LPC1549 SCTimer bug report

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LPC1549 SCTimer bug report

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Contributor II

Being a bit new to all this, apologies if I have posted in the wrong place. (I confess that I don't really understand or like these modern forums with 'likes' and 'follows' and other such nonsense.)

I wanted to report an apparent bug in the LPC1549 device but it seems that there is no bug-tracker site active any more.

Anyway, here's the bug which manifests when using any SCTimer in non-unified mode whereby the timer runs as two 16-bit independent timers - high and low.

Each split timer has a separate HALT bit allocated within the CTRL register - HALT_H and HALT_L.

The apparent bug is that setting the HALT_L bit not only stops the lower timer but also stops the higher timer. Big show-stopper if you don't know about it.

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Contributor II

Looks like I missed a "Remark" in the user manual that states:

"If the SCTimer/PWM is operating as two 16-bit counters, events can only modify  
the state of the outputs when neither counter is halted. This is true regardless of what  
triggered the event."

Since I was depending on output changes to monitor the functioning of the timers, it appeared as a bug to me.

So much for the upper and lower timers being independent as claimed! It's simply not true.

I think this should have been made as a prominent warning in the manual instead of just one of thousands of "remarks" that I frankly don't have the time or patience to read through.

Anyway, apologies to anyone whose time I have wasted with this post.

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Contributor II

Looks like I missed a "Remark" in the user manual that states:

"If the SCTimer/PWM is operating as two 16-bit counters, events can only modify  
the state of the outputs when neither counter is halted. This is true regardless of what  
triggered the event."

Since I was depending on output changes to monitor the functioning of the timers, it appeared as a bug to me.

So much for the upper and lower timers being independent as claimed! It's simply not true.

I think this should have been made as a prominent warning in the manual instead of just one of thousands of "remarks" that I frankly don't have the time or patience to read through.

Anyway, apologies to anyone whose time I have wasted with this post.

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NXP TechSupport
NXP TechSupport

Hi Colin Burn,

Thank you for your interest in NXP Semiconductor products and the opportunity to serve you.

Thanks for your reporting, and I'll check it later.
Have a great day,
TIC

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