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555 timer circuits for digital camera trigger

Discussion in 'Electronic Design' started by DorkyGrin, Sep 29, 2008.

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  1. DorkyGrin

    DorkyGrin Guest

    I've got a digital camera that I am trying to connect to a motion
    sensor. I've disassembled it and have the wires available to wire into
    a circuit. I have three relays. I need a circuit to trigger the camera
    in this fashion:

    1. Receive signal, activate Relay A and hold for 10 seconds
    2. Same signal, after a couple of seconds, activates Relay B for 5
    3. Same signal, after a couple of seconds, activates Relay C for 2
    4. Then reset all relays for next event

    These steps simulate Power, Focus and Shutter.

    It's been awhile since I've worked with 555 timers, but I think tying
    them together in a circuit might be the simplest way to make this
    happen. I believe a 555 timer configured as a monostable one-shot
    could be used for Relay A. What I'm not sure about is steps 2 and 3,
    maybe a 556 timer that has some sort of startup delay?

    Or would this project be easier with some sort of PIC?

    Open to ideas.

  2. Yes.

    OTOH many digital cameras have an USB interface, and there exists a protocol
    (PTP mode) that these days many cameras support, to take a picture.
    So a small Linux computer, running perhaps gphoto2 software, with some
    sensor interface with USB PIC perhaps, more complicated.....
    All depends.
  3. DorkyGrin

    DorkyGrin Guest

    Or would this project be easier with some sort of PIC?

    I was thinking 555 or PIC because of size requirements (needs to be
    portable and run off a 6-12v battery). I had not considered USB.

    Are there any PICs that don't require a steep learning curve for
    programming? Something like a PIC for dummies?
  4. default

    default Guest

    Picaxe to the rescue! Check them out. The 8/14/20 pin basic (M
    series) versions only require a serial port or usb to serial cable to

    The basic language software is free. The parts go for ~$3-4. They are
    a snap to use - almost no learning curve. A/D converters with 8 or 10
    bit resolution, PWM output, runs on 2-5 volts in the microamp range.

    I'm using them for time lapse cameras among other things. It sits
    there waiting for the sun to come up, then snaps pictures at an
    adjustable interval (using a pot). All the timing is done in the
    'axe. I even count the pictures and slightly lengthen the time the
    camera stays on, so they get into memory - as the card fills up the
    camera needs more time. Camera runs for 10+ days and takes 1,000+
    shots in high res JPG format - 0n 3 AA rechargeable cells (3.6V).

    I'm using one 8 pin version on one camera and one 14 pin chip on
    another. Pins are assignable as input or output. The 14 and 20 still
    have assignable pins but they default to inputs or outputs without a
    program command.

    They sell all kinds of fancy hardware but all you really need is the
    PC and serial cable or USB adaptor and three resistors to program it.
    A solder less breadboard is nice too.

    Use 4.5 volts - they are damned serious about the 5 volt absolute
    maximum and batteries are convenient. Anderson (below) is probably
    still including programming resistors with the purchase of the 'axe.

    Official site (download software and manuals)

    Best cheapest fastest place to get them in the US

    another good fast inexpensive

    The forum - these guys can answer most any question you have and the
    manufacturer monitors and participates
  5. You're trying to implement a state machine, and need some memory
    components-- flip flops and such. Not terribly difficult if you have a
    basic understanding of digital circuits. Much easier to put together
    with a small PIC, assuming all your development tools are in place. If
    not, its a great small project with which to learn the environment.
  6. DorkyGrin

    DorkyGrin Guest

    Seems like that PICAXE might be just the ticket. Probably easier then
    trying to cascade a bunch of 555's. And it sure it cheap enough. I'll
    take a look at the software and try to get an idea how hard it would
    be to write the code. Thanks for the tips.

    Are of lots of examples of picaxe code out there?

    Thanks again

  7. mpm

    mpm Guest

    Wow. This smells like a nightmare in the making.
    My first thought is what happens when the focus doesn't snap first
    Will this un-synch the whole contraption?
  8. default

    default Guest

    There's tons of examples. The forum is rife with them. All you're
    doing, according to your post is sequential timing functions.

    The code would look something like
    high 4 'make pin 3 (logical output #4) high
    pause 10,000 'wait for 10 seconds (10,000 milliseconds)
    high 2 'turn on pin 5 (output #2)
    pause 'etc.

    To turn off, it is low 4 etc.

    I use a A/D input to read a pot and adjust the pause time.

    One of my outputs is a 40 KHZ 10% duty PWM that I use to toggle an
    inductor to make a small low power bias supply to turn on a mosfet.

    Regarding your camera - the ones I've played with just require an open
    collector to pull the switch signal to ground to actuate the functions
    - no relays necessary. But its all in how you want to do it - I
    wanted everything including the camera to work from one battery. The
    mosfet pulls the camera minus low to provide camera power.

