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AVR
®
ATmegaICE User Guide
6-1
Section 6
External Triggers
The AVR ATmegaICE has five external trigger inputs and five trigger outputs, all located
on the AUX connector next to the pod connector.
■
The trigger inputs can act as break signals to the emulator, and/or they can be logged
in the trace buffer. If an input is enabled for breaking the emulator, a rising edge on
that input is required to break the emulator.
■
The trigger outputs may be set as trigger points on any instruction in the code window
in AVR Studio. If enabled on an instruction, the output(s) will remain high for one AVR
clock cycle when the marked instruction is executed. This can be used to trigger a
logic analyzer or an oscilloscope.
The details on how to enable and setup triggers and mask registers are presented in the
AVR Studio User Guide.
There are three global mask registers that are used to control the behavior of the trig-
gers:
■
The
Trigger Output Global Mask Register
controls which of the output pins are
allowed to be controlled by the trigger settings in the code. An output pin which is
disabled will remain low even if a trigger point for that particular pin is set in the code.
■
The
Trigger Input Global Mask Register
controls which of the input pins are allowed to
break the emulator. If more than one line is enabled, the emulator will break on either
one, but will not store any information about which input caused the event. Note that
unconnected inputs are pulled high by internal pull-up resistors. Unused lines must
either be pulled low or disabled in the Trigger Input Global Mask Register. Otherwise,
the emulator may break on the first line (on start up, all lines are disabled, so this only
applies if input triggers are enabled by the user).
■
The
External Trace Mask Register
controls which of the input pins will be stored in the
trace memory. Input pins that are not enabled in this register will be stored as zero in
the trace memory. To be traced, input signals must be valid and stable at the rising
edge of the AVR clock and for 50ns thereafter. It is also necessary that the trace buffer
is enabled and turned on.
The trigger input and the external trace are two independent functions acting on the
same input pins. Note that the trigger logic is asynchronous and edge driven, whereas
the trace logic is clocked on the AVR clock. The emulator may therefore break on a
glitch signal which is too narrow to be traced.
Содержание AVR ATmegaICE
Страница 3: ...Introduction AVR ATmegaICE User Guide 1 3 Figure 1 4 ATmega103 ATmega603 Probe ...
Страница 4: ...Introduction 1 4 AVR ATmegaICE User Guide ...
Страница 6: ...Preparing the ATmegaICE System for Use 2 2 AVR ATmegaICE User Guide ...
Страница 10: ...ATmegaPOD 3 4 AVR ATmegaICE User Guide ...
Страница 14: ...Connecting to the System 4 4 AVR ATmegaICE User Guide ...
Страница 16: ...Trace Buffer 5 2 AVR ATmegaICE User Guide ...
Страница 18: ...External Triggers 6 2 AVR ATmegaICE User Guide ...
Страница 20: ...Troubleshooting Procedures 7 2 AVR ATmegaICE User Guide ...