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Scottl
Joined: 21 Feb 2005 Posts: 25
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PIC12F683 Upgrade |
Posted: Mon Sep 11, 2006 9:52 pm |
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I have an existing board that currently use the PIC12F675. I would like to add some floating point math by adding a PIC12F683. I have the following code that I am using with the PIC12F675 but have added the Floating Point math.
Can someone with more experience with the PIC12F683 tell me what I am doing wrong in my code? I am running PCWH version 3.205
/* Code Below
#include <12f683.h>
#device adc=10
#use delay(clock=4000000)
#fuses NOWDT,INTRC_IO,PUT,NOPROTECT,NOBROWNOUT,NOMCLR,NOCPD
#use rs232( baud=9600, xmit=PIN_A5 )
long ad = 0;
float temp = 0;
float lowbat = 0;
void init(void) // Hardware initialization
{
set_tris_a( 0x1f );
setup_adc_ports( AN0_ANALOG );
setup_adc_ports( AN2_ANALOG );
setup_adc(ADC_CLOCK_DIV_8);
setup_comparator( NC_NC_NC_NC );
output_high(PIN_A4);
delay_ms( 5 );
output_low(PIN_A4);
delay_ms( 500 );
}
void main()
{
init(); // Configure peripherals/hardware
while(1) // Continuous loop
{
// check thermocouple sensor data
set_adc_channel( 0 ); // Set AD channel to AN0
delay_us(20);
ad = read_adc(); // Read A/D channel 0 or AN0 into ad variable
temp = (float)ad * (5.0/1023); // Convert 10-bit reading
temp = (float)temp / 100;
temp = (float)temp * 1.8 + 32;
printf("%6.2fF\r\n",temp);
delay_ms(500);
// check battery voltage for < 3.6V if so send l for low battery
set_adc_channel( 2 ); // Set AD channel to AN2
delay_us(20);
ad = read_adc(); // Read A/D channel 2 or AN0 into ad variable
lowbat = (float)ad * (5.0/1023); // Convert 10-bit reading
if ( lowbat <= 3.6 )
printf("lb\r\n");
delay_ms(500);
}
}
/* End code
Thanks in advance,
Scott |
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PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Posted: Mon Sep 11, 2006 10:19 pm |
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First, the #use delay() statement should go after the #fuses statement,
as shown in bold below. Then the compiler will automatically insert code
to setup the OSCCON register to the correct frequency. It worked for
you anyway, because the power-on reset state of OSCCON is for 4 MHz.
But if you ever want to use a different frequency for the internal
oscillator, then it's important to put #use delay() after #fuses.
Quote: | #include <12f683.h>
#device adc=10
#fuses NOWDT,INTRC_IO,PUT,NOPROTECT,NOBROWNOUT,NOMCLR,NOCPD
#use delay(clock=4000000)
#use rs232( baud=9600, xmit=PIN_A5 ) |
In your init() function below, you don't need to set the TRIS because
you're using the default "standard i/o" mode of the compiler, and it
will automatically set the correct TRIS in that mode, as long as you
use CCS i/o functions (which you are doing).
The 2nd problem below is in your Port A setup. You don't setup the A/D
pins with sequential statements. If you do that, only the last statement
will take effect. If you want more than one Analog pin enabled, you
need to bitwise OR the constants together, as shown in bold below.
The constants come from the 12F683.H file. I installed vs. 3.205 and
verified this.
Quote: | void init(void) // Hardware initialization
{
//set_tris_a( 0x1f );
//setup_adc_ports( AN0_ANALOG );
//setup_adc_ports( AN2_ANALOG );
setup_adc_ports(sAN0 | sAN2);
setup_adc(ADC_CLOCK_DIV_8);
setup_comparator( NC_NC_NC_NC );
output_high(PIN_A4);
delay_ms( 5 );
output_low(PIN_A4);
delay_ms( 500 );
} |
There might be other problems, but these were the immediate ones
that I saw. |
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Scottl
Joined: 21 Feb 2005 Posts: 25
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Posted: Tue Sep 12, 2006 4:57 am |
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I will make the changes and give it another try this evening! Thanks for the reply!
