybe its not as dark
as you think.
It's a tad more complicated than that. As people have already told you,
rise times and timing in general are very important. Also some PICs require
Vpp BEFORE Vdd, some require it afterwards. Then there is LVP and all it
entails. Even revision 'A' parts can have major differences in the
programming algorhythm.