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New board for 3.5" LCD — Parallax Forums

New board for 3.5" LCD

RaymanRayman Posts: 14,646
in Propeller 1
Just soldered up this new board and it seems to be working.
Main feature is a 3.5" LCD display. It's transreflective so should be good for outdoor use.
It's the same exact size as Propeller Activity Board, so should be a drop in upgrade for my 3D Printed robot.

Only needs 12 pins to control the LCD. I've used some special pin sharing tricks to reduce the pin count with this board...
Has a rechargeable LiPo circuit to power the Prop and LCD and a barrel input for powering servos.

Here's video of the famous "Graphics Demo" in action: https://youtu.be/XmAZjru4vtk

IMG_3113_small.jpg
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IMG_3110_small.jpg
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Comments

  • PublisonPublison Posts: 12,366
    Nice Ray! Is it a touch screen?
  • RaymanRayman Posts: 14,646
    edited 2017-07-09 15:17
    Yes, it's a resistive touchscreen. Nice thing about that is that it's simple and controller also has extra analog inputs. So, it monitors the LiPo and power input voltages. Also, there are two general purpose analog inputs.

    I just took it outside into direct 11 AM sunshine. Well, it's not as good as I was hoping. Can read the text, but hard to see the graphics. I think the touchpanel actually ruins the outdoor visibility.
    I might put one on a hotplate and take the touchpanel off...
  • maccamacca Posts: 780
    Interesting, what display is that ?
    Does it have its own controller or is driven entirely by the Propeller ?
  • RaymanRayman Posts: 14,646
    It doesn't have any memory...
    Basically, a tiny VGA monitor with QVGA resolution.

    I'm using a modified version of the Parallax VGA driver to control it.

    If one googles "rayslogic PTP" or "rayslogic PTP2", you can find my past endeavors with this display, back when I used to sell stuff....

    Somebody from a GPS company gave me about 600 of these displays...
    Trying figure out some use for them...
    Here's the datasheet.
    pdf
    pdf
    LTV350QV - Copy.pdf
    714K
  • RaymanRayman Posts: 14,646
    Here's the code for the graphics demo:
    zip
    zip
    RayBot_GraphicsDemo - Archive [Date 2017.07.09 Time 13.36].zip
    34K
  • RaymanRayman Posts: 14,646
    Here are the Eagle design files for the board:
    zip
    zip
    RayBot1l_eagle.zip
    158K
  • RaymanRayman Posts: 14,646
    I'm testing to see how long it can last on a small, 400 mAH LiPo battery.

    Gone about 4 hours now running Graphics Demo with backlight on full.
    Not too bad...
  • RaymanRayman Posts: 14,646
    edited 2017-07-09 17:53
    Did make at least one mistake here...

    I put the Wii Nunchuck compatible connector on the centerline, which looks good.
    But, doesn't work with my robot design... I should have put it more towards the edge.

    It's fun to drive the robot with Wireless Nunchuck...
  • David BetzDavid Betz Posts: 14,516
    Rayman wrote: »
    If one googles "rayslogic PTP" or "rayslogic PTP2", you can find my past endeavors with this display, back when I used to sell stuff....
    Ah, that explains why I couldn't find any of your modules on your site. Why did you decide to stop selling modules? This new one looks pretty interesting.
  • RaymanRayman Posts: 14,646
    edited 2017-07-09 20:12
    Have to file taxes every quarter now in all states... The hobby business just makes it harder...

    Plus, my kids are keeping me busier than they used to...
  • msrobotsmsrobots Posts: 3,709
    Rayman wrote: »
    Have to file taxes every quarter now in all states... The hobby business just makes it harder...

    Plus, my kids are keeping me busier than they used to...

    You honestly need to file taxes in every state you sell stuff to? Wow. 50+ Tax Forms every 3 month? What a waste of time.

    this world is getting crazier every day.

    Mike

  • RaymanRayman Posts: 14,646
    It's not because of me, it's my wife's job... Her company works in all 50 states and she's a part owner now...
  • David BetzDavid Betz Posts: 14,516
    Rayman wrote: »
    Have to file taxes every quarter now in all states... The hobby business just makes it harder...

    Plus, my kids are keeping me busier than they used to...
    I'm sorry to hear that. I liked your boards. Be sure to let us all know if you change your mind.

  • RaymanRayman Posts: 14,646
    Got to do something with my pile of LCDs though...

    I wonder if Parallax would make a board with these LCDs... Qty might be too low for them though...
  • jmgjmg Posts: 15,173
    Rayman wrote: »
    Got to do something with my pile of LCDs though...

    I wonder if Parallax would make a board with these LCDs... Qty might be too low for them though...

    Depends if they can get more ?

