How to find Register Addresses

Alexander Kolot

Can you please tell me how to find out the address of the register of the PC counter, the SR status register and the SFR registers?

over 6 years ago

0 JD Crutchfield over 6 years ago

TI__Mastermind 29105 points

Hello Alex,

What device are you looking at? Register addresses would be located in the device datasheet. You can find SFR's address here.

The PC, SP, and SR registers don't have memory addresses as they are internal registers of the CPU. You would address them directly by name.

Thanks,
JD

0 Keith Barkley over 6 years ago

Guru 42085 points

If you mean a table like this:

As was pointed out these are only for the peripherals, not the ARM Core, where you just use the name of the register to refer to it.

0 Alexander Kolot over 6 years ago in reply to JD Crutchfield

Prodigy 160 points

Thanks for the reply, I am reviewing slau144j.pdf. I'm trying to create a complete table of command codes.
But in the code table it is not clear how the complete command code is formed. What command to write the address in the register PC? Which team read the contents of the SR register?
Thank.

0 Alexander Kolot over 6 years ago in reply to Keith Barkley

Prodigy 160 points

Thanks for the reply, but I'm studying MSP430 slau144j.pdf. I'm trying to create a complete table of command codes.
But in the code table it is not clear how the complete command code is formed. What command to write the address in the register PC? Which team read the contents of the SR register?
Thank.

0 JD Crutchfield over 6 years ago in reply to Alexander Kolot

TI__Mastermind 29105 points

Hey Alexander,

Are you working in C or assembly? Also, I can't think of a time where you would ever directly write an address to the PC.

I'm not sure which MSP you are looking at, but there are both C and Assumbly code examples for all MSP430F2xxx here: dev.ti.com/.../node

Thanks,
JD

0 Tomasz Kocon over 6 years ago

Guru 26200 points

Alex,

some CPU/MCU architectures have physical address for all registers.
According to JD, MSP430 does not provide this feature.

However, you can do direct operations on PC register like the following:
MOV #LABEL,PC ; Branch to address LABEL
MOV LABEL,PC ; Branch to the address contained in address LABEL
MOV @R14,PC ; Branch indirect, indirect R14

For more info. on MSP430 registers check this: www.ti.com/.../chp9.pdf

0 Alexander Kolot over 6 years ago in reply to JD Crutchfield

Prodigy 160 points

Thanks for the answer, I do not work either in C or in assembler, in this case. I want to make a complete tab of machine codes for programming in machine codes.

0 Alexander Kolot over 6 years ago in reply to Tomasz Kocon

Prodigy 160 points

0 Tomasz Kocon over 6 years ago in reply to Alexander Kolot

Guru 26200 points

www.ti.com/.../slau367o.pdf
Check CPUX chapter.

0 Alexander Kolot over 6 years ago in reply to Tomasz Kocon

Prodigy 160 points

Nowhere in the documentation is not specified, but I seem to have guessed: in the command format, 2 fields of 4 bits are allocated for registers. There are only 16 registers, we translate the decimal number of the register into a binary number, this will be the 4-bit code of the destination register or the source register. I understood correctly?

0 Tomasz Kocon over 6 years ago in reply to Alexander Kolot

Guru 26200 points

Probably you are right.
I do not know, sorry.

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How to find Register Addresses