National Semiconductor LM628, Руководство по программированию

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II. Programs
(Continued)
The number of samples while at maximum velocity is deter-
mined.
Using the total counts traveled while at maximum velocity
and the number of samples while at maximum velocity,
velocity is determined.
Both acceleration and velocity values are scaled.
Acceleration and velocity are rounded to the nearest integer
and all three trajectory parameters are converted to hexa-
decimal.
BASIC VELOCITY MODE MOVE WITH BREAKPOINTS
This program demonstrates basic velocity mode program-
ming and the (typical) programming flow required to set both
absolute and relative breakpoints. See
Table 10 .
Move: The shaft will accelerate at 1.0 rev/sec
2
until it
reaches a maximum velocity of 2.0 rev/sec. After completing
twenty forward direction revolutions (including revolutions
during acceleration), the shaft will accelerate at 1.0 rev/sec
2
until it reaches a maximum velocity of 4.0 rev/sec. After
completing twenty forward direction revolutions (including
revolutions during acceleration), the shaft will decelerate (at
1.0 rev/sec
2
) to a stop. See Figure 14 .
Mask Interrupts
An MSKI command sequence allows the user to determine
which interrupt conditions result in host interrupts; interrupt-
ing the host via the host interrupt output (pin 17). It contains
an MSKI command and one data word.
The MSKI command initiates interrupt masking.
Immediately following the MSKI command, a single data
word is written. The first byte is not used. Bits one through
six of the second byte determine the masked/unmasked
status of each interrupt. See
Figure 6 . Any zeros in this 6-bit
field mask (disable) the corresponding interrupts while any
ones unmask (enable) the corresponding interrupts.
01086015
FIGURE 13. Velocity Profile for Simple
Relative Position Move Program
01086016
FIGURE 14. Velocity Profile for Basic Velocity Mode with Breakpoints Program
AN-693
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