5
Serial Ports
5 – 3
• Bidirectional: each SPORT has independent transmit and receive
sections.
• Double-buffered: each SPORT section (both receive and transmit) has a
data register for transferring data words to and from other parts of the
processor and a register for shifting data in or out. The double-
buffering provides additional time to service the SPORT.
• Clocking: each SPORT can use an external serial clock or generate its
own in a wide range of frequencies down to 0 Hz. See Section 5.5.
• Word length: each SPORT supports serial data word lengths from
three to sixteen bits. See Section 5.6.
• Framing: each SPORT section (receive and transmit) can operate with
or without frame synchronization signals for each data word; with
internally-generated or externally-generated frame signals; with active
high or active low frame signals; with either of two pulse widths and
frame signal timing. See Section 5.7.
• Companding in hardware: each SPORT can perform A-law and µ-law
companding according to CCITT recommendation G.711. See
Section 5.10.
• Autobuffering with single-cycle overhead: using the DAGs, each
SPORT can automatically receive and/or transmit an entire circular
buffer of data with an overhead of only one cycle per data word.
Transfers between the SPORT and the circular buffer are automatic in
this mode and do not require additional programming. See
Section 5.11.
• Interrupts: each SPORT section (receive and transmit) generates an
interrupt upon completing a data word transfer, or after transferring
an entire buffer if autobuffering is used. See Section 5.13.
• Multichannel capability: SPORT0 can receive and transmit data
selectively from channels of a serial bitstream that is time-division
multiplexed into 24 or 32 channels. This is especially useful for T1
interfaces or as a network communication scheme for multiple
processors. See Section 5.12. Note: The ADSP-2105 has only one serial
port (SPORT1) and does not support multichannel operation.
• Alternate configuration: SPORT1 can be configured as two external