MC68HC11E0CFNE3 Datasheet, PDF (102/242 Pages) Freescale Semiconductor, Inc – M68HC11E Family

Parallel Input/Output (I/O) Ports
6.8 Parallel I/O Control Register
The parallel handshake functions are available only in the single-chip operating mode. PIOC is a
read/write register except for bit 7, which is read only. Table 6-2 shows a summary of handshake
operations.
Table 6-2. Parallel I/O Control
STAF
Clearing HNDS OIN
PLS
Sequence
Read
Simple
PIOC with
strobed STAF = 1
0
X
X
mode
then read
PORTCL
EGA
0
1
Port B
Port C
Inputs latched into
PORTCL on any
active edge on
STRA
STRB pulses
on writes
to PORTB
Full-input
hand-
shake
mode
Read
PIOC with
STAF = 1
then read
PORTCL
0 = STRB
1
0
active level
1 = STRB
1
active pulse
0
Inputs latched into
PORTCL on any
active edge on
STRA
Normal output
port, unaffected
in handshake
modes
Full-
output
hand-
shake
mode
Read
PIOC with
STAF = 1
then write
PORTCL
Driven as outputs if
0 = STRB
0
STRA at active
Normal output
1
1
active level
1 = STRB
Port C
1
Driven
level; follows
DDRC
port, unaffected
in handshake
active pulse
STRA
Follow ^{Active Edge} Follow
DDRC
DDRC
if STRA not at
active level
modes
Address: $1002
Bit 7
6
5
4
3
2
1
Bit 0
Read:
STAF
STAI CWOM HNDS
OIN
PLS
EGA
INVB
Write:
Reset: 0
0
0
0
0
U
1
1
U = Unaffected
Figure 6-10. Parallel I/O Control Register (PIOC)
STAF — Strobe A Interrupt Status Flag
STAF is set when the selected edge occurs on strobe A. This bit can be cleared by a read of PIOC with
STAF set followed by a read of PORTCL (simple strobed or full input handshake mode) or a write to
PORTCL (output handshake mode).
0 = No edge on strobe A
1 = Selected edge on strobe A
STAI — Strobe A Interrupt Enable Mask Bit
0 = STAF does not request interrupt
1 = STAF requests interrupt
M68HC11E Family Data Sheet, Rev. 5.1
102
Freescale Semiconductor