Product Specs

Table Of Contents
16 Debug and trace
Page
75
Real-time debugging will allow interrupts to execute to completion in real time when breakpoints are set
in Thread mode or lower priority interrupts. This enables the developer to set a breakpoint and single-
step through their code without a failure of the real-time event-driven threads running at higher priority. For
example, this enables the device to continue to service the high-priority interrupts of an external controller or
sensor without failure or loss of state synchronization while the developer steps through code in a low-priority
thread.
16.5 Trace
The device supports ETM and ITM trace.
Trace data from the ETM and the ITM is sent to an external debugger via a 4-bit wide parallel trace port
(TPIU), see TRACEDATA[0] through TRACEDATA[3] and TRACECLK in Figure 11: Debug and trace
overview on page 72.
In addition to parallel trace, the TPIU supports serial trace via the Serial Wire Output (SWO) trace protocol.
Parallel and serial trace cannot be used at the same time.
ETM trace is only supported in parallel trace mode while ITM trace is supported in both parallel and serial
trace modes.
For details on how to use the trace capabilities, please read the debug documentation of your IDE.
TPIU's trace pins are multiplexed with GPIOs, and SWO and TRACEDATA[0] use the same GPIO, see Pin
assignments on page 13 for more information.
Trace speed is configured in the TRACECONFIG on page 108 register.
The speed of the trace pins depends on the DRIVE setting of the GPIOs that the trace pins are multiplexed
with, see PIN_CNF[14] on page 142, PIN_CNF[15] on page 143, PIN_CNF[16] on page 144,
PIN_CNF[18] on page 145 and PIN_CNF[20] on page 146. Only S0S1 and H0H1 drives are suitable
for debugging. S0S1 is the default DRIVE at reset. If parallel or serial trace port signals are not fast enough
in the debugging conditions, all GPIOs in use for tracing should be set to high drive (H0H1). The user shall
make sure that these GPIOs' DRIVE is not overwritten by software during the debugging session.
16.5.1 Electrical specification
Trace port
Symbol
Description
Min.
Typ.
Max.
Units
T
cyc
Clock period, as defined by ARM (See ARM Infocenter,
Embedded Trace Macrocell Architecture Specification, Trace
62.5
500
ns
Port Physical Interface, Timing specifications)