* Init.asm

**********************************************************************
* Initialize the I/O, ICG, KBD, IRQ                                  *
**********************************************************************

**********************************************************************
* Init_Vars                                                          *
* Initialize the RAM variables.                                      *
**********************************************************************
Init_Vars:      MOV     #$FF,SWITCH                     ;Default configuration is for FSK.
                MOV     #$FF,LAST_SWITCH

                LDHX    #FLASHVARS
                MOV     X+,THRESHOLD
                MOV     X+,LFID
                MOV     X+,LFID+1
                MOV     X+,LFID+2
                MOV     X+,LFID+3
                MOV     X+,RFID
                MOV     X+,RFID+1
                MOV     X+,RFID+2
                MOV     X+,RFID+3
                MOV     X+,LRID
                MOV     X+,LRID+1
                MOV     X+,LRID+2
                MOV     X+,LRID+3
                MOV     X+,RRID
                MOV     X+,RRID+1
                MOV     X+,RRID+2
                MOV     X+,RRID+3

                CLR     LFCNTH                          ;Clear the timeout counters.
                CLR     LFCNTL
                CLR     LRCNTH
                CLR     LRCNTL
                CLR     RRCNTH
                CLR     RRCNTL
                CLR     RFCNTH
                CLR     RFCNTL
                CLR     FAST_MODE
                CLR     TEMP
                CLR     TEMPTIME
                CLR     TEMPTIME+1
                CLR     TIMESTAMP
                RTS


**********************************************************************
* Init_KBD                                                           *
* We don't use keyboard or IRQ interrupts in this program.           *
**********************************************************************
Init_KBD:       BSET    1,KBSCR                         ;
                BSET    1,ISCR                          ;Mask interrupts
                BSET    2,KBSCR                         ;
                BSET    2,ISCR                          ;Clear any pending interrupt requests
                RTS

**********************************************************************
* Init_ICG                                                           *
* Initializes the internal clock generator module for the            *
* external oscillator.                                               *
* For now, 4.9152MHz crystal yielding 1.2288MHz bus frequency.       *
**********************************************************************
Init_ICG:       LDA     #%00010011                      ;Mask for external clock
LOOP_ICG        STA     ICGCR                           ;Try to set CS, ECGON and clear ICGON.
                CMP     ICGCR                           ;Check to see if ICGCR okay.
                BNE     LOOP_ICG                        ;Keep looping until ICG settles.
                RTS

**********************************************************************
* Init_Ports                                                         *
* Initializes PTA and PTB.                                           *
* PTA[4] = MISO (Input during config mode, unused output in RCV mode)*
* PTA[3] = SCK (Output during config mode, input in RCV mode)        *
* PTA[2] = MOSI (Output during config mode, input in RCV mode)       *
* PTA[1] = /RST (Output)                                             *
* PTA[0] = "RCV" LED                                                 *
* PTB[3:0] = RF, RR, LR, LF LEDs                                     *
**********************************************************************
Init_Ports:     MOV     #%00000010,PTA                  ;Keep /RST high
                MOV     #%00010011,DDRA                 ;Soft SPI, one LED
                CLR     PTB                             ;LEDs off
                MOV     #%00001111,DDRB                 ;LEDs
                RTS

**********************************************************************
* Init_SCI                                                           *
* Initializes the serial communications interface.                   *
**********************************************************************
Init_SCI:       MOV     #%01000000,SCC1                 ;Enable SCI
                MOV     #%00001000,SCC2                 ;Enable Tx
                MOV     #%00000011,SCBR                 ;With a 4.9152MHz XTAL, 9600 bauds.
                RTS

**********************************************************************
* Init_TBM                                                           *
* Initializes the timebase module.  This generates periodic          *
* interrupts to control the LED flashing when no data is received    *
* from a tire.  Vector points to 'TBM_Interrupt.'                    *
* With 4.9152MHz crystal, interrupts occur every 6.67ms while TBM    *
* is enabled.                                                        *
**********************************************************************
Init_TBM:       BCLR    1,TBCR                          ;Disable TBM
                MOV     #%00001110,TBCR                 ;Select TBM divider and enable TBM
                RTS

**********************************************************************
* Init_Timer                                                         *
* Initialize the timer module.  This is used during the SPI receive  *
* routine, to assure that we're receiving an entire data frame.  If  *
* the timer overflows, an interrupt is triggered which resets the    *
* bit and byte counters and goes back to the beginning.              *
**********************************************************************
Init_Timer:     LDA     TSC
                MOV     #%01110000,TSC                  ;Get the timer ready, stop the counter.
                MOV     #$13,TMODH                      ;Set the modulo registers so that the
                MOV     #$33,TMODL                      ;timer will overflow in 1ms.
                RTS

**********************************************************************
* Init                                                               *
* Initializes the MCU                                                *
**********************************************************************
Init:           MOV     #%00101000,CONFIG2              ;Enable external oscillator, SCI uses CGMXCLK
                MOV     #%00011011,CONFIG1              ;Disable COP

                JSR     Init_Vars                       ;Initialize RAM variables
                BSR     Init_Ports                      ;Initialize I/O
                BSR     Init_ICG                        ;Initialize external crystal
                BSR     Init_KBD                        ;Initialize keyboard interrupts
                BSR     Init_Timer                      ;Initialize the timer
                BSR     Init_SCI                        ;Initialize the SCI
                BSR     Init_TBM                        ;Initialize the TBM

                CLRA
                CLRH
                CLRX
                CLI
                RTS