bldc motor

[sanjeev]

#define DrivePort PORTC

#define SensorMask B’00000111’

#define SensorPort PORTE

#define DirectionBit PORTA, 1

Commutate

movlw SensorMask ;retain only the sensor bits

andwf SensorPort ;get sensor data

xorwf LastSensor, w ;test if motion sensed

btfsc STATUS, Z ;zero if no change

return ;no change – return

xorwf LastSensor, f ;replace last sensor data with current

btfss DirectionBit ;test direction bit

goto FwdCom ;bit is zero – do forward commutation

;reverse commutation

movlw HIGH RevTable ;get MS byte to table

movwf PCLATH ;prepare for computed GOTO

movlw LOW RevTable ;get LS byte of table

goto Com2

FwdCom ;forward commutation

movlw HIGH FwdTable ;get MS byte of table

movwf PCLATH ;prepare for computed GOTO

movlw LOW FwdTable ;get LS byte of table

Com2

addwf LastSensor, w ;add sensor offset

btfsc STATUS, C ;page change in table?

incf PCLATH, f ;yes – adjust MS byte

call GetDrive ;get drive word from table

movwf DriveWord ;save as current drive word

return

GetDrive

movwf PCL

FwdTable

retlw B’00000000’ ;invalid

retlw B’00010010’ ;phase 6

retlw B’00001001’ ;phase 4

retlw B’00011000’ ;phase 5

retlw B’00100100’ ;phase 2

retlw B’00000110’ ;phase 1

retlw B’00100001’ ;phase 3

retlw B’00000000’ ;invalid

RevTable

retlw B’00000000’ ;invalid

retlw B’00100001’ ;phase /6

retlw B’00000110’ ;phase /4

retlw B’00100100’ ;phase /5

retlw B’00011000’ ;phase /2

retlw B’00001001’ ;phase /1

retlw B’00010010’ ;phase /3

retlw B’00000000’ ;invalid

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