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main.asm
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main.asm
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;*******************************************************************************
; OXYGEN THERAPY PROJECT
;*******************************************************************************
; * Program name: Oxygen Therapy Controller
; * Program description: a system that uses the PIC16F877A microcontroller to
; mimic the process of delivering oxygen to patients and at the same time
; monitor the available oxygen reservoir and notifying the user when it
; is too low
; *
; * Program version: 1.0
; * Created by Ehab Younes and Zeyad Al Najjar
; * Date Created: May 19th, 2021
; * Date Last Revised: May 20th, 2021
;*******************************************************************************
; * Inputs:
; * Rate 1 (Potentiometer) RA0
; * Rate 2 (Potentiometer) RA1
; * VREF- (Voltage) RA2
; * VREF+ (Voltage) RA3
; * Fill (Button) RB0 (interrupt)
; * Bed 1 (Switch) RB1
; * Bed 2 (Switch) RB2
; * LCD View (Switch) RB3
; *
; * Outputs:
; * Alarm (LED) RC0
; * Pump (MOTOR) RC2
; * LCD CONFIG (LCD) RC5-RC7
; * LCD DATA (LCD) RD0-RD7
;*******************************************************************************
__CONFIG _DEBUG_OFF&_CP_OFF&_WRT_HALF&_CPD_OFF&_LVP_OFF&_BODEN_OFF&_PWRTE_OFF&_WDT_OFF&_XT_OSC
#include <P16F877A.INC>
;*******************************************************************************
;* Performs 16-bit subtraction (DST = DST - SRC)
;* Inputs: DST, SRC
;* Outputs: DST
;*******************************************************************************
SUB16 macro DST, SRC
movf (SRC), W ; Get low byte of subtrahend
subwf (DST), F ; Subtract DST(low) - SRC(low)
movf (SRC)+1, W ; Now get high byte of subtrahend
btfss STATUS, C ; If there was a borrow increment SRC(high)
incfsz (SRC)+1, W
subwf (DST)+1, F ; Subtract DST(high) - SRC(high)
endm
;*******************************************************************************
;* Moves SRC_BIT in SRC_REG to DST_BIT in DST_REG
;* Inputs: SRC_REG, SRC_BIT, DST_REG, DST_BIT
;* Outputs: DST_REG
;*******************************************************************************
MOVE_BIT macro SRC_REG, SRC_BIT, DST_REG, DST_BIT
btfsc SRC_REG, SRC_BIT
bsf DST_REG, DST_BIT
btfss SRC_REG, SRC_BIT
bcf DST_REG, DST_BIT
endm
;*******************************************************************************
;* Adds NUM1 and NUM2 (RESULTS = NUM1 + NUM2)
;* Inputs: NUM1, NUM2
;* Outputs: RESULT
;*******************************************************************************
ADDFF macro RESULT, NUM1, NUM2
movf NUM1, W
addwf NUM2, W
movwf RESULT
endm
;*******************************************************************************
;* Sends a 2 digit BCD number to the LCD
;* Inputs: BCD
;*******************************************************************************
SEND_BCD macro BCD
swapf BCD, W ; Take the high nibble first (Left-to-right)
andlw 0x0F
iorlw 0x30
call SEND_CHAR
movf BCD, W ; Then take the low nibble
andlw 0x0F
iorlw 0x30
call SEND_CHAR
endm
;*******************************************************************************
;* Determines the inputs to the subroutine DISPLAY_BED
;* Inputs: BED_FLAG, RATE_IN
;* Outputs: BED_NUMBER, RATE, CURRENT_MODE
;*******************************************************************************
DBED_INPUTS macro BED_FLAG, RATE_IN
movlw BED_FLAG
andlw 0x0F
iorlw 0x30
movwf BED_NUMBER ; Convert number to BCD
movf RATE_IN, W
movwf RATE
movlw MODE_2_ON_INDEX ; Assume CURRENT_MODE = MODE_2_ON_INDEX
btfss FLAGS, BED_FLAG
movlw MODE_2_OFF_INDEX ; Correct CURRENT_MODE if the switch is open
