cx28560 Mindspeed Technologies, cx28560 Datasheet - Page 154

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

Functional Description
6.2
6.2.1
6-8
Channel Operations
Channel Activation
After the previous levels of configuration are completed, individual channels are
ready to be activated. Service requests are used to activate channels. Each channel
consists of a transmit and a receive direction. Each direction is independent of the
other and maintains its own state machines, configuration registers, and internal
resources. To activate both transmit and receive directions of a channel, two separate
service requests are required, one directed to the transmit direction and one to the
receive. The CX28560 responds to each service request with the SACK Interrupt
Descriptor, which notifies the host that the task was initiated. Note that the SACK
interrupt will only be generated if the SACKIEN bit is asserted in the Service Request
Descriptor.
If the channel to be activated requires a new Flexiframe, the new Flexiframe should
first be written into the CX28560 (via the service request mechanism). Once the
system has detected that the new Flexiframe is in place and in use (either by receiving
a NFFRAME interrupt, or detecting that the NFFRAME bit has been set to zero by the
CX28560), a channel that has now been included in the Flexiframe can be activated.
Not writing the new Flexiframe first may cause overflows in the receive direction.
Channel Activation should only be performed on a non-active channel. Attempting to
reactivate a channel by sending an activate command to an already active channel will
produce undefined behavior by the CX28560. A channel has not been successfully
deactivated until the End Of Command (EOC) interrupt is received.
NOTE:
The notification to the host that the channel activation was completed is an
EOC interrupt. This acknowledges the host that the SRQ was completed. The
SACK command signifies that the CX28560 is ready to receive the next
command, but not that the activation was completed.
Mindspeed Technologies™
Advance Information
CX28560 Data Sheet
28560-DSH-001-B