Enabling 24MHz crystal clock source

1.How I can enable 24 MHz crystal source ?

--> Our radio only runs on 24MHz crystal, and the software takes care of that transition. You don't need to do anything, if you have connection/advertising, that means your 24MHz is running

2.What are the power modes in which my board works and how I can put the board in particular power mode.
I have gone through the "Power management guide" .There all power modes are explained in detail and what configurations are needed to put the board in that particular power mode.
But where I have to do all these configurations ? What are the files ? Do these configurations are part of stack.

--> Default setting of simpleBLEPeripheral, power_saving is enabled from the preprocessor symbols, which means whenever device is idle, it enters standby mode. You can take a look at our software developer's guide section 3.7

3.What is the relation between crystal source and power modes.In "Power management guide" at Pg-6 there is a table listing which crystal source should work in which mode.Right now what happening is my board is taking clock from 32 KHz only, even while making connections (which is an active state).So what are exactly are the effect on the performance if I am not at all using 24 MHz clock and using this 32khz clock.

--> TI-RTOS makes the transition for you so that's why you don't see it. But as stated from previous answer, radio won't run on 32kHz crystal. It can only run from 24MHz xtsal.

4.Do power modes also related with GAP layer.As in the following discussion the last comment  by Eirik states that in broadcaster and peripheral board will use 32KHz and in central mode it will use 24MHz .
e2e.ti.com/.../472450

--> what he said was internal 32kHz crystal only supports peripheral and broadcaster, external 32kHz crystal is needed for Central

Hi Christin,

Thanks for all your answers.

After referring your answers and document, I still have certain queries-

1.) What is the main reason for using 32KHz crystal ? Because majority of things are happening with the help of 24MHz.

2.) In 2nd answer you said that "whenever device is idle, it enters standby mode". But there are four power modes
                                        a.) Active                                       c.)  standby                  
                                        b.) Idle                                           d.) Shutdown
So what I understand is whenever device is advertising/connecting it is in active state and else it is in standby mode.When board goes into "shutdown" and "Idle" mode.

3.)In 3rd answer you said "TI-RTOS makes the transition for you so that's why you don't see it" .Then how I can confirm this in my custom board.As probing the signal is not allowed ?

Regards,
Abhi