DSP56303 FREESCALE [Freescale Semiconductor, Inc], DSP56303 Datasheet - Page 79

• Manufacturer Part Number: DSP56303
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

4.6 Bus Interface Unit (BIU) Registers
The three Bus Interface Unit (BIU) registers configure the external memory expansion port (Port
A). They include the following:
To use Port A correctly, configure these registers as part of the bootstrap process. The following
subsections describe these registers.
4.6.1 Bus Control Register (BCR)
The Bus Control Register (BCR), depicted in Figure 4-6, is a read/write register that controls the
external bus activity and Bus Interface Unit (BIU) operation. All BCR bits except bit 21, BBS,
are read/write bits. The BCR bits are defined in Table 4-8.
Freescale Semiconductor
BA2W1
Bit Number
BRH
23
11
14–12
11–0
15
Bus Control Register (BCR)
DRAM Control Register (DCR)
Address Attribute Registers (AAR[3–0])
Reserved bit. Read as zero; write to zero for future compatibility
BA2W0
22
10
Bit Name
MF[11–0]
Table 4-7. PLL Control Register (PCTL) Bit Definitions (Continued)
DF[2–0]
XTLR
BA1W4
BBS
21
9
Reset Value
BDFW4
BA1W3
20
8
Figure 4-6. Bus Control Register (BCR)
0
0
0
BDFW3
BA1W2
DSP56303 User’s Manual, Rev. 2
19
7
Crystal Range
Controls the internal crystal oscillator transconductance. The XTLR bit is
cleared (0) during hardware reset.
Division Factor
Define the DF of the low-power divider. These bits specify the DF as a power
of two in the range from 2
PLL Multiplication Factor
Define the multiplication factor that is applied to the PLL input frequency. The
MF bits are cleared during hardware reset and thus correspond to an MF of
one.
BDFW2
BA1W1
18
6
BDFW1
BA1W0
17
5
0
to 2
BDFW0
BA0W4
16
7
4
.
Description
BA3W2
BA0W3
15
3
Bus Interface Unit (BIU) Registers
BA0W2
BA3W1
14
2
BA3W0
BA0W1
13
1
BA2W2
BA0W0
12
0
4-21