movwf CURRENT_MODE
endm
;*******************************************************************************
;* CONSTANTS
;*******************************************************************************
OXYGEN_VOLUME_LO_MAX equ 0xC4
OXYGEN_VOLUME_HI_MAX equ 0x09
OXYGEN_VOLUME_ALARM_LO equ 0xF3
OXYGEN_VOLUME_ALARM_HI equ 0x01
ALARM_FLAG equ 0
BED1_FLAG equ 1
BED2_FLAG equ 2
ALARM_BIN equ 0
BED1_BIN equ 1
BED2_BIN equ 2
DISPLAY_SWITCH_BIN equ 3
MODE_1_INDEX equ 0
MODE_2_ON_INDEX equ 1
MODE_2_OFF_INDEX equ 2
MODE_ALARM_INDEX equ 3
TIMER1_COUNTER equ 2
;*******************************************************************************
;* VARIABLES
;*******************************************************************************
cblock 0x20 ; Used in delay loop calculation
LSD
MSD
SEC_CALC
endc
cblock 0x25 ; Printing on the LCD
STR_INDEX
FLAGS
CURRENT_MODE
endc
cblock 0x30 ; 16-bit Oxygen Volume register
OXYGEN_VOLUME_LO
OXYGEN_VOLUME_HI
endc
cblock 0x35 ; 16-bit binary number to packed BCD
NUMBER_LO
NUMBER_HI
BCD_LO
BCD_HI
BITS
endc
cblock 0x40 ; Subtraction temporary registers
DST_LO
DST_HI
SRC_LO
SRC_HI
TEMP
endc
cblock 0x45 ; ADC and Rate GPRs
ADC_VALUE
ADC_VALUE1
ADC_VALUE2
RATE1
RATE2
OXYGEN_RATE
OXYGEN_RATE_HI
endc
cblock 0x55 ; subroutine inputs for DISPLAY_BED
RATE
BED_NUMBER
endc
;*******************************************************************************
;* Program starts here
;*******************************************************************************
MAIN_PROG
org 0x0000
goto INITIAL ; go to beginning of program
INT_SVC
org 0x0004 ; process ISR
goto ISR
;*******************************************************************************
;* System configuration and initialization
;*******************************************************************************
INITIAL
banksel TRISA
movlw b'00001111'
movwf TRISA ; RA0 to RA3 are inputs
movwf TRISB ; RB0 to RB3 are inputs
clrf TRISC ; Port C & Port D as outputs
clrf TRISD
movlw b'11000000' ; External interrupt is on the rising edge
movwf OPTION_REG
bsf INTCON, GIE
bsf INTCON, PEIE
bsf INTCON, INTE
bcf INTCON, INTF
bsf PIE1, TMR1IE
; Timer2 setup
movlw b'01100011' ; PWM Period = (99 + 1) * 4 * 1us = 0.4ms
movwf PR2 ; PWM Frequency = 2.5kHz
banksel T2CON
movlw b'00000101' ; Prescalar = 4
movwf T2CON
; Timer1 setup
banksel PORTA
call SETUP_TIMER1
; LCD setup
clrf PORTC
clrf PORTD
movlw b'00111000' ; 8-bit mode, 2-line display, 5x7 dot format
call SEND_CMD
movlw b'00001100' ; Display on, Cursor Underline off, Blink off
call SEND_CMD
call RESET_DISPLAY
; ADC setup
banksel TRISA
movlw b'00001101' ; Left justified, AN0 and AN1 with Vref
movwf ADCON1
banksel PORTA
movlw b'01000001' ; Fosc/8, Channel0 selected
movwf ADCON0
clrf FLAGS
clrf OXYGEN_RATE
clrf OXYGEN_RATE_HI
clrf ADC_VALUE1
clrf ADC_VALUE2
clrf RATE1
clrf RATE2
;*******************************************************************************
;* Main Routine
;*******************************************************************************
MAIN
call FILL_TANK
call PROCESS
goto $
;*******************************************************************************
;* Sets up Timer1 to generate 1 second delay 1,000,000 = 8 * 62500 * 2
;*******************************************************************************
SETUP_TIMER1
movlw 0xDC
movwf TMR1L
movlw 0x0B
movwf TMR1H ; <TMR1H:TMR1L> = 62500
movlw b'00110001' ; prescalar = 8, and turn on the timer
movwf T1CON ; Prescalar is reset when changing TMR1L/TMR1H
return
;*******************************************************************************
;* This subroutine prints to the LCD based on the current display mode
