6.2 10GBASEKR Demo using Two PolarFire Evaluation Boards

The following figure shows the setup of two PolarFire Evaluation boards with short reach.
Figure 6-3. Short Reach Connection between Two PolarFire Evaluation Boards
The boards which are used in backplane setup are shown in following figure.
Figure 6-4. Backplane
Figure 6-5. Daughter Board
By using a backplane setup with varying channel lengths, the induced loss can be adjusted. The following tables list the loss associated with the channel length.
Important: The daughter cards connected at both ends of the backplane has loss of 5 dB each. Hence, the total loss induced by the daughter cards is 10 dB.
Table 6-1. Recommended Settings for Different Loss
Reach Channel Loss (in dB) CTLE Tx Emphasis RX Insertion Loss
Short 4 5GHz+7.3 dB 1000 mv+ 0 dB 25 dB
Medium 18
Long 24
The setup with two PolarFire boards, connected with a 16-inch backplane, is shown in the following figure.
Figure 6-6. Two PolarFire Evaluation Boards with Backplane
To setup the two PolarFire boards with backplane, perform the following steps:
  1. Connect two PolarFire Evaluation boards using SMA cables for short reach as listed. The following connections must be followed while using the backplane.
    • Connect J41 (TXP) of PolarFire Evaluation board 1 to F6 connector of daughter card 1 of Backplane. At the other end, the F6 connector from daughter card 2 of backplane must be connected to J37(RXP) of PolarFire Evaluation board 2.
    • Connect J42 (TXN) of PolarFire Evaluation board 1 to E6 connector of daughter card 1 of Backplane. At the other end, the E6 connector from daughter card 2 of backplane must be connected to J38(RXN) of PolarFire Evaluation board 2.
    • Connect J37 (RXP) of PolarFire Evaluation board 1 to O6 connector of daughter card 1 of Backplane. At the other end, the O6 connector from daughter card 2 of backplane must be connected to J41(TXP) of PolarFire Evaluation board 2.
    • Connect J38 (RXN) of PolarFire Evaluation board 1 to N6 connector of daughter card 1 of Backplane. At the other end, the N6 connector from daughter card 2 of backplane must be connected to J42(TXN) of PolarFire Evaluation board 2.
  2. Ensure that the preceding listed connections are made while using the backplane
  3. Connect the 12V DC power supply and USB serial connector to PolarFire Evaluation boards
  4. Open the associated serial terminals of two PolarFire boards to control and monitor the status
  5. Program the PolarFire boards with the job file

Link Status

Once the Auto-Negotiation and Link Training is done, the link is established. The status of the link is observed using LED11 (H21), glowing of this LED indicates the Link Training completion and prints are seen in the UART terminal connected to PolarFire Evaluation Kit.

The following command shows the terminal status in PolarFire Evaluation board 1.

*** Core10GBaseKR PHY ***

Starting Auto-Negotiation!!
LT Link Established!!
Link: Good!!
Packet testing:
     Total packets (msb):  0
     Total packets (lsb):  42744986
     Good packets (msb):   0
     Good packets (lsb):   42744775
     Bad packets (msb):    0
     Bad packets (lsb):    0

The following command shows the terminal status in PolarFire Evaluation board 2.

*** Core10GBaseKR PHY ***

Starting Auto-Negotiation!!
LT Link Established!!
Link: Good!!
Packet testing:
     Total packets (msb):  0
     Total packets (lsb):  42745001
     Good packets (msb):   0
     Good packets (lsb):   42745578
     Bad packets (msb):    0
     Bad packets (lsb):    0

Break Link Test

The test is performed by turning off one of the PolarFire Evaluation Kits. In this case, PolarFire Evaluation Kit 1 is off. It was observed that the link is broken in PolarFire Evaluation Kit 2, which is on. After turning on the power of the PolarFire Evaluation Kit 1, the link re-establishes. This is observed in the UART terminal of PolarFire Evaluation Kit 2, as shown in the command.

Link: Broken!!
Starting Auto-Negotiation!!
LT Link Established!!
Link: Good!!
Packet Testing:
     Total packets (msb):  0
     Total packets (lsb):  167147494
     Good packets (msb):   0
     Good packets (lsb):   122898839
     Bad packets (msb):    0

Traffic Test with Two PolarFire Evaluation Kits

To perform the traffic test with two PolarFire Evaluation Kits, perform the following steps:
  1. Traffic is sent continuously between two PolarFire Evaluation Kits. The data statistics of PolarFire Evaluation Kit 1 and PolarFire Evaluation Kit 2 are shown in the following command terminals.
  2. From the following command terminals, we can observe that the Transmitted packet count matches with Received packet count in PolarFire Evaluation Kit 1 and vice-versa.
  3. No errors are observed in the received packets (No bad packets).
  4. Eye diagram is captured in two kits using the Smart Debug tool to observe eye opening which is shown in the following eye diagram figures.
Important: To stop the packet transmission, open Smart Debug tool, go to pckt_generator module, and assert the stop bit.

The following command shows the PolarFire Evaluation Kit 1 board data statistics.

Link: Good!!
Packet testing:
     Total packets (msb):  0
     Total packets (lsb):  1117149554
     Good packets (msb):   0
     Good packets (lsb):   1065094727
     Bad packets (msb):    0
     Bad packets (lsb):    0
Important: In the preceding data statistics generated by the PolarFire Evaluation board, the text in:
Orange
Represents the Transmitted Packet count
Blue
Represents the Received Packet count

The following command shows the PolarFire Evaluation Kit 2 board data statistics.

Link: Good!!
Packet testing:
     Total packets (msb):  0
     Total packets (lsb):  1065094727
     Good packets (msb):   0
     Good packets (lsb):   1117149554
     Bad packets (msb):    0
     Bad packets (lsb):    0
Important: In the preceding data statistics generated by the PolarFire Evaluation board, the text in:
Orange
Represents the Transmitted Packet count
Blue
Represents the Received Packet count

Transmitted packet count of PolarFire 1 board matches with Received packet count of PolarFire 2 board and vice-versa. With these statistics, it is confirmed that there is no packet loss during transmission with two PolarFire Evaluation boards connected to each other. The same behavior is observed with 6.5 dB, 17 dB, and 25 dB loss. These loss values are calculated based on channel lengths.

The following eye diagrams depict the packet transmission with different channel losses.
Figure 6-7. Eye Diagram with 6.5 dB Loss
Figure 6-8. Eye Diagram with 17 dB Loss
Figure 6-9. Eye Diagram with 25 dB Loss