Sport Loopback - Analog Devices ADSP-21261 SHARC Hardware Reference Manual

SPORT Operation Modes
incoming time slot data, while SPORT0, 2, and 4 compress selected out-
going time slot data.

SPORT Loopback

When the SPORT loopback bit,
, or
SPMCTL23 SPMCTL45
internal loopback connection as follows: SPORT0 and SPORT1 work as a
pair for internal loopback, SPORT2 and SPORT3 work as pairs, and
SPORT4 and SPORT5 work as pairs. The Loopback mode enables pro-
grams to test the serial ports internally and to debug applications.
When loopback is configured the:
•
SPORTx_DA
SPORT0 and SPORT1 are internally connected (where x = 0 or 1)
• The
SPORTy_DA
SPORT2 and SPORT3 are internally connected (where y = 2 or 3)
• The
SPORTz_DA
SPORT4 and SPORT5 are internally connected (where z = 4 or 5)
In Loopback mode, either of the two paired SPORTS can be transmitters
or receivers. One SPORT in the loopback pair must be configured as a
transmitter; the other must be configured as a receiver. For example,
SPORT0 can be a transmitter and SPORT1 can be a receiver for internal
loopback. Or, SPORT0 can be a receiver and SPORT1 can be the trans-
mitter when setting up internal loopback. The processor ignores external
activity on the
the SPORT is configured in Loopback mode. This prevents contention
with the internal loopback data transfer.

Only transmit clock and transmit frame sync options may be used
in loopback mode—programs must ensure that the serial port is set
up correctly in the
not allowed. Only Standard DSP Serial, Left-justified Sample Pair,
9-32
control registers, the serial port is configured in an
, ,
SPORTx_DB SPORTx_CLK
,
SPORTy_DB
,
SPORTz_DB
,
SPORTx_CLK SPORTx_FS
SPCTLx
ADSP-2126x SHARC Processor Hardware Reference
bit 12 is set in the
SPL
and
SPORTx_FS
, , and
SPORTy_CLK
, and
SPORTz_CLK
A and B channel data signals when
control registers. Multichannel mode is
,
SPMCTL01
signals of
signals of
SPORTy_FS
signals of
SPORTz_FS