Temp project using LM34

[Philley]

Hi just started getting into the whole Microcontroller world and have a problem that I can't wrap my head around. I've made some code up that will use the LM34 to measure the temperature in C and F and display them on the LCD. But my problem now is that I want to be able use SW1 on the 16F877 to switch from a Celsius reading to a Farenheit reading but still being able to get current temperature readings. Below I have the code that I'm using at the moment but figuring out how to use the SW1 to switch back and forth is bothering me to say the least. Any help or guide me in the right direction would be appreciated.

The board I'm using is a LabX-1 16F877.

DEFINE LCD_DREG PORTD 'data register
DEFINE LCD_RSREG PORTE 'register select
DEFINE LCD_RSBIT 0 'pin number
DEFINE LCD_EREG PORTE 'enable register
DEFINE LCD_EBIT 1 'enable bit
DEFINE LCD_RWREG PORTE 'read/write register
DEFINE LCD_RWBIT 2 'read/write bit
DEFINE LCD_BITS 8 'width of data
DEFINE LCD_LINES 2 'lines in display
DEFINE LCD_COMMANDUS 2000 'delay in micro seconds
DEFINE LCD_DATAUS 20 'delay in micro seconds

'Set the port directions. We are setting PORTA.0 to an input, all rest outputs
'all of PORTD is set to outputs to run the LCD
'and all of PORTE as outputs even though PORTE has only 3 lines.

TRISA = %11111111 'set PORTA lines
TRISD = %00000000 'set all PORTD lines to output
TRISE = %00000000 'set all PORTE lines to output
'Set the Analog to Digital control register
ADCON1=%10000010 'see discussion above
'Define the variables used
ADVAL VAR BYTE 'Create ADVAL to store result
TEMP VAR BYTE 'temperature Farenheit variable
TEMPC VAR BYTE 'temperature Celsius variable
DEG CON 223 'write an degree mark on lcd
'define the adcin parameters
DEFINE ADC_BITS 10 'Set number of bits in result
DEFINE ADC_CLOCK 3 'Set clock source (3=rc)
DEFINE ADC_SAMPLEUS 50 'Set sampling time in uS
LCDOUT $FE, 1 'clear screen

LOOP: 'The main loop of the program
PAUSE 250 'pause 0.5 seconds
ADCIN 4, ADVAL 'Read channel 0 to adval
ADVAL =(ADVAL*/500)>>2
TEMP=ADVAL
TEMPC=((TEMP-32) *100) /180
LCDOUT $FE, 2 'go to home position
LCDOUT "Temp=", DEC3 TEMP,DEG, "F" 'print to line 1 of 2 line display
LCDOUT $FE,$C0, "Temp=", DEC3 TEMPC,DEG, "C"
GOTO LOOP
END

[mackrackit]

I would say have LOOPC and LOOPF and MAIN program blocks. SW1 sits in main and depending on HIGH or LOW GOTO LOOPC or LOOPF. Then go back to main to check SW1.

Add a PAUSE 250 in the LOOPs before going back to MAIN.

You can shorten this up a bit, but try this first.

[mister_e]

PAUSE 200 ' or whatever
if SW1=1 then
    LCDOUT "Temp=", DEC3 TEMP,DEG, "F" 
    ELSE
        LCDOUT "Temp=", DEC3 TEMPC,DEG, "C"
    ENDIF
GOTO LOOP

mmm SW1 is an Tact switch connected between PORTB.0 and PORTB.4 right?

