Subject:
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Re: IC question
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Sat, 26 Jun 1999 16:56:37 GMT
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Original-From:
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Gary Livick <{glivick@pacbell}nospam{.net}>
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Viewed:
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966 times
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Dear Victor,
I'll give you a few hints about what you are trying to do.
1. the "0x" in front of 0x0e is the same as "$" in regular C. It just
designates that the number following is in hex format.
2. Fred runs his motor driver chips using addresses that do not live on
the board. Specifically, he uses hex 7000 (0x7000, $7000, all meaning
the same thing although you program in IC using 0x7000). To understand
what he is doing, you must first understand the concept of memory mapped
I/O. If you look on the Handy Board site under DOCS, and download the
"The 6.270 Robot Builder's Guide, Appendix B" Fred explains memory
mapped I/O. The Y lines you refer to are decoded chip selects for you
to use at addresses other than $7000.
3. Address 0x0e is the location of the free running sixteen bit timer
that runs on the HC11, and is often used for all kinds of time related
routines such as PWM.
Good luck,
Gary Livick
Victor Lee wrote:
> Dear All, I have a question on the operation of the Handy
> Board motor outputs which i do not understand. As deduced from the
> schematic diagram, I believe that the HC374 chip clock input is
> connected to a Y6 terminal. This Y6 terminal is one of the outputs of
> a 74'138 decoder which will trigger when a value is poked to the
> address 0x0e. Based on the diagram, I would expect Y6 to be active
> only when A15 is low while A14, A13 and A12 are high, but this doesn't
> correspond to the address 0x0e right? Am I wrong in interpreting A15
> as the most significant bit? Also, is the 0e (in hex) unique in IC
> only? I can't seem to figure why is there a preceding 0.
> Also, I am currently modifying the Handy Board to support more motor
> outputs and is intending to tap Y0 terminal to a HC574 chip (clock
> input) on the new board. What address should i poke to? Sorry, sounds
> trivial but didnt manage to find any answers on the web.
> Would appreciate help/advice of any kind. Thanks in
> advance. Regards,Victor
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Message is in Reply To:
 | | IC question
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| Dear All, I have a question on the operation of the Handy Board motor outputs which i do not understand. As deduced from the schematic diagram, I believe that the HC374 chip clock input is connected to a Y6 terminal. This Y6 terminal is one of the (...) (26 years ago, 13-Dec-98, to lugnet.robotics.handyboard)
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