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PSoC Creator & Designer Software

Esteemed Contributor

In the component datasheet there is this at beginning -




 Level – IRQ source is sticky and remains active until firmware clears the source of the
request with an action (for example, clear on read). Most fixed-function peripherals have
level-sensitive interrupts, including the UDB FIFOs and status registers.




In the application note AN54460 a much better description -




  LEVEL: This option routes the interrupt source through the direct path in the DSI interface, as Figure 9 on page 6 shows.
Select this option for interrupt sources that you want to be level-triggered, for example UDB-based Components such as
UART, SPI, timer, counter, and PWM.


Note Select only the LEVEL option for interrupts generated by UDB-based components such as UART and SPI. The reason is
that these components generate a level interrupt to indicate the UDB FIFO buffer status signal. The FIFO buffer, which is
4 bytes deep, is used to temporarily store data to be transmitted (Tx FIFO) or received (Rx FIFO).




I think datasheet should reflect the content of both, eg. sticky and the components that have to have a LEVEL


setting. Further a complete table of what components can use what interrupt settings.




Ideally Creator should flag when  a user connects isr component to another component that


wants a LEVEL configured isr. No shortage of confusion over this.




Lastly one of the selections is DERIVED. Call me stupid but this leads me to always believe that


tool was smart enough to assign the right default for the component source for the isr. That is the


way it is described. Of course nothing could be further from the truth. So the word "DERIVED"


seems inadequately described in the isr component datasheet and above referenced ap note.






Regards, Dana.

1 Reply

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