CN8478 Datasheet, PDF (155/221 Pages) Conexant Systems, Inc – Multichannel Synchronous Communications Controller (MUSYCC)

CN8478/CN8474A/CN8472A/CN8471A
Multichannel Synchronous Communications Controller (MUSYCC™)
6.0 Basic Operation
6.3 Channel Operation
pTxMsgDescr[1]->BufferDescr = 0x90000200;
/* msg descr 2 */
pTxMsgDescr[2]->BufferDescr = 0x90000200;
/* msg descr 3 */
/* only difference is EOM bit */
pTxMsgDescr[3]->BufferDescr = 0x92000200;
/* fill data buffer with outbound traffic. each buffer contains 256-bytes of
data */
/* set the head pointer, for example for channel 0, to point to the top of */
/* the just formed message descriptor list */
/* activate transmit channel by issuing a service request */
/* ServiceRequest( ACTIVATE_CHANNEL, Group, Channel, Direction ); */
6.3.16 Channel Activation
6.3.16.1 Transmit
Channel Activation
After the previous levels of configuration are completed, individual channels
within a channel group are ready to be activated. Service requests activate
channels.
Each channel within a channel group consists of a transmitter and receiver
section. Each section is independent of the other and maintains its own state
machine, configuration registers, and internal resources. To activate both
transmitter and receiver sections, two separate service requests are required, one
directed to the transmitter and one to the receiver. MUSYCC responds to each
service request with the SACK Interrupt Descriptor, notifying the host that the
task was completed.
Channel Activation is an asynchronous command from the host interface to a
transmit or receive section of a channel to jump to a new message. Message
Descriptors in shared memory describe the attributes of the new message, what to
do between messages, and the location of message data buffers in memory to use
for transmit data or receive data.
The following describes what MUSYCC does when the transmit channel is
activated:
1. Reads the Tx Head Pointer for the channel from shared memory, and stores
it in the Internal Channel Descriptor map.
2. Reads the Message Descriptor pointed to by Tx Head Pointer, and stores it
in Internal Channel Descriptor map.
3. Checks bit field OWNER and NP in Buffer Descriptor.
If OWNER = 1, MUSYCC is the buffer owner. Load Channel Descriptor
map with data buffer pointer and data buffer length. Go to 4.
If OWNER = 0, MUSYCC is not the buffer owner. Can enter polling mode
until MUSYCC owns buffer or receives another service request to activate
channel or jump to new message. Repeat 3.
100660E
Conexant
6-21