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Sorry - I am not sure what exactly you are looking for [:(] More information on your system will be helpful to answer your question - what harwdare platform are you using? Are you looking for hardware reset circuits? if so, control card or eZdsp board schematic will provide you the circuitry. If you are looking for code to setup PLL and clock correctly then look at example software provided by TI.

I am sorry for not being clear. I wrote a simple program in which I am toggling a GPIO in a forever loop. Usually on an 8051 the program would yeild a square wave with one half the frequency of the SYSCLK since toggling is a one cycle instruction. Here with TMS320F2808, the program is giving a square wave whoose frequency is 780kHz which is 72 times less than the expected value of 50MHz (since the SYSCLK is 100MHz). So I wanted to look at the SYSCLK to check for the CPU frequency. The documentation on this chip suggested me that I can look at the SYSCLK using XCLK register. In order to activate this register we need to activate the reset pin. RESET can be activated using watchdog timer (in which the system is reset only for 512 OSSCLK cycles), so the other way is to set the XRS pin externally on the circuit board. The problem is that when I checked the circuit diagram of the TMS320C2000 docking station there is no pin which says XRS, the pins available are either GPIOs or ADCs. So I was looking for a way to check whether the CPU is running at 100MHz. I hope it is clear now. By the way thank you Mohammad.

I am little rusty on this but I believe (check 2808 datasheet) XCLKOUT pin is not multiplexed and you should be able to see clockout at a frequency depending on your XCLKOUTDIV setting. At reset your clockout should be 1/4 of sysclock. I recommend you to first try example projects provided with header files and/or control card based tools. 

Thank you Mohammad, I did try the example projects, but none of them are designed to work at MHz frequency range. Another thing I observed was that, when I declare a variable the frequency is further reduced by 200kHz. I do not why it's happening as declaring a variable is again a single clock cycle instruction. The reset pin is given on the control card of F2808 where as the docking station has only ADC and GPIO pins and reset pin is not multiplexed with these pins.

One more thing I think the reason would be that, because I am running the microcontroller from the USB power, does the frequency change to 6MHz which is the frequency of the USB circuit. Does this make any difference? By using a power supply would make the controller run at 100MHz? Please let me know your thoughts in this. Thank you.

If you are looking to generate a square wave in MHz range then my suggestion is first to look at an example project which shows how to generate PWM outputs. Once you confirm PWM generation with a scope then you can change PWM period to generate high frequency output.  These example projects explain all required hardware connections - read the comments in source file or the documentation. By the way, USB power should be just fine to observe PWM outputs and debugging.