SEMC_CLK_ROOT divider question

[EdSutter]

Referring to iMXRT1060 Reference manual CCM Clock Tree...

The diagram shows a divide-by-3 function that supposedly is in the CBCDR register.

It refers to CBCDR[AXI_PODF] field, but the description of the CBCDR register doesn't have any AXI_PODF field.  Does this divide-by-3 block exist?  If so what register is it controlled in?

Ed

[mjbcswitzerland]

Hi Ed

I am pretty sure that the 105x..106x user's manuals mix up the names in this register, whereas the 1021 has of correctly.

The AXI_CLK_ROOT is "also" called SEMC_CLK_ROOT and there are three fields in that register that control this path. In the clock root generator they are referred to as
axi_alt_clk_sel, axi_clk_sel and axi_podf

but in the register description the are named
SEMC_ALT_CLK_SEL, SEMC_CLK_SEL and SEMC_PODF

I have used these on 1021, 1052, 1062 and 1064 to control the path and also SDK examples use these names in their header files.

Therefore I think the diagrams in the 1050 and 106x user's manuals are a bit at fault since they use the AXI name instead of the SEMC name, which then doesn't correctly match with the actual register field names.

Regards

Mark
[uTasker project developer for Kinetis and i.MX RT]
Contact me by personal message or on the uTasker web site to discuss professional training, solutions to problems or product development requirements

[EdSutter]

Thanks Mark,

Just to be clear, in the case of the 1062's clock tree diagram, when looking at the clock tree..

AXI_PODF should be replaced with SEMC_PODF.  

Correct?

[mjbcswitzerland · Accepted solution]

Ed

This is how it looks in the 1021 user's manual:

And in the Clock Root Generator section

Compared with the 1052/1062/1064 diagram:

As can be seen both feed AXI_CLK_ROOT, AKA SEMC_CLK_ROOT but for some reason the 1052/1062/1064 version has the register mask names set to axi rather than semc.

All occurrences of AXI_ in the CBCDR register should therefore be SEMC_ (so yes, replacing AXI_PODF with SEMC_PODF is the solution).

Regards

Mark