1 / 16

CDC

CDC. Clock Domain Crossing. Outline. Introduction Basic terminology Types of synchronizers CDC protocols CDC verification Summary. Basic Terminology. Clock Domain. - Single clock domain. - Multiple clocks domain. Basic Terminology. Clock Domain. divCLK. CLK. CLK.

tovah
Télécharger la présentation

CDC

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. CDC Clock Domain Crossing

  2. Outline • Introduction • Basic terminology • Types of synchronizers • CDC protocols • CDC verification • Summary

  3. Basic Terminology • Clock Domain - Single clock domain - Multiple clocks domain

  4. Basic Terminology • Clock Domain divCLK CLK CLK divCLK Single clock domain

  5. Basic Terminology • Clock Domain CLK A CLK B CLK A CLK B Multiple clocks domain

  6. Basic Terminology • Clock Domain Crossing Paths D DA DB CLK A CLK B

  7. CLK A DA CLK B DB Basic Terminology • Metastability D DA DB CLK A CLK B

  8. D CLK A CLK B Basic Terminology • Synchronizers Circuits that conditions CDC signals in order to reduce the probability of metastability DA

  9. Types Of Synchronizers • Basic Synchronizer (Level Signal) • Edge-detecting Synchronizer CLK B XOR • Pulse Synchronizer CLK B

  10. CDC Protocols • Why do we need protocols ? In may applications, simple signals aren’t the only information crossing clock domains. Data, address and control buses also travel together across domains.

  11. CDC Protocols • Handshake TX RX Sync tx_v rx_v tx_d Sync rx_d tx_datat rx_datat

  12. CDC Protocols • FIFO TX RX FIFO r_datat w_datat wr rd

  13. CDC Verification • Do i have synchronizers on all • CDC signals? • Do my CDC protocol prevent corruption • of data across clock domains?

  14. CDC Verification • Assertion Based Verification. • Netlist Analysis. • User Specification of Design Intent. • Verifying CDC Monitors Using Simulation. • Verifying CDC Assertion Using Formal Verification.

  15. Summary • Traditional verification techniques for CDC’s • fail to address the critical issue of the correctness • of the CDC protocols within the design. • If these protocols go unchecked, there is a • significant risk that designs will contain errors • that can only be detected in post-silicon • testing….

  16. THANK YOU FOR LISTENING

More Related