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  VS Arduino › › › PROGMEM F() macro warning
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Very Hot Topic (More than 25 Replies) PROGMEM F() macro warning (Read 24303 times)
nevereven
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PROGMEM F() macro warning
Jan 5th, 2015 at 11:58pm
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I've done some searching and I can find some old messages relating to this issue, but nothing in the last two years.

I'm using the F() macro extensively to store strings in PROGMEM rather than RAM. Unfortunately, these each generate a warning:
"warning: only initialized variables can be placed into program memory area"

I'm getting 98 of these in my current project which makes finding genuine errors difficult. Is there a fix or workaround?
« Last Edit: Jan 6th, 2015 at 12:00am by nevereven »  
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Tim@Visual Micro
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Re: PROGMEM F() macro warning
Reply #1 - Jan 6th, 2015 at 12:26pm
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Hi,

You will only see the warning if you have switched on verbose or show warnings using the tools>visual micro menu.

I have seen this warning in many arduino projects. I am surprised arduino have allowed their code to produce the warning because the F() option is used so frequently and is very useful.

Actaully I was looking at another users project a few days ago and hit the same issue so I am considering having visual micro ignore the warning and not display it in the output window.

Thanks
  
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nevereven
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Re: PROGMEM F() macro warning
Reply #2 - Jan 6th, 2015 at 2:01pm
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I find some of the other verbose warnings useful so I wouldn't want to turn them off completely. Some way to filter these particular warnings out as a project property would probably be a better workaround.
  
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Tim@Visual Micro
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Re: PROGMEM F() macro warning
Reply #3 - Jan 6th, 2015 at 2:02pm
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Yes good idea, maybe a tools>options property that you can set for yourself

I will add it to the list.
  
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Tim@Visual Micro
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Re: PROGMEM F() macro warning
Reply #4 - Jan 11th, 2015 at 3:05am
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please test in the latest beta 1412.10 sp4

Thanks
  
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nevereven
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Re: PROGMEM F() macro warning
Reply #5 - Jan 11th, 2015 at 3:32am
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Wow,

Cheesy That's great!!!!

This will make errors and real warnings so much easier to find.

Thanks!

I'm slowly learning my way around the software. The learning curve is daunting, but in 10 years of trying, this is the first IDE I've stuck with.
  
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Tim@Visual Micro
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Re: PROGMEM F() macro warning
Reply #6 - Jan 11th, 2015 at 3:39am
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Thanks for the quick feedback, good to know it works better.
  
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nevereven
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Re: PROGMEM F() macro warning
Reply #7 - Jan 28th, 2015 at 8:30pm
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Was this un-fixed in the latest release?

I see that 1412.10 sp4 has "Redfined F for intellisense purposes" but was this un-fixed by 1412.10 sp6 "Fix: Ensure that all compiler error messages are shown in the output window!!".

I'm still getting many "only initialized variables can be placed into program memory area" warnings from my F(). 

Is there an option I need to change?

Thanks
  
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Tim@Visual Micro
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Re: PROGMEM F() macro warning
Reply #8 - Jan 28th, 2015 at 10:22pm
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Hi,

The fix was that the F() function had red squiggles and was reported by intellisense as being an error which was confusing.

The "only initialized variables can be placed into program memory area" is a valid and correct compiler warning that was missing along with a few other warnings in the previous release. It is correct that the use of F() causes this compiler error and correct for Visual Micro to show it. The issue is also evident in the Arduino ide if you switch on verbose compile as you have done in Visual Micro.

Does this make sense or have I missed the point?

Thanks
  
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Serenifly
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Re: PROGMEM F() macro warning
Reply #9 - Jan 28th, 2015 at 11:45pm
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This is really a bug in the ancient version of the gcc compiler that comes with older Arduino versions. The warning shouldn't appear, but the bug generates it.

Download Arduino 1.5.7 or 1.5.8 and it's gone.

But note that the newer gcc version requires data in PROGMEM space to be const now. And arrays of C strings need to be const * const (const pointer to const data). There were some libraries that didn't do this (Time and UTFT for me), but current versions have that fixed.
« Last Edit: Jan 28th, 2015 at 11:48pm by Serenifly »  
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nevereven
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Re: PROGMEM F() macro warning
Reply #10 - Jan 29th, 2015 at 1:31am
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Thanks, I'll try 1.5.8. Are there any downsides to the newer version?
  
