How to setup and use the PWM in a PIC16F818?

[chevymn1964]

Hello, does anyone know how to setup and use the PWM in a PIC? Im using a PIC16F818 and it has a built in PWM... I looked at the data sheet but their is no examples to go by? any help wouldl be great! thank you!

 

[atferrari]

ccpr1l pic

Please tell exactly what part of the respective section you don't understand.

Always show that you did some effort to grasp the concepts.

 

[waseem]

pwm ccp1con

Hi!

Which language are you using,Assembly or C?
I will send you the code to do that.

Regards.

 

[senkum812002]

setting pwm duty cycle in pic

Hi,
Please go through application note of PWM which is available in Microchip website or else ref. 16F series manual which ia also available in the same site.

 

[vsmGuy]

pic pwm

Please visit CCS Info forum. We have indepth discussion on this topic there.

 

[raghupathi1m]

ccp1con

hi here iam sending u to how initiaze i/o ports for pwm signal generation
Assume PIC runs at 4MHz 1000Hz wanted at 50% duty cycle
These PWM enable steps are taken from the 16F87X data sheet


Set the PWM period (1000Hz = 0.001S) by writing to the PR2 register.
PWM Period = [PR2 + 1]*4*Tosc*TMR2 PreScale value
Use 4 for TMR2 prescale. You can try other values but make sure it works with the duty cycle calcs as well.

Tosc = 1/4000000 = 2.5*10-7
Rearranging the equation gives...

PR2 = (Period/(4 * Tosc * TMR2 Prescale)) - 1
Therefore...

PR2 = (0.001/(4 * 2.5 * 10-7 * 4)) - 1 = 249

bsf STATUS,RP0
movlw d'249' ; when TMR2 = 249 = end of Period
movwf PR2
bcf STATUS,RP0

Set the PWM Duty Cycle by writing to the CCPR1L register and CCP1CON<5:4> bits.
CCPR1L contains the upper 8 bits of the 10 bit Duty Cycle value CCP1CON<5:4> contain the lower 2 bits

PWM Duty Cycle = (CCPR1L:CCP1CON<5:4>)*Tosc*TMR2 Prescale Value

CCPR1L:CCP1Con<5:4> = PWM Duty Cycle / (Tosc * TMR2 Prescale)

PWM Duty Cycle = 50% of Period

PWM Duty Cycle = 50% of 0.001 = 0.0005

CCPR1L:CCP1Con<5:4> = 0.0005 / (2.5 * 10-7 * 4)

CCPR1L:CCP1Con<5:4> = 500

500 in 10 bit binary = 0111110100

CCPR1L = 01111101 CCP1Con<5:4> = 00
Write the 10 bit value

movlw b'01111101' ; set bits 9 - 2
movwf CCPR1L
bcf CCP1CON,CCP1X ; set bit 1
bcf CCP1CON,CCP1Y ; set bit 0

Make the CCP1 pin an output by clearing the TRISC<2> bit
bsf STATUS,RP0
movlw b'11111011'
andwf TRISC
bcf STATUS,RP0
Set The TMR2 prescale value and enable TMR2 by writing to T2CON.
We decided previously to set the prescale value to 4.

TMR2 prescale are bits 1 and 0 in T2CON
TMR2 enable is bit 2

movlw b'00000101' ; TMR2 = on, prescale = 1:4
movwf T2CON
Configure the CCP1 module for PWM
movf CCP1CON,W
andlw b'00110000' ; mask all but previously set Duty Cycle bits
iorlw b'00001111' ; and enable PWM mode
movwf CCP1CON
A 1000 Hz square wave with a 50% duty cycle should now be coming out of RC2.

 

[ragav4456]

please send a sample embedded c coding for Hitech c complier.