pot command

[lerameur]

Hi,

Little problem trying to switch POrt on my pot command.
I am geting good result using the default port . The port command only goes to port B. I want to use portA, so I would like to use this command but it do not work: PortA.02,175,B0

The follwoing is my working code:

B0 var byte
Start:
Pot 2,175,B0 ' would like PortA.2,175,B0
Lcdout $fe, 1 'Clear screen
Lcdout "Pot: ", Dec B0 'Display the decimal value
Pause 300

k

[mister_e]

Once again, we can't guess wich PIC you're using so try one or all of the following lines

CMCON=7
ADCON1=7
ADCON1=$0F
ANSEL=0
ANSELH=0

if any of ADCON or ANSEL setting work... you may discover something interesting and NEVER EVER use POT command

[lerameur]

sorry pic16F88

[mister_e]

Now you have to forget POT but use ADCIN instead. Just your POT on your PORTA, no capacitor in serie.

Your PIC have ADCs AND analog comparator on PORTA... it's useless to use POT.

Datasheet section 12.0 and 13.0.

You need to disable the comparator first.. something is right in my previous thread about that.

[lerameur]

well the adcon1 I used before doing some A/d conversion.
I also tried setting the port to output using the Tris command. NOthing works.
Also, I guess when you say I donthave to use the Pot command you are refering to making A/D conversion ??

k

[mister_e]

Probably you have disable the ADCs but not the comparator? Both have to be disable.

And yes i'm talking about doing a A/D conversion... that's already built-in, free and far better than POT

[lerameur]

by just using a pot on that pin, wont I have to use a voltage divider. If I just put a pot, then it will the same voltage and the convertion will be the same.
Right now with this I am getting weird characters on the lcd.
I did not touch portB..
To disable I guess by using the ADCON1 = 0 it is disable (bit 2 and 3)

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
B0 var byte
Start:
TRISA = 3 ' Set PORTA to all input
ADCON1 = 0 ' PORTA is analog
ADCIN 0, B0 ' Read channel 0 to B0

Lcdout $fe, 1 'Clear screen
Lcdout "Pot: ", Dec B0 'Display the decimal value
Pause 300

[Archangel]

Once again, we can't guess wich PIC you're using so try one or all of the following lines

<h4>CMCON=7</h4>
<h4>ADCON1=7</h4>
ADCON1=$0F
<h4>ANSEL=0</h4>
ANSELH=0

if any of ADCON or ANSEL setting work... you may discover something interesting and NEVER EVER use POT command

Hi Lerameur,
I think we gave mister_e a headache tonight, The data sheet chap. 5, 12, 13 makes mention of these. Get it here if you do not have.
Cheers
JS
http://www.microchip.com/stellent/id...cName=en010243

[lerameur]

yes I am printing them out and carefully reading them now.
But, i am curious, if I wanted to use the POT command, what do i have to do to read from port A?

k

[Archangel]

yes I am printing them out and carefully reading them now.
But, i am curious, if I wanted to use the POT command, what do i have to do to read from port A?

k

lerameur,
without actually doing it to verify it works . . .as I do not have a 16F88
put the three BOLD commands into your code to make the PortA pins digital and turn off the analog comparators

CMCON=7              ' Disable comparators
ANSEL=0               ' Set port as digital I/O
ADCON1=7
TrisA = %11111111  'sets all port a as input
TrisB = %00000000  ' sets all port b as output
B0 var byte            ' establishes a variable called B
Start:
Pot PortA.2,255,B0           ' would like PortA.2,175,B0 use number to suit you
Lcdout $fe, 1                   'Clear screen
Lcdout $FE,$80,"Pot: ", #B0       'Display the numerical value
Pause 300 
goto start
end

This should work.
JS

[peterdeco1]

Hi Lerameur. I have an 'F88 and this program works. The 'F88 has 5 ADC's which are better than using the pot command. I connected pin 17 (ana 0) to the center terminal of a 1 meg pot. The CCW terminal to ground, CW terminal to B+.

OSCCON = $60 'SET INT OSC TO 4MHZ
ANSEL = 0 'SELECT ANALOG INPUTS 0 = NONE AND ALL DIGITAL
ADCON0 = 0 'AD MODULE OFF & CONSUMES NO CURRENT
CMCON = 7 'COMPARATORS OFF
TRISA = %11111111 'PORTA INPUTS
TRISB = %00000000 'PORTB OUTPUTS
X VAR BYTE 'VARIABLE TO PUT POT VALUE
PORTB = 0 'ALL OUTPUTS LOW

START:
ADCIN 0, X 'READ VALUE ON ANA 0
IF X > 0 AND X <= 50 THEN LED1
IF X > 50 AND X <= 100 THEN LED2
IF X > 100 AND X <= 200 THEN LED3
IF X > 200 THEN LED4
GOTO START

LED1:
HIGH PORTB.0
PAUSE 1000
LOW PORTB.0
GOTO START

LED2:
HIGH PORTB.1
PAUSE 1000
LOW PORTB.1
GOTO START

LED3:
HIGH PORTB.2
PAUSE 1000
LOW PORTB.2
GOTO START

LED4:
HIGH PORTB.3
PAUSE 1000
LOW PORTB.3
GOTO START