pef82902 Infineon Technologies Corporation, pef82902 Datasheet - Page 66

• Manufacturer Part Number: pef82902
• Description: 4b3t Second Generation Modular Isdn Nt Intelligent Extended
• Manufacturer: Infineon Technologies Corporation

or an external D-channel HDLC controller (transmission of an HDLC frame in the D-
channel). A software access request to the bus is effected by setting the BAC bit in
register CIX0 to ’1’ (resulting in BAC = ’0’ on IOM
In the case of an access request by the T-SMINT
of last octet of CH2 on DU, see
indicated by a logical ’1’. If the bus is free, the T-SMINT
bus address TAD programmed in the CIX0 register (CIX0.TBA2-0). While being
transmitted the TIC bus address TAD is compared bit by bit with the value read back on
DU. If a sent bit set to ’1’ is read back as ’0’ because of the access of an external device
with a lower TAD, the T-SMINT
remaining TAD bits are not transmitted. The TIC bus is occupied by the device which
sends and reads back its address error-free. If more than one device attempt to seize
the bus simultaneously, the one with the lowest address values wins. This one will set
BAC=0 on TIC bus and starts D-channel transmission in the same frame.
•
Figure 27
When the TIC bus is seized by the T-SMINT
occupied via the DU Ch2 Bus Accessed-bit state ’0’ until the access request is
withdrawn. After a successful bus access, the T-SMINT
lower priority class, that is, a new bus access cannot be performed until the status "bus
free" is indicated in two successive frames.
If none of the devices connected to the IOM
I0 channels, the TIC bus address 7 will be present. The device with this address will
therefore have access, by default, to the D and C/I0 channels.
Note: Bit BAC (CIX0 register) should be reset by the
Data Sheet
requested, to grant other devices access to the D and C/I0 channels.
DU
Structure of Last Octet of Ch2 on DU
B1
B2
MON0
D CI0
Figure
â
IX withdraws immediately from the TIC bus, i.e. the
MR
MX
IC1
27) is checked for the status "bus free“, which is
52
â
IC2
â
-2 interface request access to the D and C/
IX, the bus is identified to other devices as
BAC
MON1
â
â
-2).
TIC-BUS Address (TAD 2 - 0)
IX, the Bus Accessed-bit BAC (bit 5
Bus Accessed ("1" no TIC-BUS Access)
2
CI1
TAD
1
â
â
IX transmits its individual TIC
IX is automatically set into a
0
C when access is no more
MR
MX
Functional Description
BAC
TAD
PEF 81902
ITD02575.vsd
2001-11-12