"cheap" timer IRQ on PSoC4?

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Anonymous
Not applicable

 On my PSoC5LP designs I often create a periodic interrupt for basic system timekeeping and timing. I do this by taking a Clock component and connecting it directly to an Interrupt component. On PSoC4 this doesn't appear to be possible. CyDsFit errors out with

   

Interrupt "SysTickIRQ" is driven with a logic low and the interrupt will never be asserted, the component will be removed.

   

This occurs no matter what interrupt "type" I select, although on PSoC5LP I leave it at the usual "derived" type. I'm using Clock component v2.20 and Interrupt component v1.70, which are the latest as far as I can tell. I'm also using PSoC Creator v3.0SP2.

   

 

   

I know that I can get around this by instantiating a Timer component and configuring it similarly but it's wasteful of the already limited resources on the PSoC4.

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4 Replies
Bob_Marlowe
Level 10
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There is a bit more hardware within a PSoC4: The Tick-timer. Look into the System Reference Guide for the APIs, search for "SysTick".

   

 

   

Bob

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odissey1
Level 9
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First comment on KBA 1000 replies posted 750 replies posted

@akohlsmith,

   

on PSoC4 clocks are  not allowed to connect to interrupt directly, you typically need to insert D flip-flop (DFF) in between, or frequency decimator.

   

odissey1

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ETRO_SSN583
Level 9
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The Systick Timer in PSOC 4 can generate an interrupt.

   

 

   

    

   

         

   

http://www.cypress.com/?id=4&rID=94607     PSOC 4 Systick

   

http://www.cypress.com/?docID=49253     AN90799 (Systick as well)

   

 

   

 

   

Regards, Dana.

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Anonymous
Not applicable

Thank you, Bob and Dana. I completely overlooked SysTick and it's exactly what I need!

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