Hey guys, will this work?

[mister_e]

HPWM limit is as stated in your manual. To reach higher frequency, you need to write the PWM register manually. Use PICMultiCalc to find PR2 and Timer Prescaller value, then plug the DutyCycle values in CCP1CON and CCPR1L registers... double check your datasheet to confirm.

For Buck converter, usually the higher the better for reducing coil and capacitors size.

Make sure your ADCONx setting don't interfer with PBP ADCINs defines. You may want to place your define after those ADCONx lines, or get rid of ADCIN. Once again PICMultiCalc may give you some hints about min acquisition time and faster clock conversion source.... which is probably a must for buck converter. Don't forget to check the Resolution for the frequency you choosed. @8Mhz & 200KHz, you should have something like 7 bit of resolution.. 40 dutycycle steps... not bad, not good, depending how fancy you want it.

In some case it's not a so good idea to use a PIC for that, just for the reaction time and what your PIC will also need to do apart the voltage regulation.

[jmgelba]

Hmm, eventually I have to get this running over 100kHz, so I will need to learn how to manually write to the registers and preload timers etc. I have never done this.
All the links I've come across for the multicalc are dead. I had it once but lost it at some point.
There is not much else going on with the pic really. If a pin goes high, it turns on a FET and runs the converter. Pin the goes low, it switches off. Thats it really.

I've swapped the location of the DEFINE's.
Other than that, at 32.767kHz, will that code do what I think it should do?

[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.