justDIY
Active Member
I have to admit I don't know much about pic assembly. I know most of the simpler instructions, enough that I can poke around an asm file if my basic program has some sort of weird glitch, but for the most part, I'm spoiled by basic.I'm trying to modify the source for TINY BOOTLOADER to operate with the internal OSC + PLL on my 18F2620. I've changed the necessary fuses, and added what I think are the correct instructions, but it has a few weird problems.
problem 1) the bootloader operates at 28800 bps, not 57600 bps as instructed, which indicates the cpu is running slower than calculated... is it running at 16mhz instead of 32mhz, since 57600/2 = 28800?
problem 2) the bootloader self-destructs when it programs the pic, as if it is overwriting part of itself. after uploading my main program (which skips several bytes for the bootloader's block), I'm not able to connect to the bootloader again, after resetting the pic.
Here's what I've managed to cobble together from the original code example, the parts I've changed are in red:
Code:
radix DEC
LIST P=18F2620 ; change also: Configure->SelectDevice from Mplab
xtal EQU 32000000 ; you may want to change: _XT_OSC_1H _HS_OSC_1H _HSPLL_OSC_1H
[COLOR="Red"]baud EQU 57600[/COLOR] ; the desired baud rate, originally 115200
; The above 3 lines can be changed and buid a bootloader for the desired frequency (and PIC type)
;********************************************************************
; Tiny Bootloader 18F series Size=100words
; claudiu.chiculita@ugal.ro
; http://www.etc.ugal.ro/cchiculita/software/picbootloader.htm
;********************************************************************
#include "icdpictypes.inc" ;takes care of: #include "p18fxxx.inc", max_flash, IdTypePIC
#include "spbrgselect.inc" ; RoundResult and baud_rate
[COLOR="Red"]#define first_address max_flash-204[/COLOR] ;102 words originally 100
[COLOR="Red"]CONFIG OSC = INTIO67
CONFIG FCMEN = OFF
CONFIG IESO = OFF
CONFIG PWRT = ON
CONFIG BOREN = ON
CONFIG BORV = 2 ; 4.2v
CONFIG WDT = OFF
CONFIG WDTPS = 1
CONFIG MCLRE = ON
CONFIG PBADEN = OFF
CONFIG CCP2MX = PORTC
CONFIG STVREN = ON
CONFIG LVP = OFF
CONFIG XINST = OFF
CONFIG DEBUG = OFF
CONFIG CP0 = OFF
CONFIG CP1 = OFF
CONFIG CP2 = OFF
CONFIG CP3 = OFF
CONFIG CPB = OFF
CONFIG CPD = OFF
CONFIG WRT0 = OFF
CONFIG WRT1 = OFF
CONFIG WRT2 = OFF
CONFIG WRT3 = OFF
CONFIG WRTB = OFF
CONFIG WRTC = OFF
CONFIG WRTD = OFF
CONFIG EBTR0 = OFF
CONFIG EBTR1 = OFF
CONFIG EBTR2 = OFF
CONFIG EBTR3 = OFF
CONFIG EBTRB = OFF[/COLOR]
;----------------------------- PROGRAM ---------------------------------
cblock 0
crc
i
cnt1
cnt2
cnt3
counter_hi
counter_lo
flag
endc
cblock 10
buffer:64
endc
SendL macro car
movlw car
movwf TXREG
endm
;0000000000000000000000000 RESET 00000000000000000000000000
ORG 0x0000
GOTO IntrareBootloader
;view with TabSize=4
;&&&&&&&&&&&&&&&&&&&&&&& 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
[COLOR="Red"]movlw b'01110000'[/COLOR] ;set intrc to 8mhz
[COLOR="Red"]movwf OSCCON[/COLOR]
;init serial port
movlw b'00100100'
movwf TXSTA
movlw spbrg_value
movwf SPBRG
movlw b'10010000'
movwf RCSTA
[COLOR="Red"]bsf OSCTUNE,6,0 [/COLOR] ;enable 4x PLL
;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 ;is EEPROM data?
bra noeeprom
movlw b'00000100' ;Setup eeprom
rcall Write
bra waitwre
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
