LVDS Tunneling Protocol and Interface (LTPI) IP User Guide: Agilex™ 3 and Agilex™ 5 FPGAs and SoCs

ID 844310
Date 8/15/2025
Public
Document Table of Contents

1.4.6.3. Operational Mode

Operational mode is the primary state for most of the LTPI link, during which the SCM and HPM continuously exchange I/O frames in both directions.
Figure 12. LTPI Operational State with I/O Frames Stream

When a data channel frame is generated, it interleaves the I/O frame traffic as shown in the following figure.

Figure 13. LTPI Operational State with Data Frames Interleaving I/O Frames Stream
The operational state remains infinite between SCM and HPM until the following conditions occur:
Table 31.  Condition and Switch State
No. Condition Switch State
1 Soft reset active high Switch to advertise state
2

Hard reset active high

(CPLD/FPGA reset or power lost)

Switch to link detect state
3 Signal lost after 7 consecutive frames are lost in the operational state. Switch to link detect state

The following figure illustrates an end-to-end flow from the link reset to the link operational example.

Figure 14. Link Training and Configuration Flow