[SOLVED] DS18B20 and PIC16F877A (Need Program Help)

nirob · Feb 12, 2013

I am using Micro C Pro and Proteus for simulation. Here is The Program of Temperature Sensor (DS18B20 + PIC16F877A)

It woks almost right but does not show the negative (-) sign before the negative Temp. where is the problem? Can anyone please help me to modify the code

here is my simulation pic

Code:

// LCD module connections
sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;

sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;
// End LCD module connections

//  Set TEMP_RESOLUTION to the corresponding resolution of used DS18x20 sensor:
//  18S20: 9  (default setting; can be 9,10,11,or 12)
//  18B20: 12
const unsigned short TEMP_RESOLUTION = 12;

char *text = "000.0000";
unsigned temp;

void Display_Temperature(unsigned int temp2write) {
  const unsigned short RES_SHIFT = TEMP_RESOLUTION - 8;
  char temp_whole;
  unsigned int temp_fraction;

  // Check if temperature is negative
  if (temp2write & 0x8000) {
     text[0] = '-';
     temp2write = ~temp2write + 1;
     }

  // Extract temp_whole
  temp_whole = temp2write >> RES_SHIFT ;

  // Convert temp_whole to characters
  if (temp_whole/100)
     text[0] = temp_whole/100  + 48;
  else
     text[0] = '0';

  text[1] = (temp_whole/10)%10 + 48;             // Extract tens digit
  text[2] =  temp_whole%10     + 48;             // Extract ones digit

  // Extract temp_fraction and convert it to unsigned int
  temp_fraction  = temp2write << (4-RES_SHIFT);
  temp_fraction &= 0x000F;
  temp_fraction *= 625;

  // Convert temp_fraction to characters
  text[4] =  temp_fraction/1000    + 48;         // Extract thousands digit
  text[5] = (temp_fraction/100)%10 + 48;         // Extract hundreds digit
  text[6] = (temp_fraction/10)%10  + 48;         // Extract tens digit
  text[7] =  temp_fraction%10      + 48;         // Extract ones digit

  // Print temperature on LCD
  Lcd_Out(2, 5, text);
}

void main() {
 ADCON1=0x06;

  Lcd_Init();                                    // Initialize LCD
  Lcd_Cmd(_LCD_CLEAR);                           // Clear LCD
  Lcd_Cmd(_LCD_CURSOR_OFF);                      // Turn cursor off
  Lcd_Out(1, 1, " Temperature:   ");
  // Print degree character, 'C' for Centigrades
  Lcd_Chr(2,13,223);                             // Different LCD displays have different char code for degree
                                                 // If you see greek alpha letter try typing 178 instead of 223

  Lcd_Chr(2,14,'C');

  //--- Main loop
  do {
    //--- Perform temperature reading
    Ow_Reset(&PORTE, 2);                         // Onewire reset signal
    Ow_Write(&PORTE, 2, 0xCC);                   // Issue command SKIP_ROM
    Ow_Write(&PORTE, 2, 0x44);                   // Issue command CONVERT_T
    Delay_us(120);

    Ow_Reset(&PORTE, 2);
    Ow_Write(&PORTE, 2, 0xCC);                   // Issue command SKIP_ROM
    Ow_Write(&PORTE, 2, 0xBE);                   // Issue command READ_SCRATCHPAD

    temp =  Ow_Read(&PORTE, 2);
    temp = (Ow_Read(&PORTE, 2) << 8) + temp;

    //--- Format and display result on Lcd
    Display_Temperature(temp);

    Delay_ms(500);
  } while (1);
}

Tahmid · Feb 12, 2013

You are overwriting the -ve sign with the first digit of the temperature - in your image, "0".

Try with this code:

Code:

// LCD module connections
sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;

sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;
// End LCD module connections

//  Set TEMP_RESOLUTION to the corresponding resolution of used DS18x20 sensor:
//  18S20: 9  (default setting; can be 9,10,11,or 12)
//  18B20: 12
const unsigned short TEMP_RESOLUTION = 12;

char *text = "000.0000";
unsigned temp;

void Display_Temperature(unsigned int temp2write) {
  const unsigned short RES_SHIFT = TEMP_RESOLUTION - 8;
  char temp_whole;
  unsigned int temp_fraction;

  // Check if temperature is negative
  if (temp2write & 0x8000) {
     LCD_Chr(2,4,'-');
     temp2write = ~temp2write + 1;
     }
  else{
     LCD_Chr(2,4,' ');
  }

  // Extract temp_whole
  temp_whole = temp2write >> RES_SHIFT ;

  // Convert temp_whole to characters
  if (temp_whole/100)
     text[0] = temp_whole/100  + 48;
  else
     text[0] = '0';

  text[1] = (temp_whole/10)%10 + 48;             // Extract tens digit
  text[2] =  temp_whole%10     + 48;             // Extract ones digit

  // Extract temp_fraction and convert it to unsigned int
  temp_fraction  = temp2write << (4-RES_SHIFT);
  temp_fraction &= 0x000F;
  temp_fraction *= 625;

