Datasheet

42023GS–SAM–03/2014

ATSAM4L8/L4/L2

The FPB unit contains:

• Two literal comparators for matching against literal loads from Code space, and remapping to

a corresponding area in System space.

• Six instruction comparators for matching against instruction fetches from Code space and

remapping to a corresponding area in System space.

• Alternatively, comparators can also be configured to generate a Breakpoint instruction to the

processor core on a match.

8.6.2 DWT (Data Watchpoint and Trace)

The DWT contains four comparators which can be configured to generate the following:

• PC sampling packets at set intervals

• PC or Data watchpoint packets

• Watchpoint event to halt core

The DWT contains counters for the items that follow:

• Clock cycle (CYCCNT)

• Folded instructions

• Load Store Unit (LSU) operations

• Sleep Cycles

• CPI (all instruction cycles except for the first cycle)

• Interrupt overhead

8.6.3 ITM (Instrumentation Trace Macrocell)

The ITM is an application driven trace source that supports printf style debugging to trace Oper-

ating System (OS) and application events, and emits diagnostic system information. The ITM

emits trace information as packets which can be generated by three different sources with sev-

eral priority levels:

• Software trace: This can be done thanks to the printf style debugging. For more information,

refer to Section “How to Configure the ITM:”.

• Hardware trace: The ITM emits packets generated by the DWT.

• Time stamping: Timestamps are emitted relative to packets. The ITM contains a 21-bit

counter to generate the timestamp.

How to Configure the ITM:

The following example describes how to output trace data in asynchronous trace mode.

• Configure the TPIU for asynchronous trace mode (refer to Section “5.4.3. How to Configure

the TPIU”)

• Enable the write accesses into the ITM registers by writing “0xC5ACCE55” into the