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Serial LCD Interfacing — Parallax Forums

Serial LCD Interfacing

Chris SavageChris Savage Parallax EngineeringPosts: 14,406
edited 2004-11-23 21:38 in General Discussion
If I could impose, I'd like to get a few opinions, or at least do a little survey regarding Serial LCDs...

·· Knight Designs has been using Hitachi-Based Parallel LCD Displays in all of our designs since 1990.· Since our switch from Z80s and other CPUs to the BASIC Stamp line, we've been using a Serial Chip to interface an LCD using only 1 I/O line.··Our need for information comes from the fact that·we've received numerous e-mails over the last 2 or 3 years wondering exactly what it is that we're using, since people cannot seem to figure out the non-standard command codes associated with this chip.

·· We recently purchased several chips from another individal who has his own line of Serial Backpack Chips, however,·we recently realized that this would be the same basic situation.· We would like to know what the majority of the Forum readers are using for LCD Displays, and how you're interfacing them.· Are they serial already?· If so, what brand?

···We'd like to eventually make it so that the free projects we post online can easily be built and understood by anyone.· We've seen far too much difference in the way that some displays work with different backpacks and chips, so we're trying to standardize.· I personally think what we need is an inexpensive (Under $6.00) Serial Chip that accepts standard commands, instead of using it's own language.· It should also support the BELL control code, so that sending CNTL-G will cause a beep.· And a few programmable I/O pins would be nice.· Last item should be backlight control.· All of these features exist on chips now, but either they are expensive or non-standard in the commands to do things.

·· LCD Displays can be gotten surplus for $10.00 for a 40X2 display.· Add a $5.00 serial chip, and for $15.00 you have a serial LCD.· We just need standardization.· Anyway, if anyone who wants to share could please reply, we'd appreciate it!

Thanks!


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Chris Savage

Knight Designs
324 West Main Street
P.O. Box 97
Montour Falls, NY 14865
(607) 535-6777

Business Page:·· http://www.knightdesigns.com
Personal Page:··· http://www.lightlink.com/dream/chris
Designs Page:··· http://www.lightlink.com/dream/designs
·

Comments

  • Tronic (Greece)Tronic (Greece) Posts: 130
    edited 2004-10-08 07:02
    I recently designed and assebled a small appmod for connecting
    my parallel hitachi compatible 2x16 LCD on my BS2 board appmod header

    I used a simple shift register 74HC595 for simulating serial connection
    using just 3 ports on my BS2. I also used the program that John Williams
    write about this in some Nuts & volts issue i saw... (the comments are in GREEK)

    I attached photos and Schematics about my board... I hope this help anyone
    had the same problem connecting parallel LCDs on BS2.


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  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-10-08 17:25
    Well, the idea was to try and determine what people prefer in terms of a "standard" for serial interfacing.· Feedback I have received outside of this thread seems to indicate people prefer the Scott Edwards (Seetron) communication standard and commands.· Which is interesting, since I myself have never used a Seetron display (Due to cost).· Nor have I used the Matrix Orbital (Same reason) of any other pre-packaged serial display.

    The end goal is to make interfacing an LCD display more cost-effective to the hobbyist (Whom I believe makes up a huge chunk of Parallax's customers), as well as meeting the industry or common standard for commands associated with these serial displays, since most have special commands for line/cursor position, controlling extra ports, or beeping a piezo speaker attached.



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    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs
    ·
  • John Raplee, JrJohn Raplee, Jr Posts: 32
    edited 2004-10-26 03:39
    My buddy Chris is sooo smart...· roll.gifhop.gif

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  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-10-27 01:46
    blush.gif

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    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs
    ·
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-10-27 02:33
    I created my own serial LCD controller using an SX28. It is basically SEETRON compatible, but I've made the communication 2-way and given the user control over the extra port bits on the SX28. I will post plans for it next week ... I'm a bit busy to get that all together now.

