PEB2085 SIEMENS [Siemens Semiconductor Group], PEB2085 Datasheet - Page 284

• Manufacturer Part Number: PEB2085
• Description: ISDN SubscribernAccess Controller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Int_ICC ()
Evaluates and handles the ISAC-S interrupts.
Interrupt service procedure:
The bits of the interrupt status register ISTA are scanned. XPR, TIN, RSC, and EXI interrupts
are handled directly by Int_ICC. For RPF and RME interrupts the function RX_ICC is called,
for CISQ interrupts IntL1_SBC is called. The interrupt related actions performed are:
– XPR(transmit pool ready) interrupt, but no TIN and no PCE (EXIR:PCE) interrupt:
– TIN interrupt:
– RSC (receiver status change of remote station) interrupt:
– EXI (extended) interrupt:
RX_ICC ()
Handles the receive pool full and receive message end (RPF and RME) interrupts if TIN and
PCE (EXIR:PCE) interrupt are not indicated. Received frames are handed over to the higher
software levels. Errors detected during the frame reception are reported to the higher layers.
RPF interrupt:
RME interrupt:
Check_TREC_status_ICC ()
Check_TREC_status_ICC () is called periodically by the operating system, if 'timer recovery
status' (STAR2:TREC) was detected during a previous XPR interrupt handling. A 'transmit
frame acknowledge' for an HDLC I-frame is generated if the TREC status is left and no timer
interrupt (ISTA:TIN) is indicated.
Semiconductor Group
The HDLC controller's internal timer has expired (in auto-mode only).
A status change of the remote station's receiver has been detected. This is reported to the
higher layers.
One of the six non-critical interrupts has been generated. The exact cause is read from
register EXIR and reported to the higher layers.
a)
b)
HDLC controller reset was given previously.
last transmission is finished. The XFIFO will be loaded if there are more bytes to
be sent. If not, a 'transmit frame acknowledge' can be generated (if depends on
the message transfer mode and some other conditions).
Interrupt Handler
Interrupt Handler
received and the message is not complete.
The receive message is complete. The RFIFO contains the last bytes of a
frame greater than 32 bytes long or a complete frame. In the case of a
long frame the beginning of this frame will already have been received
using the RPF interrupt. Address and control field information is
examined, the type of frame (HDLC U, UI, I or S-frame) is determined and
the validity of the frame is checked. Finally the frame or a error condition
message is sent to the higher layers.
32 data bytes are in the RFIFO. The end of the received frame is yet to be
284
Low Level Controller