Pic12f683 Cmcon0 = 7

[penelopepug]

Hi! I just purchased some PIC12F683s and am having some problems. The simple program I wrote takes a 0 to 5V analog voltage from a 5k potentiometer and this adjusts HPWM. I have 0.1uF caps in place from VDD to VSS and another on the pot's wiper. At the moment, the HPWM drives an LED. Ultimately it will feed a mosfet that will control a small toy motor.

Compiler - PisBasic Pro 2.47
Using MicroCode Studio
Pic - PIC12F683

I get a syntax error on the line "CMCON0 = 7" which disables the comparators. Yes, I tried "0" and "O" and just "CMCON". As well, I am getting irratic behavoir from the HPWM where as I adjust the pot, the duty cycle jumps around irraticaly. I used an oscilloscope to verify the behavior.

Any advice would be appreicated. The program is below;

INTCON = %10001000 ‘internal oscillator
OSCCON = %01110000 ‘ 8mHz
CMCON0 = 7 'Comparators off
GPIO = %00000000 'outputs low
TRISIO = %00010000 'GP3 as input
ANSEL = %00111000 'AN3 analog

'Define ADCIN parameters
Define ADC_BITS 10 ' Set number of bits in result
Define ADC_CLOCK 3 ' Set clock source (3=rc)
Define ADC_SAMPLEUS 50 ' Set sampling time in uS
Define CCP1_REG GPIO 'PWM Output on gpio
Define CCP1_BIT 2 'Bit 2

‘ Variables
Posit var Word
Speed var byte
Pause 100

Scan:
ADCIN 3, Posit ' Read channel AN3 to Posit
Speed = Posit/4
HPWM 1,Speed,1000
Pause 10
Goto Scan
End

[sayzer]

...and another on the pot's wiper.

Remove the cap.

...I get a syntax error on the line "CMCON0 = 7" which disables the comparators. Yes, I tried "0" and "O" and just "CMCON".

Select the correct PIC model from the drop down menu in MicroCode Studio.

...
INTCON = %10001000 'internal oscillator
OSCCON = %01110000 '8mHz

Add, DEFINE OSC 8.

...
Define CCP1_REG GPIO 'PWM Output on gpio
Define CCP1_BIT 2 'Bit 2

Not sure why you used these?

[Archangel]

Hi! I just purchased some PIC12F683s and am having some problems. The simple program I wrote takes a 0 to 5V analog voltage from a 5k potentiometer and this adjusts HPWM. I have 0.1uF caps in place from VDD to VSS and another on the pot's wiper. At the moment, the HPWM drives an LED. Ultimately it will feed a mosfet that will control a small toy motor.

Compiler - PisBasic Pro 2.47
Using MicroCode Studio
Pic - PIC12F683

I get a syntax error on the line "CMCON0 = 7" which disables the comparators. Yes, I tried "0" and "O" and just "CMCON". As well, I am getting irratic behavoir from the HPWM where as I adjust the pot, the duty cycle jumps around irraticaly. I used an oscilloscope to verify the behavior.

Any advice would be appreicated. The program is below;

INTCON = %10001000 ‘internal oscillator
OSCCON = %01110000 ‘ 8mHz
CMCON0 = 7 'Comparators off
GPIO = %00000000 'outputs low
TRISIO = %00010000 'GP3 as input
ANSEL = %00111000 'AN3 analog

'Define ADCIN parameters
Define ADC_BITS 10 ' Set number of bits in result
Define ADC_CLOCK 3 ' Set clock source (3=rc)
Define ADC_SAMPLEUS 50 ' Set sampling time in uS
Define CCP1_REG GPIO 'PWM Output on gpio
Define CCP1_BIT 2 'Bit 2

‘ Variables
Posit var Word
Speed var byte
Pause 100

Scan:
ADCIN 3, Posit ' Read channel AN3 to Posit
Speed = Posit/4
HPWM 1,Speed,1000
Pause 10
Goto Scan
End

Hello,
Without checking to see if this code works, and without reading for understanding, I did compile as presented below and it compiles. I found 3 things which prevented it from compiling. You used ` instead of ' on some of your comments and you defined
Define CCP1_REG GPIO 'PWM Output on gpio
Define CCP1_BIT 2 'Bit 2
which are already defined in the 12f683.bas file. I just commented them out.
HTH
JS
Oh, BTW, a scratchy pot can do wild things when used here too, and Sayzer will never steer you wrong.

