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AM1808 EMIFA Clock

Inderjit Bains
Expert 2745 points
Other Parts Discussed in Thread: OMAP-L138

Where does the EMIFA Clock get set?  Is it in UBL, U-Boot, or Linux?  I'm using am180x-evm-sdk-src-05.05.00.00, with OMAP-L138_FlashAndBootUtils_2_40.  For this combination, what is the EMIFA Clock frequency?  There is a spreadsheet available for calculating the NAND controller register values, but it assumes an EMIFA clock frequency of 100MHz:

http://processors.wiki.ti.com/index.php/Programming_Asynchronous_EMIF_on_OMAP-L13x_/_C674x_/_AM1x

  • 0
    TI__Guru** 116170 points

    Generally the EMIFA clock frequency is setup by the AIS Gen utility that converts the UBL to a .bin file but this configuration can be changed in the UBL, Uboot or linux. By default EMIFA frequency is sourced from SYSCLK3 (CPU_freq/3) so for operating point of 300Mhz this turns out to be 100Mhz. Look at the device clocking and PLLC chapter in the AM180x TRM to find out how to configure the peripheral clocks.

    If you have an emulator, you can connect to the device after the device has booted to see the PLL settings and determine the EMIF clock.

    Regards,

    Rahul

  • 0 in reply to Rahul Prabhu
    Expert 2745 points

    The CPU is 456 MHz.  Without any modifications to the UBL, U-Boot, or Linux code with regards to the PLLC registers, what is the EMIFA clock with the versions listed above?

  • 0 in reply to Inderjit Bains
    TI__Genius 10440 points

    Inderjit,

    Based on Rahul's response the EMIFA clock defaults to CPUfreq/3. So, without any modification and a CPU clock at 456 MHz your EMIFA clock should be 456/3 MHz (152 MHz). To verify this you can connect to the device with an emulator after boot and check the PLL settings as Rahul suggested.

    Thanks,

    Jason Reeder