[mister_e]

try this

<code><font color="#000000">        <font color="#000080">DEFINE  </font>LCD_DREG	PORTD 	<font color="#008000">'data register
        </font><font color="#000080">DEFINE  </font>LCD_RSREG	PORTE	<font color="#008000">'register select
        </font><font color="#000080">DEFINE  </font>LCD_RSBIT	0	<font color="#008000">'pin number
        </font><font color="#000080">DEFINE  </font>LCD_EREG	PORTE	<font color="#008000">'enable register
        </font><font color="#000080">DEFINE  </font>LCD_EBIT 	1	<font color="#008000">'enable bit
        </font><font color="#000080">DEFINE  </font>LCD_RWREG	PORTE	<font color="#008000">'read/write register
        </font><font color="#000080">DEFINE  </font>LCD_RWBIT 	2	<font color="#008000">'read/write  bit
        </font><font color="#000080">DEFINE  </font>LCD_BITS 	8	<font color="#008000">'width of data 
        </font><font color="#000080">DEFINE  </font>LCD_LINES	2	<font color="#008000">'lines in display
        </font><font color="#000080">DEFINE  </font>LCD_COMMANDUS	2000	<font color="#008000">'delay in micro seconds
        </font><font color="#000080">DEFINE  </font>LCD_DATAUS 	20	<font color="#008000">'delay in micro seconds
        
                'Set the port directions.  We are setting PORTA.0 to an input, all rest outputs
                'all of PORTD is set to outputs to run the LCD
                'and all of PORTE as outputs even though PORTE has only 3 lines.
        </font>TRISA = %11111111		<font color="#008000">'set PORTA lines
        </font>TRISD = %00000000		<font color="#008000">'set all PORTD lines to output
        </font>TRISE = %00000000		<font color="#008000">'set all PORTE lines to output 
</font>        				<font color="#008000">'Set the Analog to Digital control register
        </font>ADCON1=%10000010		<font color="#008000">'see discussion above

                '   added
                '   -----
        </font>TRISB = %00001111           	<font color="#008000">'PORTB&lt;3:0&gt; = input
</font>                                    	<font color="#008000">' others to output
        </font>OPTION_REG.7=0              	<font color="#008000">' ENABLE INTERNAL PULL-UPS
                '   -----
                
                'Define the variables used
        </font>ADVAL	<font color="#000080">VAR</font>	<font color="#000080">BYTE</font>		<font color="#008000">'Create ADVAL to store result
        </font>TEMP    <font color="#000080">VAR</font> 	<font color="#000080">BYTE</font>		<font color="#008000">'temperature Farenheit variable
        </font>TEMPC	<font color="#000080">VAR</font> 	<font color="#000080">BYTE</font>		<font color="#008000">'temperature Celsius variable
        </font>DEG <font color="#000080">CON </font>223 			<font color="#008000">'write an degree mark on lcd
        
        </font>Mode    <font color="#000080">VAR BIT
        </font>C       <font color="#000080">CON </font>1
        F       <font color="#000080">CON </font>0
        
        
                <font color="#008000">'define the adcin parameters
        </font><font color="#000080">DEFINE</font>	ADC_BITS	10	<font color="#008000">'Set number of bits in result
        </font><font color="#000080">DEFINE</font>	ADC_CLOCK	3	<font color="#008000">'Set clock source (3=rc)
        </font><font color="#000080">DEFINE</font>	ADC_SAMPLEUS	50	<font color="#008000">'Set sampling time in uS

        </font><font color="#000080">PAUSE </font>500   
        <font color="#000080">LCDOUT </font>$FE, 1			<font color="#008000">'clear screen 
        </font>PORTB.4=0                                   
        Mode = C

LOOP:					<font color="#008000">'The main loop of the program
        </font><font color="#000080">ADCIN </font>4, ADVAL 			<font color="#008000">'Read channel 0 to adval
        </font>ADVAL =(ADVAL*/500)&gt;&gt;2
        TEMP=ADVAL
        TEMPC=((TEMP-32) *100) /180

        <font color="#000080">IF </font>PORTB.0=0 <font color="#000080">THEN
            </font>Mode = Mode ^ 1
            <font color="#000080">WHILE </font>PORTB.0 = 0 : <font color="#000080">WEND
            PAUSE </font>50
            <font color="#000080">ENDIF
                                    
        PAUSE </font>200
        <font color="#000080">LCDOUT </font>$FE, 1,&quot;Temp=&quot;
        <font color="#000080">IF </font>Mode=F <font color="#000080">THEN
            LCDOUT DEC3 </font>TEMP,DEG, &quot;F&quot; 	<font color="#008000">'print to line 1 of 2 line display
            </font><font color="#000080">ELSE
                LCDOUT DEC3 </font>TEMPC,DEG, &quot;C&quot;
            <font color="#000080">ENDIF
            
        GOTO </font>LOOP
        <font color="#000080">END


</font></code>

sure a INT0 interrupt would have it's own advantages as well. Begin with it.

