Table 2.1 shows the valid trace packets that the STM generates.
| Name | Type | Description |
|---|---|---|
| ASYNC | Alignment | Provides alignment synchronization for the trace stream. This packet is always followed by a VERSION packet. |
| C8, C16 | Channel | Channel indicator. This packet is sent only when the software channel is changed. If any of the upper 8 bits of the channel number change, C16 is sent. C8 is sent if the channel change is limited to any of the lower 8 bits. The default channel is 0, set when VERSION is generated. |
| D4, D8, D16, D32 | Data | Data only. |
| D4M, D8M, D16M, D32M | Data | Data with marker. |
| D4TS, D8TS, D16TS, D32TS | Data | Data with timestamp. |
| D4MTS, D8MTS, D16MTS, D32MTS | Data | Data with marker and timestamp. |
| M8 | Master | Master indicator. This packet is sent only when the source master for the trace is changed. The default master is 0, set when VERSION is generated. |
| MERR | Error | Master Error. Generated when written stimulus is dropped because of a full buffer. |
| GERR | Error | Global Error. Generated when written stimulus from multiple masters is dropped because of a full buffer and MERR cannot be sent for each master. |
| FLAG | Marker | Flag, can be used to indicate message boundaries. |
| FLAG_TS | Marker | Flag with timestamp. |
| NULL | Filler | Filler packet. The STM can insert this to byte align the trace stream for ATB output. |
| TRIG | Trigger | Trigger. |
| TRIG_TS | Trigger | Trigger with timestamp. |
| VERSION | Version | Indicates protocol version. Always sent immediately after ASYNC. Also resets the active master and channel values to 0. The STM generates the following VERSION values only: 3 = STPv2 with natural binary STPv2 timestamps 4 = STPv2 with Gray coded STPv2 timestamps. |
| FREQ | Frequency | Indicates the frequency of the global system counter supplying timestamp information, in Hertz. This packet is always sent immediately after an ASYNC-VERSION sequence. |
Note
There are a number of STPv2 trace packets that the STM does not generate. See Constraints and limitations of use for details of these trace packets.