MT9079 Mitel Semiconductor, MT9079 Datasheet - Page 18

• Manufacturer Part Number: MT9079
• Description: CMOS ST-BUS FAMILY Advanced Controller for E1
• Manufacturer: Mitel Semiconductor

MT9079
Circular Buffers
The MT9079 is equipped with two 16 byte circular
receive buffers and two 16 byte circular transmit
buffers, which can be connected to any PCM 30 time
slot. Connection is made through control bits 3 to 0
of the per time slot control words on pages 7 and 8.
These buffers will transmit and receive time slot data
synchronously with the CRC-4 multiframe.
Transmit circular buffer zero is located on page 9
(TxB0.0 to TxB0.15) and transmit circular buffer one
is located on page 10 (TxB1.0 to TxB1.15).
The two circular 16 byte receive buffers (page 11 -
RxB0.0 to RxB0.15 and page 12 - RxB1.0 to
RxB1.15) record the data received in an associated
channel for the next 16 frames beginning with the
CRC-4 multiframe boundary. The assigned channel
data from the next multiframe will over-write the
current data until the buffer is disconnected.
The STOP and START maskable interrupts extend
the normal operation of the receive buffers in the
following manner.
a) STOP - once activated, receive circular buffer 0 or
1 records time-slot data until that data either
matches or mismatches a user-defined eight bit
pattern, then the interrupt occurs. This user-defined
bit pattern is determined by the Code Detect Word
4-254
Notes:
1) The interrupt vector value associated with these interrupts is 02H (page 4, address 12H)
2)
3) Circular Buffer Accumulate Control Word (page 2, address 12H).
1EH, bit 2)
1EH, bit 1)
particular pattern.
The START and STOP interrupts can be used to record the data between two pre-defined eight bit data patterns received in a
Interrupt
(page 1,
(page 1,
address
address
START
STOP
Mask
Function*
START0
START1
START0
START1
(note 3)
STOP0
STOP1
STOP0
STOP1
Table 6 - START and STOP Interrupt Control
Circular buffer zero stops recording on a match with CDW and CDM.
Circular buffer one stops recording on a match with CDW and CDM.
Circular buffer zero stops recording on a mismatch with CDW and
CDM.
Circular buffer one stops recording on a mismatch with CDW and
CDM.
Circular buffer zero starts recording on a match with CDW and CDM.
Circular buffer one starts recording on a match with CDW and CDM.
Circular buffer zero starts recording on a mismatch with CDW and
CDM.
Circular buffer one starts recording on a mismatch with CDW and
CDM.
Description (see notes 1 and 2)
(CDW) and Detect Word Mask (CDM) mentioned
below.
or 1 begins recording time-slot data and initiates an
interrupt when a user-defined eight bit pattern is
received. This user-defined bit pattern is determined
by the Code Detect Word (CDW) and Detect Word
Mask (CDM) mentioned below.
The functionality and control of the START and
STOP interrupts is described in Table 6.
PCM 30 Time-Slot Code Insertion and Detection
Idle line codes, flags or user-defined codes can be
inserted and detected on any combination of PCM 30
time-slots. This is done as follows:
a) CIW7-0 - Code Insert Word 7 to 0 (page 1, address
17H) is an eight bit code that is transmitted on
user-defined PCM 30 time-slots. Transmit time-slots
are selected through bit 7 of the per time slot control
words (pages 7 and 8).
b) CDW7-0 - Code Detect Word 7 to 0 (page 1,
address 18H) is an eight bit code, which is compared
with the contents of user-defined PCM 30 receive
time-slots. When the contents of the selected channels
matches the CDW7-0 the DATA interrupt, if unmasked,
will be triggered. Receive time-slots are selected
b) START - once activated, receive circular buffer 0