How can I use C macros to define PIC microcontroller pin names?

Question

PIC microcontrollers have 3 basic registers to set GPIO (General Purpose I/O) pin status. These are: TRIS (Tri-status, the direction register. Sets the pin as in or out) PORT (The input buffer) LAT (Latch, the output burffer).

Ports can be A, B, C... etc. So the TRIS register for the port A is TRISA.

Then finally there is the pin number. For example, TRISA1.

TRISA1 is defined as:

// TRISA<TRISA1>
extern volatile __bit                   TRISA1              __at(0x461);    // @ (0x8C * 8 + 1)
#define                                 TRISA1_bit          BANKMASK(TRISA), 1

I would like to define a macro to easily name the pins as:

#define _DATA_OUTPUT A2

So I can do code like:

LAT_DATA_OUTPUT = 1;
PORT_DATA_OUTPUT = 0;

and have it converted by the preprocessor to:

LATA2 = 1;
PORTA2 = 0;

so I can later expand to other pin registers such as ANSEL, WPU, etc, without rewriting the macros or add special cases.

Is this possible? Or what's the closest thing I can do to emulate this?

bashar bashar · Accepted Answer · 2019-05-26T00:10:30

You can do that by create macro like that:

#define _DATA_OUTPUT A2
#define LAT_DATA(X) LAT##X
#define LAT_DATA_OUTPUT    LAT_DATA(_DATA_OUTPUT)

#define PORT_DATA(X) PORT##X
#define PORT_DATA_OUTPUT PORT_DATA(_DATA_OUTPUT)

you can use it as example .

How can I use C macros to define PIC microcontroller pin names?

2 Answers