Infrared HPWM setup

[astanapane]

Hi Richard,

thanks for the clarification and answer.

I found in the manual what you said regarding the Resolution bits.

[richard]

the duty cycle is a 10 bit value at best for that chip, not all frequencies can have the full 10bit range available
it totally depends on choices made with regard to prescaler and period.
no matter what bit resolution is possible the CPRxL value is the upper 8 bits of the duty cycle word valueCCP1CON bit 4 and 5 are the lower two bits

[astanapane]

i've also noticed you've shifted 2 bits on the right the CCPR1L

CCPR1L = 210>>2 ' Set PWM Duty-Cycle to 50%

So the CCPR1L value will be 52.

(11010010) 210>>2 = 00110100 = 52

why have we shifted?

[richard]

why have we shifted?
CPRxL value is the upper 8 bits of the duty cycle word valueCCP1CON bit 4 and 5 are the lower two bits



(011010010) 210>>2 = 00110100 = 52 ;high 8bits
(011010010) 210 & 3 = 00000010 = 2 ;low 2 bits

00000010<<4 = 00100000
CCP1CON = 00100000 |12 to set low bits in pwmmode

C version from microchip

void PWM1_LoadDutyValue(uint16_t dutyValue)
{
   // Writing to 8 MSBs of pwm duty cycle in CCPRL register
    CCPR1L = ((dutyValue & 0x03FC)>>2);
    
   // Writing to 2 LSBs of pwm duty cycle in CCPCON register
    CCP1CON = ((uint8_t)(CCP1CON & 0xCF) | ((dutyValue & 0x0003)<<4));
}

[astanapane]

thanks Richard. now is clear.

i will get back once i have a working code and establish an IR communication.

[astanapane]

with the following configuration i got this on the scope. So i guess we are in a good path.

To mention that the main OSC is at 64Mhz using HPWM on the PIC18f26K22 on portc.2

TRISC.2 = 0          ' CCP1 (PortC.2 = Output)
PR2 = 104            ' Set PWM Period for approximately 38KHz
CCPR1L = 52          ' Set PWM Duty-Cycle to 50% (011010010) 210>>2 = 00110100 = 52
T2CON = %00000101    ' Timer2 ON + 4 prescale
CCP1CON = %00001100  ' Mode select %00001100 = PWM

all thanks to Richard.

now im going on the next step.

[richard]

very good.
you could set the lower two bits of the Duty-Cycle word [CCP1CON bits 4:5] to get the duty cycle
even closer to exactly 50%, if you wanted to
CCP1CON = %00101100

[astanapane]

I will do that thanks a lot.

Yesterday i tried till late at night to set a code for the TX and RX, a very simple one but didnt work.

tx:

'*-----------------------------------------------------------------------------|
'*                        |  --------------------- |                           |
'*----------------------- | EUART 1 Configuration  | --------------------------|
'*                        |  --------------------- |                           |
'*-----------------------------------------------------------------------------|                                                                             |
        DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive
        DEFINE HSER_TXSTA 24h ' Enable transmit, BRGH = 1
        DEFINE HSER_CLROERR 1 ' Clear overflow automatically
        DEFINE HSER_SPBRG 130 ' 9600 Baud @ 64MHz, -0.02%
        SPBRGH = 6
        BAUDCON.3 = 1         ' Enable 16 bit baudrate generator             
'------------------------------------------------------------------------------|

ID	    VAR BYTE
button1 var porta.0  ' we configure this button 1 at porta.0
button2 var porta.1  ' we configure this button 2 at porta.1
RED     var latc.3   ' a RED LED indicates the PIC working condition
Blue    var lata.2   ' a Blue LED indicates the push button everytime

high red
pause 100
low red 
pause 50
high red
'------------------------------------------------------------------------------|
BEGIN:

   ID	= 10
if button1 = 0 then 
    gosub button1_pressed
	endif

low blue
	GOTO BEGIN
'------------------------------------------------------------------------------|

button1_pressed:
high blue
	    hSEROUT [ID]  ' we send at portc.6 which is connected the IR module at the 74LS00 in pin No2 
	    PAUSE 100
    return

button2_pressed:
high blue
	    hSEROUT [ID]  ' we send at portc.6 which is connected the IR module at the 74LS00 in pin No3 
	    PAUSE 100
    return
end

RX:

'*-----------------------------------------------------------------------------|
'*                        |  --------------------- |                           |
'*----------------------- | EUART 2 Configuration  | --------------------------|
'*                        |  --------------------- |                           |
'*-----------------------------------------------------------------------------|                                                                             |

        DEFINE HSER2_RCSTA 90h ' Enable serial port & continuous receive
        DEFINE HSER2_TXSTA 24h ' Enable transmit, BRGH = 1
        DEFINE HSER2_CLROERR 1 ' Clear overflow automatically
        DEFINE HSER2_SPBRG 130 ' 9600 Baud @ 64MHz, -0.02%
        SPBRGH2 = 6
        BAUDCON2.3 = 1         ' Enable 16 bit baudrate generator
        
'-------------------------------------------------------------------------------|
ID	    con 10
Green   var lata.1   ' a Green LED which indicates the 1st output of the IR input code
Blue    var lata.0   ' a Blue LED indicates the 2nd output of the IR input code 
Red     var lata.2   ' a Red LED indicates the PIC working condition
'------------------------------------------------------------------------------|
'                 RED LED indicates that PIC is up and running                 |
'------------------------------------------------------------------------------|

high red
pause 100
low red 
'------------------------------------------------------------------------------|

Begin:

hSERin2 [wait(ID)]
high red
'pause 100

   gosub FIRST_SIGNAL
'   endif

'------------------------------------------------------------------------------|

FIRST_SIGNAL:
high green
pause 500
low green
return

end