MC33972 Interface

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MC33972 Interface

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testbed
Contributor III

Hi,

I am planning to use MC33972 in my application. However while evaluating i found that for momentary-push-to-on switches the IC generates two interrupts - one for switch closure and other for when you release it.

The only way to prevent this from happening is to disable the IRQ generation at the MC33972 in the handler, read the switch status and re-enable the handler.

The application has two kinds of interactions with the switches - short press and long press, i.e. A single switch must be used for short press and long press with different handlers for each event.

My Q therefore is this - Is it even possible with this IC ?

Are there any application notes on using this IC?

Thanks...

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reyes
NXP TechSupport
NXP TechSupport

Hi,

Correct, the MC33972 is designed to detect the closing and opening of up to 22 switch contacts. The switch status, either open or closed, is transferred to the microprocessor through SPI, and the /INT interrupt generation will be triggered when there is a change in the switch state (either from open-to-close or close-to-open).

Your application seems possible, as you mention, by disabling the /INT interrupt and monitoring the switch status, I don’t see any problem using it this way.

 

Unfortunately, the only application note associated with the MC33972 is the AN2409 which provides guidelines for handling and assembly of Small Outline Integrated Circuit (SOIC) package during Printed Circuit Board (PCB) assembly. You can find it in the following link: https://www.nxp.com/docs/en/application-note/AN2409.pdf

Jose

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