    There's a book called "programming and Customizing the Picaxe" by
    David Lincoln ISBN # 0-07-145765-8. The book is OK - the table of
    contents don't agree with the content page numbers, and they'd added
    the 14M and 20M since the book was published.

    Download the two part manual from the revved site and you'll see how
    easy it can be.

    I have next to no programming experience and had no trouble using it.
    I like messing with it now.
  9. DorkyGrin

    DorkyGrin Guest

    Wow, lots of resources, downloaded and looked at the manual last
    night. Good stuff.

    I'm going to order a 14m and an 8m and play with them.

    Are there any components necessary for a to protect a picaxe input pin
    to sense
    a signal from my motion sensor?

    OK to email me directly. dorkygrin at yahoo

  10. default

    default Guest

    No pin can exceed the supply voltage of the axe. If it might go
    higher you have to use a voltage divider or clamp it with a diode or

    It was more hassle for me to get the USB to serial adapter recognized
    by Windows than it was to get the axe to blink a led. There's a
    debugger built into the "program editor" software - it toggles the
    RS232 output line high and low. That proved invaluable in getting the
    USB working for me. You click on a led on the PC screen to toggle the
    line high and low, and can monitor it with a voltmeter on the
  11. DorkyGrin

    DorkyGrin Guest

    No pin can exceed the supply voltage of the axe.  If it might go

    I'm just going to use serial, that eliminates the USB issue!

    As for the trigger, I'll have to think about that as the motion sensor
    output will probably run from a different power supply. That might be
    an issue even if that voltage were 5v or less. Hummmmm....

    Ever ordered picaxe stuff from here?:
  12. default

    default Guest

    No. Two reasons. Cost. Last time I checked they wouldn't sell a few
    picaxes without a $8 handling fee due to minimum order constraints and
    their shipping was higher.

    Anderson was only charging a couple of bucks for shipping with no
    minimum. (sparkfun and ebay were also cheap in that respect)

    Reason two was Anderson maintains circuits, code and useful glue parts
    at a reasonable cost. He also ships faster than spark or ebay. I
    don't know how fast world-ed is.

    Open collectors can work - tie an NPN transistor to ground turn on the
    base with the axe and it pulls the collector low - this assumes both
    circuits have negative grounds - the OC protects the axe - read the
    manual they show how to do it. If in doubt, post your schematic to
    the forum and ask for suggestions. ditto code.
  13. default

    default Guest

    I don't know the "full story." The 'axe has a programmed in boot
    loader - its only claim to fame. You pay extra for that, over the
    bare pic. The advantage is it allows easy programming in Basic and
    you don't need a development system - a solderless breadboard is all
    it takes in that respect.

    Can you clone the boot loader? I don't know. Reved makes their money
    and maintains the educational info on their profit, so don't expect
    them to give you that.

    Kicchip is another company trying to do the same thing as reved but
    they don't sell in the US and seem to be having some start up

    Arduino is an open source version using a more sophisticated pic with
    lots more capability - but the boards cost $13 and up (similar to
    basic stamp but program in basic and C.

    The basic Arduino chip with the boot loader is ~$6
    No you can't use the programmer because the 'axe bootloader is
    I would guess you'd need something like a programmer but- there are
    some open source attempts to program using an Axe to work as the
    loader for a bare pic - I haven't kept current but you can search for
    I run my 08M at 2.7 in one camera - 3 volt supply (2-AA) and one
    germanium diode to isolate it from the camera. (camera sucked down
    the supply rail when it turned on, and would reset the axe - causing
    it to oscillate on and off)

    The spec I saw said 2-5 volts and I can run at 2.4 when the battery is
    low. Programming should or must be done at ~4.5 or more due to
    voltage levels on the serial port. I use 4.5 and it seems to program
    fine at 3 volts also . . .

    The brownout in the chip can be over written in programming but I
    haven't fooled with it and use low voltages with no problems.
  14. Sorry for the late reply.
    I did see some recommend custom solutions like pic-axe (spelled right?).

    In my view it is much better to just take the time, and learn PIC asm.

    You will, as electronics person, work close to the hardware,
    and really, writing a delay loop in asm is just as simple, and a lot more versatile,
    then doing it in some higher language.

    You will want to write to IO ports, read AD the converter, do interrupts too, later.

    Learning curve? There is always one.
    If you _ever_ programmed in a language, say BASIC or whatever, then
    you understand the idea of having something execute your instructions.
    In such a case learning PIC asm (or any other asm) is just having a good read of
    the data sheets, the instruction set, and start with something simple like lighting a LED
    for example.

    There are lots and lots of examples for asm on the Microchip website,
    and the cheapest programmer is less the 50 $ IIRC.
  15. Rich Grise

    Rich Grise Guest

    That's what optoisolators are for. :)

  16. default

    default Guest

    My own application - running at low voltages - the optos I tried had
    too much VCEsat to work with a mosfet on the camera's minus (raising
    the whole camera above ground slightly).