  // Convert temp_fraction to characters
  text[4] =  temp_fraction/1000    + 48;         // Extract thousands digit
  text[5] = (temp_fraction/100)%10 + 48;         // Extract hundreds digit
  text[6] = (temp_fraction/10)%10  + 48;         // Extract tens digit
  text[7] =  temp_fraction%10      + 48;         // Extract ones digit

  // Print temperature on LCD
  Lcd_Out(2, 5, text);
}

void main() {
 ADCON1=0x06;

  Lcd_Init();                                    // Initialize LCD
  Lcd_Cmd(_LCD_CLEAR);                           // Clear LCD
  Lcd_Cmd(_LCD_CURSOR_OFF);                      // Turn cursor off
  Lcd_Out(1, 1, " Temperature:   ");
  // Print degree character, 'C' for Centigrades
  Lcd_Chr(2,13,223);                             // Different LCD displays have different char code for degree
                                                 // If you see greek alpha letter try typing 178 instead of 223

  Lcd_Chr(2,14,'C');

  //--- Main loop
  do {
    //--- Perform temperature reading
    Ow_Reset(&PORTE, 2);                         // Onewire reset signal
    Ow_Write(&PORTE, 2, 0xCC);                   // Issue command SKIP_ROM
    Ow_Write(&PORTE, 2, 0x44);                   // Issue command CONVERT_T
    Delay_us(120);

    Ow_Reset(&PORTE, 2);
    Ow_Write(&PORTE, 2, 0xCC);                   // Issue command SKIP_ROM
    Ow_Write(&PORTE, 2, 0xBE);                   // Issue command READ_SCRATCHPAD

    temp =  Ow_Read(&PORTE, 2);
    temp = (Ow_Read(&PORTE, 2) << 8) + temp;

    //--- Format and display result on Lcd
    Display_Temperature(temp);

    Delay_ms(500);
  } while (1);
}

Hope this helps.
Tahmid.

nirob · Feb 12, 2013

Thank you Tahmid. Its really helpful.

nirob · Feb 13, 2013

I want to modify the above circuit and program.
When the (temp<=20 ), the PORTD.RD0 and PORTD.RD1 should be power ON. And connecting this port with ULN2003A (1C & 2C) , i want to drive two relays(RL1 , RL2) to drive a Heater ON (In the schematic)

Again when the (temp>=30), the PORTD.RD2 and PORTD.RD3 should be power ON. And connecting this port through ULN2003A (port 3C & 4C), i want to drive two relays for power On A Motor/ DC-Fan.

Also again When the (temp >= 100), the PORTD.RD4 should be power On and connectign through ULN2003A (port 5C), a LED and a BUZZER should be on.

how can i compare the temp it with these conditions. what is the IF or While conditions, or should i use goto statement or switch/case statement. please help me about this code and suggestion .

modification circuit

Proteus simulation DSN file

nouni299 · Mar 18, 2013

Hi everyone,

I'm new, I'm on my graduation project which is to store and control the temperature and the wet storage area, and I chose this sensor and I have a programming problem:

How did you do to display the '-', I tried but I can not because it is always the last instruction text [0] = '0 ', I wanted to elevate it but after m 'always displays' -' even if the value is positive.

Please another thing, why it always multiplies by 8, I did not understand,

Thank you in advance

nouni299 · Mar 19, 2013

thank you I found the answer, the problem was the 'else' is missing, and the multiplication by 8 problem as solved, the problem was a bad resolution, as it must always be a difference of 4-bit shift.
thank you

Pictou · Mar 21, 2013

@nirob

I did the same thing for one of my project.
You can use a string compare for that.
For instance you will send the characters to the UART for display, you can use a string compare to see in which case it is fitting at the same time.

If(temperature > 20) do "and so on".

I made a lot of if (as I'm a bad programmer) but it worked. Every 2seconds, my DS18B20 sensored the temperature and I made a string compare each time in the interrupt for instance.

---------------

Should have checked the date first, sorry

mido_ameer · Jun 19, 2013

Anyone knows how program PIC16F877A with DS1820 using MikroC
If yes please tell me some explainations in comments in the .c file

tpetar · Jun 19, 2013

mido_ameer said:
Anyone knows how program PIC16F877A with DS1820 using MikroC
If yes please tell me some explainations in comments in the .c file

Original MikroElektronika MikroC Example :
(Uses PIC18F45K22 but the same is with PIC16F877. Look to migrate from old 16F family to 18F)

Code:

