Re: Conceptual understanding of IOC software architecture

[Eric Norum <wenorum@lbl.gov>]

Right.  Keep in mind also that very few EPICS routines are allowed be called from an actual hardware interrupt service routine.  In particular, none of the ASYN ‘interrupt’ xxxxxxInterrupt->callback routines  can be called from an interrupt service routine.  Instead the hardware interrupt service routine must activate a thread (one of the standard EPICS callback threads or a custom driver-specific one) and then this thread will invoke the ASYN xxxxxxInterrupt->callback routine(s) to push the values into records.

On Jun 5, 2014, at 7:36 AM, Mooney, Tim M. <mooney@aps.anl.gov> wrote:

Hi Diego,

The word "interrupt" is used to mean different things at different levels of description.  In the asynDriver documentation (http://www.aps.anl.gov/epics/modules/soft/asyn/R4-22/asynDriver.html) you'll find the quote 'Interrupt just means: "I have a new value." '  In the section of the EPICS Application Developer's Guide you mentioned, "interrupt" means "actual interrupt signal from the hardware."

When an asyn client registers to receive interrupts, it's asking to be called when the driver has a new value, whether that value came from a hardware interrupt, or from the driver's polling of the hardware.

Tim Mooney

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From: tech-talk-bounces@aps.anl.gov [tech-talk-bounces@aps.anl.gov] on behalf of Diego Sanz [dshernan80@gmail.com]
Sent: Thursday, June 05, 2014 8:49 AM
To: tech-talk@aps.anl.gov
Subject: Conceptual understanding of IOC software architecture

Hello everyone,

Reviewing EPICS Application Developer's Guide, I have noted some point in the figure contained in chapter 3, point 3.3 (IOC Software componentes) that let me a little bit confused. I am refering to the box "Driver or Device Interrupt Routines", that interconnects directly the line (VME) with the box "scanners". I have implemented some Epics Device support for RIO/FlexRIO devices using AsynDriver, and the way I have implemented is using interrupt calls, that in the upper layer of the asynDriver, are epics device standard docallback interrupts. This software layer I'll integrate in the box "Device Suport"... but then I don't know what the box "Driver or Device Interrupt Routines" refers to. Does It means that there is other ways in EPICS to implement pices of code that generate interrupts on the EPICS Core? Could someone explain or refering me to some document that explain this?

Thank you very much

Regards

-- 
Eric Norum
wenorum@lbl.gov