A base protocol for application-specific trace functions

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Overview

The MIPI System Trace Protocol (MIPI STPSM) was developed as a generic base protocol that can be shared by multiple, application-specific trace protocols. It was not intended to supplant or replace the highly optimized protocols used to convey data about processor program flow, timing or low-level bus transactions, but rather, STP is designed so that its data streams coexist with these optimized protocols as part of a complete debug system.

The STP protocol is now in its second generation (v2.2), and is backward compatible with the first generation.

MIPI STP includes the following features:

  • A trace stream composed of 4-bit frames
  • Support for merging trace data from up to 65,536 independent data sources (masters)
  • Up to 65,536 independent data channels per master
  • Basic trace data messages that can convey 4-, 8-, 16-, 32-, or 64-bit wide data
  • Time-stamped data packets using one of several timestamp formats including:
    • Gray code
    • Natural binary
    • Natural binary delta
    • Export buffer depth (legacy STPv1 timestamp that requires DTC support)
  • Data packet markers to indicate packet usage by higher-level protocols
  • Flag packets for marking points of interest (for higher-level protocols) in the stream
  • Packets for aligning timestamps from different clock domains
  • Packets for indicating to the DTC the position of a trigger event, which is typically used to control actions in the DTC (e.g., to control trace capture)
  • Packets for cross-synchronization events across multiple STP sources
  • Support for user-defined data packets
  • Facilities for synchronizing the trace stream on bit and message boundaries

MIPI STP is developed by the MIPI Debug Working Group. It is available as v2.2.

Note: This specification is available to only to MIPI Alliance members. For information about MIPI Alliance membership, visit Join MIPI.