Frame Sync Options
9-36
ADSP-2126x SHARC Processor Hardware Reference
Active Low Versus Active High Frame Syncs
Frame sync signals may be active high or active low (for example,
inverted). The
LFS
bit of the
SPCTLx
Control register determines the frame
sync’s logic level.
• When
LFS
is cleared (=0), the corresponding frame sync signal is
active high.
• When
LFS
is set (=1), the corresponding frame sync signal is active
low.
Active high frame syncs are the default. The
LFS
bit is initialized to zero
after a processor reset.
Active low or active high frame syncs are selected using the
LTDV
and
LRFS
bits. These bits are located in the
SPCTLx
Control registers.
Sampling Edge for Data and Frame Syncs
Data and frame syncs can be sampled on the rising or falling edges of the
serial port clock signals. The
CKRE
bit of the
SPCTLx
Control registers
selects the sampling edge.
For sampling receive data and frame syncs, setting
CKRE
to 1 in the
SPCTLx
register selects the rising edge of
SPORTx_CLK
. When
CKRE
is cleared (=0),
the processor selects the falling edge of
SPORTx_CLK
for sampling receive
data and frame syncs. Note that transmit data and frame sync signals
change their state on the clock edge that is not selected.
For example, the transmit and receive functions of any two serial ports
connected together should always select the same value for
CKRE
so inter-
nally-generated signals are driven on one edge and received signals are
sampled on the opposite edge.
Содержание ADSP-21261 SHARC
Страница 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Страница 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Страница 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Страница 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Страница 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...