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MC68F375
SINGLE-CHIP INTEGRATION MODULE 2 (SCIM2E)
MOTOROLA
REFERENCE MANUAL
Rev. 25 June 03
4-66
Like ADDR[2:0] (which can be disabled by setting the ABD bit in SCIMMCR), the R/W
line and instruction tracking pins (IPIPE/DSO and IFETCH/DSI) can be disabled by
setting RWD and CPUD bits in SCIMMCR, respectively.
4.7.8.4 Fully (16-bit) Expanded Mode
Operation in 16-bit expanded mode is selected when BERR = 1 and DATA1 = 0 at the
release of RESET. In this configuration, ADDR[18:11]/PA[7:0] and ADDR[10:3]/
PB[7:0] become part of the address bus. Likewise, DATA[15:8]/PG[7:0] and
DATA[7:0]/PH[7:0] become the data bus. The ABD, RWD, and CPUD bits in SCIM-
MCR are clear, enabling ADDR[2:0], R/W, and the instruction tracking pins (IPIPE/
DSO and IFETCH/DSI), respectively. Ports A, B, G, and H are unavailable in 16-bit
expanded mode. The initial configuration of all other SCIM2E pins is controlled by
DATA[11:2] and DATA0 and is outlined in Table 4-27 below.
Table 4-27 Fully (16-bit) Expanded Mode Reset Configuration
Select Pin
Affected Pin(s)
Default Function
(Pin Held High)
Alternate Function
(Pin Held Low)
DATA0
CSBOOT
16-bit CSBOOT
8-bit CSBOOT
DATA2
BR/CS0
FC0/CS3/PC0
FC1/PC1
FC2/CS5/PC2
CS0
CS3
FC1
CS5
BR
FC0
FC1
FC2
DATA[7:3]
ADDR23/CS10/ECLK
ADDR[22:19]/CS[9:6]/PC[6:3]
DATA8
DSACK0/PE0
DSACK1/PE1
AVEC/PE2
RMC/PE3
DS/PE4
AS/PE5
SIZ0/PE6
SIZ1/PE7
DSACK0
DSACK1
AVEC
RMC
DS
AS
SIZ0
SIZ1
PE0
PE1
PE2
PE3
PE4
PE5
PE6
PE7
DATA9
FASTREF/PF0
IRQ[7:1]/PF[7:1]
FASTREF1
IRQ[7:1]
NOTES:
1. The FASTREF function is used only at reset and serves no purpose during normal operation.
PF0
PF[7:1]
DATA102
2. If DATA1 and DATA10 are low at the rising edge of RESET, the SCIM2E will operate in emulation mode, a special
variation of 16-bit expanded mode.
BGACK/CSE
BG/CSM
BGACK
BG
CSE
CSM3
3. For CSM to be active, the SCIM2E must be configured for emulation mode, as described above, and any on-chip
masked ROM modules must be disabled by driving their associated data bus pins low at the rising edge of
RESET. At present, only masked ROM modules support memory emulation by means of the CSM chip select.
CSM will not assert on MCUs with flash EEPROM modules.
DATA114
4. DATA11 must be high at the rising edge of RESET for normal MCU operation.
External Bus Interface
Normal Operation
Factory Test
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Freescale Semiconductor, Inc.
For More Information On This Product,
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