Hey guys, will this work?

[mister_e]

In theory it should work. Theory is always theory

PicMultiCalc download
http://www.picbasic.co.uk/forum/atta...7&d=1225550328

Probably you can get some inspiration of the following
http://www.picbasic.co.uk/forum/show...0&postcount=10

[jmgelba]

Ok, so using the calc I get PR2 = 9, duty register = 20 and with a 1:1 prescaler.

Is this about right?:

OSCCON = $70
define osc 8

CSET   VAR WORD 'CURRENT SET
CSEN   VAR WORD 'CURRENT SENCE  
DUTY   VAR wORD 'HPWM DUTY CYCLE

ADCON0 = %00011001
ADCON1 = %00001111
ADCON2 = %10111111
TRISA = %00000000
TRISB = %00110011
Define  ADC_BITS        10     	' Set number of bits in result
Define  ADC_CLOCK       3     	' Set clock source (3=rc)
Define  ADC_SAMPLEUS    10    	' Set sampling time in uS


'DUTY = 30 'SET INITIAL OUTPUT CURRENT HIGH TO ENABLE FAST STARTUP 
CSET = 0
CSEN = 0

duty = 20                           ' duty value for 50% duty cycle
PR2 = 9                             '
T2CON = %00000100                   ' timer2 on, prescale 1:1
CCPR1L = duty>>2                    ' MSB of duty cycle value
CCP1CON=%00001100 | (dUTY<<5)       ' set PWM mode and store the 
                                    '   2 LSB of duty




LOOP:
ADCIN 6, CSET 'READ VALUE OF CURRENT SET POT
ADCIN 4, CSEN   'READ VALUE OF CURRENT SENCE
IF CSEN > CSET THEN LET DUTY = DUTY - 1
IF CSEN < CSET THEN LET DUTY = DUTY + 1
CCPR1L = duty>>2                    ' MSB of duty cycle value
CCP1CON=%00001100 | (dUTY<<5)       ' set PWM mode and store the 
                                    '   2 LSB of duty

'HPWM 1,DUTY,32767 'OUTPUTS THE DUTYCYCLE AT 32.767KhZ
GOTO LOOP

[mister_e]

Almost... but no cigar. Check CCP1CON for YOUR particular PIC. CCP1CON is a bit different on this one (and I think my example was false anyway ... dooh) as usual, MicroChip can't be consistent between all their PIC model. Good idea to release a datasheet for each and every different model though

CCP1CON=%00001100 | (Duty<<4)

[jmgelba]

I did, it looks the same to me. I must have missed something.

bit 7 and 6 are 00 = Single output; P1A modulated; P1B, P1C, P1D assigned as port pins

bit 5 and 4 are the two LSbs of the PWM duty cycle. The eight MSbs are found in CCPR1L. I guess I do not know what to put in here or how to find out what should go in here. I thought duty>>2 took care of this.

and 3 - 0 are 1100 = PWM mode; P1A, P1C active-high; P1B, P1D active-high

[mister_e]

The change is above... <<4 instead of <<5... but as i said... <<5 was wrong anyway... not sure why, but wrong anyways... few years after... no one complaint

It is more code efficient... and obviously safer to use
CCPR1L = duty>>2
CCP1CON.4=Duty.0
CCP1CON.5=Duty.1

unless you'll screw up the CCP module on that 18F (think about the bit <7:6> of CCP1CON when duty value change). This was my major point here.

[jmgelba]

Ok, I think I understand all except how did you fill in bits 4 and 5? Why a 0 and 1 in the location you put them in?

The lsb's of the duty cycle go in there. Its a 10 bit duty cycle. The top 8 are shifted away leaving to 2 lsb's. In decimal the duty cycle is 20. Is the binary representaion of 20 used? Is that how you get the last 2 bits?
20 = 00010100 so the lsb's should be 00, no?

[mister_e]

Ok, I think I understand all except how did you fill in bits 4 and 5? Why a 0 and 1 in the location you put them in?

assuming a 10 bits results as follow

'Bit number 9876543210
   MyVar = %1111110011

In red the MSB, in Blue the LSBs for PWM.

Shift them all two position to the right you have

   MyVar = %0011111100

Now, where are the LSB now... gone... you need to extract them 2 from the original 10bit value, so Bit0 and BIT1, and transfer them to Bit4 and BIT5 of CCP1CON register
CCP1CON.4=MyVar.0 ' bit0 to bit4 of CCP1CON
CCP1CON.5=Myvar.1