![Texas Instruments TMS320TCI6482 Скачать руководство пользователя страница 36](http://html.mh-extra.com/html/texas-instruments/tms320tci6482/tms320tci6482_design-manual_1094767036.webp)
www.ti.com
9.12.2
System Implementation of Utopia
9.12.3
TCI6482 Utopia vs TCI100 Utopia
9.13 VLYNQ
9.13.1
Configuration of VLYNQ
9.13.2
System Implementation
Peripheral Section
The Utopia interface can support multiple devices on the same bus using multi-PHY mode.
The 50MHz operation should not be an issue in a point-to-point connection. However, if multiple devices
are loaded on the bus, operation at 50MHz may not be possible. It is recommended to run IBIS
simulations to check the signal integrity and maximum operating frequency for a particular board topology.
The same Utopia module is in the TCI6482 as the TCI100. There should be no differences in the
implementations other than the method for configuring the peripheral.
Documentation for VLYNQ:
•
TCI6482 IBIS Model File
•
Using IBIS Modes for Timing Analysis (
SPRA839
)
The VLYNQ interface is multiplexed with both McBSP ports and some GPIO pins. It is selected on
power-up using the boot strap options. If it is selected, software must enable the interface after a reset.
The VLYNQ module logic operates off an internal clock of CPU core clock / 6. For the interface clock,
VLYNQ can be configured to use the VCLK pin as an input (external clock mode) or it can use internal
clock mode and the VCLK pin becomes an output. The internal clock mode operates from SYSCLK4
which is CPU core clock / 8 by default. This clock is programmable via PLL1. SYSCLK4 is used by both
VLYNQ and EMIFA so changing the divider will affect both of these interfaces. The maximum VLYNQ
operating frequency (both for internal and external clock modes) is 125MHz.
If the VLYNQ peripheral is not used or some of the signals are not used, the unused VLYNQ pins can be
left unconnected. Internal pull-ups/pull-downs will pull the pins to a static level.
VLYNQ is used in point-to-point connections only but it can be setup as a daisy chain between multiple
devices. For the TXD signals series resistance should be used to reduce over/under-shoot. Generally
acceptable values are 10, 22 or 33 ohms. All TXD terminals of a VLYNQ™ device connected to RXD
terminals of another VLYN device must have equal length point-to-point signal traces without stubs.
If VCLK is used as an output a series termination is required since this is also used as the VCLK input.
The series termination should be between 22 and 50 ohms. To determine the optimum series resistance
values simulations using the IBIS models should be performed to check signal integrity and AC timings.
For the VCLK routing, the circuit board should be designed using point-to-point connections without stubs
and enough bandwidth to support the maximum clock rate. If the VLYNQ clock rate is reduced by
changing the value of the “clkdiv” bits in the VLYNQ Control Register, the circuit board must be designed
to support half the maximum clock rate. This is necessary because the VLYNQ clock is only high for one
cycle of the pre-divided VLYNQ clock for all clkdiv values except zero.
Figure 14
below shows an example
where the pre-divided VLYNQ clock rate is 125 MHz and the “clkdiv” bits are set to 100 binary. In this
example the VLYNQ clock rate is 25 MHz (high for 8 ns and low for 32 ns). However, the 8 ns high pulse
width requires the circuit board to be designed for 62.5 MHz.
36
TMS320TCI6482 Design Guide and Migration from TMS320TCI100
SPRAAC7B – April 2006
Submit Documentation Feedback