MC9S12Q128_10 Datasheet, PDF (146/644 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

Chapter 4 Multiplexed External Bus Interface (MEBIV3)
This register is not in the on-chip memory map in expanded and special peripheral modes. Therefore, these
accesses will be echoed externally.
NOTE
These bits have no effect when the associated pin(s) are outputs. (The pull
resistors are inactive.)
Table 4-9. PUCR Field Descriptions
Field
7
PUPKE
4
PUPEE
1
PUPBE
0
PUPAE
Description
Pull resistors Port K Enable
0 Port K pull resistors are disabled.
1 Enable pull resistors for port K input pins.
Pull resistors Port E Enable
0 Port E pull resistors on bits 7, 4:0 are disabled.
1 Enable pull resistors for port E input pins bits 7, 4:0.
Note: Pins 5 and 6 of port E have pull resistors which are only enabled during reset. This bit has no effect on
these pins.
Pull resistors Port B Enable
0 Port B pull resistors are disabled.
1 Enable pull resistors for all port B input pins.
Pull resistors Port A Enable
0 Port A pull resistors are disabled.
1 Enable pull resistors for all port A input pins.
4.3.2.11 Reduced Drive Register (RDRIV)
Module Base + 0x000D
Starting address location affected by INITRG register setting.
R
W
Reset
7
RDRK
0
6
5
4
3
2
0
0
0
0
RDPE
0
0
0
0
0
= Unimplemented or Reserved
Figure 4-15. Reduced Drive Register (RDRIV)
1
RDPB
0
0
RDPA
0
Read: Anytime (provided this register is in the map)
Write: Anytime (provided this register is in the map)
This register is used to select reduced drive for the pins associated with the core ports. This gives reduced
power consumption and reduced RFI with a slight increase in transition time (depending on loading). This
feature would be used on ports which have a light loading. The reduced drive function is independent of
which function is being used on a particular port.
This register is not in the on-chip memory map in expanded and special peripheral modes. Therefore, these
accesses will be echoed externally.
146
MC9S12Q128
Freescale Semiconductor
Rev 1.10