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Forum: µC & Digital Electronics Microcontroller with Track and Hold Capability (or Dedicated Sampling Stop trigger)


von Vishvanath K. (vish)


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Hi,

I have been using a Cypress FM3 Series Processor for the last 6 months, 
unfortunately I am facing a problem now. The Successive Approximation 
(SAR)ADC Peripheral does not have a dedicated "trigger/switch" to stop 
sampling at an instance in time. That is, "Track and Hold" is not 
possible.

dsPIC33 and PIC24 Series have a dedicated Trigger to Stop Sampling at an 
instant, thereby allowing "Track and Hold".

I have looked into various ARM cortex M controllers but they seem to 
lack this feature. Can anyone correct me and guide me if such a 
microcontroller exists with ARM Cortex M based core.

My Goal is to measure the Amplitude of a Voltage Spike. The Sampling 
will be stopped by a trigger at the precise moment where the Spike 
almost achieves its Maximun Value. After the sample has been taken, the 
ADC Converter can take the required time to analyze the sampled value.

I would be happy to receive advice on this.

von minifloat (Guest)


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Hello Vish,

There are two possibilities
a) use cyclically triggered sampling, triggering by a timer, then
a1)  store the result of interest in a variable before ADC result is 
overwritten with next sampling
a2) stop the timer and thus the triggering

b) use triggered sampling and trigger the ADC once shortly before you 
expect the voltage spike maximum

I've seen both possible with CM0 and CM4 based ARM MCUs.

br, mf

von Patrick C. (pcrom)


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Cypress PSOC 5lp

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