bootload.asm

PIC18F452单片机bootloader源代码

; *****************************************************************************
;        Software License Agreement				    
;								    
; The software supplied herewith by Microchip Technology 	    
; Incorporated (the 揅ompany? for its PICmicro?Microcontroller is 
; intended and supplied to you, the Company抯 customer, for use     
; solely and exclusively on Microchip PICmicro Microcontroller	    
; products. The software is owned by the Company and/or its         
; supplier, and is protected under applicable copyright laws. All   
; rights are reserved. Any use in violation of the foregoing 	    
; restrictions may subject the user to criminal sanctions under	    
; applicable laws, as well as to civil liability for the breach of  
; the terms and conditions of this license.			    
;								    
; THIS SOFTWARE IS PROVIDED IN AN 揂S IS?CONDITION. NO WARRANTIES, 
; WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT NOT LIMITED 
; TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 	    
; PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. THE COMPANY SHALL NOT, 
; IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL OR 	    
; CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.		    
;								    
;								    
; Bootloader for the PIC18F252/452
;
; DESCRIPTION:
; This is an example of a bootloader routine for the PIC18FX52. The 
; PICDEM2 was used for development. A 10MHz clock was selected.
;
; INSTRUCTIONS:
; Press button RA4 and reset on the PICDEM2. Release reset. Then 
; release button RA4. Now the device is waiting for a text data stream
; to be parced and loaded into the part.  //按下A4和DEM2上的复位键，先释放复位键，然后在释放A4按纽，
                                           则单片机等待一个数据流，进入引导模式。
;
; Use 'Hyperterm' to download the HEX file to be bootloaded. Set 
; the terminal for 57.6kb, 8, N, 1, and enable XON/XOFF. Use the 
; 'Send Text File' option to transfer the HEX file. The HEX file
; must be INTEL32 HEX format.  //使用windows的超级终端
;
; RB0 will light if an error occured.            //错误发生RB0亮
; RB1 will light if the code loaded successfully and an EOL was received.//下载代码成功并收到一个结束标志RB1亮
; RB2 will toggle for each HEX line recieved.//每一个HEX记录收到则RB1触发
;
;
; GENERAL INFO:
; When writing code to be bootloaded, be aware of the re-mapping of
; the reset and interrupt vectors.   //注意重新映射复位和中断向量
;
; Memory Map
;	-----------------
;	|    0x0000	|		
;   	|		|
;	|  Boot Block 	|	(this program)  //bootload代码区 
; 	|		|
;	|    0x0200	|	Re-mapped Reset Vector   //复位向量重新映射
;	|    0x0208	|	Re-mapped High Priority Interrupt Vector  //高优先级中断向量重新映射
;	|    0x0218	|	Re-mapped Low Priority Interrupt Vector   //低优先级中断向量重新映射
;	|		|
;	|	|	|
;	|		|
;    	|  Code Space 	|       //用户代码区
;	|		|
;	|	|	|
;	|		|
;	|    0x7FFE     |
;	-----------------
; *****************************************************************************

 

; *****************************************************************************
	#include P18F452.INC		; Standard include
; *****************************************************************************



; *****************************************************************************
#define BRG_VAL		D'10'		; Desired baud rate  //串口波特率发生器 值为10
; *****************************************************************************



; *****************************************************************************
_BOOTLOAD	UDATA_ACS

DATACNT		res	1		; Storage area for INHX32
ADDRESS_H	res	1
ADDRESS_L	res	1
RECORD		res	1
DATA_BUFF	res	0x10              //16字节数据缓存区

LAST_BYTE	res	1

CHKSUM		res	1		; Checksum accumulator   //按照HEX的一个记录格式定义

COUNTER		res	1		; General counter

TEMP1		res	1		; Temp storage

RXDATA		res	1		; Receive storage area

ADDRESS_UH	res	1		; Upper word for 32-bit HEX
ADDRESS_UL	res	1
; *****************************************************************************



; *****************************************************************************
_V_RESET	CODE	0x0000
	btfss	PORTA, 4		; Enter bootloader if button 
	bra	Setup			;  RA4 is pressed.
	bra	0x0200           //检测RA4
; *****************************************************************************



; *****************************************************************************
_V_INT_HIGH	CODE	0x0008
	bra	0x0208			; Re-map Interrupt vector
; *****************************************************************************



; *****************************************************************************
_V_INT_LOW	CODE	0x0018
	bra	0x0218			; Re-map Interrupt vector
; *****************************************************************************


; *****************************************************************************
_V_ERROR	CODE	0x001A		; Bootload error vector

