- Debug Executive
- A small program used in conjunction with your application code to facilitate the on-chip debug process. It is used by all Microchip PIC MCU and dsPIC DSC debug tools including the MPLAB® REAL ICE in-circuit emulator, MPLAB ICD 3 in-circuit debugger, and PICkit™ 3 in-circuit debugger, as well as the stand-alone starter kits.
The Debug Executive
When using an in-circuit debugger to debug your program, some of the chip's resources are reserved for debugging functions. Your code isn't the only thing that gets programmed into the device. A small program called the Debug Executive is automatically added to your code when you build and program for debugging. Its job is to run commands sent by the PC and to control the debug process. While your program is running, it sits quietly in the background. However, whenever a breakpoint is reached or a command is received from the PC, control over the device is transferred to the debug executive.
The debug executive requires a small amount of code space, a few registers in data memory and one or two levels of stack. In addition to on-chip resources, the ICSP™ lines must be dedicated to the debug process. This means that the I/O pins multiplexed with debug clock, data, and PGM (if used) may not be used by your application while debugging.
Resource Needs
- Exclusive use of two I/O pins
- Shared control of the MCLR pin
- Some file registers (RAM)
- Some program memory locations (Flash)
- One or two hardware (return) stack locations
To determine what device memory and other resources are reserved when debugging, see MPLAB X IDE Start Page, Learn & Discover, Getting Started, Users Guide & Release Notes, Reserved Resources.
Example Resource Needs
| RI, ICD3, PK3 | RI, ICD3 | RI, ICD3, PK3 | ||||||||
| Device | Header | Alt. Header | Program Memory Reserved | File Registers Reserved | Program Memory Reserved (SW BP Support) | File Registers Reserved (SW BP Support) | MCLR Pin Reserved / Shared | LVP Disabled | Device Pins Reserved | Stack Reserved |
| PIC18F4520 PIC18LF4520 |
N/A | N/A | 0x7DC0-0x7FFF | 0x05F4-0x05FF 0x0F9C 0x0FD4 0x0FDB-0x0FDF 0x0FE3-0x0FE7 0x00FEB-0x0FEF 0x0FFD-0x0FFF |
0x7D30-0x7FFF | 0x05EF-0x05FF 0x0F9C 0x0FD4 0x0FDB-0x0FDF 0x0FE3-0x0FE7 0x0FEB-0x0FEF 0x0FFC 0x0FFD-0x0FFF |
Reserved, Shared with Vpp | Required | Pgm Pins | 2 Levels, TOS registers |
| PIC24FJ128GA010 | AC162065 (optional) | AC244022 (optional) | None | 0x0800-0x084F | None | None | Reserved, Shared with Vpp | N/A | Pgm Pins, Emul Pins | None |
