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IDT821054A QUAD PROGRAMMABLE PCM CODEC WITH MPI INTERFACE INDUSTRIAL TEMPERATURE
9 APPENDIX: IDT821054A COE-RAM MAPPING
Figure - 11 Coe-RAM Mapping
Generally, 6 bits of address are needed to locate each word of the 40 Coe-RAM words. In the IDT821054A, the 40 words of Coe-RAM are divided
into 5 blocks with 8 words per block, so, only 3 address bits are needed to locate each of the block. When the address of a Coe-RAM block (b[2:0]) is
specified in a Coe-RAM command, all 8 words of this block will be addressed automatically, with the highest order word first (The IDT821054A will
count down from '111' to '000' so that it accesses the 8 words successively). Refer to “3.1.4 Addressing the Coe-RAM” for details.
The address assignment for the 40 words of Coe-RAM is as shown in Table - 4. The number in the “Address” column is the actual address of each
Coe-RAM word. As the IDT821054A handles the lower 3 bits of address automatically, only the higher 3 bits of address (in bold style) are needed for
a Coe-RAM Command. It should be noted that, when addressing the GRX RAM, the FRR RAM will be addressed at the same time.
Table - 4 Coe-RAM Address Allocation
Block # Word # Address Function Block # Word # Address Function
5
39 100,111 GRX RAM
3
19 010,011
GIS RAM
38 100,110
FRR RAM
18 010,010
37 100,101 17 010,001
36 100,100 16 010,000
35 100,011
2
15 001,111
ECF RAM
34 100,010 14 001,110
33 100,001 13 001,101
32 100,000 12 001,100
4
31 011,111 GTX RAM 11 001,011
30 011,110
FRX RAM
10 001,010
29 011,101 9 001,001
28 011,100 8 001,000
27 011,011
1
7 000,111
IMF RAM
26 011,010 6 000,110
25 011,001 5 000,101
24 011,000 4 000,100
3
23 010,111 Amplitude Coefficient of Tone Generator 1 3 000,011
22 010,110 Frequency Coefficient of Tone Generator 1 2 000,010
21 010,101 Amplitude Coefficient of Tone Generator 0 1 000,001
20 010,100 Frequency Coefficient of Tone Generator 0 0 000,000
GRX RAM
FRR RAM
GTX RAM
FRX RAM
ECF RAM
IMF RAM
TONE RAM
GIS RAM
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b[2:0] of a Coe-RAM
Command
Word #
000
001
010
011
100
7
0
15
8
23
16
31
24
39
32
Block #
5
4
3
2
1
