How to define persistent variables in IAR compiler for AVR

Hello,

I can't realize how to define persistent variables (that will be not reset after power up) in IAR compiler for AVR.

What I found in the manual is to use __no_init keyword before the definition of variable.

So...
__no_init char my_var;

should be declared like persistent variable.

When I compile the project I don't get errors, but when I link it I got the following:

Error[e16]: Segment NEAR_N (size: 0x1 align: 0) is too long for segment definition. At least 0x1 more bytes needed. The problem occurred while processing the segment placement command "-Z(DATA)NEAR_N=_..X_EXT_NV_BASE-_..X_EXT_NV_END", where at the moment of placement the available memory ranges were "-none-"


Please, can you explain what I'm doing wrong? I will be very thankful for any help, because I need badly to finish one project where I hav eto define persistent variable.

best regards
Luben

Re: How to define persistent variables in IAR compiler for A

Hi Luben,

I faced the same problems with IAR for AVR.

I think it wants to place _no_init variables into flash or eeprom and as it does not know where to put it you get this error??

I used __eeprom which worked for me but places the variable into EEPROM you could also use __flash to place it into flash memory.

There is no persistent keyword at IAR no idea why.

Hope this helps and best regards

Re: How to define persistent variables in IAR compiler for A

Hello,

Thank you for your reply.

Yes, maybe if I put the variable into EEPROM it will work, but unfortunately this is not exactly what i want.

I just want after reset occures to understand is it "hot" reset, I mean - when you bring low RESET line the chip goes to reset, but doesn't change the contents of variables. So, if I put into some variable some value (for example 0xAA) after the reset if I get read the same value that means I had "hot reset". This allows to do some opreations with reset.

But if I can't get other approach I'll do in this way.

Best regards
Luben

Re: How to define persistent variables in IAR compiler for A

Yes I know what you mean, I am using this "trick" myself using Keil and Hi-Tech compilers but could not find a way in IAR except __eeprom or __flash.

No idea why IAR does not support the persistant keyword :-(

best regards and good luck for your project

Re: How to define persistent variables in IAR compiler for A

Dear All,

I had the same problem, but I manage to solve it:

You can use the Keyword __no_init, but the memory model needs to be Tiny bot Small.

I took me ages to find this. Unfortunately it is hard to find good advance documentation on IAR AVR.

Samuel