bootloader

    radix DEC
    LIST      P=18F1320 ; change also: Configure->SelectDevice from Mplab
xtal EQU 8000000        ; you may want to change:
    ;oscil: _HS_OSC_1H  HS extern
    ;   _INTIO1_OSC_1H  Internal RC, OSC1 as RA7, OSC2 as Fosc/4
    ;   _INTIO2_OSC_1H  Internal RC, OSC1 as RA7, OSC2 as RA6
baud EQU 19200          ; standard TinyBld baud rates: 115200 or 19200
    ; The above 3 lines can be changed and buid a bootloader for the desired frequency and PIC type

    ;********************************************************************
    ;   Tiny Bootloader     for 18F series      Size=100words
    ;   claudiu.chiculita@ugal.ro
    ;   http://www.ac.ugal.ro/staff/ckiku/software/picbootloader.htm
    ;********************************************************************


    #include "../icdpictypes.inc"   ;takes care of: #include "p18fxxx.inc",  max_flash, IdTypePIC
    #include "../spbrgselect.inc"   ; RoundResult and baud_rate

        #define first_address max_flash-200     ;100 words

    __CONFIG _CONFIG1H, _IESO_OFF_1H & _FSCM_OFF_1H & _INTIO2_OSC_1H

    __CONFIG _CONFIG2L, _PWRT_ON_2L & _BOR_ON_2L & _BORV_20_2L
    __CONFIG _CONFIG2H, _WDT_OFF_2H & _WDTPS_32K_2H ;
    __CONFIG _CONFIG3H, _MCLRE_ON_3H
    __CONFIG _CONFIG4L, _DEBUG_OFF_4L & _LVP_OFF_4L & _STVR_ON_4L
    __CONFIG _CONFIG5L, _CP0_OFF_5L & _CP1_OFF_5L
    __CONFIG _CONFIG5H, _CPB_OFF_5H & _CPD_OFF_5H
    __CONFIG _CONFIG6L, _WRT0_OFF_6L & _WRT1_OFF_6L
    __CONFIG _CONFIG6H, _WRTC_OFF_6H & _WRTB_OFF_6H & _WRTD_OFF_6H
    __CONFIG _CONFIG7L, _EBTR0_OFF_7L & _EBTR1_OFF_7L
    __CONFIG _CONFIG7H, _EBTRB_OFF_7H


;----------------------------- PROGRAM ---------------------------------
    cblock 0
    crc
    i
    cnt1
    cnt2
    cnt3
    counter_hi
    counter_lo
    flag
    endc
    cblock 10
    buffer:64
    dummy4crc
    endc

SendL macro car
    movlw car
    movwf TXREG
    endm

;0000000000000000000000000 RESET 00000000000000000000000000

        ORG     0x0000
        GOTO    IntrareBootloader

;&&&&&&&&&&&&&&&&&&&&&&&   START     &&&&&&&&&&&&&&&&&&&&&&
;----------------------  Bootloader  ----------------------
;PC_flash:      C1h             U       H       L       x  ...  <64 bytes>   ...  crc
;PC_eeprom:     C1h             40h   EEADR   EEDATA    0       crc
;PC_cfg         C1h         U OR 80h    H       L       1       byte    crc
;PIC_response:     type `K`

    ORG first_address       ;space to deposit first 4 instr. of user prog.
    nop
    nop
    nop
    nop
    org first_address+8
IntrareBootloader
    movlw b'01110000'       ;switch internal oscillator to 8MHz
    movwf OSCCON
    ; Don't I have to wait for the clock to stabilize ?
    movlw b'01100000'
    movwf ADCON1            ;disable analog on tx/rx
                            ;init serial port
    movlw b'00100100'
    movwf TXSTA
    movlw spbrg_value
    movwf SPBRG
    movlw b'10010000'
    movwf RCSTA
                            ;wait for computer
    rcall Receive
    sublw 0xC1              ;Expect C1h
    bnz way_to_exit
    SendL IdTypePIC         ;send PIC type
MainLoop
    SendL 'K'               ; "-Everything OK, ready and waiting."
mainl
    clrf crc
    rcall Receive           ;Upper
    movwf TBLPTRU
        movwf flag          ;(for EEPROM and CFG cases)
    rcall Receive           ;Hi
    movwf TBLPTRH
        movwf EEADR         ;(for EEPROM case)
    rcall Receive           ;Lo
    movwf TBLPTRL
        movwf EEDATA        ;(for EEPROM case)

    rcall Receive           ;count
    movwf i
    incf i
    lfsr FSR0, (buffer-1)
rcvoct                      ;read 64+1 bytes
        movwf TABLAT        ;prepare for cfg; => store byte before crc
    rcall Receive
    movwf PREINC0
    decfsz i
    bra rcvoct

    tstfsz crc              ;check crc
    bra ziieroare
        btfss flag,6        ;EEPROM data is not supported
        bra noeeprom
        ;;;movlw b'00000100'    ;Setup eeprom
        ;;;rcall Write
        ;;;bra waitwre
        bra ziieroare

noeeprom
        btfss flag,7        ;is CFG data?
        bra noconfig
        tblwt*              ;write TABLAT(byte before crc) to TBLPTR***
        movlw b'11000100'   ;Setup cfg
        rcall Write
        bra waitwre
noconfig
                            ;write
eraseloop
    movlw   b'10010100'     ; Setup erase
    rcall Write
    TBLRD*-                 ; point to adr-1

writebigloop
    movlw 8                 ; 8groups
    movwf counter_hi
    lfsr FSR0,buffer
writesloop
    movlw 8                 ; 8bytes = 4instr
    movwf counter_lo
writebyte
    movf POSTINC0,w         ; put 1 byte
    movwf TABLAT
    tblwt+*
    decfsz counter_lo
    bra writebyte

    movlw   b'10000100'     ; Setup writes
    rcall Write
    decfsz counter_hi
    bra writesloop
waitwre
    ;btfsc EECON1,WR        ;for eeprom writes (wait to finish write)
    ;bra waitwre            ;no need: round trip time with PC bigger than 4ms

    bcf EECON1,WREN         ;disable writes
    bra MainLoop

ziieroare                   ;CRC failed
    SendL 'N'
    bra mainl

;******** procedures ******************

Write
    movwf EECON1
    movlw 0x55
    movwf EECON2
    movlw 0xAA
    movwf EECON2
    bsf EECON1,WR           ;WRITE
    nop
    ;nop
    return


Receive
    movlw xtal/2000000+1    ; for 20MHz => 11 => 1second delay
    movwf cnt1
rpt2
    clrf cnt2
rpt3
    clrf cnt3
rptc
        btfss PIR1,RCIF         ;test RX
        bra notrcv
        movf RCREG,w            ;return read data in W
        addwf crc,f             ;compute crc
        return
notrcv
    decfsz cnt3
    bra rptc
    decfsz cnt2
    bra rpt3
    decfsz cnt1
    bra rpt2
    ;timeout:
way_to_exit
    bcf RCSTA,  SPEN            ; deactivate UART
    bra first_address
;*************************************************************
; After reset
; Do not expect the memory to be zero,
; Do not expect registers to be initialised like in catalog.

            END