SPORT Control Registers and Data Buffers
9-64
ADSP-2126x SHARC Processor Hardware Reference
can initiate periodic transfers. The counting of serial clock cycles applies
to internally- or externally-generated serial clocks.
The formula for the number of cycles between frame sync pulses is:
# of serial clocks between frame syncs = FSDIV + 1
Use the following equation to determine the value of
FSDIV
, given the
serial clock frequency and desired frame sync frequency:
The frame sync is continuously active when
FSDIV
= 0. The value of
FSDIV
should not be less than the serial word length minus one (the value of the
SLEN
field in the Serial Port Control register), as this may cause an external
device to abort the current operation or cause other unpredictable results.
If the serial port is not being used, the
FSDIV
divisor can be used as a
counter for dividing an external clock or for generating a periodic pulse or
periodic interrupt. The serial port must be enabled for this mode of oper-
ation to work properly.
Exercise caution when operating with externally-generated transmit clocks
near the frequency of one-quarter of the processor’s internal clock. There
is a delay between when the clock arrives at the
SPORTx_CLK
node and
when data is output. This delay may limit the receiver’s speed of opera-
tion. Refer to the data sheet for exact timing specifications.
Externally-generated late transmit frame syncs also experience a delay
from when they arrive to when data is output. This can also limit the max-
imum serial clock speed. Refer to the product-specific data sheet for exact
timing specifications.
SPORT Interrupts
Each serial port has an interrupt associated with it. For each SPORT, both
the A and B channel transmit and receive data buffers share the same
f
SPORTx_CLK
f
SPORTx_FS
– 1
FSDIV =
Summary of Contents for ADSP-21261 SHARC
Page 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Page 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Page 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Page 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Page 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Page 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Page 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Page 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Page 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Page 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Page 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Page 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...