PIC12F683 Upgrade

[Scottl]

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

[PCM programmer]

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.

[Scottl]

I will make the changes and give it another try this evening! Thanks for the reply!

Scott

[Scottl]

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

[PCM programmer]

If the PIC gets hot, then check the connections. Check if you reversed
power and ground. If you did, that PIC might be destroyed.

[newguy]

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.

[Scottl]

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

[PCM programmer]

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.

[Scottl]

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

[PCM programmer]

Your version of the compiler is buggy with the 12F683.

Here is one of the problems, and a fix for it:
http://www.ccsinfo.com/forum/viewtopic.php?t=25417

There might be other problems.

[Scottl]

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