cx28500 Mindspeed Technologies, cx28500 Datasheet - Page 147

• Manufacturer Part Number: cx28500
• Description: Cx28500 Multichannel Synchronous Communications Controller
• Manufacturer: Mindspeed Technologies

1. PADCNT = 0: Shared open/close flag
2. PADCNT = 1: Separate open/close flags, no idle code
3. PADCNT = 2: Separate open/close flags, at least one idle code
This pad fill feature enables rate adaptation applications (i.e., ISDN Rate Adaptation), as defined in ITU Standards
V.110 and V.120. Furthermore, CX28500 also allows the reduction of the number of pad fill octets to compensate
for the number of zero-bit insertion. One pad fill octet is omitted from transmission for every eight zero-bit
insertions. The number of zero-bit insertions is rounded up to the nearest number of octets for pad fill adjustment.
Pad Count Adjustment can be enabled in the TLSP Channel Configuration Register. For details, please see
Section 6.7.2
8.2.5.3
If BLEN = 0 in any transmit buffer descriptor, CX28500 interprets it as a request to end an in-progress message
with the abort sequence. If the previous buffer descriptor (before the BLEN = 0 buffer) contained an End-Of-
Message (EOM) indication, the abort request is simply ignored and CX28500 moves on to the next message
descriptor. If the previous buffer descriptor was not EOM (i.e., a transmit message was in-progress), an abort code
sequence is transmitted to end that partially sent message. Transmission of an abort code sequence is defined as
16 consecutive 1s.
8.2.6
Transmit events are informational in nature and do not require channel recovery actions.
8.2.6.1
Reason:
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Effects:
•
•
8.2.6.2
Reason:
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Effects:
•
28500-DSH-002-C
TDMA reached the end of a shared memory buffer by servicing the number of bytes equal to BLEN in the
Transmit Buffer Descriptor. Note that transmit EOB and transmit EOM events are not coincident in time, so they
result in two separate events being generated.
TxEOB interrupt (if EOBIEN = 1 in Transmit Buffer Descriptor).
CX28500 continues with normal message processing. If the TDMA does not get more data from shared
memory before the TSLP needs to output the next data bit (assuming the message did not end), the TSLP
enters underflow state, described below.
TSLP has transmitted (actually, transferred to the TSIU) the last bit of a data buffer (excluding the FCS and
closing flag) and the Transmit Buffer Descriptor signifies that buffer contained an end of a message (EOM = 1).
TxEOM interrupt (if EOMIEN = 1 in
NOTE:
Ending a Message with an Abort or Sending an Abort Sequence
Transmit Events
End Of Buffer [EOB]
End Of Message [EOM]
EOB and EOM are not coincident, resulting in separate events.
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Section
6.7.2).
®
Basic Operations
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