Can't understand assembly?

Lykos1986 · Joined: 26 Nov 2005 Posts: 68

Hi! I was creating a little bit of code and I wanted to use assembly language in different section of my firmware.

It seems that CCS (version 4.140) can't understand this code! For example I am writing:

temtronic · Posted: Wed Jul 17, 2013 11:01 am

It doesn't like the ...

mov.w ........... opcode.

I checked the 18F46k22 instruction set and mov.w is not there so you should tell us which PIC you're using.
It may be a valid opcode for your PIC that the compiler can't figure out due to a bug?

hth
jay

Lykos1986 · Joined: 26 Nov 2005 Posts: 68

I am using the 24F32KA304.

Basically I haven't used assembly language for more than 6 years now.
But because I am using MpLab (with CCS compiler plugin) I've compile a CCS example and then looked at the Disassembly Listing provided from the MpLab in order to understand what is going on with a problem I am facing.

The Disassembly Listing was using exactly this type of assembly language that it is diferent from the one I've learned for the PIC microcontrollers. Then I download a couple of manuals and start learning this instruction set believing that this is the correct one for PICs nowadays.

It seams that this instruction set is more for x86 architectures... but somehow it is the one that MpLab understands.

temtronic · Posted: Wed Jul 17, 2013 2:47 pm

Sorry, I don't use the 24 series PICs so I'm not familiar with their opcodes, but if 'mov.w' is correct, then it sounds more like a bug in the compiler version you're using.
Someone that use the 24s probably knows..

Ttelmah · Joined: 11 Mar 2010 Posts: 19349

It isn't.
The PCD manual will list the opcodes. mov, and mov.d. Not mov.w.
Though CCS doesn't use Microchip assembler, the data sheet also does not give mov.w. Only the PIC33 chips have this instruction.

Best Wishes

Lykos1986 · Joined: 26 Nov 2005 Posts: 68

If only the PIC33 chips have these instructions why the Disassembly Listing of a 24F PIC with CCS compiler is using only those instruction (mov.w) from top to bottom?

Ttelmah · Joined: 11 Mar 2010 Posts: 19349

They use mov.w as the displayed mnemonic for mov.d. I know it is insane. Look at the list in the manual for the supported instructions.
This happens with the other chips as well. The 'asm' they generate, can not be typed in as 'input assembler'.....
You could close to what you seem to want by just word definitions and C.

Best Wishes

Lykos1986 · Joined: 26 Nov 2005 Posts: 68

Ok, I will try the old good assembly instructions and hopefully I will have good results.

Many thanks for your answers and your help!