me again

[BobSpencerr]

Sorry to keep bothering you all but can anyone tell me how to get both HPWM channels working on a 16F877.
I get a pwm signal out of one channel but not the other. I have tried the declares listed below but no good.

My code is here.

@ Device pic16F877A, WDT_OFF, BOD_OFF, DEBUG_OFF , LVP_OFF, PROTECT_OFF, CPD_OFF, XT_OSC
include "Interrupter.bas"

Define LCD_DREG PORTD
Define LCD_DBIT 4
Define LCD_RSREG PORTC
Define LCD_RSBIT 7
Define LCD_EREG PORTC
Define LCD_EBIT 6

DEFINE ADC_BITS 8 ' Set number of bits in result
DEFINE ADC_CLOCK 3 ' Set clock source (rc = 3)
DEFINE ADC_SAMPLEUS 50 ' Set sampling time in microseconds

'DEFINE CCP1_REG PORTC 'Hpwm 1 pin port
'DEFINE CCP1_BIT 2 'Hpwm 1 pin bit
'DEFINE CCP2_REG PORTC 'Hpwm 2 pin port
'DEFINE CCP2_BIT 1 'Hpwm 2 pin bit
'DEFINE HPWM1_TIMER 1
'DEFINE HPWM2_TIMER 2

TRISC = %00000000

DUTY VAR WORD

T2CON=%00000100
PR2=1
DUTY=4
CCP1CON=%00001100 ' PWM MODE
CCP1CON.5=DUTY.1
CCP1CON.4=DUTY.0
CCPR1L=DUTY>>2



PlugOutput var portd.2
volts var word[2] 'to recieve the A2D value
PlugOn var byte
plugon = 0
low PlugOutput
INTCON.5 = 0
t1con.0 = 0
low portd.3
low portc.1
low portc.2


pause 500

main:
pause 100
lcdout $FE,1,"PWM Test:" ,#volts / 10, "." , #volts // 100
lcdout $FE, $C0, "Val = ", " : ", dec2 i_sec

'Run the glow plug for a set time
if portc.4 = 1 then
plugon = 1
i_sec = 0
endif

if plugon = 1 then
INTCON.5 = 1
t1con.0 = 1
endif

if i_sec >= 10 then
intcon.5 = 0
t1con.0 = 0
plugon = 0
i_sec = 0
low PlugOutput
low portd.3
endif
call SetVoltage1
call SetVoltage2
call SetVoltage3
'pause 100
goto main

SetVoltage1: '5vDc out put control (Gyro and Tail servo)
input porte.2
ADCON1 = 2 ' PORTA is analog
pause 50
ADCIN 7, volts ' Read channel 7 to variable Volts
volts = (volts * 1000)/((256 / 5)*10)
'if volts > ReqVolts1 then duty1 = duty1 - 1
'if volts < ReqVolts1 then duty1 = duty1 + 1
HPWM 1, 25, 200 'Channel1, duty cycle%, 2kHz
return

SetVoltage2: '5 to 7 vDc out put control (RX and other servos)
input porte.1
ADCON1 = 2
pause 50
ADCIN 6, volts
volts = (volts * 1000)/((256 / 5)*10)
'if volts > ReqVolts2 then duty2 = duty2 - 1
'if volts < ReqVolts2 then duty2 = duty2 + 1
HPWM 2, 50, 200
return

SetVoltage3: '1.2 vDc out put plug
input porte.0
ADCON1 = 2
pause 50
ADCIN 5, volts
volts = (volts * 1000)/((256 / 5)*10)
'if volts > PlugVolts then duty3 = duty3 - 1
'if volts < PlugVolts then duty3 = duty3 + 1
return

[khaynes]

Hi,
The two PWM channels on the 16F877 share the same timer, which is timer 2. The two PWM channels must have the same period. They can have different duty cycles. You can check the data sheet to see if the 16F877A has the same restrictions about the timer.

Thanks,

Keith

[BobSpencerr]

I have the same frequency for both dont I?
Have I missed something, I have been looking at the same thing for too long now and could miss something realy obvious.

[khaynes]

Hi,
I think you are using the same frequency, but more than that you have to use exactly the same timer.

'DEFINE HPWM1_TIMER 1
'DEFINE HPWM2_TIMER 2

I think that you should use:
'DEFINE HPWM1_TIMER 2
'DEFINE HPWM2_TIMER 2

but I am not sure, having never used PICBASIC to control PWM's

Thanks, Keith

[mister_e]

HPWM 1, 25, 200 'Channel1, duty cycle%, 2kHz

try with

HPWM 1, 25, 2000 'Channel1, duty cycle%, 2kHz

        @  __CONFIG _XT_OSC & _LVP_OFF

PORTC=0
TRISC=0

duty var byte
DEFINE HPWM2_TMR 2

Start:
    for duty =0 to 255
        hpwm 1,(255-DUTY),2000
        hpwm 2,DUTY,2000
        pause 10
        next
    goto start

[BobSpencerr]

Once again mate,
Thanks for the help

This is what the help file says in the package I have been using

DEFINE HPWM2_TIMER 1 'Hpwm 2 timer select
DEFINE HPWM3_TIMER 1 'Hpwm 3 timer select

Example

HPWM 1,127,1000 ' Send a 50% duty cycle PWM signal at 1kHz
HPWM 1,64,200 ' Send a 25% duty cycle PWM signal at 2kHz

See Also

PWM

Copyright © 2001 microEngineering Labs, Inc.
All rights reserved.


That is where the 200 came from. I thought it didnt look right at the time but didnt have enough experience to challenge it.

Anyway. It all works now.