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Re: [avr-libc-dev] [bug #12941] Table of Signal Names in "Interrupts and

From: Rolf Ebert
Subject: Re: [avr-libc-dev] [bug #12941] Table of Signal Names in "Interrupts and Signals" is wrong/incomplete
Date: Fri, 06 May 2005 20:35:46 +0200
User-agent: Opera M2/7.54 (Win32, build 3929)

On Thu, 5 May 2005 08:33:45 +1100, Dmitry K. <address@hidden> wrote:

On Wednesday 04 May 2005 08:26, Rolf Ebert wrote:

* the interrupt short names in the XML files sometimes contain funny
characters that cannot be part of an identifier. I replace all of comma,
blank, or slash to underscores in the Python script.  I don't know why
Atmel created interrupt names containing these characters in the first


First, the speech is about INTERRUPT SERVICE ROUTINES names. Not about of
electrical signals or human readable designations.

Yes, that's what I was talking about. Excuse my sloppy wording.

Let us look ATtiny2313 datasheet (next page after Table 21).
ISR names differ from specified above:
    rjmp   INT0
    rjmp   TIM1_CAPT
    rjmp   TIM1_OVF

This is sample assembler code. In assembler you can use whatever name pleases you. The rjmp labels are not related in any way to the names of the interrupts. Perhaps that is what you wanted to say above.

gcc doesn't have the same freedom for choosing names of the interrupt service routines. Their internal names are fixed to __vector_<xx> anyway. The corresponding io header file predefines the names that are to be used in "SIGNAL(<name>)". Certainly it makes sense to call the ISR the same as the triggering interrupt. AVR libc prepends SIG_ to all names, it could as well append _HANDLER, that's not the point.

I still think the ISR name should be based on the documented (in the Atmel data sheets) interrupt names. The XML for the three mentioned interrupts of attiny2313 reads:

 <DEFINITION>External Interrupt Request 0</DEFINITION>
 <DEFINITION>Timer/Counter1 Capture Event</DEFINITION>
 <DEFINITION>Timer/Counter1 Overflow</DEFINITION>

Note the blanks in the values of SOURCE of vector4 and vector6.

The Atmel assembler include file (AvrAssembler/Appnotes/tn2313def.inc) reads:

.equ    INT0addr        = 0x001     ;External Interrupt0
.equ    ICP1addr        = 0x003     ;Input capture interrupt 1
.equ    OVF1addr        = 0x005     ;Overflow1 Interrupt

It claims to be autogenerated from the XML file. Although, I don't know which algorithm generates "OVF1addr" from the XML info above...

Certainly, it would be good to use names from Atmel's datasheets from the
first. But, unfortunately, Atmel is very inaccurate in ISR's names.
Identical subroutines have different names for different chips (for example, EE_RDY in AT90S4433 and EE_READY in ATtiny2313). Sometimes the name clashes
with other identificators (INT0 above).


It won't clash with a prefix like SIG_ to all names, as it is right now.

Different names for different chips triggered by the same interrupt is another topic. Personally, as a programmer I'd rather look up the name of an identifier in the doc, i.e. data sheet, than to guess the name from another chip. But then, there are projects that want to use a single piece of code for several chips and it isn't beautiful to have #ifdefs all over the place.


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