System Integration Module (SIM)
MCF5272 ColdFire Integrated Microprocessor User’s Manual, Rev. 3
Freescale Semiconductor
6-5
6.2.3
System Configuration Register (SCR)
The system configuration register (SCR),
Figure 6-3, provides information and control for a variety of
system features.
15
14
13
12
11
9
8
7
6
5
4
3
2
0
Field 1
0
RSTSRC
—
Priority
AR
SoftRST
—
BusLock
HWR
Reset 1
0
0000_1000_0111
R/W
R/W; except for RSTSRC[1:0], which are read only
Address
MBAR + 0x004
Figure 6-3. System Configuration Register (SCR)
Table 6-3. SCR Field Descriptions
Bits
Field
Description
15-14
—
Reserved. Bit 15 always reads as a 1, bit 14 as a 0. Writing to these bits has no effect.
13–12
RSTSRC
Reset source. Indicates the source of the last device reset.
00 Reserved
01 RSTI asserted, DRESETEN not asserted
10 Software watchdog
11 RSTI and DRESETEN asserted
11–9
—
Reserved, should be cleared.
8
Priority
Selects the bus arbiter priority scheme.
0 Ethernet has highest priority, DMA has next highest priority, CPU has lowest priority.
1 CPU has highest priority, DMA has next highest priority, Ethernet has lowest priority.
This bit should be cleared if the Ethernet module is enabled.
7
AR
Assume request. Selects the bus mastership scheme.
0 Current bus master relinquishes the bus after the current bus cycle.
1 Assume current bus master wants the bus for the next bus cycle and include it in the arbitration process.
If AR is set and the current bus master has a higher priority than other requesting masters but is not
requesting the bus for the next cycle, there is a 1 clock dead cycle before the arbiter can reassign the
bus to the next highest priority master.
6
SoftRST
Writing a one to this bit resets the on-chip peripherals, excluding the chip select module, interrupt
controller module, GPIO module, and SDRAM controller, and asserts RSTO. The CPU is not reset. The
reset remains asserted for 128 clock cycles. This bit is automatically cleared on negation of the reset.
5–4
—
Reserved, should be cleared.