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Hi,

Shouldnt the #use delay(clock=10000000) be 20000000 as I am using a 20MHz
clock?

* If your processor is running at 20MHz, then yes.

Also, the delay of 100ms.  Why have you chosen this, is it the time for the
pic to register and process the analogue to digital conversion, so after
100mS it is ready to sample again?

* You asked for some example code to show the CCS built-in functions and
that is what I posted - maybe I got the wrong end of the stick but you did
not ask for code for a specific application...Do you have the CCS compiler
already ? I posted that to show the "ease" of using the inbuilt
functionality with respect to on board hardware not to provide a solution.
The delay is simply there to allow the A2D conversion to take place - the
precise time it takes will be available in the PIC documentation. You could
poll the conversion complete flag (or get an interrupt) before getting the
value from the ADC - it's up to you.

I assume that the result of the conversion is stored in value. Say for
example I nputed 2.5v into the PIC how can I actually see what this value
is to ensure that the A2D is functioning correctly.

* With the CCS compiler, you can printf statements to redirect output
through the UART, via a serial cable (via a MAX232 etc) to a PC and use
Hyperterminal to monitor it. If you put 2.5V on the A2D (and it was
configured for 0-5V full range) then you would expect to see something like
"7F" coming up in Hyperterminal. The example code I posted omits the setup
of the serial port but it is as simple as :

#use rs232(baud=9600,xmit=PIN_C6,rcv=PIN_C7)

Use then need to interface the PIC and PC via a MAX232 using these pins.

Regards,
Dan




 (Embedded     "MATTHEWS, DEAN (D.)" <dmatth14@FORD.COM>@MITVMA.MIT.EDU>
 image moved   29/10/2001 12:50
 to file:
 pic20803.pcx)





Please respond to pic microcontroller discussion list
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cc:
Subject:  Re: [PIC]: USING CCSC C COMPILER

Security Level:?         Internal


Shouldnt the #use delay(clock=10000000) be 20000000 as I am using a 20MHz
clock?
Also, the delay of 100ms.  Why have you chosen this, is it the time for the
pic to register and process the analogue to digital conversion, so after
100mS it is ready to sample again?
I assume that the result of the conversion is stored in value. Say for
example I nputed 2.5v into the PIC how can I actually see what this value
is to ensure that the A2D is functioning correctly.


Dean Matthews
Reliability Engineering
Ford Engine Plant Bridgend
South Wales, U.K
Tel No:(01656)672597
Fax No:(01656)672558
Email: dmatth14@ford.com
` Please consider your environmental responsibility before printing this
e-mail


-----Original Message-----
From: D Lloyd [mailto:dan.lloyd@GB.ABB.COM]
Sent: 29 October 2001 12:04
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC]: USING CCSC C COMPILER


Hi,

"Does anybody have any example C programs using the CCSC compiler for using
the onboard A2D converter on the PIC16F877."

A derivative of one of CCS' own examples - presumably they won't mind me
posting it if they sell a compiler on the back of it ;-)

#use delay(clock=10000000)

void main (void)
{
   int value;

   setup_port_a( ALL_ANALOG );           // Next 3 lines are inbuilt
functions
   setup_adc( ADC_CLOCK_INTERNAL );
   set_adc_channel( 0 );

   do {
         value = Read_ADC();
         delay_ms(100);
         printf("\n\r%2X\r\n", value);
   } while (TRUE);
}


Regards,
Dan

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