;*******************************************************************************
DISPLAY_ON_LCD
call RESET_DISPLAY ; Start with a clear display w/ cursor home
btfss FLAGS, ALARM_FLAG
goto NON_ALARM_STATE ; Oxygen volume >= 500
call DISPLAY_ALARM_MODE ; Oxygen volume < 500
goto FIHISH_DISPLAY_ON_LCD
NON_ALARM_STATE
bcf PORTC, ALARM_BIN ; Turn off the LED
btfss PORTB, DISPLAY_SWITCH_BIN
call DISPLAY_MODE_1
btfsc PORTB, DISPLAY_SWITCH_BIN
call DISPLAY_MODE_2
FIHISH_DISPLAY_ON_LCD
return
;*******************************************************************************
;* This subroutine displays mode 1
;*******************************************************************************
DISPLAY_MODE_1
movlw MODE_1_INDEX
movwf CURRENT_MODE
call DISPLAY_STR ; Display "Oxygen Volume"
call GO_TO_LINE2
call DISPLAY_OXYGEN_VOLUME
; Print the 16-bit volume
call DISPLAY_STR ; Display " Liter(s)"
return
;*******************************************************************************
;* This subroutine displays mode 2
;*******************************************************************************
DISPLAY_MODE_2
DBED_INPUTS BED1_FLAG, RATE1 ; Calculate the inputs for DISPLAY_BED
call DISPLAY_BED
call GO_TO_LINE2
DBED_INPUTS BED2_FLAG, RATE2
call DISPLAY_BED
return
;*******************************************************************************
;* Displays the information for a certain bed (ON/OFF and rate)
;* Inputs: BED_NUMBER, CURRENT_MODE, RATE
;*******************************************************************************
DISPLAY_BED
clrf STR_INDEX
call DISPLAY_STR ; Display "Bed"
movf BED_NUMBER, W
call SEND_CHAR ; Print bed number
call DISPLAY_STR ; Display " ON" or " OFF --"
movlw MODE_2_ON_INDEX
xorwf CURRENT_MODE, W
btfss STATUS, Z ; Skip if a switch is turned on (CURRENT_MODE = MODE_2_ON_INDEX)
goto FINISH_DISPLAY_BED
call DISPLAY_RATE ; Print the rate
call DISPLAY_STR ; Display " L/s"
FINISH_DISPLAY_BED
return
;*******************************************************************************
;* This subroutine displays alarm mode
;*******************************************************************************
DISPLAY_ALARM_MODE
movlw MODE_ALARM_INDEX
movwf CURRENT_MODE
bsf PORTC, ALARM_BIN ; Turn on the LED
call DISPLAY_STR ; Display "Oxygen Level Low"
call GO_TO_LINE2
call DISPLAY_STR ; Display "Fill Tank!"
return
;*******************************************************************************
;* Clears the display and resets the cursor
;*******************************************************************************
RESET_DISPLAY
clrf STR_INDEX
movlw b'00000010' ; Display and cursor home
call SEND_CMD
movlw b'00000001' ; Clear display
call SEND_CMD
return
;*******************************************************************************
;* Sets the cursor at line 2 in the LCD
;*******************************************************************************
GO_TO_LINE2
movlw b'11000000' ; go to the second line
call SEND_CMD
return
;*******************************************************************************
;* Sends the string at STR_INDEX until a zero (0x00) is encountered
;* Inputs: STR_INDEX
;* Outputs: STR_INDEX
;*******************************************************************************
DISPLAY_STR
call STR_LOOKUP ; Get ASCII character
incf STR_INDEX, F ; Move to the next character (or 0x00)
addlw 0
btfsc STATUS, Z ; If WREG == 0, then reached end of word/line
goto FINISH_DISPLAY_STR
call SEND_CHAR
goto DISPLAY_STR ; repeat until a 0x00 is encountered
FINISH_DISPLAY_STR
return
;*******************************************************************************
;* String lookup table
;* Inputs: CURRENT_MODE, STR_INDEX
