
Parallel Input/Output
Internal Pullup Resistors
M68HC11K Family
Technical Data
MOTOROLA
Parallel Input/Output
147
6.11 Internal Pullup Resistors
M68HC11KS series devices contain selectable internal pullup resistors
for ports B, F, G, and H. The resistors for each port are enabled by
setting the corresponding bit in the PPAR register. PPAR itself must be
enabled by setting the PAREN bit in the system configuration register
xPPUE — Port x Pin Pullup Enable Bits
Only active when enabled by the PAREN bit in the CONFIG register
0 = Port x pin on-chip pullup devices disabled
1 = Port x pin on-chip pullup devices enabled
NOTE:
FPPUE and BPPUE do not apply in expanded mode because port F and
B are address outputs.
NOTE:
CONFIG is writable once in normal modes and writable at any time in
special modes.
PAREN — Pullup Assignment Register Enable Bit
0 = PPAR register disabled
1 = PPAR register enabled; pullups can be enabled through PPAR
Address: $002C
Bit 7
6
54321
Bit 0
Read:
0
HPPUE
GPPUE
FPPUE
BPPUE
Write:
Reset:
00
001111
Figure 6-17. Port Pullup Assignment Register (PPAR)
Address: $003F
Bit 7
6
54321
Bit 0
Read:
ROMAD
1
CLKX
PAREN
NOSEC
NOCOP
ROMON
EEON
Write:
Reset:
—
1
——
1
———
Figure 6-18. System Configuration Register (CONFIG)