MC9S12E256 Datasheet, PDF (527/602 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

18.3.2.10 Pull Control Register (PUCR)
Chapter 18 Multiplexed External Bus Interface (MEBIV3)
7
6
R
0
PUPKE
W
Reset¹
1
0
5
4
3
0
0
PUPEE
0
1
0
2
1
0
0
PUPBE
PUPAE
0
0
0
1. The default value of this parameter is shown. Please refer to Chapter 1, “MC9S12E256 Device Overview
(MC9S12E256DGV1)” to determine the actual reset state of this register.
= Unimplemented or Reserved
Figure 18-15. Pull Control Register (PUCR)
Read: Anytime (provided this register is in the map).
Write: Anytime (provided this register is in the map).
This register is used to select pull resistors for the pins associated with the core ports. Pull resistors are
assigned on a per-port basis and apply to any pin in the corresponding port that is currently configured as
an input. The polarity of these pull resistors is determined by chip integration. Please refer to Chapter 1,
“MC9S12E256 Device Overview (MC9S12E256DGV1)” to determine the polarity of these resistors.
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 18-9. 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.
MC9S12E256 Data Sheet, Rev. 1.08
Freescale Semiconductor
527