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Author Topic: Analog output pulses of ~0.5ms  (Read 871 times)
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I was wondering if anyone would know this is feasible as my current research into this shows it will be difficult.

I am trying to output a predefined analog pulse with a duration of ~0.5ms from an Arduino Uno I have recently bought.
I know I could use a PWM pin but the key is the sampling rate from the analog pulse needs to be sufficient to adequately hold the pulse shape in PWM.
I can change Timer0 to have a divisor of 1 meaning a PWM frequency of 62500Hz, which gives a sampling rate of 0.016ms. This therefore would generate ~31 sampling points across the pulse which should be sufficient for the application.

The key is now to convert this into an analog signal, preserving the pulse length and shape as much as possible. I have looked at using a low pass filter, where this which potentially achieve what I am after but I know there is a offset delay between the PWM signal and the analog signal. This would be fine if the delay is a fixed value but I am unsure if the change in frequency changes this delay value to significantly distort the pulse length.

Or is there a suitable DAC chip for this application instead?

Any help would be greatly appreciated. Thanks
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I am trying to output a predefined analog pulse with a duration of ~0.5ms from an Arduino Uno I have recently bought.

The term 'analog' can mean many different things, especially in an Arduino environment where it can also mean a PWM square wave output, which is not at all what most people expect 'analog' to mean.

Can you explain exactly what sort of output you're trying to produce? Are you trying to generate a variable DC voltage, reproduce a wave form, output a sequence of digital pulses, or what?
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The analog signal I wish to produce is a short varying DC voltage between 0-5Volts which will be normally be roughly of a 'n-shaped hump' shape. It isn't a continuous sent of pulses either, it is just one pulse.

I hope this helps, for any further information jusk ask. smiley
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The analog signal I wish to produce is a short varying DC voltage between 0-5Volts which will be normally be roughly of a 'n-shaped hump' shape. It isn't a continuous sent of pulses either, it is just one pulse.

I hope this helps, for any further information jusk ask. smiley

Perhaps if you could post a picture showing the shape (amplitue) and duration of your 'analog pulse' it might lead to better feedback. Off the top of my head I would think you would require a true DAC module and in your software have a predefined data array of values to be sent to the DAC at a fixed 'update' rate that would recreate the single pulse shape anytime you wish to output it.

Lefty

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