Function of SFR_16BIT?

SFR_16BIT() is just a macro-short-cut so you don't have to spell out:  extern volatile unsigned int "address" every time.
Plus if something change you only need to edit it at one location.

As it uses extern, it is declared implicitly globally and is often placed in common.h etc.
as somewhere volatile unsigned int "address, without the extern is also placed.

WDTCTL is defined in msp430f5529.h,
Any decent complier when you select target you only have to use #include msp430.h and it will use mcu specific .h file automatically.

Tony,

Thanks for the reply. but I still cannot find the definition of WDTCTL in my msp430f5529.h, allI can find is:

SFR_16BIT(WDTCTL);                            /* Watchdog Timer Control */

SFR_8BIT(WDTCTL_L);                           /* Watchdog Timer Control */

SFR_8BIT(WDTCTL_H);                           /* Watchdog Timer Control */

My msp430f5529.h is attached below

Eric

msp430f5529.h

It's in msp430f5529.cmd

/************************************************************
* WATCHDOG TIMER A
************************************************************/
WDTCTL             = 0x015C;
WDTCTL_L           = 0x015C;
WDTCTL_H           = 0x015D;

Hi Christos,

Thanks for the reply.

I can find it under ccs_base/msp430/include now

But I also notice that there is another cmd file called lnk_msp430f5529.cmd in the project

What is the difference between these two cmd files?

Eric

That's a completely different file mate.
The lnk_msp430f5529.cmd contains information for the linker (where to put different code segments, memory ranges and stuff like that).
Double click it to open it and see what it contains. Then you'll see the differences between the two files.

Hi Christos,

If I write

WDTCTL             = 0x015C;

in a cmd file, and WDTCTL is an volatile unsigned int "address", it means WDTCTL represents the value stored in address 0x015C, by reading or writing WDTCTL, we basically operates the value in 0x015C.

But if a write

volatile unsigned int i;

i = 0x015c;

in a c file, it means i is stored in stack, we obviously cannot find i but we can find WDTCTL in the generated map file.

So the difference is where to write WDTCTL, am I right?

Thanks,

Eric

 

I guess CCS is different, as in IAR they are just like any regular #define and don't use  equal char

#define WDTCTL_             (0x0120u)          /* Watchdog Timer Control */
DEFW(   WDTCTL            , WDTCTL_)

So the hardware address is 0x0120 (on a G2553)
It then uses the DEFW define as a wrapper

#define DEFW(name, address) __no_init volatile unsigned short name @ address;

Hi Christos,

Thanks, I can understand what you said clearly, but I still don't quite understand what the example codes from TI represent, which leads back to my original question 1: what is the data type of WDTCTL?

(1)Unlike

extern volatile unsigned int *i = 0x15C;

nor

unsigned int i = 0x15C;
extern volatile unsigned int *WDTCTL_NAME_2;
WDTCTL_NAME_2 = i;

WDTCTL is not a pointer, because in the h file

#define SFR_16BIT(address)  extern volatile unsigned int address

(2) Now I think it's more like a

volatile unsigned int

type which is assigned to the address 0x015C by the way you mentioned in the

msp430f5529.cmd

/************************************************************

* WATCHDOG TIMER A

************************************************************/

WDTCTL             = 0x015C;

But I'm still confused by the difference between writing

WDTCTL             = 0x015C;

in a c file and in a cmd file.

Eric