Infrared HPWM setup

[astanapane]

Dear all,

just a quick question. I didnt want to open a new thread but most of the Infrared threads are closed.

I would like to set up the PIC18F26k22 in order to use HPWM for the 38khz IR.

First of all i would like to ask if i can use 64Mhz as the main PIC frequency.

i tried to use mister e's pic multi-calc and set 64Mhz. The following are the results i got.



but from the calculations i made:

(64Mhz / (4*TMR2 prescale value * 38Khz))-1 = PR2
(64Mhz / (4*1*38Khz)) - 1 = PR2
(64Mhz / (152000)) - 1 = PR2 <=>

            64,000,000
<=> PR2 =  ------------ -1 <=>
             152,000

<=> PR2 = 420

Also calculating the bits:

              log(FOSC / FPWM)
 Resolution = ------------------- bits
                  Log(2)

log(64,000,000 / 38,000) = 3.226

log(2) = 0.301

so we have:
3.226
------- = 10.17 ~ 10 bits
0.301

and calculating the CCPRL1:

(PR2 + 1) * TMR2 prescale * 50% Duty Cycle = value for CCPRL1, or
(420 + 1) * 1 * 0.50 = 421 * 0.50 = 210

So i set in the code the following:

TRISC.2 = 0 ' CCP1 (PortC.2 = Output)
PR2 = 420 ' Set PWM Period for approximately 38KHz
CCPR1L = 210 ' Set PWM Duty-Cycle to 50%
T2CON = %00000100 ' Timer2 ON + 1:1 prescale --> i know this might not be right as at 64Mhz there is no 1:1 scale based on mister's e multi-calc.
CCP1CON = %00001100 ' Mode select = PWM

could you please help me to clear things up?

I dont mind using 16Mhz as a base frequency, but still the calculations i get are not match with mister's e multi-calc.

Thanks for your help in advance.