Designing for Low Power and Estimating Battery Life for BLE Applications

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Document No. 001-92584 Rev. *A

13

*

Place code to place the application components to deepsleep here

************************************************************************/

break;

}

}

System Power Management

The application should call the

function puts the system into the allowed low-power modes as follows:



[C9] Get the current internal state of the BLESS by calling the



[C10, C11] If the BLESS is in the DEEPSLEEP mode and the non-BLE application components are also in the

Deep-Sleep mode [C10], then put the system into the Deep-Sleep mode [C11]. The code execution halts here

until the system wakes up from the Deep-Sleep mode due to an interrupt.



[C12] If the BLESS does not enter the DEEPSLEEP mode, it is either because it is at the beginning or in the

middle of an event. The system can be put into the Sleep mode in this period except in the



[C13, C14, C15, C16] There are two possibilities about the application power mode under the above condition. If

the application is in the Deep-Sleep mode [C13], the system can use the ECO instead of the IMO as the clock

source in the Sleep mode. First, the HFCLK source is switched to the ECO and the IMO is stopped [C14]. The

system is then put into the Sleep mode [C15]. The code execution halts here until the system wakes up from the

Sleep mode due to an interrupt. The IMO is restarted upon wakeup and the clock source for HFCLK is reverted

to the IMO [C16].



[C17, C18] If the application is in the Sleep mode and requires the IMO [C17], then the system is put into the

Sleep mode [C18], without switching OFF the IMO.

Note 1: It is important that the code to handle the low-power transitions is protected in a critical section and that

interrupts are not allowed to change the thread of operation. In the code snippet, this critical section is bound by

the end. If you do not put the code in this critical section, it may result in race conditions between the system and

the BLESS in entering the BLESS low-power modes, causing the device to enter an unknown state from which it

cannot recover.

Note

2:

When

you

put

the

BLESS

into

the

DEEPSLEEP

mode

in

the

application

using

the

C

application need not do an explicit ECO OFF. However, if you are not using the BLESS, then you need to

explicitly stop the ECO in the system if it is not required. This is because the system API call,

C

will

not

turn

OFF

the

ECO.

This

can

be

done

by

calling

the

C

The code snippet follows.

{

/* Variable declarations */

CYBLE_BLESS_STATE_T blePower;

/* Disable global interrupts to avoid any other tasks from interrupting this

section of

code*/

interruptStatus

= CyEnterCriticalSection();

/* C9. Get current state of BLE sub system to check if it has successfully