MC68HC11KW1 Datasheet, PDF (82/238 Pages) Motorola, Inc – High-density complementary metal oxide semiconductor HCMOS) microcontroller unit

G2POL — General-purpose chip select 2 polarity select
1 (set) – CSGP2 active high.
0 (clear) – CSGP2 active low.
G2AV — General-purpose chip select 2 address valid select
1 (set) – CSGP2 is valid during address valid time.
4
0 (clear) – CSGP2 is valid during E high time.
G2SZA–G2SZD — General-purpose chip select 2 size
These bits select the size for general-purpose chip select 2. Refer to Table 4-16.
Table 4-16 General-purpose chip select 2 size control
G2SZx
A
B
C
D
Size (bytes)
Valid bits
Valid bits
(MXGS2 = 0) (MXGS2 = 1)
0
0
0
0
Disabled
None
None
0
0
0
1
2K
G2A[15:11] G2A[18:11]
0
0
1
0
4K
G2A[15:12] G2A[18:12]
0
0
1
1
8K
G2A[15:13] G2A[18:13]
0
1
0
0
16K
G2A[15:14] G2A[18:14]
0
1
0
1
32K
G2A15
G2A[18:15]
0
1
1
0
64K
None
G2A[18:16]
0
1
1
1
128K
None
G2A[18:17]
1
0
0
0
256K
None
G2A18
1
0
0
1
512K
None
None
1
0
1
0 Follow Window 1
None
None
1
0
1
1 Follow Window 2
None
None
11100 – 1111
Default to 512K
None
None
4.5.6 One chip select driving another
The general-purpose chip selects can be programmed to drive the program chip select as well as
each other. General-purpose chip select 1 drives general-purpose chip select 2 only. There are
eight combinations of the bits G1DG2, G1DPC, and G2DPC. Although all possible combinations
are allowed, some combinations cause operations which do not perform as one might expect. The
results of all combinations are defined in the following table. The priorities defined in the previous
sections still apply. The following table assumes that none of the chip select ranges overlap.
4-38
OPERATING MODES AND ON-CHIP MEMORY
MC68HC11KW1