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PEB 20321
PEF 20321
Basic Functional Principles
Data Sheet
81
2001-02-14
In receive direction, the MUNICH32X reads a receive descriptor, calculates the data
address, writes the current receive descriptor address into the CCB, and exchanges data
between the on-chip receive buffer and the external memory. After the data section has
been filled, the MUNICH32X writes the number of stored bytes (BNO) into the descriptor.
If a frame end has occurred, the frame status is written into the descriptor and an
interrupt is generated.
The frame status includes the CRC check results and transmission error information like
– ‘
non octet of bits
’
(NOB),
– ‘
aborted frame
’
(RA),
– ‘
data overflow
’
(ROF),
– ‘
maximum frame length exceeded
’
(LFD) and
– ‘
frames with less than or equal the CRC length, which equals 2 bytes for CRC16 and
4 bytes for CRC32
’
(SF).
An activated reception-hold in the descriptor prevents the MUNICH32X from processing
the receive data. The incoming frames are discarded until the hold is deactivated.
Because the MUNICH32X is divided into two non-synchronized parts by the on-chip
buffers, two different kinds of aborting a channel transmission are implemented.
–
Normal abort: This abort of a receive or transmit channel is processed in the
formatters of the serial interface. The interframe time-fill code is sent after aborting the
current issued frame. No accesses to the on-chip buffers are carried out, until the
abort is withdrawn. The handling of the link lists and the processing of the buffers by
the DMA controller are not affected by normal abort.
–
Fast abort: A fast abort is performed by the DMA controller and does not disturb the
transmission on the serial interface. If this abort is detected the current descriptor is
suspended with an abort status immediately followed by a branching to the new
descriptor defined in the channel specification of the CCB.
For initialization and control, the host sets up a
Control and Configuration Block
(CCB)
, including the action specification, time slot assignment and the channel
specification. The host initiates an action, e.g. reconfiguration, change of the channel
mode, reset or switching of a test loop by updating the CCB and issuing an action
request. This is done by writing a
‘
1
’
to the CMD.ARPCM bit field in Command register
for the serial PCM core, or by writing a
‘
1
’
to the CMD.ARLBI bit field for LBI related
action requests.
When the action request is detected by the MUNICH32X, it reads the control start
address in CCBA register, then the action specification and (if necessary) additional
information from the CCB. After execution, the action request is acknowledged by the
STAT.PCMA or STAT.LBIA interrupt bit fields in Status register.
MUNICH32X indicates an interrupt by activating the interrupt line and storing the
interrupt information (including the corresponding channel number) in the associated
interrupt queue, which is indicated by a flag in Status register STAT. Interrupts may be
masked in Interrupt Mask register IMASK.