dsPIC30/33 and PIC24 Specifics   dsPIC30/33 and PIC24 Specifics >

dsPIC30/33 and PIC24 Specifics

In order to get the most from the mikroBasic PRO for dsPIC30/33 and PIC24 compiler, the user should be familiar with certain aspects of dsPIC30/33 and PIC24 MCU. This knowledge is not essential, but it can provide a better understanding of the dsPIC30/33 and PIC24's capabilities and limitations, and their impact on the code writing as well.

Types Efficiency

First of all, the user should know that dsPIC30/33 and PIC24's ALU, which performs arithmetic operations, is optimized for working with 16-bit types. Although mikroBasic PRO for dsPIC30/33 and PIC24 is capable of handling types like byte, char or short, dsPIC30/33 and PIC24 will generate a better code for 16-bit types word and integer type so use byte, char and short only in places where you can significantlly save RAM (e.g. for arrays dim a as byte[30]).

Nested Calls Limitations

There are no Nested Calls Limitations, except by RAM size. A Nested call represents a function call within the function body, either to itself (recursive calls) or to another function.

Recursive calls, as a form of cross-calling, are supported by mikroBasic PRO for dsPIC30/33 and PIC24, but they should be used very carefully due to dsPIC30/33 and PIC24 stack and memory limitations. Also calling functions from interrupt is allowed. Calling function from both interrupt and main thread is allowed. Be carefull because this programming technique may cause unpredictable results if common resources are used in both main and interrupt.

Limits of Indirect Approach Through PSV

Constant aggregates are stored in Flash and are accessible through PSV. mikroBasic PRO for dsPIC30/33 and PIC24 can allocate more than 32KByte of constants. See near and far memory specifiers.

Limits of Pointer to Function

Currently pointer to functions are 16-bit variables. For functions which address exceeds 16 bit limit, the compiler uses handle (16-bit pointer on GOTO). A handle usage is automatic compiler process so there is no need for the user to intervene.

Variable, constant and routine alignment

Simple type variables whose size exceeds 1 byte (word, integer, dword, longint, real) are always set to alignment 2 (i.e. are always allocated on even address).
Derived types and constant aggregates whose at least one element exceeds size of 1 byte are set to alignment 2.
Routines are always set to aligment 2.