cx28560 Mindspeed Technologies, cx28560 Datasheet - Page 155

• Manufacturer Part Number: cx28560
• Description: Hdlc Controller
• Manufacturer: Mindspeed Technologies

CX28560 Data Sheet
6.2.1.1
6.2.1.2
28560-DSH-001-B
Transmit Channel Activation
The following describes what the CX28560 does when a transmit channel is
activated:
Receive Channel Activation
The following describes what the CX28560 does when a receive channel is activated:
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The internal channel FIFO is flushed in preparation for new messages.
All counters connected to the channel being activated are zeroed in preparation
for a new channel connection.
Abort codes (all 1s) are transmitted until new data arrives for transmission.
Once fragments start arriving for the newly activated channel, the CX28560
assumes that these fragments are the start of a new packet. The internal buffer
threshold is used to ensure that enough data to start transmitting without
causing an underrun. Once the threshold has been crossed, transmission of
messages can begin.
If the channel is configured in HDLC mode, the CX28560 transmits the
message as HDLC frames, otherwise, the data is transmitted as if starting from
a first time slot in the Serial Port frame.
Once a complete message has been transmitted, if the EOM interrupt is
enabled, an EOM interrupt is generated, and the CX28560 transmits inter-
message idle codes according to the fragment header received.
Go to 3.
The internal channel FIFO is flushed in preparation for new messages.
All counters connected to the channel being activated are zeroed in preparation
for a new channel connection.
In the case of a channel configured for HDLC processing, data is discarded
until an opening flag sequence is detected. In the case of a transparent channel,
data is discarded until the first time slot of a frame.
For an HDLC channel, the data is processed according to the HDLC standard,
or for transparent channels, the data is simply collected.
Once either enough data for a fragment has been collated in the channel’s FIFO
or an end of message is detected, a fragment header is attached to the fragment
data, and the complete fragment is passed to the host over the POS-PHY
interface.
Once a complete message has been received, if the EOM interrupt is enabled,
an EOM interrupt is generated, and the CX28560 scans the idle codes received
between messages.
If the idle code has been swapped since the previous message, and the CHIC/
CHABT interrupt is enabled, a CHIC/CHABT interrupt is generated. CHIC is
generated when the change was to HDLC flags, CHABT is generated when the
change was to an all 1s intermessage fill.
Go to 3.
Mindspeed Technologies™
Advance Information
Functional Description
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