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IAR Embedded Workbench for Arm 9.70.x

Live Watch window

In this section:

What do you want to do?

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The Live Watch window is available from the View menu.

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This window repeatedly samples and displays the value of expressions while your application is executing. Variables in the expressions must be statically located, such as global variables.

The following possibilities for live watch apply:

Device

Cortex-M

Live watch is fully supported for Cortex-M. Access to memory or setting breakpoints is always possible during execution.

Cortex-A/R

Live watch is only possible when you use the C-SPY I-jet driver or J-Link/J-Trace driver, and only when you use the option ‑‑drv_mem_ap, see ‑‑drv_mem_ap.

Armxxx-S

The support for live watch is limited for Armxxx-S cores, see below. Setting hardware breakpoints during execution is always possible for all supported C-SPY drivers.

Arm7/Arm9, including Armxxx-S, and when using the C-SPY J-Link/J-Trace driver

Memory accesses must be made by your application. By adding a small program—a DCC handler—that communicates with the debugger through the DCC unit to your application, memory can be read/written during execution. Software breakpoints can also be set by the DCC handler.

Just add the files JLINKDCC_Process.c and JLINKDCC_HandleDataAbort.s located in arm\src\debugger\dcc to your project and call the JLINKDCC_Process function regularly, for example every millisecond.

In your local copy of the cstartup file, modify the interrupt vector table so that data aborts will call the JLINKDCC_HandleDataAbort handler. See also ‑‑jlink_dcc_timeout.

Table 20. Live watch for the different devices 


Requirements

This window is available for all combinations of C-SPY drivers and devices, except for the C-SPY Stellaris driver. However, note that the actual support for live watch is limited for all cores except Cortex-M, see the table above.

Display area

This area contains these columns:

Expression

The name of the variable.

A name in square brackets, for example [fieldname], is either the name of a base class for a struct/class object or—if shown in gray and italic)—a pointer to the full object when of a class type derived from the original class.

Value

The value of the variable. Values that have changed are highlighted in red.

Dragging text or a variable from another window and dropping it on the Value column will assign a new value to the variable in that row.

This column is editable.

Location

The location in memory where this variable is stored.

Type

The data type of the variable.

Context menu

This context menu is available:

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Note

The contents of this menu are dynamic and depend on which features that your combination of software and hardware supports. However, the list of menu commands below is complete and covers all possible commands.

These commands are available:

Remove

Removes the selected expression from the window.

Remove All

Removes all expressions listed in the window.

Default Format, Binary Format, Octal Format, Decimal Format, Hexadecimal Format, Char Format

Changes the display format of expressions. The display format setting affects different types of expressions in different ways. Your selection of display format is saved between debug sessions. These commands are available if a selected line in the window contains a variable.

The display format setting affects different types of expressions in these ways:

Variables

The display setting affects only the selected variable, not other variables.

Array elements

The display setting affects the complete array, that is, the same display format is used for each array element.

Structure fields

All elements with the same definition—the same field name and C declaration type—are affected by the display setting.

Show As

Displays a submenu that provides commands for changing the default type interpretation of variables. The commands on this submenu are mainly useful for assembler variables—data at assembler labels—because these are, by default, displayed as integers.For more information, see Viewing assembler variables.

Save to File

Saves content to a file in a tab-separated format.

Right Align ‘Value’ Column

Right-aligns the contents of the Value column.

Options

Displays the IDE Options dialog box where you can set various options for C-SPY windows.