using the pwm's in pic18f2431-2331-4331-4431

[jorge_jaqa]

hi, im looking the way to use the pwm's (no ccp) pins of this micro family.it has 5 or 9 outputs of this kind but i don't care about the frequency or assembler code. i just whant to know if picbasic pro support this pwm's pins.
i dont what to use the darrel taylor rutines because there are in assembler and i just want to use picbasic!!!!!!!! (that's why im in this forum!!)
thnks. a lot for this view

[BrianT]

The manual with version 2.50 is vague on how many HPWM channels the new PBP or PBPL will support but it is at least 5 with the appropriate PIC.
The manual is also vague on whether you can have different frequencies on different HPWM channels. This will relate to how the various timers are associated with the HPWM modules - read the data sheet for your particular PIC. The maximum frequency with PBP is 32767 Hz but with PBPL looks like it will be higher - vague manual again.

I routinely use two channels HPWM in the 16F877A and both using the same frequency is not a problem in my case.

HTH
Brian

[Darrel Taylor]

NO, PBP DOES NOT support the PWM/CAPTURE modules of those chips directly.

Neither does any of the "darrel taylor rutines".

But that doesn't mean you can't use them with PicBasic Pro.
You just need to handle the registers manually.

I think Bruce made an example or two.
<br>

[Bruce]

HPWM is for control of CCP PWM. Not Power Control PWM. To use PCPWM you'll need to do
things manually.

The example below is for the 18F2431. It's all in PBP.

 
    DEFINE LOADER_USED 1
    DEFINE OSC 20
    
    ' At 20MHz, to figure a PWM frequency of 19.455kHz
    '
    ' TPWM = time period of PWM frequency
    ' PTPER = 12-bit period register PTPERL and PTPERH
    ' PTMRPS = PWM time base prescaler
    ' 
    '        (PTPER+1)*PTMRPS         257
    ' TPWM = ----------------  =  ------------ = 0.0000514 
    '             Fosc/4            5000000
    '
    ' Frequency = 1/TPWM = 1/0.0000514 = 19.455kHz
    '
    ' PWM resolution (bits resolution for duty cycle)
    '
    '              log(20MHz/19.455kHz)    3.01
    ' Resolution = ------------------ = ----------- = 10 bits
    '                    .301              .301
      
    ' so we'll need a word sized var for Duty
    Duty Var Word
   
    PORTB = 0               ' clear port latch
    TRISB = %11000000       ' PWM0,1,2,3,4,5 outputs
    
    TRISC = 2               ' RC1 = FLTA input (ground RC1 to halt PWM)
                            ' RC1 should be pulled high for normal PWM operation
                            ' when fault A is enabled.
    ' PCPWM init
    DTCON = %00000101       ' ~500nS dead-time (for complementary outputs only)
    PTCON0 = %00000000      ' 1:1 postscale, Fosc/4 1:1 prescale, free running mode
                            ' PTCON0 = %00000100 would give 19.45kHz/4
    PTPERL = 0              ' 
    PTPERH = 1              ' PTPER = $0100 or 256d for ~19.45kHz
	
    ' PWM4,5 independent, PWM0,1,2,3 complementary
    PWMCON0 = %01010100     ' PWM[5:0] outputs enabled
    PWMCON1 = 1             ' updates enabled, overrides sync w/timebase
    PTCON1 = %10000000      ' PWM time base is ON, counts up
    FLTCONFIG = %00000011   ' enable fault A, cycle-by-cycle mode

    Duty = 800              ' ~50%
    PDC2L = Duty.LowByte    ' maintain a fixed 50% duty cycle on PWM4,5
    PDC2H = Duty.HighByte   ' independent PWM outputs.
        
