Analog Devices SHARC ADSP-214 Series Hardware Reference Manual page 624

Functional Description
connected to high, as it affects the functioning of certain bits in the
register.
SPICTLx
Functional Description
Each SPI interface contain its own transmit shift (
shift ( ,
RXSR RXSRB
ally transmit data and the
the SPI clock signal (
SHARC processor SPI interface. The data is shifted into or out of the shift
registers on two separate pins: the master in slave out (
master out slave in (
During data transfers, one SPI device acts as the SPI master by controlling
the data flow. It does this by generating the
device select signal (
pin and transmits using the
slave by receiving new data from the master into its receive shift register
using the pin. It transmits requested data out of the transmit shift
MOSI
register using the
Each SPI port contains a dedicated transmit data buffer (
and a receive data buffer (
and then automatically transferred into the transmit shift register.
TXSPIx
Once a full data word has been received in the receive shift register, the
data is automatically transferred into
read. When the processor is in SPI master mode, programmable flag pins
provide slave selection. These pins are connected to the
devices.
The SPI has a single DMA engine which can be configured to support
either an SPI transmit channel or a receive channel, but not both simulta-
neously. Therefore, when configured as a transmit channel, the received
data is essentially ignored. When configured as a receive channel, what is
15-8
www.BDTIC.com/ADI
) registers (not user accessible). The
registers receive data synchronously with
RXSRx
). Figure 15-1
SPICLK
) pin.
MOSI
). The SPI master receives data using the
SPIDS
pin. The other SPI device acts as the SPI
MOSI
pin.
MISO
,
RXSPI RXSPIB
ADSP-214xx SHARC Processor Hardware Reference
,
TXSR TXSRB
TXSRx
shows a block diagram of the
MISO
and asserting the SPI
SPICLK
). Transmitted data is written to
, from which the data can be
RXSPIx
SPIDS
) and receive
registers seri-
) pin and the
MISO
, )
TXSPI TXSPIB
of the slave