Before initiating a reference clock switch, ensure that your Native PHY instance defines
more than one reference clock source. Specify the Number of reference clocks
inputs per channel parameter.
The number of exposed
refclk
ports varies according to the number of reference
clocks you specify. Use the reconfiguration interface to look up the mux settings for
the different
refclk#
and write the look up value into the channel.
When performing a reference clock switch, you must specify the lookup register
address and respective bits of the replacement clock. After determining the values,
follow this procedure to switch to the selected reference clock:
1. Place the Native PHY IP core in digital reset. Refer to Resetting Transceiver
Channels for more information.
2. Place the PMA in reset by sending attribute code 0x0001.
3. Read from the lookup register address, and save the required 4-bit pattern. For
example, switching the clock mux associated with PMA's
refclk_in_A
to logical
refclk2
requires the use of bits
[3:0]
at address 0xEF.
4. Perform a read-modify-write to bits
[3:0]
at address 0xEC using the 4-bit value
obtained from the lookup register.
5. Follow the steps in PMA Analog Reset. This is required because the internal
controller is clocked by the reference clock, so changing the reference clock can
cause a glitch.
6. Set 0x91 to 0x01 if you want to:
•
Go to the initial PMA configuration (when the embedded reconfiguration
streamer is not used)
•
Go to the last selected profile (when the embedded reconfiguration streamer is
used)
0x91[0] automatically clears once the PMA is loaded with the correct settings.
7. If you want to change the PMA to a new configuration, you must send the
following attributes in the following order:
a. Set the TX data rate to refclk ratio by sending attribute code 0x0005.
b. Set the RX data rate to refclk ratio by sending attribute code 0x0006.
c. Set the PMA's serializer/deserialzer ratios and NRZ/PAM4 by sending attribute
code 0x0014.
d. Set the TX equalization by sending attribute code 0x0015.
e. Request PMA calibration when it is enabled by sending attribute code 0x0011.
f.
Bring the PMA out of reset by sending attribute code 0x0001.
8. Bring the Native PHY IP core out of digital reset.
Note:
0x8A[7] is 1 after either using the embedded reconfiguration stream to change to a
new profile, or using register 0x91[0] to restore the previous profile. You must clear
register 0x8A[7] by writing 0x8A[7] to 1 before sending any attributes to the PMA.
Related Information
Resetting Transceiver Channels
on page 100
7. Dynamic Reconfiguration
UG-20056 | 2019.02.04
Intel
®
Stratix
®
10 E-Tile Transceiver PHY User Guide
130