;* Outputs: WREG
;*******************************************************************************
STR_LOOKUP
movf CURRENT_MODE, W
addwf PCL, F ; Go to the correct lookup table based on LCD mode
goto MODE_1_LOOKUP
goto MODE_2_ON_LOOKUP
goto MODE_2_OFF_LOOKUP
goto MODE_ALARM_LOOKUP
MODE_1_LOOKUP
movf STR_INDEX, W
addwf PCL, F
dt "Oxygen Volume", 0x00
dt " Liter(s)", 0x00
MODE_2_ON_LOOKUP
movf STR_INDEX, W
addwf PCL, F
dt "Bed", 0x00
dt " ON ", 0x00
dt " L/s", 0x00
MODE_2_OFF_LOOKUP
movf STR_INDEX, W
addwf PCL, F
dt "Bed", 0x00
dt " OFF --", 0x00
MODE_ALARM_LOOKUP
movf STR_INDEX, W
addwf PCL, F
dt "Oxygen Level Low", 0x00
dt "Fill Tank!", 0x00
;*******************************************************************************
;* Main Processing Routine: executes every one second
;*******************************************************************************
PROCESS
call UPDATE_VOLUME
call READ_BED_SWITCHES
call READ_ADC_VALUES
call CALCULATE_RATES
call UPDATE_PUMP_PWM
call DISPLAY_ON_LCD
return
;*******************************************************************************
;* Subtracts the rate of the last cycle from the volume
;* and tests if the alarm volume was reached
;* Outputs: ALARM_FLAG
;*******************************************************************************
UPDATE_VOLUME
SUB16 OXYGEN_VOLUME_LO, OXYGEN_RATE
btfss STATUS, C ; If volume < 0 then volume = 0
call EMPTY_TANK
movf OXYGEN_VOLUME_LO, W ; We don't want to change the volume
movwf DST_LO
movf OXYGEN_VOLUME_HI, W
movwf DST_HI
movlw OXYGEN_VOLUME_ALARM_LO ; Move constants to temp registers
movwf SRC_LO
movlw OXYGEN_VOLUME_ALARM_HI
movwf SRC_HI
SUB16 SRC_LO, DST_LO
MOVE_BIT STATUS, C, FLAGS, ALARM_FLAG
return
;*******************************************************************************
;* Sets the volume to zero
;* Outputs: OXYGEN_VOLUME_LO, OXYGEN_VOLUME_HI
;*******************************************************************************
EMPTY_TANK
clrf OXYGEN_VOLUME_LO
clrf OXYGEN_VOLUME_HI
return
;*******************************************************************************
;* sets the oxygen volume to the max value
;* Outputs: OXYGEN_VOLUME_LO, OXYGEN_VOLUME_HI
;*******************************************************************************
FILL_TANK
movlw OXYGEN_VOLUME_LO_MAX
movwf OXYGEN_VOLUME_LO
movlw OXYGEN_VOLUME_HI_MAX
movwf OXYGEN_VOLUME_HI
return
;*******************************************************************************
;* Reads the beds switches and saves them to FLAGS
;* Inputs: PORTB
;* Outputs: FLAGS
;*******************************************************************************
READ_BED_SWITCHES
MOVE_BIT PORTB, BED1_BIN, FLAGS, BED1_FLAG
MOVE_BIT PORTB, BED2_BIN, FLAGS, BED2_FLAG
return
;*******************************************************************************
;* Reads the potentiometers (the most significant 8 bits)
;* Inputs: FLAGS
;* Outputs: ADC_VALUE1, ADC_VALUE2
;*******************************************************************************
READ_ADC_VALUES
clrf ADC_VALUE1
btfss FLAGS, BED1_FLAG ; only read the ADC if the switch is on
goto BED2 ; read the ADC for the 2nd bed
movlw b'01000001' ; Fosc/8, channel-0
movwf ADCON0
call READ_ADC
movwf ADC_VALUE1
BED2
clrf ADC_VALUE2
btfss FLAGS, BED2_FLAG
goto FINISH_READ_ADC
movlw b'01001001' ; Fosc/8, channel-1
movwf ADCON0
call READ_ADC
movwf ADC_VALUE2
FINISH_READ_ADC
return
;*******************************************************************************
;* Reads the selected ADC value (blocking)
;* Outputs: WREG
;*******************************************************************************
READ_ADC
