EFM32WG Datasheet, PDF (27/834 Pages) List of Unclassifed Manufacturers – The EFM32WG Wonder Gecko is the ideal choice for demanding 8-, 16-, and 32-bit energy sensitive applications.

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For more information on how to enable the debug pin outputs/inputs the reader is referred to
Section 32.3.4.1 (p. 754) , the ARM Cortex-M4 Technical Reference Manual and the ARM CoreSight
Technical Reference Manual.
Note
Leaving the debug pins enabled will lead to an increase in current consumption in EM2-
EM4.
6.3.2 Embedded Trace Macrocell v3.5 (ETM)
The ETM makes it possible to trace both instruction and data from the processor in real time. The
trace can be controlled through a set of triggering and filtering resources. The resources include 4
address comparators, 2 data value comparators, 2 counters, a context ID comparator and a sequencer.
Before enabling the ETM, the AUXHFRCO clock needs to be enabled by setting AUXHFRCOEN in
CMU_OSCENCMD. The trace can be exported through a set of trace pins, which include:
• Trace Clock (TCLK): Functions as a sample clock for the trace. This pin is disabled after reset.
• Trace Data 0 - Trace Data 3 (TD0-TD3): The data pins provide the compressed trace stream. These
pins are disabled after reset.
For information on how to configure the ETM, see the ARM Cortex-M4 Technical Reference Manual and
the ARM CoreSight Technical Reference Manual. The Trace Clock and Trace Data pins can be enabled
through the GPIO. For more information on how to enable the ETM Trace pins, the reader is referred
to Section 32.3.4.2 (p. 754) .
6.4 Debug Lock and Device Erase
The debug access to the Cortex-M4 is locked by clearing the Debug Lock Word (DLW), see
Section 7.3.2 (p. 33) .
When debug access is locked, the debug interface remains accessible but the connection to the Cortex-
M4 core is blocked as shown in Figure 6.2 (p. 28). This mechanism is controlled by the Authentication
Access Port (AAP) as illustrated by Figure 6.1 (p. 27) .
Figure 6.1. AAP - Authentication Access Port
ALW[ 3:0] = = 0xF
Se r i a l W i r e
debug
interface
SW-DP
DLW[ 3:0] = = 0xF
Au t h en t icat ion
Access Port
(AAP)
Cort e x
AHB-AP
DEVICEERASE
ERASEBUSY
The device can be erased through the AAP if the AAP Lock Word (ALW) has not been cleared, see
see Section 7.3.2 (p. 33) . This can be useful if the device has been programmed with code that,
e.g., disables the debug interface pins on startup, or does something else that prevents communication
with a debugger.
Obtaining debug access by unlocking the device must take place during the AAP window. The AAP
window can also be extended giving the debugger more time to access the device by issuing the bit
pattern on SWDIO/SWCLK as shown in Figure 6.3 (p. 28). After the AAP window has closed, program
execution will start provided that the device was successfully unlocked.
2013-05-08 - Wonder Gecko Family - d0233_Rev0.50
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