1997 Jan 22
24
Philips Semiconductors
Preliminary specification
Universal codec
PCD5096
9.5
IOM control table
The selection of active slots in the IOM-2 interface and the logic connection between an IOM slot and an IOM data buffer
is defined in the IOM control table located at addresses 20H to 3FH of the SDR. The IOM control table is ‘n’ words long.
The number ‘n’ is the number of slots resulting from the IOM mode selection in Control Register 1. Speech slot 0 is
defined by word 0 (address 20H) in the IOM control table, and speech slot ‘n’ by word ‘n’ (address 20H + n). The IOM
interface block reads all words in the IOM control table once every speech frame (125
μ
s). In every IOM slot in a speech
frame the IOM-2 interface block reads the corresponding word in the IOM control table. The function of the bits within
each word is shown in Table 30. Depending on the IOM mode selected, only part of the IOM control table address space
is used. The unused space is free for extra IOM data buffers or for other applications.
Table 30
Word definition in the IOM control table
Table 31
IOM data buffers location in SDR
BIT
FUNCTION
B15 to B10
B9
not used
Mute.
If B9 = 1, data on the DO output is forced to zero regardless of the contents of the IOM data
buffer. The input data on DI is not affected. If B9 = 0, then normal operation is selected.
Local.
If B8 = 1, swap in/out buffers. If B8 = 0, then normal operation is selected. See Section 9.7.
Select byte.
When byte transfer is selected (B6 = 1); B7 = 1, selects the high byte and B7 = 0 selects
the low byte.
Byte/word transfer.
If B6 = 1, then byte transfer is selected. If B6 = 0, then word transfer is selected
and two consecutive slots are activated.
Active slot.
If B5 = 1, the slot is active. If B5 = 0, the slot is idle.
IOM data buffer assigned to the slot.
These 4 bits select the locations in SDR where the IOM data
buffer will reside. The allowed values are 10000 to 11101; see Table 31.
B8
B7
B6
B5
B4 to B0
IOM BUFFER CODE
ADDRESS IN SDR (HEX)
B4
B3
B2
B1
B0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
40 to 43
44 to 47
48 to 4B
4C to 4F
50 to 53
54 to 57
58 to 5B
5C to 5F
60 to 63
64 to 67
68 to 6B
6C to 6F
70 to 73
74 to 77