cx28500 Mindspeed Technologies, cx28500 Datasheet - Page 142

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

4. The receive channel remains in the suspended state until the channel is activated. The current channel
7.2.3
A jump request is issued by the Host via a service request (CH_JMP). Notice that the jump service request
acknowledge (via the SACK interrupt descriptor) is output toward the Host immediately. The EOCE Interrupt
acknowledges that the CH_JMP service request was performed, and the next Head Pointer was read. However,
this does not mean that CX28500 starts working on the new message descriptors table pointed by the new Head
Pointer immediately. Channel jump takes effect after an End Of Message (EOM) is fetched from or stored to
memory buffer or while the channel is in suspended state.
7.2.3.1
For a receiver, channel jumps do not affect the current message being transferred to the Host (if there is such a
message). The command is executed only after the current message transfer to the Host is completed. No internal
FIFO flushing happens; the next messages are transferred using the new message descriptors provided by the
Jump command. The channel state is not reset as in the channel activate sequence. For a receiver, channel jumps
provide a non-destructive way of storing incoming data using a new message descriptors table.
7.2.3.2
For a transmitter, channel jumps are non-destructive to currently serviced messages. The channel state is not reset
as in the channel activate sequence. Hence, a transmitter channel must be activated first, then subsequent jump
requests can be made using the channel jump service request. For a transmitter, channel jumps provide a
nondestructive way to start transmitting the new message list. CX28500 waits until the completion of the current
message before jumping to the new message array pointed to by a new Head Pointer.
7.2.4
A channel reactivation happens when an activate command is issued to an active channel. CX28500 behavior is as
if the channel was deactivated and then activated again. This means that the sequence described in
happens followed by the sequence described in
interrupt are generated. SACK is generated to indicate the initiation of the operation, and EOCE is generated to
indicate the completion of channel reactivation.
7.2.5
The Host can stop CX28500 from processing certain time slots regardless of the channel activation/deactivation/
jump/reactivation commands. This can be performed by programming time slots in RSIU Time Slot Configuration
and TSIU Time Slot Configuration to indicate that the specific time slots are not mapped (see RTS_ENABLE and
TTS_ENABLE bit fields in
Configuration
28500-DSH-002-C
direction configuration is maintained.
Descriptor, respectively).
NOTE:
Channel Jump
Receive Channel Jump
Transmit Channel Jump
Channel Reactivation
Unmapped Time Slots
Table 6-26, RSIU Time Slot Configuration Descriptor
The TDAT signal is either set to logic 1 or three-state according to bit TRITx in
6.7.5.
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Section
7.2.1. However, only one SACK interrupt and one EOCE
®
and
Table 6-34, TSIU Time Slot
Functional Description
Section
Section 7.2.2
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