SNLA415 August   2022 DS160PT801

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2History
  5. 3Components of PCIe Communication
    1. 3.1 Root Complex
    2. 3.2 Repeater
    3. 3.3 Endpoints
  6. 4Signaling
    1. 4.1 PERST
    2. 4.2 WAKE and CLKREQ
    3. 4.3 REFCLK
  7. 5Link Training
    1. 5.1 Receiver Detect (Rx Detect)
    2. 5.2 Polling
    3. 5.3 Configuration
  8. 6Link Equalization
    1. 6.1 Phase 0 and 1
    2. 6.2 Phase 2 and 3
  9. 7Summary
  10. 8References

4.2 WAKE and CLKREQ

WAKE and CLKREQ signals are both used for transitioning to and from low power states. WAKE signal is an active-low signal that is used to return the PCIe interafce to an active state when in a low-power state. CLKREQ signal is also an active-low signal and is used to request the reference clock. In Figure 4-1, these are referred as "WAKE#" and "CLKREQ#", respectively.