IMX 6 Solo Free run Clock

[DK4509]

Hi,

Currently, we are designing the MCIMX6S5EVM10AD part number IMX 6 Solo CPU.

Question - 1

We planned to use the Input reference clock to the ACLK pin (EIM_ACLK_FREERUN) 104MHz to enable the EIM module.

Whether it is mandatory to source the external clock 104MHz to the ACLK clock to drive/enable the BCLK which it act as a reference clock for CPLD?

Please confirm once on the above point.

Question - 2 

If so, we placed crystal oscillator externally to generate 104MHz continously is there any impact on BCLK genertaion.

Because there are few steps to enable the BCLK to work as in Synchronous mode, in that first step Disable the EIM clock was mentioned in the datasheet.

If we are using external cryctal oscillator the clock should be continous then the first step is not matching as per the datasheet recommendation. please confirm whether it is prefered to use the crystal oscillator externally for ACLK pin. Please suggest your comments.

Thanks,
Dinesh

[Sanket_Parekh]

Hello @DK4509 

I hope you are doing well.

->Yes, It is mandatory to source the external clock (EIM clock max = 133MHz) to the ACLK clock to enable the BCLK.
-As it is seen from the diagram ACLK expects input from an external source then the output will be got from the BCLK side.

->There will not be any impact on BCLK generation if one has used a 104 MHz external crystal oscillator, Because as it is seen in the diagram BCLK generation depends upon 2 major things, first is ACLK & second is bit configuration that is set to the synchronous or asynchronous core, So one can have the output based on the settings that are made.
-In section 22.5.1 as suggested, to let EIM work properly under continuous BCLK MODE, the initialization must follow the below procedure.

The recommended initialize flow is as follows
1. Disable the EIM clock by clearing bit 4 of the EIM_WIAR Register.
2. Select Continuous BCLK by setting bit 3 of the EIM_WCR Register.
3. Enable DLL by setting bit 0 of the EIM_DCR Register.
4. Enable the EIM clock by setting bit 4 of the EIM_WIAR Register.
5. Reset DLL by toggling bit 1 of EIM_DCR Register(1->0->1).
6. Wait for DLL lock (Both bit 0 and bit 1 of EIM_DSR Register are asserted).
After initialization, EIM can be programmed to various access timing, but BCD MUST be kept to 0.

-for more detail please refer to the reference manual, I've shared the link for the same, please find the same.
https://www.nxp.com/webapp/Download?colCode=IMX6SDLRM

Thanks & Regards

Sanket Parekh