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9.14 Serial Rapid I/O (SRIO)
9.14.1
Configuration of SRIO
Peripheral Section
Figure 14. VLYNQ Clock Divider Example
If the VLYNQ clock is provided by an external source, the circuit board must be designed so transmission
line reflections do not generate glitches or invalid transitions of the VLYNQ clock. In most applications, the
external clock source should be connected to the CLK terminal of each VLYNQ device with two equal
lengths of etch. This configuration may require series termination resistors near the source of each clock
driver trace to prevent signal distortion. It may be possible to optimize timing on the VLYNQ interface by
allowing one VLYNQ device to receive the VLYNQ clock before the interconnected VLYNQ device. Refer
to
Section 4
for more details related to VLYNQ timing. However, series termination may not be the best
method for terminating some configurations used to interconnect the external clock source to the two
VLYNQ devices.
The width of VLYNQ is adjustable down to 1 bit wide for a 3 signal interface (clock, tx data bit, rx data bit)
and has a max width of 4 bits.
Relevant documentation for SRIO:
•
TMS320TCI648x DSP Serial Rapid I/O User's Guide (SPRUE13)
•
Implementing Serial Rapid IO PCB Layout on a TMS320TCI6482 Hardware Design (
SPRAAB0
)
•
TCI6482 System Boot
•
TCI6482 SRIO/DDR Example Schematics
Since the SRIO port is not multiplexed with other peripherals, there is no boot strapping option to
enable/disable the SRIO port. SRIO, as with all peripherals, defaults disabled and must be enabled by
software before use.
There are 4 SRIO lanes. These can be configured for operation as a single 4x link or as 4 separate 1x
links.
SRIO requires a dedicated differential reference clock: RIOCLK, RIOCLK. Recommended frequencies for
this clock are 125MHz and 156.25MHz. The SERDES (serializer/deserializer) used in the SRIO solution
has a PLL which needs to be configured based on this reference clock and the desired link rate. Link rates
can be full, half or quarter rate relative to the PLL frequency. Refer to
Table 23
for PLL multiplier settings
relative to link rate.
Table 23. SRIO PLL Multiplier Settings
Reference Clock
PLL Multipler
Full Rate
Half Rate
Quarter Rate
125MHz
12.5
3.125Gbps
not used
not used
125MHz
10
2.5Gbps
1.25Gpbs
not used
156.25MHz
10
3.125Gbps
not used
not used
156.25MHz
8
2.5Gpbs
1.25Gbps
not used
SPRAAC7B – April 2006
TMS320TCI6482 Design Guide and Migration from TMS320TCI100
37
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