;************************************************************************************ ; Software License Agreement ; ; The software supplied herewith by Microchip Technology Incorporated (the "Company") ; for its PICmicro(r) Microcontroller is intended and supplied to you, the Company's ; customer, for use solely and exclusively on Microchip PICmicro Microcontroller ; products. ; ; The software is owned by the Company and/or its supplier, and is protected under ; applicable copyright laws. All rights are reserved. Any use in violation of the ; foregoing restrictions may subject the user to criminal sanctions under applicable ; laws, as well as to civil liability for the breach of the terms and conditions of ; this license. ; ; THIS SOFTWARE IS PROVIDED IN AN "AS IS" CONDITION. NO WARRANTIES, WHETHER EXPRESS, ; IMPLIED OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF ; MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. THE ; COMPANY SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL OR ; CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER. ; ;************************************************************************************ ; ; Filename: DisplayTemp.asm ; Date: March 14,2005 ; File Version: 1.00 ; ; Company: Microchip Technology Inc. ; ;************************************************************************************ ; ; Files required: ; DisplayTemp.inc ; 16f917.lkr ; ;************************************************************************************ ; ; Notes: ; This code reads and analog temperature sensor (TC1047A) and converts the result ; into degrees Celsius using the following algorithms: ; ; Valid temperature exists: 21 < ADC Value(10-bit) < 358 ; ; Temperature(degrees C) = (ADC Value/2) - 50 ; ; The result is displayed on the LCD. ; ; Connections: ; AN0 to the output of TC1047A ; ;************************************************************************************ #include ;********************************************************************** STARTUP code goto Initialize PORT1 code ;************************************************************************************ ; Initialize - Initialize CCP1, comparators, internal oscillator, I/O pins, ; analog pins, motor parameters, variables ; ;************************************************************************************ Initialize clrf STATUS ; bank 0 bsf STATUS,RP0 ; we'll set up the bank 1 Special Function Registers first ; Configure I/O pins for project bsf TRISA,0 ; RA0 is an input ; Set internal oscillator frequency movlw b'01110000' ; 8Mhz movwf OSCCON ; Set TMR0 parameters MOVLW b'10000111' ; PORTB PULL-UP DISABLED MOVWF OPTION_REG ; TMR0 RATE 1:256 ; Turn off comparators movlw 0x07 movwf CMCON0 ; turn off comparators ; Set up Analog Channel(s) movlw b'00000001' ; select AN0 as an analog channel (RA0) movwf ANSEL movlw b'01010000' ; select A/D converstion clock Fosc/16 movwf ADCON1 bcf STATUS,RP0 ; go back to bank 0 ; Finish ADC set up movlw b'10000001' ; right justified, Vss and Vdd as refs, AN0 is on movwf ADCON0 ; turn ADC module on ;************************************************************************************ ; Main - Calls the function to initialized the LCD registers, then reads the output ; from the temperature sensor, converts this value to degrees C, and displays ; this value on the LCD. ;************************************************************************************ Main call InitLCD ; Initialize LCD Special Function Registers ; Main program loop Loop btfss INTCON,T0IF ; Wait for TMR0 to overflow at 32ms goto Loop bcf INTCON,T0IF GetTemperature banksel ADCON0 ; Do A-to-C conversion bsf ADCON0,1 btfsc ADCON0,1 ; Wait for result before proceeding goto $-1 banksel ADRESH movf ADRESH,w ; store high two bits in TempHigh banksel TempHigh movwf TempHigh banksel ADRESL movf ADRESL,w ; store lower bits in TempLow banksel TempLow movwf TempLow CheckForValidity bcf Flag,InvalidTemp ; clear flag that indicates temperature is invalid movf TempHigh,w ; Are bits 9 or 10 set? btfss STATUS,Z goto CheckForOverTemp ; Yes, then check for an over temperature condition CheckForUnderTemp ; No, then check for an under temperature condition movlw .22 ; If the the low order bits are under 22 then the temperature is under -40C subwf TempLow,w btfss STATUS,C bsf Flag,InvalidTemp goto EndCheck CheckForOverTemp movlw .1 ; make sure high order byte only has a 1 subwf TempHigh,w btfss STATUS,Z goto NotValid movlw .102 ; then check to make sure the low order byte isn't over 102 subwf TempLow,w btfsc STATUS,C NotValid bsf Flag,InvalidTemp EndCheck ConvertToTemperature ; Temperature = (AN0/2) - 50 "in Celcius" rrf TempHigh,f ; bit 10 is never set so it is ignored rrf TempLow,f bcf Flag,Negative movlw .50 ; Subtract 50 subwf TempLow,f btfsc STATUS,C ; is value negative? goto CheckAgainstStoredValue comf TempLow,f ; make a negative value unsigned bsf Flag,Negative CheckAgainstStoredValue movf TempLow,w ; check against the stored temperature value xorwf TempSave,w btfsc STATUS,Z ; if the value is the same then check for consistancy goto CheckForConsistancy clrf Counter ; else, save the temperature value movf TempLow,w movwf TempSave goto Loop CheckForConsistancy ; if the same value is read 4 times then display the incf Counter,f ; temperature btfss Counter,2 goto Loop clrf Counter DisplayTemperature ; display the temperature call InitLCD ; clear the display first btfsc Flag,InvalidTemp ; If temperature is invalid then indicate that with "---" goto DisplayDashDashDash btfsc Flag,Negative ; If the Negative flag is set then display negative sign call DisplayNeg movf TempLow,w ; first convert the hexidecemal value to binary coded decimal call ConvertToBCD movwf TempBCD ; the ones and tens decimal values are returned in W movf TempBCD,w andlw 0x0F call DisplayDigit2 swapf TempBCD,w andlw 0x0F call DisplayDigit3 movlw 0x00 btfsc Flag,Overflow ; the hundred value is returned in Overflow flag movlw 0x01 call DisplayDigit4 movlw 0x0C ; Display C for Celcius in the first digit call DisplayDigit1 goto Loop DisplayDashDashDash ; Display "---" banksel LCDDATA0 bsf LCDDATA5,7 ; segment 1g (s1g in LCD.asm) bsf LCDDATA5,5 ; segment 2g (s2g in LCD.asm) bsf LCDDATA4,3 ; segment 3g (s3g in LCD.asm) clrf STATUS goto Loop ;********************************************************************** ; ConvertToBCD ; Converts a hexidecimal number to binary coded decimal ; Example: 0x7D becomes 125 ;********************************************************************** ConvertToBCD movwf Temp incf Temp,f clrf BCDValue bcf Flag,Overflow ConvertLoop decf Temp,f btfsc STATUS,Z goto EndConvertToBCD incf BCDValue,f movf BCDValue,w andlw 0x0F xorlw 0x0A btfss STATUS,Z goto ConvertLoop movlw 0x06 addwf BCDValue,f movf BCDValue,w andlw 0xF0 xorlw 0xA0 btfss STATUS,Z goto ConvertLoop movlw 0x60 addwf BCDValue,f bsf Flag,Overflow goto ConvertLoop EndConvertToBCD movf BCDValue,w return END ; directive 'end of program'