adsp-21371 Analog Devices, Inc., adsp-21371 Datasheet - Page 18

• Manufacturer Part Number: adsp-21371
• Description: Sharc Processor
• Manufacturer: Analog Devices, Inc.

ADSP-21371
Note the definitions of various clock periods shown in
which are a function of CLKIN and the appropriate ratio con-
trol shown in
Table 11. ADSP-21371 CLKOUT and CCLK Clock
Generation Operation
Table 12. Clock Periods
1
Use the exact timing information given. Do not attempt to
derive parameters from the addition or subtraction of others.
While addition or subtraction would yield meaningful results
for an individual device, the values given in this data sheet
reflect statistical variations and worst cases. Consequently, it is
not meaningful to add parameters to derive longer times. See
Figure 36 on Page 44
ence levels.
Switching Characteristics specify how the processor changes its
signals. Circuitry external to the processor must be designed for
compatibility with these signal characteristics. Switching char-
acteristics describe what the processor will do in a given
circumstance. Use switching characteristics to ensure that any
timing requirement of a device connected to the processor (such
as memory) is satisfied.
Timing Requirements apply to signals that are controlled by cir-
cuitry external to the processor, such as the data input for a read
operation. Timing requirements guarantee that the processor
operates correctly with other devices.
Timing
Requirements
CLKIN
CCLK
Timing
Requirements
t
t
t
t
t
t
where:
SR = serial port-to-core clock ratio (wide range, determined by SPORT CLKDIV
CK
CCLK
PCLK
SCLK
SDCLK
SPICLK
bits in DIVx register)
SPIR = SPI-to-Core Clock Ratio (wide range, determined by SPIBAUD register
setting)
SDR=SDRAM-to-Core Clock Ratio (Values determined by bits 20-18 of the
PMCTL register)
Table
11.
under Test Conditions for voltage refer-
Description
Input Clock
Core Clock
Description
CLKIN Clock Period
(Processor) Core Clock Period
(Peripheral) Clock Period = 2 × t
Serial Port Clock Period = (t
SDRAM Clock Period = (t
SPI Clock Period = (t
1
Calculation
1/t
1/t
CK
CCLK
PCLLK
CCLK
) × SPIR
PCLK
) × SDR
Rev. 0 | Page 18 of 48 | June 2007
) × SR
CCLK
Table 12