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PSoC 5, 3 & 1

AlVa_264671
New Contributor II

I everyone I would apprecite any help !!!!

   

 

   

How do hook up the output from an op amp , like opamp [ V1.90] and configured like Smith trigger inside the chip to and ISR component ?
The standard solution with a external opamp (off the Psoc 3), would be connect it to an MCU digital input.
In my case, I only have resistors off the chip, and I would like to generate an interrupt when the Smith trigger output generate a falling edge. What I am intending to do is keep as much as posible inside the Psoc 3.

   

 

   

Thank you very much

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7 Replies
ETRO_SSN583
Esteemed Contributor

Consider a comparator and config with Hysterisis -

   

 

   

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AlVa_264671
New Contributor II

Thank you very much for your answer DanaaKnight!!!.

   

But does it  means that the compartator with hysteresis is the only posibility to drive an ISR component inside the Psoc 3 from any  other analog component from the component catalog?

   

 

   

Can you please explain me why tthe following configuration does not take the rising edge from the ISR component , but I can read the logic cero value correponding to my signal?.

   

"My signal"  take normally value "1" and get value "0" only when something happens.

   

On the other handI would need more than 10 mv hysteresis, that is the reason I am using this type of Smith Trigger.

   

 

   

   

 

   

I am looking forward to get your answer!!!

   

Thanks in advance.

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Bob_Marlowe
Expert II

The OpAmp has got an analog output, while the comparator has got a digital output which the isr requires. As you can imagine the routing of analog signals differ from routing digital ones.

   

To indicate the difference for you, the wire colours differ (red for analog, green for digital).

   

There are some different kinds of comparators, so coose the one that best fits to your needs.

   

 

   

Bob

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ETRO_SSN583
Esteemed Contributor

Some thoughts -

   

 

   

1) Global interrupts must be enabled

   

2) isr_1 must be enabled, rising edge (if not used also for sleep)

   

3) Pin configed as Digital Input

   

4) If any other interrupts on port they are ored together, so you

   

have to test for that specific interrupt with a mask

   

5) For the life of me I could not figure out how to get the solid analog

   

route you show from comparator out to the pin ? Can you post the project ?

   

 

   

Regards, Dana.

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ETRO_SSN583
Esteemed Contributor

The other 2 comparators do not have Hysteresis.

   

 

   

There should be no reason you could not add external hysteresis to

   

a comparator to force greater hysteresis value as a possibility, but that

   

may be layout sensitive, as opposed to using OA as you are using.

   

 

   

Regards, Dana.

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ETRO_SSN583
Esteemed Contributor

I think you configed pin as analog, it must be digital per datasheet

   

discussion of ISR on a pin, so route must be external from the pin

   

OpAmp out is connected to the digital input pin used for ISR.

   

 

   

Regards, Dana.

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AlVa_264671
New Contributor II

Thank you very much you guys, I will try your valueable suggestion and  I let see what happens.!!!!!

   

Thank again !

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