i.MX6UL: CCM_CLKO2 arm_clk_root on SD1_DATA2 pad

[michaelschell]

Hello, we are using the i.MX6UL platform and I need to observe the arm_root_clk on CCM_CLKO2 on the SD1_DATA2 pad as detailed in the RM.  We are doing this because we need a visual representation of our operating frequency.  My settings are as follows:

CCM Clock Output Source Register (CCM_CCOSR) (0x20C_4060h)

     - set to value 0x018a0100

     - this selects arm_root_clk for CLKO2 with divider of 5

SW_MUX_CTL_PAD_SD1_DATA3 SW MUX Control Register (IOMUXC_SW_MUX_CTL_PAD_SD1_DATA3) (0x20E_01D0h)

     - set to value 0x00000006

          - this selects ALT6 mode for CCM_CLKO2

SW_PAD_CTL_PAD_SD1_DATA3 SW PAD Control Register (IOMUXC_SW_PAD_CTL_PAD_SD1_DATA3) (0x20E_045Ch)

     - set to value 0x0001F0D9

          - this sets 200Mhz max pad freq

With these setting I am unable to see a clock on SD1_DATA2.  If I change CCM_CCOSR to 0x010e0000 I will see the 24Mhz osc_clk correctly.  I can also seem to see all other CLKO2 clocks - just not the one I need.

Is there something further I need to do to view the arm_clk_root clock?

[igorpadykov · Accepted solution]

Hi michaelschell

unfortunately i.MX6UL has not selection CLKO2_SEL= 01010 arm_clk_root,

it is reserved :

i.MX6UL Reference Manual

http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6ULRM.pdf

Best regards

igor

-----------------------------------------------------------------------------------------------------------------------

Note: If this post answers your question, please click the Correct Answer button. Thank you!

-----------------------------------------------------------------------------------------------------------------------

[michaelschell]

Thanks so much igor.  Im clearly using the wrong version of the i.MX6UL reference manual.  Mine does not show that value (01010) as reserved but instead specifies it for arm_clk_root.  Ill move forward with this version of the RM.  To your knowledge then, for the i.MX6UL, is there no way to export the arm clock (cpu clock rate) off chip?