AM335X DMTIMER PWM single pulse duration - prescaler?

Wojciech Owczarek

Hi everyone,

Quick question regarding the interpretation of this statement:

AM335X TRM 20.1.3.1 Timer Mode Functionality:

" A dedicated output pin (PORTIMERPWM) is programmed through TCLR (TRG and PT bits) to generate one positive pulse (prescaler duration)"

Unfortunately I have no scope to hand so I'm not able to visually verify this, so I have to ask: in pulse mode, does this mean that the prescaler value controls the PWM pulse duration even if prescaler itself is not enabled, or does it simply mean that the PWM pulse is always one cycle long, thus longer if prescaler is used?

In my current project I'm generating a pulse per second (1PPS) signal using the PWM, and I need to be able to control the pulse duration: if the prescaler controls it, I will use pulse mode and prescaler, but if not, I will need to use toggle mode with overflow and match to control the pulse.

Thanks,

Wojciech

over 10 years ago

0 Biser Gatchev-XID over 10 years ago

TI__Guru**** 393215 points

Hi,

This is one timer clock cycle, regardless of prescaler. Since the prescaler controls the timer input frequency you will be able to control the pulse duration by setting the prescaler value as you require.

0 Wojciech Owczarek over 10 years ago in reply to Biser Gatchev-XID

Prodigy 20 points

Hi,

Not directly, but this answers my question. I have to run at maximum frequency possible, so I cannot enable the prescaler, therefore the only way I can control the pulse width is toggle on overflow and consecutive match.

Thanks,

Wojciech

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AM335X DMTIMER PWM single pulse duration - prescaler?