Scott |
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Scottl
Joined: 21 Feb 2005 Posts: 25
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Posted: Tue Sep 12, 2006 2:47 pm |
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I have been trying to test the code but nothing happens. The code works with the PIC12F675 but I cannot add Float or any other code. I have also noticed that the PIC12F683 gets very very hot! Any thoughts?
I must get this complete tonight to ship tomorrow!
Thanks for your help,
Scott |
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PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Posted: Tue Sep 12, 2006 3:03 pm |
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If the PIC gets hot, then check the connections. Check if you reversed
power and ground. If you did, that PIC might be destroyed. |
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newguy
Joined: 24 Jun 2004 Posts: 1903
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Posted: Tue Sep 12, 2006 3:03 pm |
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If the chip gets hot,
(a) check your connections, especially the pinout of the new processor and if it differs from the old one, and
(b) try a new chip.
Chips usually only get hot if they're damaged or if you have power & ground wrong. Especially a PIC. I've never had one that ran even remotely warm. |
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Scottl
Joined: 21 Feb 2005 Posts: 25
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Posted: Tue Sep 12, 2006 3:30 pm |
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The PIC12F683 and the old PIC12F675 are pin for pin compatible! Unless I am missing something. I have never had this issue before.
Can someone supply me with a simple example they have compiled for the PIC12F683 with GPIO.0 as analog and send the value over GPIO.5 non-inverted?
Scott |
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PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Posted: Tue Sep 12, 2006 3:44 pm |
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I don't have a 12F683 chip to test. I only have a 12F675 and a 12F629.
I still say that if the PIC is getting very hot, then you have a problem.
You may have +5v directly connected to an i/o pin that's set at a logic
low level with an output_low() statement. That would likely make the
PIC become very hot. Until that problem is corrected, getting new code
won't help. |
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Scottl
Joined: 21 Feb 2005 Posts: 25
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Posted: Tue Sep 12, 2006 4:22 pm |
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It seems that PIN AN2 which is monitoring the battery is making the chip get hot. I have folded the pin up and the chip does not get hot.
Here is my code for the PIC12F675:
#include <12f675.h>
#device adc=10
#fuses NOWDT,INTRC_IO,PUT,NOPROTECT,NOBROWNOUT,NOMCLR,NOCPD
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_A5)
long ad = 0;
float volts = 0;
void init(void) // Hardware initialization
{
setup_adc_ports( sAN0 ); // A/D module on for GPIO.0
setup_adc( ADC_CLOCK_DIV_8 ); // A/D clock/8 @4MHz,Tad=2uS
setup_comparator( NC_NC_NC_NC ); // disable comparator module
output_high(PIN_A4);
delay_ms( 5 );
output_low(PIN_A4);
delay_ms( 500 );
}
void main()
{
init(); // Configure peripherals/hardware
while(1) // Continuous loop
{
set_adc_channel( 0 );
delay_us(20);
ad = read_adc(); // Read A/D channel into ad variable
volts = (float)ad * (5.0/1023) ; // Convert 10-bit reading
printf("%6.2f\r\n",volts);
delay_ms(2000); // Pause 50mS between updates
}
}
It seems I should be able to change #include <12f675.h> to #include <12f683.h> and it should work.
The above code works fine and I am receiving the Analog value via serial port.
Scott |
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PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Scottl
Joined: 21 Feb 2005 Posts: 25
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Posted: Tue Sep 12, 2006 5:01 pm |
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It's working! Thanks for your help!
I will work on the remaining problem with AN2 making the PIC hot. The battery is a 3.6V battery so it should be ok. The problem may be that the A/D is latching. I may go ahead and add a 1K ohm resistor between the Battery and AN2.
Scott |
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