Analog Devices ADSP-BF59x Blackfin, Hardware Reference Manual, Page: 488 / 772

SPI Registers
13-34 ADSP-BF59x Blackfin Processor Hardware Reference
SPI Baud Rate (SPI_BAUD) Register
The
SPI_BAUD
register is used to set the bit transfer rate for a master
device. When configured as a slave, the value written to this register is
ignored. The serial clock frequency is determined by this formula:
SCK
frequency = (peripheral clock frequency
SCLK
)/(2 ×
SPI_BAUD
)
Writing a value of “0” or “1” to the register disables the serial clock.
Therefore, the maximum serial clock rate is one-fourth the system clock
rate.
Table 13-4 lists several possible baud rate values for
SPI_BAUD
.
Table 13-4. SPI Master Baud Rate Example
SPI_BAUD Decimal Value SPI Clock (SCK) Divide
Factor Baud Rate for
SCLK at 100 MHz
0 N/A N/A
1 N/A N/A
2 4 25 MHz
3 6 16.7 MHz
4 8 12.5 MHz
65,535 (0xFFFF) 131,070 763 Hz
Figure 13-12. SPI Baud Rate Register
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Baud Rate[15:0]
SCLK/(2
×
SPI_BAUD)
Reset = 0x0000
S PI Baud Rate Register ( S PI_BAUD)