;PIC Lead/Acid Grid Charger Control ;Tom Woods 3/4/2006 ;This program monitors battery voltage. When it drops below an adjustable ;preset voltage, it turns on a solid state relay that can control a battery ;charger that is connected to the public utility power grid. The relay will ;remain on for a period of time set by jumpers SW1 and SW2, or ;until battery reaches an adjustable preset high voltage cut-off. ;When the relay turns off, charging reverts to the solar or other alternative energy ;source. Grid power will not be switched on until battery voltage again drops ;below the setpoint. A reset switch will toggle the relay OFF and ON. The unit will ;turn itself ON when battery voltage is below the setpoint. ;When the reset button is pressed, the LED will blink the number of times the ;charger has turned on since the last reset. ; ; Relay ON duration is approximately as follows ; (n=no jumper, y=jumper connected to ground): ; SW1 SW2 Duration ; y y 1 hour ; n y 2 hours ; y n 3 hours ; n n 4 hours include "c:\program files\mplab ide\mchip_tools\p16f676.inc" RELAY EQU 0 ;Bit 0 (Pin 10) is the relay control line LED EQU 1 ;Bit 1 (Pin 9) is the LED line SW1 EQU 5 ;Jumpers on these bits of PORTC determine Relay ON duration SW2 EQU 4 SECONDS EQU h'20' ;Address of location that stores count of seconds MINUTES EQU h'21' ;Address of location that stores count of minutes HOURS EQU h'22' ;Address of location that stores count of hours CYCLES EQU h'23' ;Address of location that stores number of times the charger ; was turned on since the last reset. DELAY1 EQU h'24' ;Address of locations that process a delay during the LED blink. DELAY2 EQU h'25' SCRATCH EQU h'26' PAUSETIME EQU h'3' ;Number of iterations for the wait loop MAXVOLTS EQU d'128' ;This value is good when the battery high cut-off voltage ;is trimmed to 2.5 volts as measured at pin 8 and pin 12. ;Summary of 16F676 Pin Assignments ;Pin 4 MCLR Reset Button Input ;Pin 5 SW1 Relay ON duration jumpers, SW1, SW2 ;Pin 6 SW2 ;Pin 8 A/D + Battery Voltage Input ;Pin 9 LED Output to LED ;Pin 10 Relay Control Output to relay ;Pin 12 Comparator Battery + Voltage Input ;Pin 13 Comparator Reference Voltage Input ORG 0 movfw STATUS RESETVECTOR BSF STATUS,RP0 ;Select bank 1 BTFSS PCON,1 GOTO POWERUP INITIALIZE CLRF ANSEL ;Power ON and button resets initialize ;the peripherals... MOVLW b'00110100' ;Make RC2 (pin 8) an input for the A-D (AN6) ;RC5 (pin 5) and RC4 (pin 6) digital inputs, MOVWF TRISC ;and other lines of PORTC outputs BCF STATUS,RP0 ;Select bank 0 CLRF INTCON ;disable peripheral interrupts. ;Initialize A-D converter on AN6 (Pin 8) MOVLW b'00011000' ;Left justified, AN6, VDD=Vref MOVWF ADCON0 CLRF ADRESH ;Zero out the AD converter BSF STATUS,RP0 ;Bank 1 MOVLW b'01000011' ;Enable AN6, AN0, AND AN1 (Pins 8,13,12)as analog MOVWF ANSEL MOVLW b'01010000' ;Set AD clock to Fosc/16 MOVWF ADCON1 ;Initialize comparator and timer. BSF TRISA,1 ;Pin 12 is comparator input. BSF TRISA,0 ;Pin 13 is comparator input. BCF STATUS,RP0 ;Bank 0 MOVLW b'00000010' ;Comparator goes high when MOVWF CMCON ;battery voltage (pin 12) is less than ; reference voltage (pin 13) CLRF TMR0 ; Clear the clock value BSF STATUS,RP0 ;Bank 1 MOVLW b'10000110' MOVWF OPTION_REG BCF STATUS,RP0 ;Bank 0 BTFSS PORTC,RELAY ;What is the status of the relay? GOTO RELAYISOFF RELAYISON INCF CYCLES,1 CALL LEDBLINK GOTO RELAYOFF RELAYISOFF CALL LEDBLINK GOTO RELAYSET RELAYOFFA INCF CYCLES,1 RELAYOFF BCF STATUS,RP0 ;Bank 0 BCF PORTC,RELAY ;Turn OFF the relay and LED BCF PORTC,LED ;At this point everything is initialized and the relay is OFF. ;All we do is watch the voltages and the clock. COMPARATOR BTFSS CMCON,6 ;Is the battery < Vref? (was BTFSS) GOTO RELAYOFF ;No. Go back and wait. CALL WAIT ;Yes. Then resample to make sure BTFSS CMCON,6 ;we're not looking at a load spike.(was BTFSS) GOTO RELAYOFF ;Is batteryMAXVOLTS, go back and turn off the relay ;If Battery < MAXVOLTS... RELAYSET BSF PORTC,RELAY ;Turn ON the relay BSF PORTC,LED ; and LED. TLOOP MOVLW d'63' ;Approximate 'ticks' per second. SUBWF TMR0,0 BTFSS STATUS,Z GOTO TLOOP INCF SECONDS,1 ;Once per second CLRF TMR0 MOVLW D'60' SUBWF SECONDS,0 BTFSS STATUS,Z GOTO CHECKAD ADVANCE INCF MINUTES,1 ;Once per minute CLRF SECONDS MOVLW d'60' SUBWF MINUTES,0 BTFSS STATUS,Z GOTO CHECKAD INCF HOURS,1 ;Once per hour CLRF MINUTES CALL ONTIME ;Find out how long the relay should be ON. SUBWF HOURS,0 BTFSS STATUS,Z GOTO CHECKAD ;Keep counting if time is not up. GOTO RELAYOFFA ;Shut off and wait when time is up. LEDBLINK BCF PORTC,LED ;Subroutine that handles the blinking of CALL WAIT ;the LED equal to the number of times the MOVF CYCLES,W ;charger was turned on since the last reset. MOVWF SCRATCH ;The count is set to zero INCF SCRATCH,1 BLINK2 DECF SCRATCH,1 BTFSC STATUS,Z GOTO OUT BLINK3 BSF PORTC,LED CALL WAIT BCF PORTC,LED CALL WAIT GOTO BLINK2 OUT CALL WAIT CLRF CYCLES RETURN WAIT MOVLW PAUSETIME ;A subroutine to delay MOVWF DELAY1 WAIT1 MOVLW h'ff' MOVWF DELAY2 WAIT2 DECFSZ DELAY2,1 GOTO WAIT2 DECFSZ DELAY1,1 GOTO WAIT1 RETURN ONTIME CLRF SCRATCH ;Subroutine returns with W=# hrs the relay BTFSC PORTC,SW1 ;should be ON. Transfer SW2 and SW1 to W bits BSF SCRATCH,0 ;1 and 0. Then increment W so the subroutine will BTFSC PORTC,SW2 ;return with W=1,2,3,4 BSF SCRATCH,1 INCF SCRATCH MOVF SCRATCH,W RETURN POWERUP BSF PCON,1 ;The initial powerup. BCF STATUS,RP0 ;Select Bank 0 CLRF PORTC CLRF CYCLES CLRF MINUTES CLRF HOURS CLRF SECONDS BSF STATUS,RP0 ;Bank 1 GOTO INITIALIZE end