![Xilinx LogiCORE IP Spartan-6 Скачать руководство пользователя страница 26](http://html1.mh-extra.com/html/xilinx/logicore-ip-spartan-6/logicore-ip-spartan-6_getting-started-manual_3396197026.webp)
26
Spartan-6 FPGA GTP Transceiver Wizard v1.8
UG546 (v1.8) December 14, 2010
Chapter 3:
Running the Wizard
details the TXUSRCLK and RXUSRCLK source signal options.
shows the available PPM Offset settings. The PPM Offset setting optimizes the
receiver CDR logic for the desired PPM tolerance range.
shows the optional ports available for synchronization and clocking.
Table 3-7:
TXUSRCLK and RXUSRCLK Source
Option
Description
TX
TXOUTCLK
TXUSRCLK is driven by TXOUTCLK. This option is not available if the TX Phase Alignment
Circuit is used.
REFCLKOUT
TXUSRCLK is driven by REFCLKOUT. This option is required if the TX Phase Alignment
Circuit is used.
Enable External
TXUSRCLK
Brings the TXUSRCLK input signal out to a port at the top-level of the wrapper so it can be
provided by the application. Optionally available when single-byte data path width is used
and TX Buffer Bypass is disabled. Not available for two-byte data path width. Mandatory with
4-byte data path width.
RX
TXOUTCLK
RXUSRCLK is driven by TXOUTCLK. This option is not available if the RX Phase Alignment
Circuit is used.
RXRECCLK
RXUSRCLK is driven by RXRECCLK
.
This option is required if the RX Phase Alignment
Circuit is used.
REFCLKOUT
RXUSRCLK is driven by REFCLKOUT. This option is not available if the RX Phase Alignment
Circuit is used.
Enable External
RXUSRCLK
Brings the RXUSRCLK input signal out to a port at the top-level of the wrapper so it can be
provided by the application. Optionally available when single-byte data path width is used
without channel bonding. Not available for two-byte data path width. Mandatory with 4-byte
data path width.
Table 3-8:
PPM Offset
Option
Description
0 (Synchronous)
Use with synchronous applications (zero tolerance).
Up to ± 100
For applications where clock tolerance is below 100 PPM.
Up to ± 500
For applications where clock tolerance is below 500 PPM.
Table 3-9:
Optional Ports
Option
Description
RXRESET
Active-High reset signal for the receiver PCS logic.
RXRECCLK
Recovered clock signal from the CDR logic. This option is required when selected as an input
to RXUSRCLK.
RXBUFSTATUS
Indicates the condition of the RX elastic buffer. This option is not available when the RX Phase
Alignment circuit is used.
RXBUFRESET
Active-High reset signal for the RX elastic buffer logic. This option is not available when the
RX Phase Alignment circuit is used.