;   stepper.txt
;
;   06-May-2006  Keith Neufeld
;
;   Test/drive bipolar stepper motor, using external 754410 driver chip.
;   Two coils are driven in quadrature:
;
;	===|       |=======|       |=======|       |=======|
;	   |       |       |       |       |       |       |
;	   |=======|       |=======|       |=======|       |===
;
;	=======|       |=======|       |=======|       |=======|
;	       |       |       |       |       |       |       |
;	       |=======|       |=======|       |=======|       |



;------------------------------------------------------------------------------
;   Debug system
;------------------------------------------------------------------------------

constants [[debug 0]]
;constants [[debug 1]]


;------------------------------------------------------------------------------
;   Section to manipulate stepper motor.
;   Coil 1 driven by C7/C6.  Coil 2 driven by A2/A3.
;------------------------------------------------------------------------------

constants [
    [coil1-port portc] [coil1-ddr portc-ddr]
    [coil1a-bit 7] [coil1b-bit 6]

    [coil2-port porta] [coil2-ddr porta-ddr]
    [coil2a-bit 2] [coil2b-bit 3]
]

to stepper-off
    clearbit coil1a-bit coil1-port	;   set all coil outputs low
    clearbit coil1b-bit coil1-port

    clearbit coil2a-bit coil2-port
    clearbit coil2b-bit coil2-port
end

global [steps-per-sec msec-per-step]	;   timing "constants"
global [coil1-pos coil2-pos]		;   current coil state

to init-stepper
    stepper-off				;   shut down all coil outputs

    clearbit coil1a-bit coil1-ddr	;   set all coil pins as outputs
    clearbit coil1b-bit coil1-ddr

    clearbit coil2a-bit coil2-ddr
    clearbit coil2b-bit coil2-ddr

    setsteps-per-sec 2			;   2 steps per second
    setmsec-per-step 1000 / steps-per-sec	;   precalculate wait per step

    setcoil1-pos 0			;   initialize quadrature to (0,0)
    setcoil2-pos 0
end

to step-set				;   push out new quadrature values
    ifelse debug [
	send 48 + coil1-pos		;   0/1 with no CR
	send 32				;   space with no CR
	print coil2-pos
    ] [
	ifelse coil1-pos [
	    clearbit coil1b-bit coil1-port	;   clear before set
	    setbit coil1a-bit coil1-port
	] [
	    clearbit coil1a-bit coil1-port	;   clear before set
	    setbit coil1b-bit coil1-port
	]

	ifelse coil2-pos [
	    clearbit coil2b-bit coil2-port	;   clear before set
	    setbit coil2a-bit coil2-port
	] [
	    clearbit coil2a-bit coil2-port	;   clear before set
	    setbit coil2b-bit coil2-port
	]
    ]
end

;   CW pattern:
;	0110.0110
;	0011.0011

global [new1 new2]			;   temps for coil values

to step-cw
    setnew1 not coil2-pos
    setnew2 coil1-pos

    setcoil1-pos new1
    setcoil2-pos new2

    step-set				;   do it
end

to step-ccw
    setnew1 coil2-pos
    setnew2 not coil1-pos

    setcoil1-pos new1
    setcoil2-pos new2

    step-set				;   do it
end


;------------------------------------------------------------------------------
;   Routines to tie it all together
;------------------------------------------------------------------------------

to init-all
    init-stepper
end

to powerup
    init-all
end

to startup
    init-all
    loop [
	step-cw
	mwait 100
    ]
end