Counting Clock Cycles - Is there an alternative method?

Thomas Foxcroft

Other Parts Discussed in Thread: MSP430G2553

Problem: Profile clock seems to be highly inaccurate

CCS version: 5.5.0.00077 running on Windows Vista

MCU: MSP430G2553 running on the MSP-EXP430G2 development tool

My profile clock says that it takes 65,540 cycles to set P1.0 to the output direction. That's sound just way to high for a tiny line of code such as "P1DIR |= 0x01."

Is there an alternative to way to count the cycles for each instruction?
Is this a bug that has not been fixed?

I need this clock to work so I can determine where to reset the watchdog counter. The watchdog timer counter (WDTCNT) register is not directly accessible by software, so that's a dead end!

Any suggestions from anybody?

over 12 years ago

0 Gautam Iyer over 12 years ago

Guru 192875 points

Hi Thomas,

My profile clock says that it takes 65,540 cycles to set P1.0 to the output direction.

I hope you reset your clock at the break-point before "Stepping into", right?

Regards,

Gautam

0 Thomas Foxcroft over 12 years ago in reply to Gautam Iyer

Expert 2996 points

Yes, I reset the clock at the break point before stepping into it. I also tried with the normal break point and the hardware break point, but the clock still burned through 65,540 cycles. Seems very strange to me.

Maybe I need to generate some CCS log file to find a clue about this matter.

0 Gautam Iyer over 12 years ago in reply to Thomas Foxcroft

Guru 192875 points

Hi Thomas,

Your controller has some compatibility issue with profile clock feature in CCS. Here's the explanation:

http://e2e.ti.com/support/microcontrollers/msp430/f/166/t/293077.aspx

Regards,

Gautam

0 Thomas Foxcroft over 12 years ago in reply to Gautam Iyer

Expert 2996 points

OK. I give it a read. Thanks.

0 Thomas Foxcroft over 12 years ago in reply to Gautam Iyer

Expert 2996 points

Looks like the post is a discussion about the exact same problem with the exact same device and tool. No solution was identified.

0 Gautam Iyer over 12 years ago in reply to Thomas Foxcroft

Guru 192875 points

Yup, Thomas. The other 2 vague ways of doing this is;

1. Toggling GPIO before and after the instruction and observing the same on DSO.

2. Using CPU timer, start the timer -> execute the instruction -> stop the timer. Check the timer register to get the value.

Regards,

Gautam

0 Thomas Foxcroft over 12 years ago in reply to Gautam Iyer

Expert 2996 points

Gautam:

I don't follow you on the first method, toggling the GPIO, but I follow you on the second method, using the Timer Module. Good idea.

You know what is interesting? There are only two conversations in the forum about this matter. Mine and the one you pointed to. It seems to me that few people are using the Clock Profile tool, which might mean, few people are using the Watchdog Module to build reliable code. Hmmmm?

This makes me think of my piece of *** remote control supplied by my cable TV company. My goodness, what a buggy thing that is. :)

0 Gautam Iyer over 12 years ago in reply to Thomas Foxcroft

Guru 192875 points

Hi Thomas,

What I meant by first step is:

GpioDataRegs.GPBSET.bit.GPIO35 = 1;  //Set bit
//Place your instruction here
GpioDataRegs.GPBCLEAR.bit.GPIO35 = 1;  //Clear bit

By doing so your GPIO would toggle, this toggling can be easily captured on DSO. This will inturn give you the time taken for the instruction to execute. By dividing this time by the CPU cycle time, you'll get the number of cycles.

This makes me think of my piece of *** remote control supplied by my cable TV company. My goodness, what a buggy thing that is. :)

lol :)

Regards,

Gautam

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Counting Clock Cycles - Is there an alternative method?