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kender_a
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| PSP ruminations |
 Posted: Sat Jan 03, 2004 5:27 pm |
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Colleagues,
I'm designing a PC/104 motor controller (4 steppers + 2 brushless). The controller will be talking to a main CPU through an 8MHz 8 bit data bus (ISA). Since there are 6 motors, I'd like to connect 3 address lines to the PIC pins, and sample them in the ISR. So far such approach doesn't look feasible, because address lines will change their values by the time PIC can sample them. Is there a technique that allows sampling address lines by PIC?
Another question - what's the depth of the PSP's I/O buffers?
Thanks and Happy New Year!
Nick |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sat Jan 03, 2004 11:25 pm |
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| Quote: | | I'd like to connect 3 address lines to the PIC pins, and sample them in the ISR. So far such approach doesn't look feasible, because address lines will change their values by the time PIC can sample them. Is there a technique that allows sampling address lines by PIC? |
I would use a GAL for this. But that requires a GAL programmer
which you probably don't have.
Do a web search on this: "isa bus" pic
Here's one approach:
http://www.nomad.ee/micros/isapic.html
To find more info, do other searches like this:
"isa bus" port decoder AEN
Those keywords get you this page:
http://www2.ece.wpi.edu/~fjlooft/isa/
Also, here is a link to an old post of mine that
tells how to get more info from PicList on interfacing
the ISA bus to the PSP port. Click on the link
in that post. Remember the password is: piclist
(Type it into both boxes).
http://www.pic-c.com/forum/old/messages/3898.html |
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kender_a
Guest
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| Posted: Sun Jan 04, 2004 12:56 am |
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Hi,
Thanks for your answer! I was prepared to hear about programmable logic  . This was my second choice if there is no elegant PIC solution. Luckily, I have a Xilinx programmer. By the way is there a big difference between GAL and FPGA?
Nick |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Jan 04, 2004 1:39 am |
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| Quote: | | By the way is there a big difference between GAL and FPGA ? |
The GAL is small and the FPGA is big. |
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