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MC68F375
SINGLE-CHIP INTEGRATION MODULE 2 (SCIM2E)
MOTOROLA
REFERENCE MANUAL
Rev. 25 June 03
4-81
CSORBT and CSOR[0], [3] and [5:10] contain parameters that support operations
from external memory devices. Bit and field definitions for CSORBT and CSOR[0], [3]
and [5:10] are the same.
CSOR0 — Chip-Select Option Registers
0xYF FA4E
CSOR3
0xYF FA5A
CSOR5
0xYF FA62
CSOR6
0xYF FA66
CSOR7
0xYF FA6A
CSOR8
0xYF FA6E
CSOR9
0xYF FA72
CSOR10
0xYF FA76
MSB
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
LSB
0
MOD
E
BYTE[1:0]
R/W[1:0]
STRB
DSACK[3:0]
SPACE[1:0]
IPL[2:0]
AVEC
RESET:
0
Table 4-37 CSOR Bit Descriptions
Bit(s)
Name
Description
15
MODE
Asynchronous/Synchronous Mode. In asynchronous mode, chip-select assertion is synchro-
nized with AS and DS.
0 = Asynchronous mode is selected.
1 = Synchronous mode is selected, and used with ECLK peripherals.
14:13
BYTE
Upper/lower byte option. This field is used only when the chip-select 16-bit port option is
selected in the pin assignment register. This allows the usage of two external 8-bit memory
devices to be concatenated to form a 16-bit memory.
00 = Disable
01 = Lower byte
10 = Upper byte
11 = Both bytes
12:11
R/W
Read/write. This field causes a chip select to be asserted only for a read, only for a write, or for
both reads and writes.
00 = Disable
01 = Read only
10 = Write only
11 = Read/Write
10
STRB
Address strobe/data strobe. This bit controls the timing for assertion of a chip select in asynchro-
nous mode only. Selecting address strobe causes the chip select to be asserted synchronized
with address strobe. Selecting data strobe causes the chip select to be asserted synchronized
with data strobe. Data strobe timing is used to create a write strobe when needed.
0 = Address strobe
1 = Data strobe
9:6
DSACK
Data strobe acknowledge. This field specifies the source of DSACK in asynchronous mode as
internally generated or externally supplied. It also allows adjust bus timing adjustment with
internal DSACK generation by controlling the number of wait states that are inserted to optimize
bus speed in a particular application. Table 4-38 shows the DSACK[3:0] field encoding. The fast
termination encoding (0b1110) effectively corresponds to –1 wait states.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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