SBAA543 July   2022 AFE7900 , AFE7920 , AFE7950

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2JESD204C
    1. 2.1 Basic Review of JESD204C Protocol
    2. 2.2 Finding Optimal RBD for JESD204C
  5. 3JESD204B
    1. 3.1 Basic Review of JESD204B Protocol
    2. 3.2 Finding Optimal RBD for JESD204B
  6. 4Setting RBD in AFE79xx
    1. 4.1 Register Map
    2. 4.2 Setting RBD in Configuration Sequence
    3. 4.3 Finding Optimal RBD using CAPI
      1. 4.3.1 Use Case with 1 JESD Links
      2. 4.3.2 Use Case with 2 JESD Links
      3. 4.3.3 Use Case with 3 JESD Links
      4. 4.3.4 Use Case with 4 JESD Links
  7. 5Fixing Potential Alarms Related to RBD
    1. 5.1 RBD Alarm
    2. 5.2 SoEMB Close to LEMC Edge
    3. 5.3 Start of ILA Close to LMFC Edge
  8. 6References

5.2 SoEMB Close to LEMC Edge

It is possible that when the SoEMB is close to LEMC edge, some of lane0/1/2/3_f_counter_any_lane_ready read a very small value close to 0, and some lanes read values close to maximum value of fcounter (63 when E=1). The buffer index is essentially a circular indexing as the buffer has to absorb both advancements and delays in time. Such a case is shown in Figure 5-1(1).

Initially, the lane0/1/2/3_f_counter_any_lane_ready registers read from the range of (62,63,0,1,2). Specifically, lane0_f_counter_any_lane_ready reads 62 and lane3_f_counter_any_lane_ready reads 2. In such cases, it is recommended to shift the LEMC counter by writing to link0_init_f_counter, so that all fcounter values are close by values.

On rising edge of LEMC, the counter starts from value of link0_init_f_counter. In other words, the LEMC counter is shifted by link0_init_f_counter.

In Figure 5-1, we see that link0_init_f_counter is set to 7. With this, lane0_f_counter_any_lane_ready reads ((62+7)%64) = 5 and lane3_f_counter_any_lane_ready reads 2+7 = 9. RBD is set as 13 which has a margin of 4 from the last arriving lane. Note that the RBD value is also with reference to the shifted LEMC counter.

This can be done in Latte by setting the following parameter:

sysParams.jesdRxInitLmfcCounter = 7
Figure 5-1 JESD204C LEMC Edge Close to SoEMB
1.

Parts of figures were based on JEDEC JESD204C standard, Figure 5 and Figure 50. Copyright JEDEC. Modifications have not been approved by and do not reflect the views of JEDEC.