Dear All, I'm using this interrupt on my program
void timer1_ISR (void) interrupt 3 //timer1 interrupt services routine { .. } void it_ext1(void) interrupt 2 // external interrupt INT1 { .. } void timerisr(void) interrupt 1 //timer0 interrupt services routine { .. } static void com_isr (void) interrupt 4 //SERIAL COMMUNICATION INTERRUPT SERVICES ROUTINE { .. } void i2c(void) interrupt 5 //i2c interrupt services routines { .. }
hi, You can use the same register bank for each ISR that is at the same interrupt level. ...as long as you do not use these registers as variables. There are tasks for which the speed is most important. In such case, usage of the registers to keep ISR's data is rather than memory locations. For example, one of my projects uses timer 2 for control PWM of PCA which plays sound. As digital stream frequence is about 22kHz and so ISR of timer 2 executes each ~45us. This ISR updates PWM with previously prepared value, checks is sound playback done, if not then reads next byte from external flash memory. Due lack of execution time I decided to keep flash memory address (3 bytes) and playback length (3 bytes) into R1...R6 of register bank I set for the ISR. You know, it increases the speed very well. Regards, Oleg
Graham Cole said: "You can use the same register bank for each ISR that is at the same interrupt level." Oleg Sergeev replied: "...as long as you do not use these registers as variables." Oleg: Presumably you are doing this in Assembler, not 'C'? I did wonder about the kind of thing you're suggesting, but I couldn't immediately see how you'd do it in C51.
hi, yes, Andy, ISR was wrote with ASM (actually it must be wrote such way as it requires high-speed optimization I done with hands). Then it was placed in separate .A51 file together with other ASM routines. Inside ASM I used bank switching, like:
CSEG AT 0x002B ; TF2 LJMP INT2_ISR ; ... INT2_ISR_SEG SEGMENT CODE RSEG INT2_ISR_SEG USING 1 ; register bank 1 INT2_ISR: PUSH PSW MOV PSW,#REGBANK_1 ; .... POP PSW RETI
data struct { unsigned char fa_lb; unsigned char fa_mb; unsigned char fa_hb; } flash_addr _at_ 0x09; data struct { unsigned char pbl_lb; unsigned char pbl_mb; unsigned char pbl_hb; } playback_length _at_ 0x12;
oops, I did a typpo. second structure is defined from 0x0C. Sorry, Oleg