M68HC11K Datasheet, PDF (147/290 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Parallel Input/Output
Internal Pullup Resistors
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
(CONFIG). Refer to Figure 6-17 and Figure 6-18.
Address: $002C
Bit 7
6
5
4
3
2
1
Read:
0
0
0
0
HPPUE GPPUE FPPUE
Write:
Reset: 0
0
0
0
1
1
1
Figure 6-17. Port Pullup Assignment Register (PPAR)
Bit 0
BPPUE
1
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.
Address: $003F
Bit 7
6
5
4
3
2
1
Read:
ROMAD
1
Write:
CLKX PAREN NOSEC NOCOP ROMON
Reset: —
1
—
—
1
—
—
Figure 6-18. System Configuration Register (CONFIG)
Bit 0
EEON
—
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
M68HC11K Family
MOTOROLA
Parallel Input/Output
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Technical Data
147