MPC555
/
MPC556
SYSTEM CONFIGURATION AND PROTECTION
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
6-20
Table 6-5 SIUMCR Bit Descriptions
Bit(s)
Name
Description
0
EARB
External arbitration
0 = Internal arbitration is performed
1 = External arbitration is assumed
1:3
EARP
External arbitration request priority. This field defines the priority of an external master’s arbitra-
tion request. This field is valid when EARB is cleared. Refer to
for
details.
4:7
—
Reserved
8
DSHW
Data show cycles. This bit selects the show cycle mode to be applied to U-bus data cycles (data
cycles to IMB modules and flash EEPROM). This field is locked by the DLK bit. Note that instruc-
tion show cycles are programmed in the ICTRL and L-bus data show cycles (to SRAM) are pro-
grammed in the L2UMCR.
0 = Disable show cycles for all internal data cycles
1 = Show address and data of all internal data cycles
9:10
DBGC
Debug pins configuration. Refer to
11
DBPC
Debug port pins configuration. Refer to
12
ATWC
Address write type enable configuration. This bit configures the pins to function as byte write en-
ables or address types for debugging purposes.
0 = WE[0:3]/BE[0:3]/AT[0:3] functions as WE[0:3]/BE[0:3]
1
1 = WE[0:3]/BE[0:3]/AT[0:3] functions as AT[0:3]
NOTES:
1. WE/BE is selected per memory region by WEBS in the approprite BR register in the memory controller.
13:14
GPC
This bit configures the pins as shown in
15
DLK
Debug register lock
0 = Normal operation
1 = SIUMCR is locked and can be written only in test mode or when the internal freeze signal is
asserted.
16
—
Reserved
17:18
SC
Single-chip select. This field configures the functionality of the address and data buses. Chang-
ing the SC field while external accesses are performed is not supported. Refer to
19
RCTX
Reset configuration/timer expired. During reset the RSTCONF/TEXP pin functions as
RSTCONF. After reset the pin can be configured to function as TEXP, the timer expired signal
that supports the low-power modes.
0 = RSTCONF/TEXP functions as RSTCONF
1 = RSTCONF/TEXP functions as TEXP
20:21
MLRC
Multi-level reservation control. This field selects between the functionality of the reservation logic
and IRQ pins, refer to
22:23
—
Reserved
24
MTSC
Memory transfer start control.
0 = IRQ[2]/CR/SGPIOC[2]/MTS functions according to the MLRC bits setting
1 = IRQ[2]/CR/SGPIOC[2]/MTS functions as MTS
25:31
—
Reserved
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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