LCD screen

Discussion in 'The Projects Forum' started by swany34, Apr 4, 2014.

  1. swany34

    Thread Starter New Member

    Aug 28, 2013
    7
    0
    I have a working circuit that I would like to integrate an LCD screen to display some values on, but have never worked with displaying values obtained from the circuit before.

    The circuit controls is for a dual pulse welder (like you would see in a battery tab welder). The pulse lengths are very small, but need to be variable for welding different materials, as well as the voltage.

    I will be using this LCD screen: NHD‐0216SZ‐NSW‐BBW‐33V3
    http://www.newhavendisplay.com/specs/NHD-0216SZ-NSW-BBW-33V3.pdf

    5x8 dots
    16x2 char

    integrated driver: ST7066U

    I want to display supply voltage (PS), available voltage (cap), pulse 1 time, pulse delay time and pulse 2 time. The pulse times are derived from 3 555 timers.

    display will read like this:
    -12.3V--12.3V-
    -123s-123s-123s-

    I would like to stay away from using anything that requires programming, I am building this project with the intention of it being "bare bones" (not smart), but need to be able to view the variables.

    I also do not yet know how I will be measuring the values (volt, time) that I need to display, was going to work backwards from what the LCD needed.

    any help is appreciated
    let me know if I left any information out
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    5,991
    3,738
    You will need a Microcontroller to use an LCD display. Are you set up for that.
     
  3. MrChips

    Moderator

    Oct 2, 2009
    12,421
    3,357
    You can use digital displays that can take current or voltage as inputs.

    In the long haul, you would be light years ahead if you learned how to use a microcontroller.

    Working backwards from the LCD is poor system design.

    Take the systems approach. Specify all your inputs and what you are going to display. Choosing the components for implementing the design is secondary.
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605

    Well... these display is fairly easy to use (once you get thru the initialization everyone stumbles over the first time) but it is really a micro controller/computer driven device. I love these displays for doing things just like you are doing, and a computer could do the pulse settings and also generate the pulses far easier then the 555's could.

    But you're the boss of this job so let's talk about options for a non-computer controller.

    To display the voltage you can get meters such as these:
    [​IMG]

    There are plenty of styles. EBay is but one source, search "panel voltmeter" to see examples.

    That leaves the pulse settings. In the pre-computer dawn of electronics people would use "10 turn potentiometers" (an excellent search term) to accurately make analog setting such as pulse widths and delays.
    [​IMG]
    Like I said, your project, your rules. If you wish NOT to use a computer start another thread in the Projects area. If you are set on using this display (which is how I would go) and do not mind learning how to do programming then holla back and we can give you some (conflicting and quit opinionated) starting hints.
     
  5. swany34

    Thread Starter New Member

    Aug 28, 2013
    7
    0
    If I can replace the 555 timers and maybe my voltage comparator with a single microcontroller, I would be interested to see the difference it would make in efficiency and cost enough to step into the programming side. Code i can figure out, but getting started by knowing what hardware I will need to incorporate to measure voltages at multiple points in the circuit to display and change outputs based on which is greater than the other and create a variable pulse output to control MOSFETs. I do still hope to use the LCD screen I listed earlier in the same fashion, I just prefer to have all my info on one screen instead of 5 separate ones.

    Maybe I could eventually work from a microcontrolled version and dumb it down to not using one.

    Thank you for your input.
     
  6. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    Micro controllers can measure voltages all by themselves. They can also dirctly drive the LCD display. Add a few push buttons (I like using 5 arranged like the controls on my cable box remote) and you can digitally set pulse parameters like you set a clock: even better as they can also remember the settings when you turn it off.

    (Do you feel a "but" coming?)

    But... (and it's a pretty big one) I just reread your original post where it says "welder." Will there be huge currents nearby? These may upset a micro controller making it act weird, reset, get stuck or something. These effects can be eliminated but it sometimes takes some brain sweat to do it. It's more a wiring issue then more parts.

    So tell me again what this is running?
     
  7. swany34

    Thread Starter New Member

    Aug 28, 2013
    7
    0
    yes this will be controlling a capacitor that will be used to spot weld tabs/wires to parts. At most I will be seeing around 20A, 24V, and a Farad on the cap. I can easily shield the controller from the high power lines. This block diagram may help.

    [​IMG]
     
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