TEMPERATURE SENSOR CODE NEEDED USING PIC18F452

[helloarloha]

we are required to setup the PIC18F452 and enable the ADC module to read a temperature sensor uisng PIC...can anyone help to provide the code? thx in advance...

 

[Tahmid]

Hi,
What sensor you want to use and what is the highest limit of temperature? What should be the Language, Assembly or C or Mikrobasic?

 

[helloarloha]

it can be in IN MPLAB or MIcro C or CCS...I'm using LM 35 and the temperature range is not mentioned..but we can juz set it as maybe 10-50...

Added after 2 minutes:

if assembly is more preferable since i'm learning hard to it...if not micro C or CCS code also acceptable....thx...

 

[hugo]

we are required to setup the PIC18F452 and enable the ADC module to read a temperature sensor uisng PIC...can anyone help to provide the code? thx in advance...

Just take a look here :

https://www.micro-examples.com/public/microex-navig/doc/086-mcp9700a-thermometer.html

It's a similar project ( PIC16F877A + MCP9700A temp. sensor ) ...

 

[Tahmid]

Hi helloarloha,
Here I present a simple temperature sensor using PIC18F452 and LCD in mikroBASIC.

program thermometer452

dim LCD_RS as sbit at RB4_bit
    LCD_EN as sbit at RB5_bit
    LCD_D4 as sbit at RB0_bit
    LCD_D5 as sbit at RB1_bit
    LCD_D6 as sbit at RB2_bit
    LCD_D7 as sbit at RB3_bit

    LCD_RS_Direction as sbit at TRISB4_bit
    LCD_EN_Direction as sbit at TRISB5_bit
    LCD_D4_Direction as sbit at TRISB0_bit
    LCD_D5_Direction as sbit at TRISB1_bit
    LCD_D6_Direction as sbit at TRISB2_bit
    LCD_D7_Direction as sbit at TRISB3_bit

dim ADCResult as longword
dim value as word[3]
dim vstring as string[3]

sub procedure GlobInit
    TRISB = 0
    PORTB = 0
    TRISA = 1
    ADCON1 = $4E
    LCD_Init
    LCD_Cmd(_LCD_CLEAR)
    LCD_Cmd(_LCD_CURSOR_OFF)
    LCD_Out(1, 1, "Temp:")
    LCD_Out(1, 15, "'C")
end sub

main:
     GlobInit
     while true
           ADCResult = (ADC_Read(0) * 500) >> 10
           value[0] = ADCResult div 100
           value[1] = (ADCResult div 10) mod 10
           value[2] = ADCResult mod 10
           vstring[0] = value[0] + 48
           vstring[1] = value[1] + 48
           vstring[2] = value[2] + 48
           LCD_Out(1, 10, vstring)
           delay_ms(50)
     wend
end.

 

[Tahmid]

Hi helloarloha,
Here is the equivalent source code in mikroC:

unsigned long ADCResult;
unsigned int value[3];
char vstring[3];

void GlobInit(void){
    TRISB = 0;
    PORTB = 0;
    TRISA = 1;
    ADCON1 = 0x4E;
    LCD_Config(&PORTB, 4, 5, 6, 3, 2, 1, 0);
    LCD_Cmd(LCD_CLEAR);
    LCD_Cmd(LCD_CURSOR_OFF);
    LCD_Out(1, 1, "Temp:");
    LCD_Out(1, 15, "'C");
}

void main(){
    GlobInit();
    while (1){
          ADCResult = (ADC_Read(0) * 500) >> 10;
          value[0] = ADCResult / 100;
          value[1] = (ADCResult / 10) % 10;
          value[2] = ADCResult % 10;
          vstring[0] = value[0] + 48;
          vstring[1] = value[1] + 48;
          vstring[2] = value[2] + 48;
          LCD_Out(1, 10, vstring);
          delay_ms(50);
    }
}

I am not that good with C18, so I made the software in mikroC instead.

