You've got to be kidding me

[jim]

I just up graded my compiler since there was "supposed" to be a fix for setup_power_pwm(). Now when I compile the same program setup_oscillator( OSC_8MHZ ); complains "identifier expected"
WHAT!!! ????
if I take that line out, it compiles but each time I hit reset on my target board the PWM duty cycle changes sizes..
what is going on here?

[PCM programmer]

You didn't provide a test program so I had to make one, and it
compiles with no errors with PCH vs. 3.249.

[ckielstra]

[jim]

I've got to be going insane...
I had
#include<18f4331.h>

#device adc=10
#fuses INTRC_IO,NOWDT,NOPROTECT,NOLVP, NOBROWNOUT
#use delay(clock=8000000) //8Mhz
#use rs232(baud=9600,xmit=PIN_E0,rcv=PIN_E1,parity=n,bits=8,INVERT)
setup_oscillator( OSC_8MHZ);

commented it out.. copied your and all works fine.. Long day. thanks for the help

[Jim]

each time I get hit reset..I get a differn't pulse size (x2) I'm using version 3.236

#include <18F4331.h>

#device adc=10
#fuses INTRC_IO, NOWDT, NOPROTECT, NOBROWNOUT, PUT, NOLVP
#use delay(clock=8000000)
#use rs232(baud=9600,xmit=PIN_E0,rcv=PIN_E1,parity=n,bits=8,INVERT)

#define FORWARD 1
#define BACKWARD 0
#define OFF 0




//////////////// functions ////////////////////////
void move(int left_speed,int left_direction, int right_speed, int right_direction);

int16 liLeftDuty;
int16 liRightDuty;


void main(void)
{
int period=199;
setup_oscillator(OSC_8MHZ);

/***********************************
freq= Fosc / (4*(period + 1) * postscale)
or
period = (Fosc /( 4 * freq * postscale)) -1

if we want 10khz
period =( 8mhz /(4 * 10khz * 1) -1
peroid = 199;
*****************************************/



setup_power_pwm_pins(PWM_ODD_ON,PWM_ODD_ON,PWM_OFF,PWM_OFF);
setup_power_pwm(PWM_FREE_RUN,1,0,period,0,1,0);
//forward
output_B(0b01010000);

while(true)
{

delay_ms(1000);
// half speed
move(5,FORWARD,5,FORWARD);
set_power_pwm0_duty(liLeftDuty);
set_power_pwm2_duty(liRightDuty);

// printf("\n\n\rhalf");

//full speed
delay_ms(1000);
// printf("\n\n\rFull");
move(10,FORWARD,10,FORWARD);
set_power_pwm0_duty(4000);

// set_power_pwm0_duty(liLeftDuty);
set_power_pwm2_duty(liRightDuty);

}//while true


}//main()

////////////////////////////////////////////////////////////////////////////
//void move(int left_speed,int left_direction,
// int right_speed, int right_direction)
// this is used to set the speed and direction of the bot
// speed is a value for 0-10
// since this uses PWM for the motors and anything below ~40% duty is useless
// setting the speed to 1 will be ~40% duty and 0 will be off
//
// example: move(10,FORWARD,5,FORWARD);
void move(int left_speed,int left_direction, int right_speed, int right_direction)
{
//4000 will be full on
int direction;
int16 baseline = 1600; // ~40%
int16 factor = 240; // ~ (16232 - 6600 )/ 10

if(left_speed > 10)
left_speed = 10;
if(right_speed > 10)
right_speed = 10;
//output_b(0b00000000); //all off

//calc speed first and set pwm
if(left_speed == 0)
liLeftDuty = left_speed;
else
liLeftDuty = (left_speed * factor) + baseline;

if(right_speed == 0)
liRightDuty = right_speed;
else
liRIghtDuty = (right_speed * factor) + baseline;

printf("\n\r Left %ld",liLeftDuty);
printf("\n\r Right %ld",liRightDuty);



}//move

[PCM programmer]

[Jim]

#include <18F4331.h>

#device adc=10
#fuses INTRC_IO, NOWDT, NOPROTECT, NOBROWNOUT, PUT, NOLVP
#use delay(clock=8000000)


void main(void)
{
int period=199;
setup_oscillator(OSC_8MHZ);

/***********************************
freq= Fosc / (4*(period + 1) * postscale)
or
period = (Fosc /( 4 * freq * postscale)) -1

if we want 10khz
period =( 8mhz /(4 * 10khz * 1) -1
peroid = 199;
*****************************************/



setup_power_pwm_pins(PWM_ODD_ON,PWM_ODD_ON,PWM_OFF,PWM_OFF);
setup_power_pwm(PWM_FREE_RUN,1,0,period,0,1,0);

while(true)
{

delay_ms(1000);
// half speed
set_power_pwm0_duty(500);


//full speed
delay_ms(1000);


set_power_pwm0_duty(4000);


}//while true


}//main()

[Ttelmah]

Big problem here, is that the maths is being done in an int8, not an int16.
If you take this line:

freq= Fosc / (4*(period + 1) * postscale)

The arithmetic will evaluate '199+1' = 200. Then multiply by 4, which will give 32!... (it wraps round).
The problem is that the compiler defaults to int (8 bit), unless _you_ ensure that a variable/constant is an int16. Try:

freq =Fosc / (4L*(period+1)) * postscale)

Notice the 'L', which forces this to be a 'long', and will then force the arithmetic to use int16. You should also do the same with your defines for postscale and Fosc (though provided the latter is over 255, it will automatically be forced to the larger type). Depending on the value used for 'postscale', you may even have to force the arithmetic up to int32 (you do this by 'casting'), so:

freq= Fosc / (4L*(period + 1) * (int32)postscale)

Which will force postscale to be an int32 value, and the result here will then be an int32.

Best Wishes

[Jim]

That was just a comment to explain how I came up with the 199. I did the math on my calculator.

[Jim]

They hardware I'm using is an nothing more then the 18f4331 on a circuit board with the Pic's pins going to jumper pins. Aside from that I have a MCLR reset switch and ICP pings with a 5v reg and a capacitor to smooth out the signal .. I built this board for testing and prototyping so there is nothing fancy that would alter the signal.

[PCM programmer]

I compared the .LST file from your version of the compiler to vs. 3.249
and they're essentially the same. There is a Microchip Appnote, AN900,
which gives a detailed procedure on how to configure the PCPWM module.
http://ww1.microchip.com/downloads/en/AppNotes/00900a.pdf
I didn't compare it to CCS's code because it would take a while to do.

[Jim]

"..Make period an int16. The PWM time base register PTPERH and PTPERL contain 12 bits of data for the period. An 8 bit period will throw the calculations off...."

Thanks for all your help guys..

[Mit]

excuse me but I need some help.

i use those code those code from Jim last post with PIC18F4431 and 4MHz Xtal
I already change those include and INTRC_IO to 18F4431.h and XT

i got nothing from output pin

but if i get "set_power_pwm0_duty(500); set_power_pwm0_duty(500); "
out from while loop i get pulse from output pin

can anyone give me some advise