MPC5744P: TBL (Time Base Low) not accessible

[markpiffer]

Is the TB core register implemented in this MCU at all? I keep getting an exception when trying to do a "mftbl r3" in inline assembly.

Also, trying to set the TBEN bit in HID0 didn't work either, the register bit remains unset when trying to write it to 1. The Lauterbach debugger doesn't even display the TBEN bit in HID0, so is it there at all?

regards,

Mark

[nxppower912935]

What is the best way to assess fine-resolution timing characteristics of code and peripheral actions then, on this core?

From what I read, this question is still pending to be answered...?!

Any suggestions?

KR

[PetrS · Accepted solution]

Hi,

MPC5744P does not have the Time base module implemented in the core.

BR, Petr

[markpiffer]

Hohum... I wonder what a standard like the PPC Architecture Books are for, then. There is no hint in any of the documents, on the contrary, the e200z4 core documents explizitly mention the Time Base and even the Alternate Time Base (ATB) registers.

What is the best way to assess fine-resolution timing characteristics of code and peripheral actions then, on this core?

[rweiss]

You have to look at the core name more closely.

MPC5748G has the cores e200z210n3 and e200z4204n3, which don't have a timebase support.

In MPC56XX processors you'll find e200z4d (MPC5643L) or e200z448n3 (MPC5644A), which include timebase support.

[markpiffer]

And the core names help what exactly? There is neither a document describing the core nor is there a mention of the missing TB in the AN4802 (Core differences). And leaving out such a basic register (contradicting every conceivable meaning of PowerPC *standard*) is IMHO a flawed (engineering) decision :smileyangry:

[alexvinchev]

Implementation of cores is dependent on feature set implemented for certain core revision. For example on MPC5748G I was looking for DEC/DECAR (spr22/spr54), as they are defined in e200z4RM, but amazingly, they are not present in z4 core implementation, built in MPC5748G. While comparing picture, shown on page 2876 of MPC5748GRM with page 8 of e200z4RM became obvious that DEC/DECAR are not implemented at all in my MCU... In other words, look thoroughly your documentation and compare pictures present there with the ones in e200z4RM. This will give you idea what is implemented and what is not... In my case absence is because supervisor feature set (if I remember well) is not implemented. On second look today, TBx is also absent in this core as well as PSU registers for example...

I don't have access to MPC5744PRM to check if this is your case as well...