call DELAY ; Wait for the previous change to ADCON0 to finish
bsf ADCON0, GO ; Start the ADC
WAIT_ADC
btfss PIR1, ADIF
goto WAIT_ADC ; Keep polling until it is done
bcf PIR1, ADIF
movf ADRESH, W ; Take the 8 most significant bits
return
;*******************************************************************************
;* Calculate the rates from the ADC values
;* Inputs: ADC_VALUE1, ADC_VALUE2
;* Outputs: RATE1, RATE2, OXYGEN_RATE
;*******************************************************************************
CALCULATE_RATES
movf ADC_VALUE1, W
call GET_RATE
movwf RATE1
movf ADC_VALUE2, W
call GET_RATE
movwf RATE2
; Total rate (RATE1 + RATE2)
ADDFF OXYGEN_RATE, RATE1, RATE2
return
;*******************************************************************************
;* Sends a command to the LCD
;* Inputs: WREG
;*******************************************************************************
SEND_CMD
movwf PORTD
bcf PORTC, 5
bsf PORTC, 7
nop
bcf PORTC, 7
bcf PORTC, 6
call DELAY
return
;*******************************************************************************
;* Sends an ASCII character to the LCD
;* Inputs: WREG
;*******************************************************************************
SEND_CHAR
movwf PORTD
bsf PORTC, 5
bsf PORTC, 7
nop
bcf PORTC, 7
bcf PORTC, 6
call DELAY
return
;*******************************************************************************
;* A simple delay used for the LCD
;*******************************************************************************
DELAY
movlw 0x03
movwf MSD
clrf LSD
LOOP_DELAY
decfsz LSD, F
goto LOOP_DELAY
decfsz MSD, F
goto LOOP_DELAY
return
;*******************************************************************************
;* Converts the ADC value to the rate (see table in the report)
;* Inputs: WREG
;* Outputs: WREG
;*******************************************************************************
GET_RATE
movwf ADC_VALUE
sublw .127
btfss STATUS, C
retlw .10 ; ADC_VALUE >= 128
movf ADC_VALUE, W
sublw .63
btfss STATUS, C
retlw 5 ; 128 > ADC_VALUE >= 64
movf ADC_VALUE, W
btfss STATUS, Z
retlw 1 ; 64 > ADC_VALUE >= 1
retlw 0 ; ADC_VALUE = 0
;*******************************************************************************
;* Converts the calculated rate binary to BCD then sends to the LCD
;* Inputs: WREG
;*******************************************************************************
DISPLAY_RATE
movf RATE, W
movwf NUMBER_LO ; input to GET_BCD_SMALL
call GET_BCD_SMALL
SEND_BCD BCD_LO
return
;*******************************************************************************
;* Converts the oxygen volume binary to BCD then sends to the LCD
;* Inputs: OXYGEN_VOLUME_LO, OXYGEN_VOLUME_HI
;*******************************************************************************
DISPLAY_OXYGEN_VOLUME
movf OXYGEN_VOLUME_LO, W
movwf NUMBER_LO ; input to GET_BCD_BIG
movf OXYGEN_VOLUME_HI, W
movwf NUMBER_HI ; input to GET_BCD_BIG
call GET_BCD_BIG
SEND_BCD BCD_HI ; Send high first (displaying left to right)
SEND_BCD BCD_LO
return
;*******************************************************************************
;* Converts a number in the range 0 - 31 to packed BCD
;* Inputs: NUMBER_LO
;* Outputs: BCD_LO
;*******************************************************************************
GET_BCD_SMALL
clrf BCD_LO ; Clear result
movlw D'5'
movwf BITS ; Set bit counter
bcf STATUS, C
rlf NUMBER_LO, F
rlf NUMBER_LO, F
rlf NUMBER_LO, F ; take only the first 5 bits (left-justify the bits)
CONVERT_BIT_SMALL
movlw .3 ; Correct BCD value
addwf BCD_LO, F
btfss BCD_LO, .3
subwf BCD_LO, F ; Subtract the 3 because it was already correct
rlf NUMBER_LO, F ; Shift out a binary bit
rlf BCD_LO, F ; Shift that bit into the BCD value.
