[avr-libc-dev] Viewing registers while debugging (plus attachment)

[Ned Konz]

Just a helpful hint...

Another thing that the script I mentioned in my prior email (but  
didn't get around to attaching) is to spit out a linker file that  
defines the registers so you can do things like print them and set  
them symbolically from gdb.

p PORTA
p PORTA = 0xFF

x/20b &PORTA

etc.

This is very simple (and is something you can do by just linking a  
text file with your program). It just surprised me that no one seems  
to mention it when people complain about not seeing the registers in  
the debugger.

All I did was this:

I made a text file (which I named iom128.a) that contains defines for  
all the registers:

/* SFR memory addresses */
ACSR = 0x800028;
ADC = 0x800024;
ADCH = 0x800025;
ADCL = 0x800024;
ADCSR = 0x800026;
ADCSRA = 0x800026;
ADCW = 0x800024;
ADMUX = 0x800027;
ASSR = 0x800050;
DDRA = 0x80003a;
DDRB = 0x800037;
DDRC = 0x800034;

And I also came up with a slightly extended linker script (avr5.x),  
though I'm not sure that it's even needed (it's in the tarball). What  
it did was just to add two more regions that define the rest of the  
space:

MEMORY
{
  text   (rx)       : ORIGIN = 0x000000, LENGTH = 128K
  regs   (!a!irw!x) : ORIGIN = 0x800000, LENGTH = 0x20
  sfrs   (!a!irw!x) : ORIGIN = 0x800020, LENGTH = 0x40
  data   (rw!x)     : ORIGIN = 0x800060, LENGTH = 0xffa0
  eeprom (rw!x)     : ORIGIN = 0x810000, LENGTH = 64K
}

Then I added this to the linker line:

 -L. -T iom128.a -T avr5.x

which replaces the stock avr5.x with the concatenation of these two  
files.

Handy.

headerMods.tar.gz
Description: GNU Zip compressed data

--
Ned Konz
address@hidden