/*
 * Project name:
     OneWire (Interfacing the DS1820 temperature sensor - all versions)
 * Copyright:
     (c) Mikroelektronika, 2011.
 * Revision History:
     20110929:
       - initial release (FJ);
 * Description:
     This code demonstrates one-wire communication with temperature sensor
     DS18x20 connected to RA4 or RE2 pin.
     MCU reads temperature from the sensor and prints it on the LCD.
     The display format of the temperature is 'xxx.xxxx°C'. To obtain correct
     results, the 18x20's temperature resolution has to be adjusted (constant
     TEMP_RESOLUTION).
 * Test configuration:
     MCU:             PIC18F45K22
                      http://ww1.microchip.com/downloads/en/DeviceDoc/41412D.pdf
     Dev.Board:       EasyPIC7 - ac:One_Wire
                      http://www.mikroe.com/eng/products/view/757/easypic-v7-development-system/
     Oscillator:      HS-PLL 32.0000 MHz, 8.0000 MHz Crystal
     Ext. Modules:    DS18x20 Sensor, Character Lcd 2x16
                      http://www.mikroe.com/eng/products/view/277/various-components/
     SW:              mikroC PRO for PIC
                      http://www.mikroe.com/eng/products/view/7/mikroc-pro-for-pic/
 * NOTES:
     - Place LM35 in proper position and place jumper J11 in the right position (RE2). (board specific)
     - Turn on Lcd backlight switch SW4.6. (board specific)
     - Be sure to put the power supply jumper J5 in the 5V position.
 */

// LCD module connections
sbit LCD_RS at LATB4_bit;
sbit LCD_EN at LATB5_bit;
sbit LCD_D4 at LATB0_bit;
sbit LCD_D5 at LATB1_bit;
sbit LCD_D6 at LATB2_bit;
sbit LCD_D7 at LATB3_bit;

sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;
// End LCD module connections

//  Set TEMP_RESOLUTION to the corresponding resolution of used DS18x20 sensor:
//  18S20: 9  (default setting; can be 9,10,11,or 12)
//  18B20: 12
const unsigned short TEMP_RESOLUTION = 9;

char *text = "000.0000";
unsigned temp;

void Display_Temperature(unsigned int temp2write) {
  const unsigned short RES_SHIFT = TEMP_RESOLUTION - 8;
  char temp_whole;
  unsigned int temp_fraction;

  // Check if temperature is negative
  if (temp2write & 0x8000) {
    text[0] = '-';
    temp2write = ~temp2write + 1;
  }

  // Extract temp_whole
  temp_whole = temp2write >> RES_SHIFT ;

  // Convert temp_whole to characters
  if (temp_whole/100)
    text[0] = temp_whole/100  + 48;
  else
    text[0] = '0';

  text[1] = (temp_whole/10)%10 + 48;             // Extract tens digit
  text[2] =  temp_whole%10     + 48;             // Extract ones digit

  // Extract temp_fraction and convert it to unsigned int
  temp_fraction  = temp2write << (4-RES_SHIFT);
  temp_fraction &= 0x000F;
  temp_fraction *= 625;

  // Convert temp_fraction to characters
  text[4] =  temp_fraction/1000    + 48;         // Extract thousands digit
  text[5] = (temp_fraction/100)%10 + 48;         // Extract hundreds digit
  text[6] = (temp_fraction/10)%10  + 48;         // Extract tens digit
  text[7] =  temp_fraction%10      + 48;         // Extract ones digit

  // Print temperature on LCD
  Lcd_Out(2, 5, text);
}

void main() {
  ANSELE = 0;                                    // Configure PORTE pins as digital
  TRISE.B2 = 1;                                  // Configure RE2 pin as input

  Lcd_Init();                                    // Initialize LCD
  Lcd_Cmd(_LCD_CLEAR);                           // Clear LCD
  Lcd_Cmd(_LCD_CURSOR_OFF);                      // Turn cursor off
  Lcd_Out(1, 1, " Temperature:   ");
  // Print degree character, 'C' for Centigrades
  Lcd_Chr(2,13,223);                             // Different LCD displays have different char code for degree
                                                 // If you see greek alpha letter try typing 178 instead of 223
  Lcd_Chr(2,14,'C');

  // Main loop
  do {
    // Perform temperature reading
    Ow_Reset(&PORTE, 2);                         // Onewire reset signal
    Ow_Write(&PORTE, 2, 0xCC);                   // Issue command SKIP_ROM
    Ow_Write(&PORTE, 2, 0x44);                   // Issue command CONVERT_T
    Delay_us(120);

    Ow_Reset(&PORTE, 2);
    Ow_Write(&PORTE, 2, 0xCC);                   // Issue command SKIP_ROM
    Ow_Write(&PORTE, 2, 0xBE);                   // Issue command READ_SCRATCHPAD

    temp =  Ow_Read(&PORTE, 2);
    temp = (Ow_Read(&PORTE, 2) << 8) + temp;

    // Format and display result on Lcd
    Display_Temperature(temp);

    Delay_ms(500);
  } while (1);
}

Best regards,
Peter

:wink:

mido_ameer · Jun 19, 2013

Thank you for your quick reply, but unfortunately it didn't work
LCD is 000.0000 without any change

ISIS says :
simulation is not running in real time due to excessive CPU overload
[DS18B20] RAM command unsupported

tpetar · Jun 19, 2013

mido_ameer said:
Thank you for your quick reply, but unfortunately it didn't work
LCD is 000.0000 without any change

ISIS says :
simulation is not running in real time due to excessive CPU overload
[DS18B20] RAM command unsupported

Example works on real hardware, with real parts.

You need to adjust simulator.

Best regards,
Peter

:wink:

[SOLVED] DS18B20 and PIC16F877A (Need Program Help)

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