Check my tutorials, which show how to use the analogue inputs.

Virtually any port that has the peripheral you need. If you want to read an analog voltage, use one of the analog pins. If you want to output a signal, use virtually any pins. If you want to output a PWM signal to vary the speed of the motor, use an OC pin.

The best code to use is the kind you know.

OC is Output Compare, the name doesn't seem all that obvious to me unless you know how the OC pin works. In general, an output compare works by comparing a period timer to a counter value.

First, you set up a timer to run at some frequency, a good rule of thumb for a motor is 20kHz.
Set your period register to some value
The hardware will compare the timer value to the period register and set/clear the output pin based on if the timer is greater than, equal to, or less than the period register.
When you want to change the duty cycle, you just change the period register.

I've only used OC on PIC24 and PIC32 so I can't help with absolute specifics on PIC16, but it should work the same way. It may be called something other than OC on PIC16.

As for the errors in your code, you may need to post more of the code. The only thing I see wrong with what you have is that you're missing a '{' after void main(). Also, ADCON1 I think should be set to 0xFE as you only need RA0 to be analog. TRISA should be set to 0x01 to make RA0 an input and the rest an output.

With a digital input that is floating, if the pin is say 2.5v, then both the PFET and the NFET on the input gate will be partially on, which will cause additional current to flow through the chip. It won't hurt anything, but in general, it is good practice to set all unused pins to output high/low or input with pull-ups or pull-downs.

Of course, read your datasheet and make sure I'm not telling you wrong about this

Hmm.... I don't use names like "unsigned short" so I don't know how many bits wide it is (I know I should as that is fairly basic...) but I think it is 8 bit. The ADC's in PICs are generally 10 bits, which means if your function adc_read() returns a 16 bit value, you are probably losing the 2 most significant bits. What you should do is change the ADC setup to left adjust the ADC result and return only the high byte of the value (if you don't need 10 bits of resolution). This could also be done by simply shifting the result to the right by 2, but it is more efficient to have the ADC module left adjust the result and read only one byte. The datasheet will have more information on this and explain it in detail.

Originally Posted by MoRoH

3) For the ADC it seems pretty simple...from examples i've gotten this code, but it comes with errors. Help would be awesome.

line/column message no. message text
a) 1.3 11 ';' expected by ADCON1 found
b) 1.5 4 specifier needed
c) 1.5 12 internal error

Code:

unsigned short adc_val  ;
void main ( )

ADCON1 = 0x00  ;
TRISA  = 0xff  ;
TRISB  = 0x00  ;
while (1)
(
adc_val = adc_read(2)    ;
portb = adc_val     ;
)

)

Hi there,

Where did you get that code? And is that all the code? Assuming it's supposed to be C, and assuming that that's all the code there is, there is a lot wrong with it.

As Noggin pointed out, it doesn't have an opening curly brace for the main function. Actually, it doesn't have a closing brace either; the closing "brace" is actually a right parenthesis (meaning it's a ")" when it should be a "}").

Same with the while() loop. It should look like

Code:

// Right.
while (1) 
{
    // loop contents go here
}

. . .instead of:

Code:

// Wrong.
while (1) 
(
    // loop contents go here
)

The code uses ADCON1, TRISA, TRISB, adc_read(), and portb without any of these variables and functions having been defined. There should be an #include directive to include the header for the chip you're using.

What compiler are you using?

(BTW: No offense intended if you wrote that code; everybody has to start somewhere. I'm just trying to point out reasons it might not be working.)


Regards,

Torben

[Edit: Hey, you're from Corner Brook! I had a very good night followed by a very bad morning in Corner Brook a few years back. Newfs have to be the friendliest folk I've ever met.]

I feel silly I didn't notice that they were ( and ) instead of { and }