Atmel CAVR-4 Manuale Utente

CAVR-4

Part1. Using the compiler

The low-level debugger interface is used for communication between the application 
being debugged and the debugger itself. The interface is simple: C-SPY will place 
breakpoints on certain assembler labels in the application. When code located at the 
special labels is about to be executed, C-SPY will be notified and can perform an action.

When code at the labels 

?C_PUTCHAR

 and 

?C_GETCHAR

 is executed, data will be sent to 

or read from the debugger window.

For the 

?C_PUTCHAR

 routine, one character is taken from the output stream and written. 

If everything goes well, the character itself is returned, otherwise 

-1

 is returned.

When the label 

?C_GETCHAR

 is reached, C-SPY returns the next character in the input 

field. If no input is given, C-SPY waits until the user has typed some input and pressed 
the Return key.

To make the Terminal I/O window available, the application must be linked with the 
XLINK option With I/O emulation modules selected. See the AVR® IAR Embedded 
Workbench™ IDE User Guide.

The debugger stops executing when it reaches the special label 

?C_EXIT

. 

For information about how to check module consistency, see Checking module 
consistency, page 77 in the chapter The DLIB runtime environment.