AN2690 Freescale Semiconductor / Motorola, AN2690 Datasheet - Page 25

• Manufacturer Part Number: AN2690
• Description: Low Frequency EEPROM Emulation on the MC68HLC908QY4
• Manufacturer: Freescale Semiconductor / Motorola

PORset:
EEnotBlank:
ILOPset:
SwXtal:
MOTOROLA
jsr
;catches all other reset sources
mov
clr
bra
;Check for first POR
lda
cmp
bne
clr
;Init PortB
mov
;Init EEPROM
mov
clr
mov
ldhx
lda
jsr
bra
ldhx
lda
psha
sta
lda
and
sta
bra
brclr
bsr
bclr
bsr
jsr
cli
RdBlock
#$08, PORTB
ApplicationFlags
SwXtal
EeStart
#$FF
EEnotBlank
ApplicationFlags
#$08,PORTB
#$08, RamBfrStrt
RamBfrStrt+1
#$01, RamBfrStrt+2
#EeStart
#$3
WrtBlock
SwXtal
#EeStart
#3
PORTB
1,x
#mDIRECTION_FLAG
ApplicationFlags
SwXtal
PROG_EEPROM_FLAG, ApplicationFlags, OtherRst
ProgEE
PROG_EEPROM_FLAG, ApplicationFlags
SwitchToXtal
InitTimer
Low Frequency EEPROM Emulation on the MC68HLC908QY4
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;gets pointer to latest data block: Returns start address
;of most recent data in H:X and 1st Byte in accumulator
;Initilise LED sequence
;Get 1st byte in EEpage
;Check that its blank
;Not Blank
;Switch enabled
;Initilise LED sequence
;Initilise LED sequence
;ApplicationFlags Clear - DIR Left
;Count = 1
;3 Bytes to be programmed
;Go program EEPROM
;Get current count value
;save buffer size on stack
;Restore PortB
;get stored ApplicationFlags
;Only interested in Direction
;Restore saved Direction bit; Switch Enabled
;Check if EEprom to be programmed
;PROG_EPROM_FLAGS = 1
;Reset flag for next program request
;Configures QY4 for operation from 32768Hz Xtal
;Init Timer1 overflow
;enable interrupts
Appendix A: Sample Application
AN2690
25