
PEB 20560
Operational Description
Semiconductor Group
3-10
2003-08
Synchronous Transfer
For two channels, all switching paths of
Figure 3-2
can also be realized using
Synchronous Transfer. The working principle is that the
μ
P specifies an input time-slot
(source) and an output time-slot (destination). Both source and destination time-slots
can be selected independently from each other at either the PCM- or CFI-interfaces. In
each frame, the EPIC-1 first transfers the serial data from the source time-slot to an
internal data register from where it can be read and if required overwritten or modified by
the
μ
P. This data is then fed forward to the destination time-slot.
3.1.3.4
Special Functions
Hardware Timer
The EPIC-1 provides a hardware timer which continuously interrupts the
μ
P after
programmable time periods. The timer period can be selected in the range of 250
μ
s up
to 32 ms in multiples of 250
μ
s. Beside the interrupt generation, the timer can also be
used to determine the last look period for 6 and 8-bit signaling channels on IOM-2 and
SLD-interfaces and for the generation of an FSC-multiframe signal.
Power and Clock Supply Supervision
The
+
3.3 V power supply line and the clock lines are continuously checked by the
EPIC-1 for spikes that may disturb its proper operation. If such an inappropriate clocking
or power failure occurs, the
μ
P is requested to reinitialize the device.
3.1.4
Chapter 2.1.2.5
provides a detailed functional SACCO-description. This operational
section will therefore concentrate on outlining how to run these HDLC-controllers.
With the SACCO initialized as outlined in
chapter 3.1.6.3
, it is ready to transmit and
receive data. Data transfer is mainly controlled by commands from the CPU to the
SACCO via the CMDR-register, and by interrupt indications from SACCO to CPU.
Additional status information, which need not trigger an interrupt, is available in the
STAR-register.
SACCO
-
A/B
3.1.4.1
In transmit direction 2
×
32-byte FIFO-buffers (transmit pools) are provided for each
channel. After checking the XFIFO-status by polling the Transmit FIFO Write Enable bit
(XFW in STAR-register) or after a Transmit Pool Ready (XPR) interrupt, up to 32 bytes
may be entered by the CPU to the XFIFO.
The transmission of a frame can then be started issuing a XTF/XPD or XDD command
via the CMDR-register. If prepared data is sent, an end of message indication
(CMDR:XME) must also be set. If transparent or direct data is sent, CMDR:XME may but
Data Transmission in Interrupt Mode