INTCON = %10001000 'internal oscillator
OSCCON = %01110000 ' 8mHz
CMCON0 = 7 'Comparators off
GPIO = %00000000 'outputs low
TRISIO = %00010000 'GP3 as input
ANSEL = %00111000 'AN3 analog

'Define ADCIN parameters
Define ADC_BITS 10 ' Set number of bits in result
Define ADC_CLOCK 3 ' Set clock source (3=rc)
Define ADC_SAMPLEUS 50 ' Set sampling time in uS
'Define CCP1_REG GPIO 'PWM Output on gpio
'Define CCP1_BIT 2 'Bit 2

' Variables
Posit var Word
Speed var byte
Pause 100

Scan:
ADCIN 3, Posit ' Read channel AN3 to Posit
Speed = Posit/4
HPWM 1,Speed,1000
Pause 10
Goto Scan
End

[penelopepug]

Thanks for looking at this for me. I should have realized that the "bas" file sets up the HWPM for me. However I am not sure this is the source of the problem. I did look at the output of the pot and it is perfectly clean with and without the capacitor. It seems to be related to the anolog sampling or calculation (I think). As for the compiling issue, I did select the correct PIC but no matter what I do the CMCON0 shows up as a syntax error for me. I ended up commenting it out and moving the analog over to a differing port so as to not have to worry about the error.

[skimask]

However I am not sure this is the source of the problem. I did look at the output of the pot and it is perfectly clean with and without the capacitor. It seems to be related to the anolog sampling or calculation (I think).

The problem probably stems from the fact that you are most likely updating the duty cycle in the middle of performing a cycle. The datasheets talk about that sort of thing. What happens if you just run the program in a loop that doesn't change the duty cycle?
As far as the A/D output, are you sure the A/D output (the number returned by the ADCIN command) is smooth in the first place? Maybe a 10ms pause isn't enough (not likely), maybe too much. Add in a bit of code to average out the duty cycle itself, software averaging of some sort, move the duty cycle around 'slower'...see what happens.

And as far as CMCON goes, just POKE the value into the appropriate register and see what happens.

[penelopepug]

Thanks skimask. You've given me some things to try. I'll post my findings assuming I resolve the problems. Thanks again.

[sayzer]

....You used ` instead of ' on some of your comments.

penelopepug,

May be you missed what Joe talks about.

Pay attention to these characters;
`
'


as you know, they are not the same characters and will give you syntax errors.

[penelopepug]

penelopepug,

May be you missed what Joe talks about.

Pay attention to these characters;
`
'


as you know, they are not the same characters and will give you syntax errors.

Hi Sayzer. I had retyped that line and copied and pasted it a few times thinking something hidden was the problem. However I'll take a close look at that, hopefully tonight. Thanks again.

[StoneColdFuzzy]

Hello,
Edited.

INTCON = %10001000 'internal oscillator
OSCCON = %01110000 ' 8mHz
CMCON0 = 7 'Comparators off
GPIO = %00000000 'outputs low
TRISIO = %00010000 'GP4 as input
ANSEL = %00111000 'AN3 analog

'Define ADCIN parameters
Define ADC_BITS 10 ' Set number of bits in result
Define ADC_CLOCK 3 ' Set clock source (3=rc)
Define ADC_SAMPLEUS 50 ' Set sampling time in uS
'Define CCP1_REG GPIO 'PWM Output on gpio
'Define CCP1_BIT 2 'Bit 2

' Variables
Posit var Word
Speed var byte
Pause 100

Scan:
ADCIN 3, Posit ' Read channel AN3 to Posit
Speed = Posit/4
HPWM 1,Speed,1000
Pause 10
Goto Scan
End

OK, I'm still trying to understand this and use code, so I thought that I would revive this thread.

Above, the code has "ANSEL = %00111000 'AN3 analog" To me it looks like AN4 and 5 are also made analog. Is this needed? if it is not needed, I should be able to use:

ANSEL = %00001000  ' AN3 analog

~ Dave

[Archangel]

OK, I'm still trying to understand this and use code, so I thought that I would revive this thread.

Above, the code has "ANSEL = %00111000 'AN3 analog" To me it looks like AN4 and 5 are also made analog. Is this needed? if it is not needed, I should be able to use:

ANSEL = %00001000  ' AN3 analog

~ Dave

For the 12F683 there is no AN4 and AN5, those bits control the data conversion clock. see the Data sheet page 33.

[StoneColdFuzzy]

For the 12F683 there is no AN4 and AN5, those bits control the data conversion clock. see the Data sheet page 33.

OK, yes, I see that now. Are they to be set to 1 for this application? Where may I find more information in layman's terms to help me understand what that is?

~ Dave

[astouffer]

This may help you a bit. I've been playing with the 12F683.

@	__CONFIG _INTOSCIO & _FCMEN_OFF & _IESO_OFF & _BOD_OFF & _BOD_OFF & _CP_OFF & _MCLRE_ON & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF

DEFINE OSC 8           ' Internal 8MHz
DEFINE ADC_BITS 8      ' 8-bit resolution
DEFINE ADC_CLOCK 2     ' Set clock source to Frc/32
DEFINE ADC_SAMPLEUS 50 ' Sample time in uS before A/D conversion is started

CMCON0 = 7   			'Comparators off
ADCON0 = %00000001		'ADC enabled and right justified
ANSEL = %00001000		'GPIO.0 and GPIO.1 analog input
INTCON = 0				'INTERRUPTS off
OSCCON = %01110000		'8 Mhz
TRISIO = %111011		'GPIO2 output
GPIO = %00010000 		' All outputs = 0 on boot