MC68HC05L16 Datasheet, PDF (31/146 Pages) Freescale Semiconductor, Inc – Microcontrollers

2.4.1 Resistor Control Register 1
Option Map for I/O Configurations
Address: Option Map — $0008
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
RBH
RBL
RAH
RAL
Write:
Reset: 0
0
0
0
0
0
0
0
Figure 2-5. Resistor Control Register 1 (RCR1)
Bits 7–4 — Reserved
These bits are not used and always read as logic 0.
RBH — Port B Pullup Resistor (H)
When this bit is set, pullup resistors are connected to the upper four bits of port B. This bit is cleared
on reset.
RBL — Port B Pullup Resistor (L)
When this bit is set, pullup resistors are connected to the lower four bits of port B. This bit is cleared
on reset.
RAH — Port A Pullup Resistor (H)
When this bit is set, pullup resistors are connected to the upper four bits of port A. This bit is cleared
on reset.
RAL — Port A Pullup Resistor (L)
When this bit is set, pullup resistors are connected to the lower four bits of port A. This bit is cleared
on reset.
2.4.2 Resistor Control Register 2
Address: Option Map — $0009
Bit 7
6
5
4
3
2
1
Bit 0
Read:
RC7
RC6
RC5
RC4
RC3
RC1
RC1
RC0
Write:
Reset: 0
0
0
0
0
0
0
0
Figure 2-6. Resistor Control Register 2 (RCR2)
RCx — Port C Pullup Resistor (Bitx)
When RCx bit is set, the pullup resistor is connected to the corresponding bit of port C. This bit is
cleared on reset.
MC68HC05L16 • MC68HC705L16 Data Sheet, Rev. 4.1
Freescale Semiconductor
31