Shortest reliable pulse width in one-shot mode on Tiva?

Damien Dusha

Other Parts Discussed in Thread: TM4C123GE6PZ

Dear all,

I have an application where I need to generate short (1us) pulses. What is the minimum pulse that can be reliably generated using the one-shot timer on the Tiva? Assuming no external hardware factors, it limited only by the I/O pin rise times, or are there other factors at play? For example, is it limited by bus timing? (i.e. in the GPIO module, it states "Fast toggle capable of a change every clock cycle for ports on AHB, every two clock cycles for ports on APB")

Thanks in advance,

-- Damien

over 11 years ago

0 Amit Ashara over 11 years ago

TI__Guru**** 244400 points

Hi Damien

Which device are you using. TM4C123 or TM4C129.

Regards

Amit

0 Damien Dusha over 11 years ago in reply to Amit Ashara

Prodigy 190 points

Hi Amit,

We haven't built hardware yet, but were intending to target the TM4C123, probably the TM4C123GE6PZ.

Thanks for the fast response.

-- Damien

0 Amit Ashara over 11 years ago in reply to Damien Dusha

TI__Guru**** 244400 points

Hi Damien,

The fastest pulse you can get by writing 0->1->0 is 25ns for TM4C123 with System Clock at 80MHz

Regards

Amit

0 cb1_mobile over 11 years ago

Guru 117855 points

In the past - the best port output speed performance could be gained via use of a Timer config'ed as PWM - and output to that Timer pin. (this saves the clear - set - clear instruction delay - forced by gpio coding)

I suspect that the AHB vs APB distinction you provide may not extend into the Timer arena - although simple experimentation should quickly confirm.

By setting a Timer config'ed duty cycle (i.e. pulse "On") of 1 pulse - and a relatively longer PWM period - a short, robust, positive going pulse should be emitted...

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Shortest reliable pulse width in one-shot mode on Tiva?