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nevereven
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Re: PROGMEM F() macro warning
Reply #11 - Jan 29th, 2015 at 1:52am
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I tried compiling with 1.5.8 but get this error which means nothing to me.

ibc.a(isspace.o)*:In function `isspace'
(.text.avr-libc+0x2)*:relocation truncated to fit: R_AVR_13_PCREL against symbol `__ctype_isfalse' defined in .text.avr-libc section in vr6\libc.a(cty_isfalse.o)
collect2*:error: ld returned 1 exit status
Error creating .elf
  
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Serenifly
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Re: PROGMEM F() macro warning
Reply #12 - Jan 29th, 2015 at 2:53am
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All I can tell is that it's an error from the linker, but I don't know what causes it

I didn't have any real issues with either 1.5.7 or 1.5.8. As said you may need to update some libraries that don't use const correctly when declaring PROGMEM constants, but you will notice that.

Besides finally updating the AVR toolchain, there are also lots of other improvements. For example with the Serial class. So it's worth it.
  
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Tim@Visual Micro
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Re: PROGMEM F() macro warning
Reply #13 - Jan 29th, 2015 at 1:09pm
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Serenifly is right and thanks for the useful info!

1.5.x is looking good but it does seem to break many projects. Sadly, I suspect that non-experts will stick with 1.0.x for a year or so for this reason.

It might help to know that I am looking at some sort of warning filter allowing users to ignore certainly warnings.

Thanks again Serenifly
  
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nevereven
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Re: PROGMEM F() macro warning
Reply #14 - Jan 29th, 2015 at 3:25pm
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A minor issue, when I switch from Arduino 1.0.x top 1.5.x and back, it forgets what kind of board I'm using.
  
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Tim@Visual Micro
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Re: PROGMEM F() macro warning
Reply #15 - Jan 29th, 2015 at 3:46pm
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Yes I know, it's only the list thanks
  
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Serenifly
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Re: PROGMEM F() macro warning
Reply #16 - Jan 29th, 2015 at 6:50pm
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Someone posted a workaround on the Arduino Forum. I haven't tried that though:
http://forum.arduino.cc/index.php/topic,85840.0.html
  
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nevereven
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Re: PROGMEM F() macro warning
Reply #17 - Feb 8th, 2015 at 5:59pm
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nevereven wrote on Jan 29th, 2015 at 1:52am:
I tried compiling with 1.5.8 but get this error which means nothing to me.

ibc.a(isspace.o)*:In function `isspace'
(.text.avr-libc+0x2)*:relocation truncated to fit: R_AVR_13_PCREL against symbol `__ctype_isfalse' defined in .text.avr-libc section in vr6\libc.a(cty_isfalse.o)
collect2*:error: ld returned 1 exit status
Error creating .elf


So there's a very interesting post about this on Stack Overflow.

The theory is that it has to do with the linker using rjmp and rcall rather than jmp and call. There is a 4k limit on relative jump/call and sometimes the linker exceeds this. The solution is:

Quote:
You have to let the compiler know that it needs to generate JMP/CALL instructions instead of the (more efficient) RJMP/RCALL instructions. In AVR Studio/Atmel Studio this can be done in the project's properties, toolchain, AVR/GNU C compiler, optimization. The relevant option is "Use rjmp/rcall (limited range) on >8k devices (-mshort-calls)" which needs to be unchecked to prevent the named error.
As the label indicates, the relevant command line option is -mshort-calls which needs to be removed from the gcc command line parameter list to achieve the same when invoking gcc from outside of the IDE.


Unfortunately this didn't seem to make any difference to me and I get the same error either way.
  
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Re: PROGMEM F() macro warning
Reply #18 - Feb 8th, 2015 at 6:01pm
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if you are using visual micro to compile then you need to change the arduino ide hardware\avr\platform.txt or sam\platform.txt. The atmel project properties are currently unused for arduino
  
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nevereven
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Re: PROGMEM F() macro warning
Reply #19 - Feb 8th, 2015 at 9:26pm
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Thanks. I looked in platform.txt and boards.txt and didn't see any reference to -mshort-calls to remove, so I'm stuck again. Perhaps this isn't the problem.
  
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