INSTRUCTION EXECUTION TIME IN MSP 430

Ashok kumar Karnan

Hi,

i am new to MSP430.Now i want to know the instruction execution time of MSP 430.I am using SMCLK with the frequency of 1MHz.and my program is as follows..

while(1)

{

P1OUT=0x00;

P1OUT=0x01;

}

for the the above program what is instruction execution time?

i got 4us .Is it correct?

As per calculation we get 1us then why this 4uS?

please help me...

over 14 years ago

0 Gaston_Melo_Arg over 14 years ago

Mastermind 7675 points

Hi,

check here http://en.wikipedia.org/wiki/TI_MSP430

regards

Gastón

0 Jens-Michael Gross over 14 years ago

Guru 227245 points

Ashok kumar Karnan said:
As per calculation we get 1us

What calculation?

Ashok kumar Karnan said:
why this 4uS

1 clock cycle for reading the instruction. One for reading the port address. One for the write. None for the 0/1 operands as tehse are provided usign the constant generator and not as separate immediate values. Makes 3. On old MSP cores 4 for some reason.. Since there is a write in the last cycle, there is no pipelining.
And for the loop, there is also a JMP which takes 2 cycles. makes 8 (or even 10) cycles per loop. Or 8µs on 1MHz clock. I guess if you scope the signal, you'll see the output pin high for 5 and low for 3µs. on newer MSPs (MSP430X core) and 6/4µs on older ones.

0 old_cow_yellow over 14 years ago in reply to Jens-Michael Gross

Guru 58965 points

SMCLK has nothing to do with CPU cycles.

If you are using C, do not count CPU cycles.

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INSTRUCTION EXECUTION TIME IN MSP 430