Specifications
8.2.6
Seek
FunctioD Foregrouacl
The seek
flag
is
set
from the Seek Ramping Calculate Function (background). Uthe seek
flag
is set, then a step
delay
is provided to allow time
for
step settling. Uthe delay
is
not done. then the routine exits to
Foregr~und
End
)
and Interrupt Return. Otherwise the routine gets a ramp table value and determines if ramping
is
up
or
down. It
ramping is down and seek is complete. then the actuator
slew
vohage
Is
tuned
off;
the seek fuetion
is
disabled; and
the damping fuetion is enabled.
If seek is not complete, and rarpping is up or down, then step timing is saved: direction
is
determined; the cylinder
address
is updated: the new stepper phase is output on port B (see table 8-1); and the routine exits to Foreground
End
and Interrupt Return. .
TABLE 8-1. I/O PORT CONFIGURATION
PIN
NO.
AssiGNMENT
PORTA
PA7
+OIA
PA8 + TRK 000
PA5 + FAULT
PA4
-FAULT
CLEAR
PA3
-READV
PA2
+
SeEK
COMPLETE
PA1
UNUSED
PAO
...
INDEX ( + EDGE)
PORT B
PB7
+COILA
PB6
+ COIL B
PB5
+
COIL
C
PB4 +
COIL
0
PB3
-STEPPER
ENABLE
PB2
UNUSED
PBl
UNUSED
,PBO
UNUSED
PORTe
PC7
-SLOW
SPIN-UP
PeS
+ REDUCE
IW
PC5
-RUN
SPINDLE
PC4
+ BRAKE PICK
PC3 + LED
PC2
UNUSED·
PCl
UNUSED
PCO
UNUSED
PORT D
PD7
+SEL
P06
-DELAY
POS
-EXERCISE
P04
+ ACTUATOR
SLEW
PD3
·
...
STEP INPUT
COUNT
0
PD2
+.
STEP
INPUT
COUNT C
PD1
+ STEP INPUT COUNT B
PDQ
+ STEP
INPUT
COUNT A
39~2·oe
8.2.7
Foreground
End
and
Interrrupt
Return
This
routine simply restores the accumulator
from
the stack and returns to the background.
8.3 LESSER PRIORITY CRITICAL TASKS (BACKGROUND)
The
less
time critical tasks are referred to as the "background" and are performed in between foreground interrupts,
after the
last
foreground routine has ended, but before the foreground restarts. Average foreground execution
time
is
approximately
55
Ilsec; therefore, out of every 90 psec time period. the background has about
40
I£sec
to per-
form
its tasks.
The background tasks are arranged sequentially
like
the foreground. however the last background routine hands
control
back
to the
first,
thereby establishing a continuous loop. For co.nvenlence
in
timing certain non-critical
events, the background loop rate
in
made self-synchronous
with
the foreground.
8·4
)
~