Tpui Formatter; Tpui Frame Synchronization Packets; Transmission Of The Synchronization Frame Packet - ST STM32F446 Series Reference Manual

RM0390
33.17.3

TPUI formatter

The formatter protocol outputs data in 16-byte frames:
•
seven bytes of data
•
eight bytes of mixed-use bytes consisting of:
–
–
•
one byte of auxiliary bits where each bit corresponds to one of the eight mixed-use
bytes:
–
–
Note: Refer to the Arm
information
33.17.4

TPUI frame synchronization packets

The TPUI can generate two types of synchronization packets:
•
The Frame Synchronization packet (or Full Word Synchronization packet)
It consists of the word: 0x7F_FF_FF_FF (LSB emitted first). This sequence can not
occur at any other time provided that the ID source code 0x7F has not been used.
It is output periodically between frames.
In continuous mode, the TPA must discard all these frames once a synchronization
frame has been found.
• The Half-Word Synchronization packet
It consists of the half word: 0x7F_FF (LSB emitted first).
It is output periodically between or within frames.
These packets are only generated in continuous mode and enable the TPA to detect
that the TRACE port is in IDLE mode (no TRACE to be captured). When detected by
the TPA, it must be discarded.
33.17.5

Transmission of the synchronization frame packet

There is no Synchronization Counter register implemented in the TPIU of the core.
Consequently, the synchronization trigger can only be generated by the DWT. Refer to the
registers DWT Control Register (bits SYNCTAP[11:10]) and the DWT Current PC Sampler
Cycle Count Register.
The TPUI Frame synchronization packet (0x7F_FF_FF_FF) is emitted:
•
after each TPIU reset release. This reset is synchronously released with the rising
edge of the TRACECLKIN clock. This means that this packet is transmitted when the
1 bit (LSB) to indicate it is a DATA byte ('0) or an ID byte ('1).
7 bits (MSB) that can be data or change of source ID trace.
if the corresponding byte was a data, this bit gives bit0 of the data.
if the corresponding byte was an ID change, this bit indicates when that ID change
takes effect.
®
CoreSight Architecture Specification v1.0 (Arm
RM0390 Rev 4
Debug support (DBG)
®
IHI 0029B) for further
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