 

[malikmuhammadali]

/*
*******************************************************************************
* PIC DIGITAL THERMOMETER USING A MICROCHIP MCP9700A ANALOG SENSOR
*******************************************************************************
*
* source code example for mikroC users
* feel free to use this code at your own risks
*
* target : PIC16F877A, 8 Mhz crystal
* HS clock, no watchdog.
*
* easyPIC4 settings :
* MCP9700A on DS1820 socket, see web page for more details.
*
* Author : Bruno Gavand, September 2007
* see more details on https://www.micro-examples.com/
*
*******************************************************************************
*/

/*
* LCD_printfix constants
*/
#define INT_RANGE 1000 // integer part : 3 digits
#define DEC_RANGE 10 // decimal part : 1 digit

/*
* this counter is incremented on each TIMER0 overflow
*/
unsigned int cntr ;

long temp ; // Temperature in Celcius * 10
int fahr ; // Temperature in Fahrenheit * 10

/*
* offset reference of the sensor : 0°C is 500 mV => 102.4
* since the sensor is factory calibrated, there is no need for adjustment
*/
int ref = 1024 ; // offset is multiplied by 10 to get tenth of degrees

/*
* LCD character definitions, generated by mikroC LCD Custom Character tool :
*/
const char characterC[] = {8,20,8,0,3,4,4,3}; // °C
const char characterF[] = {8,20,8,0,7,4,6,4}; // °F

/*
* print character pointed to by def at line pos_row column pos_char on LCD
*/
void CustomChar(const char *def, unsigned char n, char pos_row, char pos_char)
{
char i ;

LCD_Cmd(64 + n * 8) ;
for(i = 0 ; i<=7 ; i++)
{
LCD_Chr_Cp(def) ;
}
LCD_Cmd(LCD_RETURN_HOME) ;
LCD_Chr(pos_row, pos_char, n) ;
}

/*
* print v with fixed-size integer and decimal parts
*/
void LCD_printFix(unsigned int v)
{
unsigned int w ;
unsigned int d ;
unsigned char n ;
unsigned char blk = 1 ; // zero blanking

if(v >= 0)
{
LCD_Chr_Cp('+') ;
}
else
{
LCD_Chr_Cp('-') ;
}

v = abs(v) ;
w = v / DEC_RANGE ;
for(d = INT_RANGE / 10 ; d > 0 ; d /= 10)
{
n = (w / d) % 10 ;
if
{
blk = 0 ;
}
if(blk)
{
LCD_Chr_Cp(' ') ;
}
else
{
LCD_Chr_Cp('0' + n) ;
}
}
LCD_Chr_Cp('.') ;
w = v % DEC_RANGE ;
for(d = DEC_RANGE / 10 ; d > 0 ; d /= 10)
{
LCD_Chr_Cp('0' + (w / d) % 10) ;
}
}

/*
* interrupt routine, called on each timer0 overflow
*/
void interrupt(void)
{
if(INTCON.T0IF) // timer 0 overflow ?
{
cntr++ ; // increment counter
INTCON.T0IF = 0 ; // done
}
}

/*
* program entry
*/
void main()
{
ADCON1 = 0x00 ; // set PORTA as analog input
TRISA = 0xff ; // set PORTA as inputs
TRISD = 0 ; // PORTD is output
LCD_Init(&PORTD) ; // Initialize LCD connected to PORTD
LCD_Cmd(Lcd_CLEAR) ; // Clear display
LCD_Cmd(Lcd_CURSOR_OFF) ; // Turn cursor off
LCD_Out(1, 1, "MCP9700A EXAMPLE"); // Print welcome message

OPTION_REG = 0x80 ; // start timer 0, no prescaler
INTCON = 0xA0 ; // allow timer 0 overflow interrupt

for(; // forever
{
if(cntr >= 4000) // if enough time since last sample
{
/*
* read the sensor
*/
temp = Adc_Read(7) * 10 - ref ; // read RE2 ADC, adjust to 0°C

/*
* get the result in celcius * 10
* sensor temperature coefficient is +10mV/°C
* ADC resolution is 5000/1024 = 4.88 mV so one ADC point is 0.488°C
*/
temp *= 488 ;
temp /= 1000 ;

fahr = ((9 * temp) / 5 ) + 320 ; // convert C degrees to F * 10

/*
* print temperature in °C on LCD
*/
LCD_Out(2, 1, "") ;
LCD_printFix(temp) ;
CustomChar(characterC, 0, 2, 7) ;

/*
* print temperature in °F on LCD
*/
LCD_Out(2, 10, "") ;
LCD_printFix(fahr) ;
CustomChar(characterF, 1, 2, 16) ;

cntr = 0 ; // clear counter
}
}
}

 

[sunahm]

hi, I'm doing a project which uses PIC18F452 to read LM35DZ temperature..I don't know why the temperature value on my LCD is 0.00 'C..is there any coding I need to write to configure the sensor?

 

[Tahmid]

Hi sunahm,
You're probably not reading the LM35 properly, check your ADC initialization and reading part in the code.
If you can, posting the code would help.
Hope this helps.
Tahmid.