Initialize variables:
    DataByte    (Transmit data)
    SwitchVar   (SwitchVariable)
    RXData      (Received data)
    ChargeState (State of battery charge)
    CharDischar (Charge/Discharge status)
    LampStatus  (Lamp status)
    DutyCycle   (Duty Cycle)
	ERR			(Testing error)

Set the following constants:
    Period = 194 for PWM period of 6.25ms
    SPI_Mode = 00110010 to set SSPEN=1|CKP=1
    TRISASetup = 11111111 to set RA0,1,2 as inputs for Lamp status (inputs = 1)
    TRISBSetup = 00010000 to set I/O for PortB
    TRISCSetup = 00000010 to set I/O for PortC
    CCPsetup = 00001100 to set Compare mode to set output on match
    T2Setup = 00000101 to set Timer 2 prescaler to 4
                       
Main:                            
;Initialize Timers/Clock/PWM/SPI/IO and Variables                        
INIT:            
;OSCCON - Set int osc speed to 500 kHz
Set OSCCON,IRCF0 to 1
Set OSCCON,IRCF1 to 1
Set OSCCON,IRCF0 to 0

; ANSEL - not using any analog inputs
Clear ANSEL
Clear ANSELH

; TRIS - set up input/outputs for Ports
Set TRISA = TRISASetup
Set TRISB = TRISBSetup
Set TRISC = TRISCSetup

; SPI - set up SPI communication
Clear SSPSTAT
Set SSPCON = SPI_Mode

; PWM - 
Set PR2 = Period
Set CCP1CON = CCPSetup
Initialize PWM duty cycle to 50%

; Timer - Set T0CS to use internal instruction clock for TM0 and Timer 2 for PWM
Clear T0CS bit of OPTION_REG
Set T2CON = T2Setup

Clear PortA
Clear PortB
Clear PortC			
Initialize SwitchVar = 0
Initialize DataByte = 0
Initialize ERR = 0		

START_LOOP: ; Start the loop
    If PortC bit 1 is hi,
        Set DataByte to 0x3F
    Else        
        Set DataByte to (PortA & 0x07)|0xF0
        
    Switch(SwitchVar)
        Case 1:
            If T0IF is set
                Write DataByte to SSPBUF
                Increment SwitchVar
        Case 2:
            If BF (Buffer Full) is set
                Read SSPBUF
                Write 0x00 to SSPBUF
                Increment SwitchVar                
        Case 3:
            If BF is set
                If SSPBUF is not 0xFF
                    Set ERR=1
                    End
                Write 0x00 to SSPBUF
                Increment SwitchVar                
        Case 4:
            If BF is set
                Read SSPBUF to working reg
                If PortC = 1
                    Call ChargeStat
                Write 0x00 to SSPBUF
                Increment SwitchVar
        Case 5:
            If BF is set
                If PORTC = 1
                    Set CharDischar = SSPBUF
                    If CharDischar = 0
                        Clear PortC bit 0
                    Else if CharDischar = 0xFE
                        Set PortC bit 0 (hi)                
                Else
                    Set LampStatus = SSPBUF
                    LampStatus &= 00000111
                    Left shift LampStatus bits twice                    
                    Set PortC = (PortC & 11100011)|LampStatus                                       
                Set PortC bit 6 hi (raise SS line)
                Increment SwitchVar
        If SwitchVar > 5,
            Set SwitchVar = 0
        Clear T0IF flag
        Clear Timer0
        
        Start Loop again		                     

***Functions****
ChargeStat
    SSPBUF/255 * 780 = Duty Cycle for PWM (hard code for 5% intervals)
END