PIC 16F690 PWM's ports selection - How to?

Hello,

I'm struggling a little in finding how to assign either port P1A (PORTC.5) or P1B (PORTC.4) to output the PWM signal, one at the time (= not simultaneously) on a PIC16F690.

I drive a loudspeaker via a transistor and to modulate its volume, the transistor's base is connected to a 1k2 resistor on PORTC.5 and 15k resistor PORTC.4.

Reading the DS, I need to set registers CCP1CON.P1M<1:0> and CCP1CON.CCP1M<3:0> as well as, maybe, PSTRCON.STRA and PSTRCON.STRB.

Here's my code for testing. Unfortunately, it doesn't work :(

Anyone an idea if feasible? How?

Code:

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@ __Config _FCMEN_OFF & _IESO_OFF & _BOR_OFF & _CPD_OFF & _CP_OFF & _MCLRE_OFF &_PWRTE_OFF & _WDT_OFF & _INTOSC

Registers  76543210
OPTION_REG = %10000101 'PORT A&B Pull-Ups disabled (look WPUA & WPUB)
ANSEL      = %00000000 'Select analog inputs Channels 0 to 7
ANSELH    = %00000010 'Select analog inputs Channels 8 to 11
ADCON0    = %00000000 'A/D Module ON/OFF (Bit5:2 select channels 0:11)
ADCON1    = %00000000 'A/D control register
CM1CON0    = %00000000 'Comparator1 Module is OFF
CM2CON0    = %00000000 'Comparator2 Module is OFF
INTCON    = %00000000 'INTerrupts CONtrol (TMR0 ON)
TRISA      = %00000000 'Set Input/Output (0 to 5)
PORTA      = %00000000 'Ports High/Low (0 to 5)
TRISB      = %00000000 'Set Input/Output (4 to 7)
PORTB      = %00000000 'Ports High/Low (4 to 7)
TRISC      = %00000000 'Set Input/Output (0 to 7)
PORTC      = %00000000 'Ports High/Low (0 to 7)

' HPWM registers
T2CON      = %00000101 'Timer2 = ON (bit2), prescaler (bits1:0) 00=1, 01=4, 1x=16
CCP1CON    = %00001100 'Select PWM Mode
PR2        = 255      'frequency is around 1kHz

DutyCycle VAR WORD
DutyCycle = (PR2+1)*2
CCPR1L    = DutyCycle >> 2
CCP1CON.5 = DutyCycle.1
CCP1CON.4 = DutyCycle.0

'--------------------------------------
TEST:

PSTRCON.0 = 1 'PWM on PORTC.5
PAUSE 1000
PSTRCON.0 = 0

PSTRCON.1 = 1 'PWM on PORTC.4
PAUSE 1000
PSTRCON.1 = 0

GOTO TEST:
END

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Just a quickie, when you say it doesn't work, have you scoped the pins?

My immediate thought is, what are your oscillator settings ...could it be that you're outputting a frequency that you can't hear (assuming that's what you're using to determine whether it works or not) dues to a combination of PR2 & your oscillator setting?

The above ought to work. As it is right now, you toggle a PWM from a channel to another, but never both together. To alter the Volume, you'll need a fixed duty on 1 channel, and a variable one on the other.. Not sure if this specific allow to do it.

@Mister_e,

Quote:

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Originally Posted by mister_e

The above ought to work

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Ça veut dire que mon code devrait être bon?

I have only one fixed dutycycle. To modify the volume, I vary the current on the transistor's base.

@HankMcSpank,
Yup, I scoped them all and I have never a signal on P1B (PORTC.4)

It works as expected here!

Attachment 5960

Have you tested PORTC.4 to see if it's blown, or you have a problem with something connected to it?

Well.... :o

.... a new PIC did the trick.

Thanks a lot for your help.

The biggest surprise is not that I'm a little bit stupid, it's more that I am a witness of a miracle: I understood (a part of) the datasheet by myself!!!! :D

Still not going to tell anyone how much hours I spent on this one too...

shush on that.... ta geulle :P