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Ixiasoft
Visible to Intel only — GUID: cuy1600191171857
Ixiasoft
5. Clocks
The F-Tile Reference and System PLL Clocks Intel® FPGA IP generates i_clk_ref and i_clk_sys clocks that drive the F-Tile Ethernet Intel® FPGA Hard IP (IP core).
The IP core supports the i_reconfig_clk frequency range of 100 to 250 MHz. The IP core output clock (o_clk_pll) drives both i_clk_rx and i_clk_tx input signals.
All IP core variations support the Synchronous Ethernet (SyncE) standard.
The table below describes necessary input and output clocks with required clock frequencies, and the clock-related status signals. You can use the clock status ports to hold circuits in reset or until the PLLs driving the clocks are locked.
Name | Description |
---|---|
Clock Inputs | |
i_clk_tx | TX datapath clock This clock drives the active TX interface for the port.
This clock source is:
|
i_clk_rx | RX datapath clock This clock drives the active RX interface for the port.
This clock source is:
|
i_clk_pll | PTP-related datapath clock This clock drives the internal datapath clock for the port when both, Enable IEEE 1588 PTP and Enable asynchronous adapter clocks parameters, are enabled. This clock source is the o_clk_pll output of the PTP tile adapter. You must use a single clock source when using a multiple PTP ports in your design.
Supports the following frequencies:
|
i_reconfig_clk | Avalon® memory-mapped interface reconfiguration clock The interface uses this clock to access control status registers (CSRs). The clock supports 100 to 250 MHz frequency. |
i_clk_ref | PMA reference clock
F-Tile Reference and System PLL Clock Intel® FPGA IP drives this clock.
You must specify this frequency in the F-Tile Ethernet Intel® FPGA Hard IP PMA reference frequency IP parameter and in the F-Tile Reference and System PLL Clock Intel® FPGA IP FGT refclk frequency/FHT refclk frequency IP parameter.
Note: The i_clk_ref is a virtual signal. In simulation, the signal displays as 0.
The clock source depends on the F-Tile Ethernet Intel® FPGA Hard IP PMA selection.
Unless the Custom cadence parameter is enabled, the clock must be PPM matched to the i_clk_sys clock. |
i_clk_sys | Ethernet system clock F-Tile Reference and System PLL Clock Intel® FPGA IP drives this clock.
Unless Custom cadence parameter is enabled, the clock frequency depends on the FEC type:
You must specify this frequency in the F-Tile Ethernet Intel® FPGA Hard IP System PLL frequency IP parameter and in the F-Tile Reference and System PLL Clock Intel® FPGA IP Mode of system PLL IP parameter.
Note: The i_clk_sys is a virtual signal. In simulation, the signal displays as 0.
Connect to the out_systempll_clk_i signal from the F-Tile Reference and System PLL Clocks Intel® FPGA IP. |
Clock Outputs | |
o_clk_pll | System PLL clock Clock derived from the F-Tile System PLL associated with the Ethernet IP port. The o_clk_pll frequency is equal to PLL frequency divided by 2. The following shows the o_clk_pll frequency unless you enabled custom system PLL frequency.
Supports the following frequencies:
|
o_clk_tx_div |
Supports the following frequencies:
Clock recovered from the TX SERDES rate divided by either 33/66/68, depending on the FEC mode and Ethernet mode parameters. The o_clk_tx_div is equal to:
|
o_clk_rec_div64 |
Supports the following frequencies:
Clock derived from RX recovered clock, divided by 64. |
o_clk_rec_div |
Supports the following frequencies:
Clock derived from the RX recovered clock divided by either 33/66/68, depending on the FEC mode parameter. The o_clk_rec_div is equal to:
|
Clock Status | |
o_tx_pll_locked | This clock indicates that the TX SERDES PLLs are locked.
Note: Do not use the o_clk_tx_div output clock until the o_tx_pll_locked signal is high.
|
o_cdr_lock | This clock indicates that the recovered clocks are locked to data.
Note: Do not use the o_clk_rec_div64 output clock until the o_cdr_lock signal is high.
|
- In most Ethernet IP configurations, use the output clock o_clk_pll or an equivalent clock to drive the i_clk_tx and i_clk_rx signals. In asynchronous adapter option, you can use slower clocks to drive these signals.
- PTP channel only system clock divided by 2 at frequency of 402.83 MHz or higher. When PTP is enabled, all ports with PTP enabled share the same system clock.
- Recovered frequencies from a remote link partner are shown with ± 200 ppm range, assuming that local oscillator is ± 100ppm and remote oscillator is (unrelated) ± 100ppm. For SyncE applications, local oscillator must match recovered clock within ± 4.6ppm.
You must configure the modes in the F-Tile Reference and System PLL Clock Intel® FPGA IP. The table below displays the reference clock and output frequency based on a selected System PLL mode.
Mode of System PLL | Reference Clock (MHz) | Output Frequency (MHz) |
---|---|---|
ETHERNET_FREQ_805_156 | 156.25 | 805.6640625 |
ETHERNET_FREQ_805_312 | 312.5 | 805.6640625 |
ETHERNET_FREQ_805_322 | 322.265625 | 805.6640625 |
ETHERNET_FREQ_830_156 | 156.25 | 830.078125 |
ETHERNET_FREQ_830_312 | 312.5 | 830.078125 |