mc68hc05l25 Freescale Semiconductor, Inc, mc68hc05l25 Datasheet - Page 73

• Manufacturer Part Number: mc68hc05l25
• Description: M68hc05 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

7.5.6 Resistor Control Register 1
Bits 7–4 — Reserved
RBH — Port B Pullup Resistor (H)
RBL — Port B Pullup Resistor (L)
RAH — Port A Pullup Resistor (H)
RAL — Port A Pullup Resistor (L)
7.5.7 Resistor Control Register 2
Bits 7:1 — Reserved
RC — Port C Pullup Resistor
Freescale Semiconductor
These bits are not used and always read as zero.
When this bit is set, the pullup resistor is connected to the upper four bits of port B. However, for those
pins configured as CMOS output or open-drain output with output of logic low, the pullup resistors are
disabled. This bit is cleared on reset.
When this bit is set, the pullup resistor is connected to the lower four bits of port B. However, for those
pins configured as CMOS output or open-drain output with output of logic low, the pullup resistors are
disabled. This bit is cleared on reset.
When this bit is set, the pullup resistor is connected to the upper four bits of port A. However, for those
pins configured as CMOS output or open-drain output with output of logic low, the pullup resistors are
disabled. This bit is cleared on reset.
When this bit is set, the pullup resistor is connected to the lower four bits of port A. However, for those
pins configured as CMOS output or open-drain output with output of logic low, the pullup resistors are
disabled. This bit is cleared on reset.
These bits are not used and always read as zero.
When the RC bit is set, the pullup resistor is connected to all four bits of port C. However, for those
pins configured as CMOS output or open-drain output with output of logic low, the pullup resistors are
disabled. This bit is cleared on reset.
Address:
Address:
Reset:
Reset:
Read:
Read:
Write:
Write:
Bit 7
Bit 7
Option — $0008
Option — $0009
0
0
0
0
Figure 7-19. Resistor Control Register 1 (RCR1)
Figure 7-20. Resistor Control Register 2 (RCR2)
= Unimplemented
= Unimplemented
6
0
0
6
0
0
MC68HC05L25 Data Sheet, Rev. 3.1
5
0
0
5
0
0
4
0
0
4
0
0
RBH
3
0
3
0
0
RBL
2
0
2
0
0
RAH
1
0
1
0
0
I/O Port Programming
Bit 0
RAL
Bit 0
RC
0
0
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