MSP430G2744: Errata TA12 Timing Chart

Mari Tsunoda

Expert 5726 points

Part Number: MSP430G2744

Hi Team,

My customer has a question with the errata regarding TA12.

According to this post, it explains the errata in more detail using an example.

Would it be possible to draw up a timing chart for this? I am still confused as to how the errata affects CCRx and TAR.

Best regards,

Mari Tsunoda

over 4 years ago

0 Xiaodong LI over 4 years ago

TI__Mastermind 25425 points

Hi Mari

This is very detailed question :) I need time to study the detailed.

Thanks

0 Mari Tsunoda over 4 years ago in reply to Xiaodong LI

TI__Expert 5726 points

Hi Xiaodong,

Thanks for your reply. Looking forward to the timing chart.

Best regards,

Mari

0 Mari Tsunoda over 4 years ago in reply to Xiaodong LI

TI__Expert 5726 points

Hi Xiaodong,

Any update or ETA on this? I'd like to send them an update this week.

Best regards,
Mari Tsunoda

0 Yuhao Zhao over 4 years ago in reply to Mari Tsunoda

TI__Genius 10865 points

Hi Mari,

I draw up a draft timing chart for this. Maybe this can help you.

Thanks and Best Regards

Yuhao Zhao

0 Mari Tsunoda over 4 years ago in reply to Yuhao Zhao

TI__Expert 5726 points

Hi Yuhao,

Thanks for the timing chart I think this should be very helpful in understanding the errata for them. Also I want to confirm, it seems from the errata that TAR increments on TACLK/ACLK and CCRx increments on MCLK. However from Figure 12-1. Timer_A Block Diagram in the user guide, I thought that both follow the same clock. I think I am possibly misunderstanding the errata wording. Can you help me understand this?

Best regards,

Mari

0 David Schultz over 4 years ago in reply to Mari Tsunoda

Guru 26235 points

CCRx doesn't increment automatically. The problem occurs because the code in the ISR, which runs on MCLK, runs much faster than the timer. You expect that adding 1 to CCRx in the ISR would result in another interrupt the next time the timer increments. That interrupt is lost.

That would be bad practice in any case as you have a race between code execution (which could get held up by another higher priority interrupt) and the timer. The winner of that race could vary.

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MSP430G2744: Errata TA12 Timing Chart