Main: ' ramps up & down duty-cycle on complementary PWM0,1,2,3 outputs
  For Duty = 800 To 200 STEP-1 ' ~20% to 80%
    PDC0L = Duty.LowByte
    PDC0H = Duty.HighByte
    PDC1L = Duty.LowByte
    PDC1H = Duty.HighByte
    Pause 5
  Next Duty
  
  Pause 500 ' 1/2 second delay between ramp up/down
  
  For Duty = 200 To 800   ' ~80% to 20%
    PDC0L = Duty.LowByte
    PDC0H = Duty.HighByte
    PDC1L = Duty.LowByte
    PDC1H = Duty.HighByte
    Pause 5
  Next Duty

  Pause 500 ' 1/2 second delay between ramp up/down
  
  GoTo Main

  End

The .gif attached shows all 6 PWM channels captured with a logic analyzer. PWM0 to PWM3
operate in complementary mode. PWM4 and PWM5 operate in independent mode.

PCPWM is a tad more complex than CCP PWM, but with a little time spent experimenting and
going over the data sheet, it's fairly easy to figure out.

[Sergeant]

Bruce,

What Logic Analyzer did/do you use, that you posted the screen capture (I'm making at least one or two assumptions here...) in the above post? A BitScope? or something else? I'm in the market for a USB MSO (I have a Tek 1220 LA and two Tek Scopes, but they're all analog with no comms for a PC for data analysis, etc.).

Thanks,

Brad

[Bruce]

Hi Brad,

The DigiView shown here http://www.tech-tools.com/dv_main.htm

I have the DV1-100 shown in the hand.

[mystified]

'************************************************* ***************
'* Name : UNTITLED.BAS *
'* Author : [select VIEW...EDITOR OPTIONS] *
'* Notice : Copyright (c) 2008 [select VIEW...EDITOR OPTIONS] *
'* : All Rights Reserved *
'* Date : 8/2/2008 *
'* Version : 1.0 *
'* Notes : *
'* : *
'************************************************* ***************
' pwm out
ansel0=%00000000
ansel1=%00000000


portb=%00000000 'set port as output
trisb=%00000000 'set all portb pins as output

pr2=155 ' set to get 4khz out
ccp1con=%0001101 'set duty cycle ccp1con <4:5> bits
trisc=%00000000 ' make ccp pin output by clearning trisc<2> bit
t2con =%00000110 'turn on timer2, prescale =16
' set trmr2 prescale value and enable timer2 t2con
pause 1000

portb.6 = 1 'high output
portb.7=1 'high output


pause 2000
loop:
hpwm 0,127,10
hpwm 1,127,100
hpwm 2,127,10
hpwm 3,127,10
hpwm 4,127,100
hpwm 5,127,10
pause 1000
goto loop
end
I'm trying to get the pwm to work but the only pin that light a led is RB2( 6 and 7 work)
Who do I get the rest of them to work?

[luminas]

Read Darrel comment above.
You have to setup manually, or you can use 2 CCP HPWM only with PBP

[Darrel Taylor]

On these chips, I defer to Bruce's experience. (See post #4)

Bruce,

Is there really 2 normal CCP's and 4 other PWM's on these chips? Total of 6?
Or am I looking at the datasheet wrong?
The GIF image in post #4 shows 6 traces, but the program doesn't ues CCPCON?.

Haven't used one yet.
<br>

[Bruce]

DT,

The 28-pin version has 6 power control pwm outputs, and 2 standard CCP pwm outputs
for a total of 8. The 40-pin has 8 power control pwm outputs and the 2 standard CCP.

The only thing I don't like is they use the CCP1 & CCP2 pwm outputs as power control
pwm fault inputs.

You should grab a couple samples. The motion feedback module on these is awesome.

[Darrel Taylor]

WOW, that's a tough read.

But after a few hrs in the datasheet. Yeah, these are cool.

Got the (IC) Input Capture block: Very cool.
The (QEI) Quadrature Encoder Interface: OK sorta cool.
And up to 4 14-bit PWM's. (4 additional complimentary outputs) Not usable with CCP's at the same time.
Not as cool as I expected.

Still worth further investigation.
Samples on order. Thanks Bruce.
<br>