Bikelight2.asm


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.include "m16def.inc"  

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.cseg

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.ORG $2A

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;Register_Usage----------------------------------------------------------

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;.def  Temp1  =R16

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;.def  Temp2  =R17

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;.def  Temp3  =R18

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;.def  Sevseg  =R19

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;.def  Flags  =R20

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;.def  TWIReg  =R21

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;------------------------------------------------------------------------

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;------------------------------------------------------------------------

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;Reset_and_interrupt_vector     ;VNr.  Beschreibung

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;

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  rjmp  MAIN  ;Reset Handler

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;Start,_Power_ON,_Reset

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MAIN:

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  ldi    r16,low(RAMEND)

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  out    SPL,r16

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  ldi    r16,high(RAMEND)

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  out    SPH,r16

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  ldi   r21,0B11100001

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  out    DDRC,r21

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  ldi   r21,0B00000000

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  out   PORTC,r21

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  ldi   r21,0xff

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  out    DDRA,r21;"

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mainloop:

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  ldi    r21,0B00000000  ;Port-B I/O Directions

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  out    DDRB,r21  ; "   

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  ldi    r21,0B11100011  ;Port-D I/O Directions

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  out    DDRD,r21  ; "              "

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  ldi    r20,0B00000000  ;Initialize Flag register

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  ldi    r21,0B01101111

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  out    MCUCR,r21  ;INT1 and INT0 configured for rising edge / MCU in Power down

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  ldi    r21,0B01000000

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  out    MCUCSR,r21  ;INT2 configured for rising edge

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  ldi    r21,0B11100000

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  sei

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  out    GICR,r21  ;All external interrupt sources enabled

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  RCALL   COMMU

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  out   PORTA,r23

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endless:

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  RJMP   endless

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error:

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  POP   R22

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  POP    R21

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  out    PORTA,r23

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  RET

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COMMU:

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  PUSH   R21

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  PUSH  R22  

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  ldi    r22,0x22    ;Configure Bit Rate

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  out    TWBR,r22    ;in Bitrate register

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  ldi    r22,0B00000001  ;Configure Prescaler

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  out   TWSR, r22    ;in Status register

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  ldi    r22,(1<<TWINT)|(1<<TWSTA)|(1<<TWEN)|(1<<TWEA)

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  out    TWCR,r22    ;Configure and enable I²C Interface / Bit5-Start

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  out    PORTA,r23

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wait1:

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  in    r21,TWCR  ;Wait for TWINT flag set

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  sbrs  r21,TWINT  ; "              "

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  rjmp  wait1  ;

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  in    r21,TWSR  ;read TW-Status register

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  andi  r21,0B11111000  ;Check if START status

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  cpi    r21,0B00001000  ; "               "

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  brne  error  ;jump to error

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  ldi   r17, 0B10010000

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  out    TWDR,r17  ;DS2745's slave adress + write bit

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  ldi   r17, (1<<TWINT)|(1<<TWEN)|(1<<TWEA) 

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  out    TWCR,r17  ;Clear TWINT flag for transfering

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wait2:

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  in    r21,TWCR  ;Wait for TWINT flag set

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  sbrs  r21,TWINT  ; "              "

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  rjmp  wait2  ;

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  ldi    r23,0b11000000

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  out   porta,r23

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  in    r21,TWSR  ;read TW-Status register

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  andi  r21,0B11111000  ;Check if ACK was received

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  cpi    r21,0B01000000  ; "                   "

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  brne  error1  ;

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  ldi   r17, 0x0D

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  out    TWDR,r17  ;Memory Adress voltage MSB

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  ldi   r17, 0B11000100

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  out    TWCR,r17  ;Clear TWINT flag for transfering

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  ldi    r23,0b11100010

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  out    PORTA,r23

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wait3:

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  in    r21,TWCR  ;Wait for TWINT flag set

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  sbrs  r21,TWINT  ; "              "

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  rjmp  wait3  ;

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  in    r21,TWSR  ;read TW-Status register

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  andi  r21,0B11111000  ;Check if Databyte ACK was received

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  cpi    r21,0B01010000  ; "                   "

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  brne  error1  ;

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  ldi    r23,0b11110000

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  out    PORTA,r23

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wait4: 

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  ldi   r17,0B10100101;

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  out    TWCR,r17  ;Configure for repeated start

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  in    r21,TWCR  ;Wait for TWINT flag set

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  sbrs  r21,TWINT  ; "                "

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  rjmp  wait4  ;

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  in    r21,TWSR  ;read TW-Status register

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  andi  r21,0B11111000  ;Check if START status

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  cpi    r21,0B00001000  ; "               "

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  brne  error1  ;jump to error

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  ldi   r17, 0B10010001

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  out    TWDR,r17  ;DS2745's slave adress + read bit

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  ldi   r17, 0B10000100

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  out    TWCR,r17  ;Clear TWINT flag for transfering

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  ldi    r23,0b11111000

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  out    PORTA,r23

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wait5:

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  in    r21,TWCR  ;Wait for TWINT flag set

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  sbrs  r21,TWINT  ; "              "

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  rjmp  wait5  ;

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  in    r21,TWSR  ;read TW-Status register

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  andi  r21,0B11111000  ;Check if ACK was received

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  cpi    r21,0B01100000  ; "                   "

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  brne  error1  ;

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  in    r22,TWDR  ;Voltage value stored in r22

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  ldi   r17, 0B10000001

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  out    TWCR,r17  ;Configure for no acknowledge

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  ldi    r23,0b11111100

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  out    PORTA,r23

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wait6:

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  in    r21,TWCR  ;wait for TWINT flag set

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  sbrs  r21,TWINT  ;

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  rjmp  wait6  ;

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  in    r21,TWSR  ;read TW-Status register

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  andi  r21,0B11111000  ;Check if Acknowledge was received

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  cpi    r21,0B01010000  ;Status register must contain $50

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  brne  error1  ;

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  mov   r17,r22;

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  ldi    r23,0b11111110

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  out    PORTA,r23

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  POP    r21

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  pop    r22

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  ret

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error1:

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  POP   R22

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  POP    R21

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  out    PORTA,r23

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  RET