10-8
ADSP-2126x SHARC Processor Hardware Reference
is on a single node, and every
SPICLK
pin should be connected. SPI trans-
mission and reception are always enabled simultaneously, unless the
Broadcast mode has been selected. In Broadcast mode, several slaves can
be configured to receive, but only one of the slaves can be in Transmit
mode, driving the
MISO
line. If the transmit or receive is not needed,
MISO
can be ignored. This section describes the clock signals, SPI operation as a
master and as a slave, and error generation.
SPI Enable
When the SPI is disabled (
SPIEN
= 0), the flag pins used as slave device
selects (
FLG0
–
FLG3
) are controlled by the general-purpose flag I/O module,
and no data transfers will occur. For slaves, the slave-select input acts like
a reset for the internal SPI logic.
When the
SPIPDN
bit (bit 30 in the
PMCTL
register) is set (= 1 which
shuts down the clock to the SPI), the
FLGx
pins cannot be used (via
the
FLGS7–0
register bits) because the
FLGx
pins are synchronized
with the clock.
For this reason, the
SPIDS
line must be error free. The
SPIEN
signal can
also be used as a software reset of the internal SPI logic. An exception to
this is the W1C-type (write 1-to-clear) bits in the
SPISTAT
Status register
will remain set if they are already set. For a list of write 1 to-clear-bits.
Always clear the W1C-type bits before re-enabling the SPI, as these
bits will not get cleared even if SPI is disabled. This can be done by
writing 0xFF to the
SPISTAT
register. In the case of an
MME
error,
enable the SPI port after
SPIDS
is deasserted.
Open Drain Mode (OPD)
In a multimaster or multislave SPI system, the data output pins (
MOSI
and
MISO
) can be configured to behave as open drain drivers to prevent
contention and possible damage to pin drivers. An external pull-up
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 ...