PIC16F722AT-ESLASHSP datasheet(120/284 Pages) MICROCHIP

120 / 284 page

PIC16F/LF722A/723A

DS41417A-page 120

 2010 Microchip Technology Inc.

14.6

Operation During Sleep

The capacitive sensing oscillator will continue to run as

long as the module is enabled, independent of the part

being in Sleep. In order for the software to determine if

a frequency change has occurred, the part must be

awake. However, the part does not have to be awake

when the timer resource is acquiring counts. One way

to acquire the Timer1 counts while in Sleep is to have

Timer1 gated with the overflow of the Watchdog Timer.

This can be accomplished using the following steps:

Configure the Watchdog Time-out overflow as

the Timer1’s gate source T1GSS<1:0> = 11.

Set Timer1 gate to toggle mode by setting the

T1GTM bit of the T1GCON register.

Set the TMR1GE bit of the T1GCON register.

Set TMR1ON bit of the T1CON register.

Enable capacitive sensing module with the

appropriate current settings and pin selection.

Clear Timer1.

Put the part to Sleep.

On the first WDT overflow, the capacitive sens-

ing oscillator will begin to increment Timer1.

Then put the part to Sleep.

On the second WDT overflow Timer1 will stop

incrementing. Then run the software routine to

determine if a frequency change has occurred.

Refer to Section 12.0 “Timer1 Module with Gate

Control” for additional information.

Note 1: When using the WDT to set the interval

on Timer1, any other source that wakes

the part up early will cause the WDT over-

flow to be delayed, affecting the value

captured by Timer1.

2: Timer0 does not operate when in Sleep,

and therefore cannot be used for

capacitive

sense

measurements

Sleep.

PIC16F722AT-E/SP Datasheet(PDF) 120 Page - Microchip Technology

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