DSP56303 FREESCALE [Freescale Semiconductor, Inc], DSP56303 Datasheet - Page 84

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

Core Configuration
4.6.3 Address Attribute Registers (AAR[0–3])
The Address Attribute Registers (AAR[0–3]) are read/write registers that control the activity of
the
the BAC bits in the associated AAR matches the exact number of external address bits defined by
the BNC bits, and the external address space (X data, Y data, or program) is enabled by the AAR.
Figure 4-8 shows an AAR register; Table 4-10 lists the bit definitions.
Note:
4-26
Number
23–12
11–8
Bit
AA0
BAC11
BNC3
/
RAS0
11
23
Figure 4-8. Address Attribute Registers (AAR[0–3]) (X:$FFFFF9–$FFFFF6)
Bit Name
The DSP56303 does not support address multiplexing.
BAC
BNC
BAC10
BNC2
–
Reserved Bit. Write to zero for future compatibility.
10
22
Table 4-10. Address Attribute Registers (AAR[0–3]) Bit Definitions
AA3
BNC1
BAC9
/
RAS3
21
9
Reset
Value
0
0
BNC0
BAC8
20
8
pins. The associated
Bus Address to Compare
Read/write control bits that define the upper 12 bits of the 24-bit address with which to
compare the external address to determine whether to assert the corresponding AA/RAS
signal. This is also true of 16-bit compatibility mode. The BNC[3–0] bits define the number of
address bits to compare.
Bus Number of Address Bits to Compare
Specify the number of bits (from the BAC bits) that are compared to the external address.
The BAC bits are always compared with the Most Significant Portion of the external address
(for example, if BNC[3–0] = 0011, then the BAC[11–9] bits are compared to the 3 MSBs of
the external address). If no bits are specified (that is, BNC[3–0] = 0000), the AA signal is
activated for the entire 16 M-word space identified by the space enable bits (BPEN, BXEN,
BYEN), but only when the address is external to the internal memory map. The
combinations BNC[3–0] = 1111, 1110, 1101 are reserved.
BPAC
BAC7 BAC6
19
7
18
6
DSP56303 User’s Manual, Rev. 2
BYEN
BAC5
17
5
BXEN
BAC4
16
4
AAn
BPEN
BAC3 BAC2
/
RASn
3
15
BAAP
2
14
pin is asserted if the address defined by
Description
BAT1
BAC1
13
1
BAT0
BAC0
12
0
External Access Type
AA pin polarity
Program space Enable
X data space Enable
Y data space Enable
Reserved
Packing Enable
Number of Address bit to
compare
Address to Compare
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