CT_STM is a trace module that aids in software debugging. The main features of this module are:
- Implements MIPI STP protocol (rev 2.0) with the following characteristics:
- Highly optimized for software-generated traces
- Automatic timestamping of messages
- Support for 8-, 16-, and 32-bit data types
- Collects the following information:
- Software messages
- Hardware instrumentation trace from hardware agents:
- OCP_WP_NOC
- PMI
- CMI
- SMSET
- L3 NoC statistics collectors
- Supports the following trace export paths:
- ATB export - to CS_TPIU or CT_TBR
- Available in 1-, 2-, or 4-pin mode with single- or dual-edge clock, depending on the trace bandwidth requirements and characteristics of the trace receiver
- Timestamps:
- Can use local relative timestamp if exported to the CS_TPIU/CT_TBR (through ATB)
- Dedicated 128 × 48-bit FIFO buffer
- Mechanism to generate repeat MASTER and C8 messages periodically even if not needed
A maximum of 255 different bus masters can be connected to the STM trace port through a bus arbiter. STP recognizes two distinct modes of tracing (software and hardware types), which use slightly different message combinations to output different types of data. The bus masters can be configured for either type to optimize the system for the different types of trace data.