Programming Model
18-22
ADSP-BF50x Blackfin Processor Hardware Reference
Slave Ready for a Transfer
When a device is enabled as a slave, the actions shown in
Table 18-2
are
necessary to prepare the device for a new transfer.
Programming Model
The following sections describe the SPI programming model.
Beginning and Ending an SPI Transfer
The start and finish of an SPI transfer depend on whether the device is
configured as a master or a slave, which
CPHA
mode is selected, and which
transfer initiation mode (
TIMOD
) is selected. For a master SPI with
CPHA
= 0, a transfer starts when either
SPI_TDBR
is written to or
SPI_RDBR
is read, depending on
TIMOD
. At the start of the transfer, the enabled slave
select outputs are driven active (low). However, the
SCK
signal remains
inactive for the first half of the first cycle of
SCK
. For a slave with
CPHA
= 0,
the transfer starts as soon as the
SPISS
input goes low.
For
CPHA
= 1, a transfer starts with the first active edge of
SCK
for both
slave and master devices. For a master device, a transfer is considered
Table 18-2. Transfer Preparation
TIMOD
Function
Action, Interrupt
b#00
Transmit and
receive
Interrupt is active when the receive buffer is full.
Read of SPI_RDBR clears interrupt.
b#01
Transmit and
receive
Interrupt is active when the transmit buffer is empty.
Writing to SPI_TDBR clears interrupt.
b#10
Receive with
DMA
Request DMA reads as long as SPI DMA FIFO is not empty.
b#11
Transmit with
DMA
Request DMA writes as long as SPI DMA FIFO is not full.
Summary of Contents for EZ-KIT Lite ADSP-BF506F
Page 50: ...Contents l ADSP BF50x Blackfin Processor Hardware Reference ...
Page 92: ...Development Tools 1 30 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 110: ...Interface Overview 3 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 236: ...Internal Flash Memory Control Registers 6 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 650: ...Programming Examples 15 56 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 804: ...Programming Examples 17 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1194: ...Programming Examples 24 90 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1256: ...ACM Registers A 50 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1264: ...Boundary Scan Architecture B 8 ADSP BF50x Blackfin Processor Hardware Reference ...