GeneralErr
	bsf	PORTB, 0		; Indicate some error
	bra	$                 //错误指示

EndOfRecord
	bsf	PORTB, 1		; Indicate successful write		
	bra	$                //成功完成烧写
; *****************************************************************************



; *****************************************************************************
_V_SETUP	CODE
Setup
	btfss	PORTA, 4		; Wait for button release
	bra	Setup

	clrf	LATB
	clrf	TRISB
	
	bcf	TRISC, 6		; Setup tx pin
	bsf	TRISC, 7		; Setup rx pin

	movlw	b'10010000'		; Setup rx and tx
	movwf	RCSTA
	movlw	b'00100110'		
	movwf	TXSTA

	movlw	BRG_VAL			; Setup the baud rate	
	movwf	SPBRG

	movf	RCREG, W		; Empty the buffer
	movf	RCREG, W                                      //初始化串口
; *****************************************************************************



; *****************************************************************************
; This section reads and parses one line of INTEL32 HEX.  读并解析一个HEX记录
; 

StartOfLine                                                         //此函数为保存并解析一个记录的开始
	movlw	D'17'			; XON, enable data stream
	rcall	WrRS232


	btg	LATB, 2

WaitForStart
	rcall	GetChar			; Look for a start of line
	xorlw	':'
	bnz	WaitForStart		; Go back for another character


	rcall	GetByte			; Get the data count
	movwf	CHKSUM			
	movwf	DATACNT			; Set the data counter
	addlw	0x03                          //数据长度加上两字节地址长度和一个字节的数据格式长度为3
	movwf	COUNTER		
	
                                           //一个HEX记录格式： { ：（开始）数据长度（充满16字节）  起始地址 数据格式 数据区                                                                        效验和}
        lfsr	0, ADDRESS_H	        //数据长度过后是数据存放FLASH中的起始地址
GetNextDat				; Get the data
	rcall	GetByte
	addwf	CHKSUM, F
	movwf	POSTINC0
	decfsz	COUNTER, F
	bra	GetNextDat

	rcall	GetByte			; Get the checksum
	movwf	LAST_BYTE


	movlw	D'19'			; XOFF, disable data stream
	rcall	WrRS232
; *****************************************************************************



; *****************************************************************************
; This tests, writes, and verifies the line of HEX data.
;
; Notes:
; The HEX data is assumed to be padded to fill a 16 byte 
; INHX32 line.
;
; Programming is limited to program memory space only.
;
; Not all record types are decoded.

TestChkSum				; Examine the checksum
	movf	LAST_BYTE, W
	negf	CHKSUM
	xorwf	CHKSUM, W
	bnz	GeneralErr		; Stop if an error is detected //效验和的计算：一行的所有数据相加的和取补就是chksum的                                                                            值


TestRecordType				; Check the record type
	movlw	0x00			
	xorwf	RECORD, W
	bz	NormalDataRecord	; If a normal record then process
	movlw	0x01
	xorwf	RECORD, W
	bz	EndOfRecord		; IF EOF then finish
	movlw	0x04
	xorwf	RECORD, W
	bz	ExtendedRecord		; If extended then adjust
	bra	StartOfLine		; Otherwise, undefined record type...


ExtendedRecord				; Read in upper word of 32-bit address
	movff	DATA_BUFF, ADDRESS_UH	
	movff	DATA_BUFF + 1, ADDRESS_UL	

	bra	StartOfLine


NormalDataRecord			; Normal data record

	movf	ADDRESS_UH		; Get the next line if too high
	bnz	StartOfLine

	movlw	0x20			; Write ID locations?
	xorwf	ADDRESS_UL, W
	bz	WriteIDLocations
	movlw	0x30			; Write Config locations?
	xorwf	ADDRESS_UL, W
	bz	WriteConfig
	movlw	0xF0			; Write Data EEPROM?
	xorwf	ADDRESS_UL, W
	bz	WriteEEPROM
	
	btfsc	ADDRESS_H, 7		; Get the next line if too high
	bra	StartOfLine

	movlw	0x02			; Prevent writing to boot area
	subwf	ADDRESS_H, W
	bnc	StartOfLine


EraseRow				; Erase row if pointing to first byte in row
	rcall	SetPointers                   //设置指针
	movf	ADDRESS_L, W		; Check for row all ignment
	andlw	b'00111111'
	bnz	TestForBlankMem
	movlw	b'10010100'		; Setup erase
	movwf	EECON1
	rcall	StartWrite		; Erase the row				
	 

TestForBlankMem				; Do not write unless blank
	rcall	SetPointers
TestNext
	tblrd	*+			; Read 
	comf	TABLAT			; Test for blank (0xFF)
	bnz	GeneralErr		
	decfsz	COUNTER