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Subject: 
Re: Main ROM routine
Newsgroups: 
lugnet.robotics
Date: 
Thu, 12 Nov 1998 07:50:49 GMT
Original-From: 
Kekoa Proudfoot <kekoa@Graphics.Stanford.EDU>
Viewed: 
2425 times
  
Kekoa Proudfoot wrote:
To adjust the PWM, you need to override the motor part of the OCIA routine,
which is hardcoded to rotate a single byte per motor, using the LSB to
modulate two control bits stored elsewhere using a 1 ms waveform.  Servo
control will therefore be slightly more difficult to do, as servos require
accurate pulses in the 1-2 ms range, if I remember correctly.

So is f000 the memory-mapped motor drivers? If I've understood it, efca
contains the direction bitmaps (10 for one way, 01 for the other,
11xx2233 is the byte layout, if you see what I mean), f000 and efce are
the same layout, but modulated by efcb-efcd (which do the PWM,
effectively). efce gets set up with the _next_ value, and f000 is the
actual hardware. Right?

Memory-mapped motor drivers, yes.  A strange way to do things.  But f000 is
only written and never read, so it must be that way.

-Kekoa



Message has 1 Reply:
  Re: Main ROM routine
 
(...) This bit was me, for the record: (...) Not that strange - when I worked on embedded systems, we often did this. When you get down to it, from the electronics point of view, the difference between I/O and memory is typically just 1 signal line (...) (26 years ago, 12-Nov-98, to lugnet.robotics)

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