W78ERD2 Datasheet, PDF (67/72 Pages) Winbond – 8-BIT MICROCONTROLLER

W78ERD2
21. APPLICATION NOTE
21.1 In-system Programming Software Examples
This application note illustrates the in-system programmability of the Winbond W78ERD2 Flash
EPROM microcontroller. In this example, microcontroller will boot from 64 KB AP Flash EPROM bank
and waiting for a key to enter in-system programming mode for re-programming the contents of 64 KB
AP Flash EPROM. While entering in-system programming mode, microcontroller executes the loader
program in 4KB LD Flash EPROM bank. The loader program erases the 64 KB AP Flash EPROM
then reads the new code data from external SRAM buffer (or through other interfaces) to update the
64KB AP Flash EPROM.
EXAMPLE 1:
;*******************************************************************************************************************
;* Example of 64K AP Flash EPROM program: Program will scan the P1.0. if P1.0 = 0, enters
;* in-system Programming mode for updating the content of AP Flash EPROM code else executes the
;* current ROM code.
;* XTAL = 40 MHz
;*******************************************************************************************************************
.chip 8052
.RAMCHK OFF
.symbols
CHPCON
CHPENR
SFRAL
SFRAH
SFRFD
SFRCN
EQU
EQU
EQU
EQU
EQU
EQU
BFH
F6H
C4H
C5H
C6H
C7H
ORG 0H
LJMP 100H
; JUMP TO MAIN PROGRAM
;************************************************************************
;* TIMER0 SERVICE VECTOR ORG = 000BH
;************************************************************************
ORG 00BH
CLR TR0
; TR0 = 0, STOP TIMER0
MOV TL0, R6
MOV TH0, R7
RETI
;************************************************************************
;* 64K AP Flash EPROM MAIN PROGRAM
;************************************************************************
ORG 100H
MAIN_64K:
MOV A, P1
; SCAN P1.0
ANL A, #01H
CJNE A, #01H, PROGRAM_64K ; IF P1.0 = 0, ENTER IN-SYSTEM PROGRAMMING MODE
JMP NORMAL_MODE
PROGRAM_64K:
MOV CHPENR, #87H
MOV CHPENR, #59H
MOV CHPCON, #03H
; CHPENR = 87H, CHPCON REGISTER WRTE ENABLE
; CHPENR = 59H, CHPCON REGISTER WRITE ENABLE
; CHPCON = 03H, ENTER IN-SYSTEM PROGRAMMING MODE
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Publication Release Date: April 20, 2005
Revision A4