' Macro focus rail driver
' Unipolar stepper (12V 1.8deg) connected to ULN2003A:
'    green, white, red, brown -> Out1-Out4
'    08m 2 -> ULN In2
'    08m 1 -> ULN In3
' Out4 -> optocoupler for shutter triggering (tip+, sleave-)
' IR detector codes:
'    CH+      back focus
'    CH-      front focus
'    NN       steps in one slide (in 0.01mm)
'    AV/TV    the next slide will be continuous (any key to interrupt)
'    Vol-     mark focus (front) and start moving focus back; mark focus end by any key
'       slide to the front of the stack
'    Power    start shooting

symbol slack = 5          ' how many micro steps to add when changing direction
symbol steppause = 1   ' larger number will make it go slower
'                                  - useful if you have a stepper with very few steps per revolution

symbol stepc     = b0
symbol s    = b1
symbol i    = b2
symbol direction = b3
symbol nsteps    = b4
symbol nframes   = b5
symbol nslide    = b6
symbol j     = b7
symbol irflag    = b8
symbol olddir    = b9
symbol contflag  = b10

high 1
high 2
low 4

'           (nsteps)
eeprom 0, (20)

read 0, nsteps

contflag=0

main:
    infrain2
    if infra<10 then
        infra=infra+1
        infra=infra//10
        nsteps=infra*10
        pause 500
        infrain2
        infra=infra+1
        infra=infra//10
        nsteps=nsteps+infra
        write 0, nsteps
    elseif infra=37 then
        contflag=1
        pause 500
        infrain2
        pause 500
    endif
    select infra
    case 17 ' front focus
        direction=2
        gosub slide
    case 16 ' back focus
        direction=0
        gosub slide
    case 19 ' Vol-  - mark focus start
        nslide=0
        irflag=0
        pause 200
        do
            pause 200
            direction=0
            gosub slide
            nslide=nslide+1
            'pause 200
        loop while irflag=0
        pause 2000
        for j=1 to nslide
            direction=2
            gosub slide
        next j
        gosub slide
        direction=0
        gosub slide
    case 21 ' Power - start shooting run
        gosub shoot
        for j=1 to nslide
            direction=0
            gosub slide
            gosub shoot
        next j
    endselect
    'debug
    pause 500
    goto main

shoot:
    pause 5000
    high 4  ' shoot
    pause 400
    low 4
    pause 3000    ' wait before the next slide (exposure time)
    return


slide:
    if direction<>olddir then   ' remove sprocket slack
        for i=1 to slack
            gosub onestep
        next i
    endif
    irflag=0
lup:
    for i=1 to nsteps
        gosub onestep
        pause steppause
    next i
    if irflag=0 AND contflag=1 then goto lup
    contflag=0
    olddir=direction
    return

onestep:
'   s=direction*2
    stepc=stepc+direction-1
    let stepc=stepc // 4
    lookup stepc, (%00000110, %00000100, %00000000, %00000010), s
    let pins=s
    if pin3=0 then
        irflag=1
    endif
    'pause 1
    return