M3488 ST Microelectronics, M3488 Datasheet - Page 15

• Manufacturer Part Number: M3488
• Description: 256 x 256 DIGITAL SWITCHING MATRIX
• Manufacturer: ST Microelectronics

No tes : 1. About mask bits Mi0 to Mi7 a logic ”0” level means disabling condition, a logic ”1” level means enabling condition.
M3488 WITH LESS PCM LINKS THAN 32
CHANNELS
It is also possible to use M3488 when the PCM
frames are made up of a number of channels other
than 32.
Suppose that the PCM frames are made up of N-
Channels, which will be numbered from 0 to (N-1).
Each PCM frame will thus be made up of a number
of bits multiplied by 8 ; this exactly equal to (N
Also, in this case, it is necessary to respect the tim-
ing relationshipbetween the different signals shown
on the data sheet ; in particular, a relation-ship is al-
ways carefully made between the rising edge of
INSTRUCTION5: TRANSFER OF AN OUTPUT CHANNEL CONTROL WORD
INSTRUCTION6: CHANNEL 0 SELECTION MASK STORE/DATA TRANSFER
Match C/D CS WR RD
Match C/D CS WR RD
Mask store control
First Data Transfer (after DR going low)
Repeated Data Transfer (after first OR2 transfer)
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
X
X
X
X
Control Signals
Control Signals
2. A null mask or a RESET pulse clear the mask and the deep background mask registers and disable channel 0 extraction function.
3. Reading of OR2 is optional after mask store or redefinition, because function is activated only by not-null mask writing.
4. After mask store (N2 N1 N0) is the sum of activated channels, after DR is the sum of active channels ; Tn = 1/0 means activation/sup-
5. Reading of OR2 is imperative after DR in order to step the data transfer ; reading of OR1 is also needed to scan in descending order
6. (P2 P1 P0) is the PCM bus on which the message copied in OR1 was found ; Fn is a continuation bit telling respectively on level 1/0
0
0
1
0
1
0
0
1
0
1
0
1
0
1
pression of the function after store while after DR only Tn = 1 can appear to tell a not-null configuration to be extracted.
the priority register. Relevant messages only are considered, that means only messages with a MSD label different from 0 1.
for any more/no more extraction step to be performed.
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
1
1
1
1
1
1
1
1
1
0
0
1
1
1
0
0
0
0
0
0
(Bo2
D7
C7
D7
N2
N2
A7
S7
P2
X
X
X
X
X
X
Bo1
D6
C6
D6
N1
N1
A6
S6
P1
X
X
X
X
X
X
Bo0
D5
C5
D5
N0
N0
A5
S5
P0
X
X
X
X
X
X
(previous content)
(previous content)
Data Bus
Data Bus
Co4 Co3 Co2 Co1 Co0 2
Mi4 Mi3 Mi2 Mi1 Mi0
D4
C4
C8
C8
D4
S4
Tn
Tn
Fn
X
X
X
X
.
8).
D3
C3
D3
S3
X
X
1
1
1
1
1
1
1
Bo2 Bo1 Bo0 1
Mi7 Mi6 Mi5
D2
C2
D2
S2
0
0
0
1
1
1
1
SYNC and the first clock (CK) bit contained in the
slot time for bit 0 of channel 0.
In order to use M3488 with these frames, it is suffi-
cient, using the data bytes sent by the microproces-
sor, to modify the numbering of a few channels.
In particular :
a) in all instructions in which reference is made to the
b) in all instructions in which reference is made to the
input channel (N-1), the number 31 should be
substituted for the number (N-1) ;
output channel 0, the number N should be sub-
stituted for the number 0.
D1
C1
D1
S1
0
0
0
1
1
1
1
D0
C0
D0
S0
0)
0
0
0
0
0
0
Instruction Opcode
OR1: CM selected CM word copy.
OR2: that is.
1
selection mask.
2
selection mask.
Instruction Opcode
OR1: register is not affected.
OR2: see below.
OR1: register is not affected.
OR2: see below.
OR1: expected message stored in SM.
OR2: see below.
st
nd
st
nd
Data Byte: selected output bus.
Data Byte: most sign. digits of
Data Byte: selected output channel.
Data Byte: least sign. digits of
Notes
Notes
M3488
15/18