  • RaymanRayman Posts: 14,646
    edited 2017-07-10 00:11
    Hmm... They are on Ebay for $25 each.
    But, I think you can find a similar enough display from many sources.
    Would just need small changes to PCB...

    There are some $16 ones on Aliexpress: https://www.aliexpress.com/item/SAMSUNG-3-5-inch-TFT-LCD-Touch-Screen-LMS350GF08-320-RGB-240-QVGA/1849418304.html
  • jmgjmg Posts: 15,173
    Rayman wrote: »
    Hmm... They are on Ebay for $25 each.
    But, I think you can find a similar enough display from many sources.
    Would just need small changes to PCB...

    There are some $16 ones on Aliexpress: https://www.aliexpress.com/item/SAMSUNG-3-5-inch-TFT-LCD-Touch-Screen-LMS350GF08-320-RGB-240-QVGA/1849418304.html
    I also see Aliexpress has some $12 ones, with a RaspPi adapter PCB that looks to include the LCD connectors and SPI. (via HCMOS Shifters ?)
    That has some appeal, as it gets volume, and is much better mechanically.

    How fast can P1 serve up SPI, or some LCD variant ? (what speed is the RaspPi running this at ?)

  • xanaduxanadu Posts: 3,347
    edited 2017-07-10 01:13
    David Betz wrote: »
    Ah, that explains why I couldn't find any of your modules on your site. Why did you decide to stop selling modules? This new one looks pretty interesting.

    +1

    Really nice work there, I would buy one if you do decide to sell any.



  • braindeadunitbraindeadunit Posts: 1
    jmg wrote: »
    Rayman wrote: »
    Hmm... They are on Ebay for $25 each.
    But, I think you can find a similar enough display from many sources.
    Would just need small changes to PCB...

    There are some $16 ones on Aliexpress: https://www.aliexpress.com/item/SAMSUNG-3-5-inch-TFT-LCD-Touch-Screen-LMS350GF08-320-RGB-240-QVGA/1849418304.html
    I also see Aliexpress has some $12 ones, with a RaspPi adapter PCB that looks to include the LCD connectors and SPI. (via HCMOS Shifters ?)
    That has some appeal, as it gets volume, and is much better mechanically.

    How fast can P1 serve up SPI, or some LCD variant ? (what speed is the RaspPi running this at ?)

    Just wanna plug that, if you're willing to go down to 2.8", they get a lot cheaper, even cheaper than smaller screen sizes except 2.4" and <2". I guess because there's probably a few other uses of them that they're able to be sold in great enough quantity. $7.90 a piece on aliexpress.
  • RaymanRayman Posts: 14,646
    I think this 3.5" LCD is the perfect size for an Activity Board sized PCB.
    It's big enough so that you can read the text when you're standing up and the board is on a robot on the floor.
    It's also very tough with thick glass on the front and metal backing.

    There's enough room on the sides of the board for many servo connectors.
    Room at the top for power switch.

    Now that I see it put together and on my robot, I think some components could be placed better. Have to either redesign the board or the robot...
    For example, the USB connector is in a bad place and have to remove PCB from robot to program it, at the moment...
  • jmgjmg Posts: 15,173
    Rayman wrote: »
    Only needs 12 pins to control the LCD. I've used some special pin sharing tricks to reduce the pin count with this board...
    Does this have a controller ? - Data sheet suggests it is 24b, pixel clocked only, which needs (nominally) parallel bus say 16~24b and ~ 5.284MHz min LCD clock ?
    Or is the frame 60Hz min more a suggestion and slower is ok ?

  • RaymanRayman Posts: 14,646
    Well, I'm cheating a little bit by only using 8 of 24 color pins... So, the palette is a little limited... It's 3-bits for red, 3 for green and 2 for blue.

    But, the intended use is text and some simple graphics (bar chart showing readings from octal line sensor), so I think it will be OK.
  • macrobeakmacrobeak Posts: 354
    Rayman,
    Thank you for posting your excellent development work on this display.
    I am sorry the board product selling did not work for you.
    Although you have shared the Eagle files for the board, please could you also post a simple schematic for the board as well.
    Many thanks in advance . . .
  • RaymanRayman Posts: 14,646
    Here's a multi-page PDF with the schematic
    pdf
    pdf
    RayBot1l.pdf
    73K
  • RaymanRayman Posts: 14,646
    Here's an image of the board layout (only 2 layers):
    BoardLayouti.png
    1747 x 1290 - 425K
  • Keith YoungKeith Young Posts: 569
    Sorry I found this while in the middle of a class so I couldn't read every post.

    Is the driver on OBEX so we can find it easily later?
  • RaymanRayman Posts: 14,646
    I suppose I could put it in OBEX. I think it's probably easier to search with google than to dig through OBEX, right?

    Anyway, the code is posted in this thread and I've marked it all as MIT license.
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