Visible to Intel only — GUID: cug1600843335768
Ixiasoft
Visible to Intel only — GUID: cug1600843335768
Ixiasoft
5.6. Custom Cadence
- When the reference clock for TX PMA and the reference clock for system PLL are different. Although, system PLL frequency is configured to be same as PMA parallel frequency, there might be PPM differences between TX PMA parallel clock frequency and system PLL frequency.
- When the system PLL frequency is more than the PMA parallel clock frequency. This non-standard system PLL frequency may require when several interfaces share the same system clock ( some interfaces need to run at over-clocked system PLL frequency greater than PMA parallel clock frequency). This scenario may occur due to a limited number of system PLLs or when dynamic reconfiguration is enabled.
If your interface requires custom cadence, you must enable custom cadence. To enable custom cadence, select System PLL frequency IP parameter to Custom and input your required custom system PLL frequency.
When System PLL frequency IP parameter is set to Custom, the IP internally includes a custom cadence controller.
If you require an external custom cadence controller instead, you must enable it by selecting External Custom Cadence Controller IP parameter. When selected, this option enables the external custom cadence controller and i_custom_cadence input port becomes available in the IP port list. You must drive the i_custom_cadence input port producing a steady data valid cadence.
In multiple IP instance designs, you may use the external custom cadence controller option to share the logic with multiple IPs and reduce the resource utilization.
Configuration | System PLL frequency (in MHz) | Use Case | Custom Cadence Controller Selection |
---|---|---|---|
NRZ modes
|
830.078125 |
|
The IP enables internal custom cadence controller logic when 830.078125 MHz is selected instead of typical 805.6640625 MHz. |
PCS OTN FlexE |
805.6640625 or 830.078125 |
|
The IP enables internal custom cadence controller logic when 830.078125 or 805.6640625 MHz. |
Any variant with client interface:
|
Custom PLL |
|
The IP enables internal custom cadence controller when the external custom cadence controller is disabled. When the external custom cadence controller is enabled, you must drive the i_custom_cadence port. |
Client Interface | System PLL Frequency (in MHz) | PMA/System PLL Reference Clock Source | Custom Cadence Required | Custom Cadence Controller | Client Interface Frequency | FIFO Requirement |
---|---|---|---|---|---|---|
MAC Avalon® ST | 805.6640625 | Same | No | — | Same as system PLL frequency/2 (402.83203125 MHz) |
No |
MAC Avalon® ST | 805.6640625 | Same | No | — | Different as system PLL frequency/2 (For example, 390.625 MHz) |
Enable asynchronous adapter clocks parameter is On |
MAC Avalon® ST | Custom (For example, 805.6640625) |
Different (PPM) | Yes | Internal or External | Same as system PLL frequency/2 (For example, 402.83203125 MHz) |
No |
MAC Avalon® ST | Custom (For example, 805.6640625) |
Different (PPM) | Yes | Internal or External | Different as system PLL frequency/2 (For example, 390.625 MHz) |
Enable asynchronous adapter clocks parameter is On 16 |
MAC Avalon® ST | 830.078125 | Same | Yes | Internal | Same as system PLL frequency/2 (415.078125 MHz) |
No |
MAC Avalon® ST | 830.078125 | Same | Yes | Internal | Different as system PLL frequency/2 (For example, 390.625 MHz/402.83203125 MHz) |
Enable asynchronous adapter clocks parameter is On |
MAC Avalon® ST | Custom (For example, 830.078125 or 900) |
Same or Different (PPM) | Yes | Internal or External | Same as system PLL frequency/2 (For example, 415.078125 MHz/450 MHz) |
No |
MAC Avalon® ST | Custom (For example, 830.078125 or 900) |
Same or Different (PPM) | Yes | Internal or External | Different as system PLL frequency/2 (For example, 390.625 MHz/402.83203125 MHz) |
Enable asynchronous adapter clocks parameter is On16 |
MAC segmented | 805.6640625 | Same | No | — | Same as system PLL frequency/2 (402.83203125 MHz) |
No |
MAC segmented | 805.6640625 | Same | No | — | Different as system PLL frequency/2 (For example, 390.625 MHz) |
Client Custom FIFO instantiated outside of the Ethernet IP |
MAC segmented | Custom (For example, 805.6640625) |
Different (PPM) | Yes | Internal or External | Same as system PLL frequency/2 (For example, 402.83203125 MHz) |
No |
MAC segmented | Custom (For example, 805.6640625) |
Different (PPM) | Yes | Internal or External | Different as system PLL frequency/2 (For example, 390.625 MHz) |
Client Custom FIFO instantiated outside of the Ethernet IP |
MAC segmented | 830.078125 | Same | Yes | Internal | Same as system PLL frequency/2 (415.078125 MHz) |
No |
MAC segmented | 830.078125 | Same | Yes | Internal | Different as system PLL frequency/2 (For example, 390.625 MHz/402.83203125 MHz) |
Client Custom FIFO instantiated outside of the Ethernet IP |
MAC segmented | Custom (For example, 830.078125 or 900) |
Same or Different (PPM) | Yes | Internal or External | Same as system PLL frequency/2 (For example, 415.078125 MHz/450 MHz) |
No |
MAC segmented | Custom (For example, 830.078125 or 900) |
Same or Different (PPM) | Yes | Internal or External | Different as system PLL frequency/2 (For example, 390.625 MHz/402.83203125 MHz) |
Client Custom FIFO instantiated outside of the Ethernet IP |