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-10-27 02:50
    Well Jon, as I've told everyone...I am looking forward to your design, since it meets all my needs...No sense re-inventing the wheel, but in this case you've got what I need!· scool.gif

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    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs
    ·
  • ionion Posts: 101
    edited 2004-11-06 06:21
    Hi Jon,

    I am looking forward to see your design and code.

    I use seetron ( expensive), matrix orbital ( to much code) and recently i got pic-n-lcd which i intend to test it soon. Looks like this one have more comands then seetron or others. I will post my experience with it, and wait for your code and schematic. I just bought a full evaluation set for sx and maybe this it will be my first touch with it (glad i can use basic and not assembler too)

    Ion
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-11-06 14:57
    You can get the design and code by downloading our latest (version 3.0) SX-Key software. As you now know, we've added a free BASIC compiler to the SX-Key called SX/B. It's a nice little compiler and the price can't be beat. SX/B has all of the features of the BS1, a few from the BS2, and some items that we don't do in the BASIC Stamp. That said, SX/B cannot compile your PBASIC programs -- you'll have to modify them to deal with SX/B.

    I was able to create my LCD controller in SX/B in about two hours -- start to finish. I have a lot of experience with LCDs, of course, but SX/B made it all very easy. You can find my serial LCD controller in the Projects section of the SX/B help file. It is SEETRON command compatible except that I allow bi-direction communications so that you can read back the LCD RAM, and since I used an SX28, I also give the user serial control of the extra port (RC). You can set the port DDR bits, write to the port, and read from the port -- all through the same 1-wire serial link.

    If you download and install the SX-Key software the projects folder contains a BS2 test program for the SX-based serial LCD.

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office

    Post Edited (Jon Williams) : 11/6/2004 3:04:07 PM GMT
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  • ionion Posts: 101
    edited 2004-11-06 15:40
    Thank you Jon.
    I saw the project last night when I got the SX/B , but it was to late to open it and look in details.
    I just moved a week ago and i am between boxes and work.
    I will try it ASAP
    Thanks again
    Ion
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-11-06 18:12
    ion said...
    Hi Jon,
    I am looking forward to see your design and code.
    I use seetron ( expensive), matrix orbital ( to much code) and recently i got pic-n-lcd which i intend to test it soon. Looks like this one have more comands then seetron or others. I will post my experience with it, and wait for your code and schematic. I just bought a full evaluation set for sx and maybe this it will be my first touch with it (glad i can use basic and not assembler too)
    Ion

    Ion,

    ·· I too think the Seetron and Matrix Oribital Displays are a little on the expensive side when you consider the cost of a typical LCD (Surplus) and how much it costs to build your own serial interface.· I was also using the PIC-an-LCD from Dale Wheat, but at $9.95 per chip, I was trying to find something cheaper.· And while Peter Anderson has a Serial Chip for $4.95, it has yet another instruction set.

    ·· Jon convinced me the Seetron command set was the way to go, so his chip makes the most sense for compatibility and cost.· I think that will appeal more to the hobbyists.




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    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs
    ·
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-11-06 19:01
    If you want to go even cheaper you can use an SX18 ($1.79) -- you just have to give up the extra IO port on the LCD controller

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-11-06 20:15
    That is good information Jon, however, personally I am going to use your setup.· About the only thing I would change is I might consider stealing two of the I/O pins for other·functions supported on other Serial Chips.· One is an audio output line, usually just to run a piezo speaker and generate a beep when the display receives a chr$(7) or BELL.· The other would be possibly a command controlled backlight enable pin.· Where a command sent to the display would make the pin high, and through a resistor and transistor you could have it switch on the·backlight.

    Obviously this would require small changes to the existing code.


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    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs
    ·
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-11-06 23:41
    Yep, you could do those things too; and the code changes should be pretty straightforward.

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-11-23 21:38
    Just wanted to say, in retrospect to the original discussion you and I had about using a standardized serial LCD controller...When I implement your LCD code into future designs, I am going to leave the code stock...That way when people build these projects, they won't have to mess around with modified code.· Besides, I can do what I need to by using the extra port you have provided.· And I do appreciate your putting though into this since the original topic.



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    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs
    ·
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