MC9S12E256 Datasheet, PDF (528/602 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

Chapter 18 Multiplexed External Bus Interface (MEBIV3)
18.3.2.11 Reduced Drive Register (RDRIV)
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 18-16. 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.
Table 18-10. RDRIV Field Descriptions
Field
7
RDRK
4
RDPE
1
RDPB
0
RDPA
Description
Reduced Drive of Port K
0 All port K output pins have full drive enabled.
1 All port K output pins have reduced drive enabled.
Reduced Drive of Port E
0 All port E output pins have full drive enabled.
1 All port E output pins have reduced drive enabled.
Reduced Drive of Port B
0 All port B output pins have full drive enabled.
1 All port B output pins have reduced drive enabled.
Reduced Drive of Ports A
0 All port A output pins have full drive enabled.
1 All port A output pins have reduced drive enabled.
MC9S12E256 Data Sheet, Rev. 1.08
528
Freescale Semiconductor