[Philley]

Ok thank you for the helpful ideas I've used those ideas now I want to incorporate an LED alarm that when the temp gets to >=80 degrees F that the LED 0 will flash and I won't be able to turn the alarm off until the temp goes below 80 degrees and switch 2 has been pressed.

Below I have the code that I've tried to put into the microcontroller but everytime i try to do something I get caught up with no display on the LCD, any help would be appreciated.

DEFINE  LCD_DREG	PORTD 	'data register
DEFINE  LCD_RSREG	PORTE	'register select
DEFINE  LCD_RSBIT	0		'pin number
DEFINE  LCD_EREG	PORTE	'enable register
DEFINE  LCD_EBIT 	1		'enable bit
DEFINE  LCD_RWREG	PORTE	'read/write register
DEFINE  LCD_RWBIT 	2		'read/write  bit
DEFINE  LCD_BITS 	8		'width of data 
DEFINE  LCD_LINES	2		'lines in display
DEFINE  LCD_COMMANDUS	2000	'delay in micro seconds
DEFINE  LCD_DATAUS 	20		'delay in micro seconds

'Set the port directions.  We are setting PORTA.0 to an input, all rest outputs
'all of PORTD is set to outputs to run the LCD
'and all of PORTE as outputs even though PORTE has only 3 lines.

TRISA = %11111111			'set PORTA lines
TRISB = %00101111
TRISD = %00000000			'set all PORTD lines to output
TRISE = %00000000			'set all PORTE lines to output 
							
ADCON1=%10000010			'see discussion above
OPTION_REG.7=0
'Define the variables used
ADVAL	VAR	BYTE			'create ADVAL to store result
TEMP    VAR BYTE			'temperature Farenheit variable
TEMPC	VAR BYTE			'temperature Celsius variable
DEG CON 223 				'write an degree mark on lcd
MODE	VAR BIT
C		CON	1
F		CON 0
LED		VAR	BYTE
'define the adcin parameters
DEFINE	ADC_BITS	10		'Set number of bits in result
DEFINE	ADC_CLOCK	3		'Set clock source (3=rc)
DEFINE	ADC_SAMPLEUS	50	'Set sampling time in uS
PAUSE 500
LCDOUT $FE, 1				'clear screen 
PORTB.4=0
PORTB.5=0
MODE=C

LOOP:						'The main loop of the program
	ADCIN 4, ADVAL 			'Read channel 0 to adval
	ADVAL =(ADVAL*/500)>>2
    TEMP=ADVAL
	TEMPC=((TEMP-32) *100) /180
	IF TEMP<32 THEN TEMP=32	
	IF TEMP>100 THEN TEMP=100
	IF TEMP>=80 THEN GOSUB FLASH
	IF PORTB.0=0 THEN
		MODE=MODE^1
		WHILE PORTB.0=0 : WEND
		PAUSE 50
		ENDIF
		PAUSE 100
	LCDOUT $FE, 1, "TEMP=" 			'go to home position
	IF MODE=F THEN
		LCDOUT DEC3 TEMPC,DEG, "C" 	'print to line 1 of 2 line display
	ELSE
		LCDOUT DEC3 TEMP,DEG, "F"
	ENDIF
GOTO LOOP
END
FLASH:
PAUSE 100 				' pause .1 sec to hear tone
HIGH PORTD.0
PAUSE 350
LOW PORTD.0
PAUSE 350
RETURN