[SOLVED] problem in defining bits in Winavr

[shahbaz.ele]

dear all
I want to set and clear the bits of MCUCR register
but I do not know how to define the SM0,1,2 bits and SE bit and how to set these bits.

 

[kamranravian]

you can use following instructions to set or clear bits of any register

MCUCR |= (1<<0); //to set bit 0 of MCUCR
MCUCR |= (1<<7); //to set bit 7 of MCUCR

MCUCR &= ~(1<<0); //to  clear bit 0 of MCUCR
MCUCR &= ~(1<<7); //to clear bit 7 of MCUCR

 

[shahbaz.ele]

thank you dear

 

[alexan_e]

Note that the bits of each register are defined in the header file with the name used in the datasheet.

For example for mega8 the header iom8.h includes

/* MCUCR */
#define SE	7
#define SM2	6
#define SM1	5
#define SM0	4
#define ISC11	3
#define ISC10	2
#define ISC01	1
#define ISC00	0

so this allows you to use bit names instead of numbers if you want

MCUCR |= (1<<ISC00); //to set bit 0 of MCUCR
MCUCR |= (1<<SE); //to set bit 7 of MCUCR

also take a look at https://www.edaboard.com/blog/861/

I like to use

#define SETBIT(ADDRESS,BIT) (ADDRESS |= (1<<BIT)) 
#define CLEARBIT(ADDRESS,BIT) (ADDRESS &= ~(1<<BIT)) 


SETBIT(MCUCR,ISC00); // //to set bit 0 of MCUCR
CLEARBIT(MCUCR,ISC00)  //to clear bit 0 of MCUCR

Alex