    The hardware problems and work-arounds are due to the low voltages -
    with as much as 5 volts to play with, they'd probably vanish.
  17. DorkyGrin

    DorkyGrin Guest

    Rich - thanks for the optoisolator tip, that's exactly what I need to
    do, assuming I have enough voltage.

    This is coming together nicely.

    Default -

    HOLY COW! You were right, this pixaxe is way cool. I'm lovin' it.

    I downloaded the software and very quickly wrote the following

    if pin1 = 1 then takepic

    goto main

    high 2 'make pin 1 (logical output 2) high ** power relay **
    pause 3000 'wait for 3 seconds (2000 milliseconds)
    high 3 'turn on pin 2 (logical output 3) ** focus relay **
    pause 2000 'wait for 2 seconds
    high 4 'turn on pin 3 (logical output 4) ** shutter relay **
    pause 1000 'wait 1 seconds

    low 4,3
    pause 2000
    low 2 'reset to normal, wait for next event

    Looks great in the simulator. I've already ordered a starter kit and a
    couple of extra chips. Should
    be here by the weekend. Good stuff for what I'm doing.

    So, if my motion sensor keeps sending 'events', I think that would
    keep pin1 high (I'm not exactly sure
    until I test it, unless someone can tell me how it might work). Then I
    suppose I could write in a loop to
    keep checking the status of pin1 ... and if it is still high within x
    seconds, then I could keep hitting the
    shutter relay.

    How much current does a picaxe draw when running waiting to execute?
    Gotta start thinking about power

    Thanks again folks for your assistance. Guess I need to start posting
    in the picaxe forum now. ;-)
  18. default

    default Guest

    On Wed, 1 Oct 2008 19:38:23 -0700 (PDT), DorkyGrin

    Glad you're enjoying it - get on the forum now and introduce yourself
    as a newbie and tell them what you intend and ask questions there.
    Like I said, I'm no programming wizard. My moniker is "flooby"
    The 8 and 14 M chips can both be programmed to use interrupts - where
    an external event can be read(tested) while the program is processing.

    The code looks like
    SETINT (condition) mask
    SETINT %00010000, %00010000 'enable interrupt on pin 4 high

    It is used in conjunction with a loop before going back to the main
    program - you could, for instance, write a variable to remember the
    state and have your program check it (write just a single bit variable
    in this case) to determine how to proceed with the timing

    Words, bytes, and bits, are different length variables, b0 is a
    variable byte - sixteen bit variables can be written and read in
    "word" zero; word zero also comprises bytes zero and one - so they
    can't be used more than once.

    Does that make sense?

    BTW you can also put a variable into (high) memory locations so that
    it is written into memory in a part of the flash memory that your own
    program doesn't occupy - that way it "remembers" the variable while
    the power is off. Upon startup, or in the program, you can then go
    back and retrieve the variable. I do that to count total pictures

    My camera is water proof and goes on the kayak - when I'm out of the
    boat I don't want it snapping pictures of the same weeds on the bank,
    so turn it off and on.

    I use a magnet on the outside of the watertight case to actuate a reed
    switch inside - some day I plan to see if I can't make it use an
    infrared communicator so I can change the delay time without opening
    the case.
    Power is an ongoing and much debated thing on the forum. The actual
    power would have to be measured since the chips are variable in that
    respect (some use a little more than others)

    In sleep mode (like pause, but you can't be processing while sleeping)
    its only a few micro amps - but while running it is only a milliamp or

    Power depends on voltage too (naturally).

    There are tricks you can use to minimize current drain. One is to
    change the clock frequency - the slower the clock the less power used.
    The procedure is in the manual - you "poke" (peek and poke) a number
    into an internal register to set the frequency divider on the clock to
    change the speed. That also has the effect of changing the length of
    pause and other commands like the pwm and communications (serial
    in/out baud rate).

    Another trick is to turn off the brownout monitor to save a little

    All in the manual. But if you do nothing at all you won't use a lot
    of power - the only concession I'm making to save power is to put it
    to sleep for 15 minutes at a time to recheck the light level so it
    doesn't use power when it is too dark to take photos - and get 10+
    days out of AA batteries - same batteries that power the camera.
  19. Rich Grise

    Rich Grise Guest

    I have no idea. ;-)
    Well, if it's got a "sleep" mode, you might be able to bring it way
    down, then, if it's got interrupts, and a "wake on interrupt" feature,
    then you could save power by sleeping until you get the "shoot" signal.
    Well, let us all know how it works out.

    Can it take a picture of itself? ;-)

  20. Rich Grise

    Rich Grise Guest

    Hey, if the whole schmear is running off one set of batteries, then
    isolation becomes moot. And an opto can take 10-20 mA (albeit, it
    doesn't have to be for very long); so I'd figure out how to not need

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