ADSP-2126x SHARC Processor Hardware Reference
10-11
Serial Peripheral Interface Port
If the transmit buffer remains empty, or the receive buffer remains full,
the devices operate according to the states of the
SENDZ
and
GM
bits in the
SPICTL
register.
• If
SENDZ
= 1 and the transmit buffer is empty, the device repeatedly
transmits zero’s on the
MISO
pin.
• If
SENDZ
= 0 and the transmit buffer is empty, it repeatedly trans-
mits the last word it transmitted before the transmit buffer became
empty.
• If
GM
= 1 and the receive buffer is full, the device continues to
receive new data from the
MOSI
pin, overwriting the older data in
the
RXSPI
buffer.
• If
GM
= 0 and the receive buffer is full, the incoming data is dis-
carded, and the
RXSPI
register is not updated.
Multimaster Conditions
A Multimaster mode is implemented to allow an SPI system to transition
mastership from one SPI device to another. In a multidevice SPI configu-
ration, several SPI ports are connected and any one of them can become a
master at a given time, but only one master is allowed at any one time.
If a processor is a slave and wishes to become the SPI master, it asserts the
SPIDS
pin for the processor that is currently master and then drives the
SPICLK
signal. Once it receives the
SPIDS
signal, the device that was master
is immediately reconfigured as a slave. In order to safely transition from
one master to the other the SPI port features the use of open drain outputs
for the data pad drivers in order to avoid data contention.
More information on this topic is described in
.
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 ...