Need Help ICM 7217

Discussion in 'The Projects Forum' started by chichara, Jun 26, 2014.

  1. chichara

    Thread Starter New Member

    Apr 15, 2013
    18
    0
    Dear,

    I've found the data sheet of ICM 7217 Intersil.
    Also found the example of circuit there.
    But i don't know about thumbwheel switches, is it important in that circuit?
    The data sheet explain that "The ICM7217 is intended for use in hard-wired applications where thumbwheel switches are used for loading data, and simple SPDT switches are used for chip control"
    I can't understand about this statement.
    COuld you please explain me?
    or do you have another circuits?
    it's hard to find the circuit example of ICM7217.

    Thanks.

    Here i attach data sheet.
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,998
    745
    The thumb wheels are in bcd to preload the counter, to count up or down from that value.

    Here is the datasheet from Maxim it can be used as a frequency counter, or stopwatch etc the spst switches are for reset, start/stop, latch,store etc.
     
  3. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,503
    380
    hi,
    Look at this later d/s for the 7217.

    If you use switches for the BCD input lines you must use steering diodes as shown in the d/s.
    If you connect the BCD I/Os to say 0V via 4k7 resistors it will Load '0000' into the Preset counter, or you could just use the Zero control pin.

    Whats the application? I maybe able to help, I have used this device on a number of products.

    E
     
  4. MrCarlos

    Active Member

    Jan 2, 2010
    400
    134
    Hello Chichara

    You say:
    But I do not know about thumbwheel switches, is it important in That circuit?

    The important thing is to have a means to change the input logic levels in the ICM7217.

    You say:
    The data sheet explain that:
    "The ICM7217 is intended for use in hard-wired applications where thumbwheel switches are used for loading data, and simple SPDT switches are used for chip control"
    I can't understand about this statement.

    ICM7217 is a device that "Count", Electric-Pulses.
    Is also programmable. So It requires a means to program it.
    And, It can count up or down. Also a device is required to tell that count up or down.

    To program, the starting number, you can to use any of the devices shown in the attached images.
    Also, to set the count direction you can use a SPDT switch.

    It could have been faster if you had ventured into Google.com.
    Take a look at the links below.

    Thumb Wheel Switch’s
    https://www.google.com.mx/search?q=thumbwheel+switches&source=lnms&tbm=isch&sa=X&ei=F0ysU46RItSRqAbTq4GgDg&ved=0CAYQ_AUoAQ&biw=1366&bih=589#imgdii=_

    Dip Switch’s
    https://www.google.com.mx/search?q=DIP+switches&source=lnms&tbm=isch&sa=X&ei=kVGsU8nLMoWGqgaz84LgCA&ved=0CAYQ_AUoAQ&biw=1366&bih=589

    SPDT Switch’s
    https://www.google.com.mx/search?q=DIP+switches&source=lnms&tbm=isch&sa=X&ei=kVGsU8nLMoWGqgaz84LgCA&ved=0CAYQ_AUoAQ&biw=1366&bih=589#q=SPDT+switches&tbm=isch&imgdii=_
     
  5. chichara

    Thread Starter New Member

    Apr 15, 2013
    18
    0
    Ok, noted.
    The application of ICM7217 is for counter, i count objects like tube or box.
     
  6. chichara

    Thread Starter New Member

    Apr 15, 2013
    18
    0

    hi MrCarlos,

    Thanks for complete explanation.

    "The important thing is to have a means to change the input logic levels in" so to change input logic level the thumbwheel switch is needed?

    Is it the same if i use just push button switch? or replace it with limit switch?

    Thanks.
     
  7. crutschow

    Expert

    Mar 14, 2008
    13,028
    3,237
    Any switch that can be wired to give a voltage transition to the circuit input will work. It just depends upon what you want that transition to do. But note that using a mechanical switch for counting will require a debounce circuit to prevent multiple counts for each switch closure.
     
  8. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,503
    380
    Hi,
    All you need to do to count numbers of objects is by using the circuit in this image.
    As pointed out by Carl,post #7, debouncing mechanical switches is essential to ensure reliable control and counting.

    E
     
  9. MrCarlos

    Active Member

    Jan 2, 2010
    400
    134
    Hello Chichara

    In reply to post #6.

    Take a look at the image Thumb Dip Button.jpg
    I recommend using either: Thumbwheel Switch’s or Dip Switch’s in the section where the 4 numbers are programmed.

    Now:
    PIN 8 Count, A button.
    One pin of the button, to pin 8 and a 10K resistor to Vcc,
    The other side to ground.

    PIN 9 'Store, A button.
    One pin of the button, to pin 9 and a 10K resistor to Vcc,
    The other side to ground.

    PIN 10, UP/DN, a SPDT switch.
    Common to PIN 10. The other terminals, one at the positive, the other negative.

    PIN 14 'Reset, A Button.
    One pin of the button, to pin 9 and a 10K resistor to Vcc,
    The other side to ground.

    Why:
    Because you have to have FIXED the 4 numbers you want to program. (Thumbwheel Switch’s or dip switch’s).
    To adjust the UP/DN switch according to the direction in which you want to count.
    Press button 'Store. To store the 4 numbers in the Thumbwheel or Dip Switch's
    Press button Count To Count +1 or –1 According UP/DN switch.
    Press the 'Reset button to clear the counter.

    Please Chichara give a read to the ICM7217 data sheets.
    As shown in Figure 2, the counter is incremented by the rising edge of the COUNT INPUT signal when UP/DOWN is
    high. It is decremented when UP/DOWN is low.

    A Schmitt trigger on the COUNT INPUT provides hysteresis to prevent double triggering on slow rising edges and permits operation in noisy environments.

    The COUNT INPUT is inhibited during reset and load counter operations.
     
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  10. chichara

    Thread Starter New Member

    Apr 15, 2013
    18
    0
    So if i use mechanical switch like push button or thumbwheel or DIP or limit switch i really need debounce circuit. Is it right?

    @MrCarlos:
    in this statement: A Schmitt trigger on the COUNT INPUT provides hysteresis to prevent double triggering.
    Is it same with debouncing? or not? :0

    Thumbweheel switch looks difficult to understand. hehe.
    I've never used it before. But I'll try to learn it first. :D
    If you do not mind I will ask you more. :)


     
  11. MrCarlos

    Active Member

    Jan 2, 2010
    400
    134
    Hello Chichara

    You can use any means to set the number where the counter start.
    Probably there is not required a de-bounce circuit, as long as the number is programmed, the integrated circuit is not doing anything.

    In fact COUNT INPUT on the ICL7217 brings including a de-bounce circuit.

    I hope to learn a lot of thumb-switches and watch for your new questions.
     
  12. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,503
    380
    hi,
    The inputs of the 7217 have weak pull ups and Schmitt inputs with hysteresis, however for mechanical switch inputs a debounce circuit is recommended.

    E
     
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