Embedded Linux Controller using pic microcontoller

An ICD is a hardware device that is connected between a PC and the target microcontroller to debug real-time applications quickly and easily. The ICD is controlled by a debugging application tool running on the PC. The debugging tool allows the designer to slow down the microcontroller operation by inserting breakpoints into the program 0r single-step the program execution. After the execution of a single or a group of instructions, the values of the program variables and internal registers can be examined, and modified if required. This helps to quickly identify bugs and errors in the source code and thus expedite the development process of the project.

ICD in PICMicro

In PIC microcontrollers, in-circuit debugging is achieved through the same pins that are used for In-Circuit Serial Programming (ICSP), i.e. ICSPDAT (or PGD), ICSPCLK (or PGC), V_PP/MCLR (programming mode voltage), V_DD (power supply voltage), and V_SS (Ground). This allows manufacturers to integrate ISCP programming and in-circuit debugging features into a single device. During debugging, the ICD device adds an additional block of code (along with the user application) to the target microcontroller’s program memory, which interacts with the debugging application and sends variable values, internal register values and other details to the PC through the same programming cable.

For example, Microchip’s MPLAB ICD2 and ICD3 are both programmer and real-time debugger for selected PIC MCUs and dsPIC DSCs. The functionality of the ICD is controlled by the MPLAB Integrated Development Environment (IDE) application software running on the PC. During debugging all available features of the target microcontroller are accessible interactively through the MPLAB IDE interface. These functions allow you to run the program in single-step mode, insert breakpoints into the program, examine the registers and variables, and modify them if desired.

Although an ICD is an invaluable debugging tool, it does not come at no cost. The two main disadvantages of ICD are: 1) it uses some memory of the target microcontroller, and 2) it occupies a few I/O pins of the target microcontroller to communicate with the PC. Therefore, while debugging, the PGD, PGC, and MCLR pins of the target microcontroller cannot be used for any other purposes.

PICFlash with mikroICD

The PICFlash with mikroICD is a programmer and in-circuit debugger for PIC12, PIC16, and PIC18 series microcontrollers. It is manufactured by mikroElektronika and is supported by all of its PIC compilers (mikroC, mikroBasic, and mikroPascal). The device communicates with PC through an USB interface, which also provides the necessary power for the ICD. ?It connects to the target PIC microcontroller through the PGC, PGD, V_PP/MCLR and power supply pins. When this device is used as an standalone programmer, the first three pins are released after the HEX file is loaded into the target PIC microcontroller. But if  it is used for in-circuit debugging, those three pins are used for communicating with the PC and hence cannot be used for any other purposes.