decfsz BITS, F ; Repeat for all bits
goto CONVERT_BIT_SMALL
return
;*******************************************************************************
;* Converts a number in the range 0 - 4095 to packed BCD
;* Inputs: NUMBER_LO, NUMBER_HI
;* Outputs: BCD_LO, BCD_HI
;*******************************************************************************
GET_BCD_BIG
clrf BCD_LO ; Clear result
clrf BCD_HI
movlw D'12' ; Set bit counter
movwf BITS
bcf STATUS, C
rlf NUMBER_LO, F
rlf NUMBER_HI, F
rlf NUMBER_LO, F
rlf NUMBER_HI, F
rlf NUMBER_LO, F
rlf NUMBER_HI, F
rlf NUMBER_LO, F
rlf NUMBER_HI, F ; take only the first 12 bits (left-justify the bits)
CONVERT_BIT_BIG
movlw 0x33
addwf BCD_LO, F
btfsc BCD_LO, .3
andlw 0xF0 ; Remove the low 3 because it is correct
btfsc BCD_LO, .7
andlw 0x0F ; Remove the high 3 because it is correct
subwf BCD_LO, F ; Correct the addition
movlw .3 ; Correct BCD value
addwf BCD_HI, F
btfss BCD_HI, .3
subwf BCD_HI, F ; Subtract the 3 because it was already correct
rlf NUMBER_LO, F ; Shift out a binary bit
rlf NUMBER_HI, F
rlf BCD_LO, F ; Shift that bit into the BCD value.
rlf BCD_HI, F
decfsz BITS, F ; Repeat for all bits
goto CONVERT_BIT_BIG
return
;*******************************************************************************
;* Pump Subsystem
;*******************************************************************************
;* Finds the appropriate PWM settings for the provided oxygen rate
;* according to the table in the report
;* Inputs: OXYGEN_RATE
;*******************************************************************************
UPDATE_PUMP_PWM
movf OXYGEN_RATE, w ; rate = 0
btfsc STATUS, Z
goto PUMP_0
movlw .6 ; rate <= 5
subwf OXYGEN_RATE, w
btfss STATUS, C
goto PUMP_5
movlw .11 ; rate <= 10
subwf OXYGEN_RATE, w
btfss STATUS, C
goto PUMP_10
movlw .16 ; rate <= 15
subwf OXYGEN_RATE, w
btfss STATUS, C
goto PUMP_15
goto PUMP_20 ; default case
PUMP_0 ; set speed to 0 RPM
movlw b'00000000' ; MSBs = 0 (0% duty cycle)
movwf CCPR1L
movlw b'00001100' ; LSBs = 0, PWM mode
movwf CCP1CON
goto FINISH_PUMP
PUMP_5 ; set speed to 10 RPM
movlw b'00001000' ; CCPR1 = 32 (8% duty cycle)
movwf CCPR1L
movlw b'00001100' ; PWM mode
movwf CCP1CON
goto FINISH_PUMP
PUMP_10 ; set speed to 40 RPM
movlw b'00001111' ; CCPR1 = 63 (15.75% duty cycle)
movwf CCPR1L
movlw b'00111100' ; PWM mode
movwf CCP1CON
goto FINISH_PUMP
PUMP_15 ; set speed to 70 RPM
movlw b'00010101' ; CCPR1 = 84 (21% duty cycle)
movwf CCPR1L
movlw b'00001100' ; PWM mode
movwf CCP1CON
goto FINISH_PUMP
PUMP_20 ; set speed to 100 RPM
movlw b'00011001' ; CCPR1 = 100 (25% duty cycle)
movwf CCPR1L
movlw b'00001100' ; PWM mode
movwf CCP1CON
goto FINISH_PUMP
FINISH_PUMP
return
;*******************************************************************************
;* ISR
;*******************************************************************************
ISR
btfsc INTCON, INTF
goto HANDLE_FILL_BUTTON
btfsc PIR1, TMR1IF
goto HANDLE_TIMER1
FINISH_ISR
retfie
HANDLE_FILL_BUTTON
bcf INTCON, INTF ; Clear external interrupt flag
call FILL_TANK
goto FINISH_ISR
HANDLE_TIMER1
bcf PIR1, TMR1IF ; Clear TMR1 Flag
call SETUP_TIMER1
incf SEC_CALC, F
movlw TIMER1_COUNTER ; Fosc = 2 * 500,000 = 1,000,000
subwf SEC_CALC, W
btfss STATUS, Z ; Check if a second has passed
goto FINISH_HANDLE_TIMER1
clrf SEC_CALC ; reset the software counter
call PROCESS ; Reached 1 second
FINISH_HANDLE_TIMER1
goto FINISH_ISR
END