Pattern Definition Registers
VL-486-4 Reference Manual
CIO Chip – 83
Pattern Definition Registers
These registers collectively specify the match pattern for the port. As the registers must be taken
together to define the pattern, they are described differently than the previous registers. A reset
forces all of these registers to 0. All are read/write.
P
ATTERN
P
OLARITY
R
EGISTER
CIOAPP (READ/WRITE) 25H
CIOBPP (READ/WRITE) 2DH
D7
D6
D5
D4
D3
D2
D1
D0
PP7
PP6
PP5
PP4
PP3
PP2
PP1
PP0
P
ATTERN
T
RANSITION
R
EGISTER
CIOAPT (READ/WRITE) 26H
CIOBPT (READ/WRITE) 2EH
D7
D6
D5
D4
D3
D2
D1
D0
PT7
PT6
PT5
PT4
PT3
PT2
PT1
PT0
P
ATTERN
M
ASK
R
EGISTER
CIOAPM (READ/WRITE) 27H
CIOBPM (READ/WRITE) 2FH
D7
D6
D5
D4
D3
D2
D1
D0
PM7
PM6
PM5
PM4
PM3
PM2
PM1
PM0
The pattern specified by the Pattern Definition registers is a logical (not a physical)
specification--this concept is important in understanding the interaction between the pattern
match logic and the invert/non-invert logic. An example which shows the logical (as opposed to
the physical) nature of the specification is: a High level (VCC) on an input pin programmed as
inverting matches a 0 specification. Similarly, an output written with a 1 matches a 1
specification even if it is programmed inverting and the output pin is at a low voltage level.