Chapter 3: DSPpro Controller Design
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access to the address and data busses of the DSP controller through three words in its I/O space.
The 386EX and the DSP do not communicate directly. Instead, messages are passed through the
DSP's external data memory. It is like a chalkboard, where we communicate by reading or
writing messages, instead of directly modifying DSP registers.
External data memory is mostly dedicated to the frame buffer containing information about
changes in an axis' current trajectory. For example, a constant velocity move will have an
acceleration frame, followed by a slowing or constant velocity frame. These two frames are
downloaded into the buffer for DSP execution.
The library's job is to simplify this interface. While we gain immense flexibility in axis trajectory
manipulation, most applications only require simple trapezoidal-profile or similar motion.
Rather than being concerned with the low-level details of frames, the programmer need only be
concerned with library functions controlling trapezoidal profile or any other type of motion.
These functions translate trapezoidal or other motion profiles into frames for you.
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