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DM36x CLKOUT0 and CLKOUT1 and CLKOUT2 enable procedure, includes example for Gel file hotmenus

Miguel A. Alanis
Genius 9490 points

E2E DM36x Community,

Here's a procedure that can come in handy in the case that you would want to use the CLKOUT0,  CLKOUT1 or CLKOUT2 in DM36x.  

hotmenu Clkout0_driver()
{
 *(unsigned int *)0x01C40048 &= 0xFFFFFFFE; // Enable CLKOUT0 driver
 *(unsigned int *)0x01C40010 |= 0x00300000;   // GIO37 will act as CLKOUT0
 *(unsigned int *)0x01C40000 |= 0x00008000;  // GIO 93 as CLKOUT0 
 *(unsigned int *)0x01C40948 |= 0x00000002;      // OBS CLK enabled 
 *(unsigned int *)0x01C40904 =  0x00000000;       // Oscillator divider output enabled
 *(unsigned int *)0x01C40924 =  0x00008001;  // Expecting 12 Mhz clock
 GEL_TextOut(" Clkout 0 enabled \n");
}  

hotmenu Clkout1_driver()
{
 *(unsigned int *)0x01C40048 &= 0xFFFFFFFD; // Enable CLKOUT1 driver
 *(unsigned int *)0x01C40010 |= 0x30000;    // GIO35 will act as CLKOUT1
 *(unsigned int *)0x01C40D48 |= 0x2;     // OBS CLK enabled
 *(unsigned int *)0x01C40D04 =  0x00;       // Oscillator divider output enabled
 *(unsigned int *)0x01C40D24 =  0x8001;  // Expecting 12 Mhz clock
 GEL_TextOut(" Clkout 1 enabled \n");
} 

hotmenu Clkout2_driver()
{
 *(unsigned int *)0x01C40048 &= 0xFFFFFFFB; // Enable CLKOUT2 driver
 *(unsigned int *)0x01C40010 |= 0x00000300;    // GIO31 will act as CLKOUT2
 *(unsigned int *)0x01C40904 =  0x00;       // Oscillator divider output enabled
 *(unsigned int *)0x01C40924 =  0x8001;  //  Default value  observed on CLKOUT2 will be PLLC1_VCO/(((SYSCLK99 +1)*16))- 15 Mhz clock (using 24Mhz crystal)
 GEL_TextOut(" Clkout 2 enabled \n");
}

  • Intellectual 260 points

    How to modify the default CLKOUT1 frequency, how make it output 37.125MHz?

    Any reply will be appreciated.

  • in reply to jason
    Prodigy 10 points

    Hi. I'm calling this code from my linux board init function and DM368 fails to produce the clock on either GIO37 or GIO93.

    If I unplug the jumper cable from the Leopardboard DM368 I'm testing this with and plug it into a signal generator supplying a clock of 24MHz, I can I2C (SCCB) to the CMOS sensor. With DM368 supplying the clock, the CMOS sensor doesn't respond.

    Is there something else I need to setup before I can get the clock out of CLKOUT0 (GIO37/GIO93)?

    Should I set up the direction register for those pins (GPIOs)?

    PS. I do not have the proper tools to measure clocks, but I'm using a microcontroller capable of counting edges and a multimeter (expecting it to show the mean).