OLED choice

Discussion in 'The Projects Forum' started by VVS, Jun 30, 2009.

  1. VVS

    Thread Starter Active Member

    Jul 22, 2007
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    0
    Hello,

    I am starting a project and first of all need to choose a OLED Display.

    It should have a serial port and a supply voltage of 3.3V should be possible to use with the OLED.

    Moreover it should be possible to connect the OLED to a PC to learn how to use it so that one can later connect it to a PIC and it should be easy to use for real time plotting.

    Does anybody have anu suggestion for an OLED. I found several ones, but I am not sure how to judge whether an OLED is easy to use for real time plotting. :confused:

    thx
    VVS
     
    Last edited: Jun 30, 2009
  2. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    Why an organic LED? Why not a conventional LED, which are common and easy to use?
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    There is confusion here. To us, OLED is an Organic Light Emitting Diode. What device are you speaking of? Can you post some names/numbers?
     
  4. VVS

    Thread Starter Active Member

    Jul 22, 2007
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  5. ELECTRONERD

    Senior Member

    May 26, 2009
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    OLED's have a much wider viewing angle (180 degrees) than conventional LED's and they are also thinner and more flexible. Unfortunately, they still aren't able to attain the same life expectancy of regular LED's. They are much more expensive so if you can afford it go ahead.
     
  6. Papabravo

    Expert

    Feb 24, 2006
    10,140
    1,789
    We considered using an OLED display from FEMA. We rejected it for two reasons.
    1. It has power sequencing requirements on BOTH power up and power down that would require redesigning our power supplies to give 100 millseconds warning to shut down the supplies in the correct order.
    2. There were no controllers with character generators from this manufacturer so one would have to be added to the product firmware. This is doable but would consume a significant number of processor cycles.
    I'll admit that other manufacturers may have a handle on these problems but you should go into this project with your eyes open. There are significant challenges in using these devices.
     
  7. VVS

    Thread Starter Active Member

    Jul 22, 2007
    66
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    Okay,

    thanks for everybody's advice.
     
  8. John Luciani

    Active Member

    Apr 3, 2007
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    I have used the uOLED320xx displays as well as the smaller ones in a few projects.
    They are very nice displays. 10000 to 1 contrast ratio, saturated colors, built-in
    graphics commands, uSD display of images and movies make for impressive demos.
    It will do quite a nice job of plotting data (with annotations), displaying photos or
    movies.

    The 320xxPMD3 (and most of 4D uOLED displays that I have seen) will not run off of 3.3V. The minimum voltage in the datasheet was 3.6V. You really want to be at 5V. For
    the systems I designed I used a 5V boost converter that runs off of the main 3.3V supply
    or the 3.6V Li-ion battery.

    For maximum display life the manufacturer of the OLED (and LCD) controllers recommend that you turn off of the boost converters that are in the controller IC prior to shutting off the VCC. This requires that the system uC execute a power down sequence prior to shutdown of the VCC. For my system I have the main power switch interrupt the uC, send the shutdown commands, shutdown the OLED boost converter and then shutdown the 3.3V supply. I am not sure how much display life you loose if you do not follow these recommendations.

    (* jcl *)
     
  9. Papabravo

    Expert

    Feb 24, 2006
    10,140
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    FEMA just says don't do it. I got the impression that violating the startup and shutdown requirements even one time could damage the part.
     
  10. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    Here is a link to the information I found at the 4D Systems forums ---
    http://4d.websitetoolbox.com/post?id=2944301

    The datasheet that is referenced is for one of the controllers that 4D systems
    uses. It does not get into specifics about how much damage each improper shutdown
    causes, whether the damage is additive or how much damage is necessary
    before it becomes visual. It does says that this is an issue for LCD as well as OLED controllers.

    During debug of my system I have shutoff the power many times and not seen
    any visual problems. For normal operating mode I use the sequence that I
    mentioned previously.

    (* jcl *)
     
  11. VVS

    Thread Starter Active Member

    Jul 22, 2007
    66
    0
    Oh thx a lot. I looked at the available uOLEDs. I will probably use one for which i can use the 3.3V supply.

    @ JCL: Do you think I can use the uOLED for real time plotting? Basically what I want the uOLED to plot is the acceleration as a function of time (I will use accelerometres and gyros and a PIC). But I have no idea where to to start with the command set which is given in the datasheet.

    tc
    VVS
     
  12. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    Absolutely. It would do an excellent job.

    The 4D Systems graphics processor has draw point, draw line, draw circle, draw rectangle and draw polyline commands. It also has draw text and display image commands. You would be able to create quite a nice graph. You could also save data or plot data from the uSD card. I am working on a display board that will plot real time data (using an OLED) from a variety of sensors. Data will be sent to the display using
    an XBee radio.

    It is unlikely you will be able to find an OLED display that runs from a 3.3V supply. The blue LEDs require higher voltage. I would plan on using a boost converter. The boards
    I make have a small boost converter for the OLED.

    (* jcl *)

    P.S. If you find a display you prefer over the 4D Systems please post the mfg/mfg pn. I am always interested in evaluating new parts.
     
    Last edited: Jul 2, 2009
  13. VVS

    Thread Starter Active Member

    Jul 22, 2007
    66
    0
  14. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    That is one of the displays that I use (I use the 96, 160 and 32024). If you look on page 58 the minimum voltage specification is 3.6V. I would give yourself some design margin
    and not go below 4V. If you want to use the uSD card they recommend higher voltages.
    I would go to a 5V supply.

    If I get a chance I will take a picture of my display board. It has the 160, the boost
    converter and two capacitive touch buttons and is shaped to fit in an Altoids tin ;)
    I wrote a little demo program that plots the output from the cellular automatons
    described in Wolframs "A New Kind of Science".

    (* jcl *)
     
  15. VVS

    Thread Starter Active Member

    Jul 22, 2007
    66
    0
    Hey,

    Oh that is really weird coz on page 6 it says 3.3V is the min Voltage Supply.
    But i guess i will have to get a boost as well.

    Whoa it is that small?? that is really cool!! How did u manage to make the Boost SMPS so small, does it have control hardware as well?? I remember this year in our SMPS experiments the boost circuit boards where quite big.
     
    Last edited: Jul 2, 2009
  16. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    I use high frequency converters 1 - 2MHz. For these low voltage and low current
    applications the inductors are 5-10uH and the capacitors are 10-20uF ceramics.

    Some of my older designs are at http://tinyurl.com/6jm8tu

    Since those designs were done newer chips have come out and
    ceramic cap prices have dropped. My newer designs are quite a bit
    smaller. If you have a way to solder QFN and SON packages look
    at the TI TPS series devices.

    (* jcl *)
     
  17. VVS

    Thread Starter Active Member

    Jul 22, 2007
    66
    0
    Hi,
    I ordered that uOLED and a development kit.
    Does you think you can give me some codes so I can get started?
    I read the manual but they hardly give examples so I am not sure.

    thx
    VVS
     
  18. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    All you need to do is to transmit bytes to the display using the
    uart. The first byte you need to send is a 'U'. This enables the
    the display to autodetect the baud. After that you just send
    a command byte followed by command parameters.

    Once I am done with my display board (www.wiblocks.com)
    I will be releasing a complete library for the display (including
    the power down interrupt routines). There is example code
    for the the Arduino at http://jennylc.com/4d/

    (* jcl *)
     
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