MSP430G2553: Delay function

Abhishek Dutta

Part Number: MSP430G2553
Other Parts Discussed in Thread: MSP430G2253

Hello everyone,

In msp430 ,how much delay it generates if I write the statement __delay_cycles(1000).Is that mean 1ms delay because by default msp430 works at a frequency of 1.02MHz ?

over 6 years ago

0 zrno soli over 6 years ago

Guru 33653 points

e2e.ti.com/.../303024

0 Abhishek Dutta over 6 years ago in reply to zrno soli

Expert 1575 points

So if I write the below mentioned code, then what is the delay?
#include<msp430.h>
int main(void) {
WDTCTL = WDTPW | WDTHOLD; // Stop watchdog timer
P1DIR |= 0x01; // Set P1.0 to output direction
while(1) {
volatile unsigned long i; // Volatile to prevent
//optimization
P1OUT ^= 0x01; // Toggle P1.0 using XOR
i = 50000; // SW Delay
do i--;
while(i != 0);
}
}

0 ADARSH SS over 6 years ago in reply to Abhishek Dutta

Prodigy 125 points

The answer depends on the clock frequency and the input voltage of the board. For MSP430G2253, the clock frequency is 16MHz (not sure).
If the delay you need 1ms, then (16000/16MHz) gives you the delay of 1ms. That is,

i = 16000
will give you a delay of 1ms if the clock frequency is 16MHz.

You can make sure of the clock frequency and calculate yourself the delay you need...

0 zrno soli over 6 years ago in reply to Abhishek Dutta

Guru 33653 points

Do toggle again after loop, and you will know based on P1.0 state change length of delay. Nobody can give you clear answer on this question, because you need to analyze generated assembler code for do-while loop and calculate number of cycles, and than based on MCLK, delay time.

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MSP430G2553: Delay function