topic R1 register reading in MPC5xxx

R1 register reading

abdelrhman — Mon, 13 Mar 2023 12:57:34 GMT

Hi all,

How to read or access a general register R1 in MPC5744P micro-controller?
Thanks

jiri_kral — Mon, 13 Mar 2023 18:20:33 GMT

Hi,

I'm not sure what you mean, but R1 is general purpose register and can be normally used as any other register in assembly code.

Can you please share more details?

abdelrhman — Tue, 14 Mar 2023 09:25:49 GMT

yes I meant that
but the question
Is there a memory mapped address for register R1 instead of using assembly code for accessing it?

jiri_kral — Tue, 14 Mar 2023 10:15:31 GMT

Hi,

I see. Yes, you can assign register to a variable like this:

abdelrhman — Tue, 14 Mar 2023 11:34:21 GMT

I defined a variable like this but it raises the following error
expected '=', ',', ';', 'asm' or '__attribute__' before 'asm'

jiri_kral — Tue, 14 Mar 2023 12:09:41 GMT

Can you please share the code snippet with variable definition? For me it is working normally (tested with MPC5744P).

jiri_kral — Tue, 14 Mar 2023 12:15:10 GMT

Um, I'm not sure which compiler do you use. This is working only with gcc, not with diab or GHS.

jiri_kral — Tue, 14 Mar 2023 12:21:15 GMT

For reference - here is my test project.

abdelrhman — Tue, 14 Mar 2023 13:31:32 GMT

This is my project
it is just an example

jiri_kral — Tue, 14 Mar 2023 13:59:55 GMT

this construction can be used with the S32DS default C standard, not with C99.

Anyway, this technique is almost unusable and deprecated because of optimization. Can you describe in more details what is your goal?

abdelrhman — Tue, 14 Mar 2023 15:19:36 GMT

My goal is to implement a function to monitor the value of R1 register in run time, then import this function to be used in a simulink model.