Analog Devices ADSP-BF535 Blackfin, Hardware Reference Manual

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ADSP-BF535 Blackfin Processor Hardware Reference 10-3
SPI Compatible Port Controllers
During SPI data transfers, one SPI device acts as the SPI link master ,
where it controls the data flow by generating the SPI serial clock and
asserting the SPI device select signal (
SPISS
). The other SPI device acts as
the slave and accepts new data from the master into its shift register, while
it transmits requested data out of the shift register through its SPI trans-
mit data pin. Multiple ADSP-BF535 processors can take turns being the
master device, as can other microcontrollers or microprocessors. One mas-
ter device can also simultaneously shift data into multiple slaves (known as
broadcast mode ). However, only one slave may drive its output to write
data back to the master at any given time. This must be enforced in broad-
cast mode, where several slaves can be selected to receive data from the
master, but only one slave at a time can be enabled to send data back to
the master.
Figure 10-1. ADSP-BF535 SPI Block Diagram
S P I I N TE R FA C E LO G IC
M OS I M I S O S C K S P IS S
S P I X_ R D B R R E CE I VE
R E GI S T E R
S P I I N T E R N A L
C LO C K
G E N E RA TO R
3 2
P ER IP H E R A L A C C E S S B U S
(P A B )
S P I X _ C TL
S PI X _ S T
S P IX _ T D B R T RA N S M IT
R E GI S T ER
S P I I R Q
O R
D M A
R E Q U E S T
S H I FT R E G IS T ER
M M
S
S