
PSB 2115
PSF 2115
Functional Description
Semiconductor Group
125
11.97
2.7.3
In IOM-2 terminal mode (TE mode, MODE0=0) the microprocessor can access the B and
IC (intercommunication) channels at the IOM-2 interface by reading the B1CR/B2CR or
by reading and writing the C1R/C2R registers. Furthermore it is possible to loop back the
B-channels from/to the S/T interface or to loop back the IC channels from/to the IOM-2
interface without
μ
P intervention.
These access and switching functions are selected with the Channel Connect bits
(CxC1, CxC0) in the SPCR register (
table 14, figure 60
).
External B-channel sources (voice/data modules) connected to the IOM-2 interface can
be disconnected with the IOM off function (CONF:IOF) in order to not disturb the B-
channel access (
see figure 60
).
If the B-channel access is used for transferring 64 kbit/s voice/data information directly
from the
μ
P port to the ISDN S/T interface, the access can be synchronized to the IOM
interface by means of a synchronous transfer interrupt programmed in the STCR
register.
Microprocessor Access to B and IC Channels
Note: x=1 for channel 1 or 2 for channel 2
The general sequence of operations to access the B/IC channels is:
Table 14
CxC1
μ
P Access to B/IC Channels (IOM
-2)
CxC0
CxR
CxR
Read
Write
BxCR
Read
Output
to
IOM-2
-
ICx
Applications
0
0
0
1
ICx
ICx
-
ICx
Bx
Bx
Bx monitoring, ICx monitoring
Bx monitoring, ICx looping from/to
IOM-2
Bx access from/to S;
Transmission of a constant value
in Bx channel to S
Bx looping from S;
transmission of a variable pattern
in Bx channel to S
1
0
-
Bx
Bx
Bx
1
1
Bx
Bx
-
Bx
(set configuration register SPCR)
Program Synchronous Interrupt (ST0)
Read Register (BxCR, CxR)
(Write Register)
Acknowledge SIN (SC0) within 62.5
μ
s from SIN
SIN