Chapter 4 Multiplexed External Bus Interface (MEBIV3)
Freescale Semiconductor
MC9S12C-Family / MC9S12GC-Family
147
Rev 01.24
4.3.2.12
External Bus Interface Control Register (EBICTL)
Read: Anytime (provided this register is in the map)
Write: Refer to individual bit descriptions below
The EBICTL register is used to control miscellaneous functions (i.e., stretching of external E clock).
This register is not in the on-chip memory map in expanded and special peripheral modes. Therefore, these
accesses will be echoed externally.
Table 4-10. RDRIV Field Descriptions
Field
Description
7
RDRK
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.
4
RDPE
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.
1
RDPB
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.
0
RDPA
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.
Module Base + 0x000E
Starting address location affected by INITRG register setting.
7
6
5
4
3
2
1
0
R
0
0
0
0
0
0
0
ESTR
W
Reset:
Peripheral
All other modes
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
= Unimplemented or Reserved
Figure 4-16. External Bus Interface Control Register (EBICTL)
Table 4-11. EBICTL Field Descriptions
Field
Description
0
ESTR
E Clock Stretches
— This control bit determines whether the E clock behaves as a simple free-running clock or
as a bus control signal that is active only for external bus cycles.
Normal and Emulation: write once
Special: write anytime
0 E never stretches (always free running).
1 E stretches high during stretched external accesses and remains low during non-visible internal accesses.
This bit has no effect in single-chip modes.
Summary of Contents for MC9S12C Family
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