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Thread: Wiring 5" TFT to Teensy 3.6

  1. #1

    Wiring 5" TFT to Teensy 3.6

    Hi

    Due to my little knowledge about electronics I would really appreciate some guidance on how to connect the screen in the below link to my Teensy 3.6.

    http://www.buydisplay.com/download/m..._Datasheet.pdf

    I'm going to show some engine data via CAN BUS that I successfully coded up and also trigger some functions such as antilag, throttle blip and so on via touch on the screen.

    I've googled for hours without any success for some simple example. For sure it's because of my lack of knowledge on this matter.

    Regards
    Hans

  2. #2
    Senior Member+ KurtE's Avatar
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    Hard to say with just the datasheet, as there are lots of configurations of that board, so a lot depends on what options/version did you buy?

    Like: What type of Interface did you choose? And in this case what type of connector? I have never tried their FFC type connectors so don't know how easy they work. I have ordered a few boards of theirs and try go get them 4 wire PIN connectors for SPI

    They are a power hog, so I have ordered them to run at 5v VDD, so they have their own internal 3.3v VR and not run off of the Teensy voltage regulator.

    Touch controller - They have a couple of options. none, Resistive, and Capacitive.

    Again I have only played some with their probably earlier version of their 5", and a couple of their 4.3" or so..

    But again a lot depends on your options: But if I ordered one with 4 wire SPI, 5v, CAP touch, (With pins).

    I would start out wiring something like:
    GND - Pins 1, 2 (maybe only need to connect one of these pins)
    +5v - Pins 3,4 (dito)

    SPI connections: Teensy - Display
    10 - 5 (CS)
    11 - 6 (MOSI) - I think sometimes confusing between Miso and Mosi
    12 - 7 (MISO) - Again 11 12 may be swapped here
    13 - 8 (SCLK)

    Backlight control - Maybe not needed but if you want some control
    <unused pin> - 14

    Again maybe that is enough to get something to display. Then if touch panel, may need additional wiring..

    I would then probably try out one of the RA8875 libraries that work with T3.6, I don't remember if the main one by sumotoy had the 3.6 stuff merged in or not. I know the T4 stuff is not, and a few of us have our own version of the library... (https://github.com/mjs513/RA8875/tree/RA8875_t4), don't remember how much testing of this version we did on T3.6...

  3. #3
    Thanks for quick respons KurtE.

    Of course I was a fool not to ask here before I ordered it but it is what it is...

    Next time I would definatly follow your advice about the spec.

    It looked like it could be used with Arduino and thats why I bought it.

    By the way, it's a capacitive.

    Regards

  4. #4
    Senior Member+ KurtE's Avatar
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    Good luck... When it arrives and or if you have additional questions, it might help to put a link in to the exact one you ordered...

    More details about some other experiences with these dsiplays up in the thread: https://forum.pjrc.com/threads/57280...rom-Buydisplay

  5. #5
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    Sumotoy has lots of information here about connecting these displays: https://github.com/sumotoy/RA8875/wiki

  6. #6
    It have already arrived so sitting here and stare at it,

    Heres a link to the screen
    https://www.ebay.com/itm/Serial-5-TF...72.m2749.l2649

    Thank you for your kindness to help me.

  7. #7
    Ok, here is a first question just to be absolutly certain that I'll not breaking it directly.

    It says: *We use pin header connection,5V power supply and 4-wire serial interface by default.

    sumotoy says in his wiki:
    •J8: closed (3V3, leave OPEN for 5V!) The ER-TFTM050-3 (5" 800x480) not works at 5V! This jumper must leaved closed and you need to supply 3V3 only,leaved open will break internal power and your display will not work.

    Is it the Teensy that'll break or the screen if I supply with 5V?

  8. #8
    Senior Member+ KurtE's Avatar
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    Sorry, hopefully someone else up here can give you more definitive stuff...

    But I personally have had better luck with +5v to the display an in one case I actually retrofitted their display to use +5v, which required a capacitor or two and a Voltage regulator. If you look at the PDF you mentioned. With that photo like page 5, Toward the bottom left of the image (a little to right of connector) are some capcitors and U2, which I guessing on yours is VR... Does yours have it? If so, I assume J8 is not set...

    Alternatively if yours is 3.3v (does not have VR and J8 has solder jumper set). Then you may need an external 3.3v regulator to drive the display as the Teensy may not have enough amperage left to drive it.

    But again I have only played a little with these displays, hopefully someone who uses them a lot can fill in more of the details.

  9. #9
    Yes, looks exactly like that photo and J8 is open and the the device is 4-wire serial interface as I double checked the jumpers.

    I have 5V sensor output to supply the screen from the ECU so if it'll work better with that voltage then I'll use it.

  10. #10
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    Quote Originally Posted by A6_quattro View Post
    Ok, here is a first question just to be absolutly certain that I'll not breaking it directly.

    It says: *We use pin header connection,5V power supply and 4-wire serial interface by default.

    sumotoy says in his wiki:
    •J8: closed (3V3, leave OPEN for 5V!) The ER-TFTM050-3 (5" 800x480) not works at 5V! This jumper must leaved closed and you need to supply 3V3 only,leaved open will break internal power and your display will not work.

    Is it the Teensy that'll break or the screen if I supply with 5V?
    That J8 comment is irrelevant in your case because it refers to a different display than the one you have.

  11. #11
    Great, thanks for your input neurofun.

    Thank you so much for all your answers and effort to help me!

    I'll report back if there are some interest of that.

  12. #12
    Hi all

    Having some frustrating issues with the screen running examples from the sumotoys examples (graphicAdatest and so on) from github.

    The screen doesn't work 80% of the time as it should and I spent hours Googling and reading through threads from this forum. Also tried nuber of settings in the RA8875UserSettings.h file without any success.

    Have someone got this screen to work with Teensy 3.6? If so, what is the trick?

  13. #13
    Senior Member+ KurtE's Avatar
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    @A6_quattro - Again others can answer this a lot better than I can.

    My usage/testing has been mostly in making it work with T4...

    In all cases like this it often helps if you post pictures of how you have it set up. Also again on exactly what configuration of display you have...
    Which version of the library you are using...

    Often times it can be things like: maybe you are using jumper wires, which don't make good contact, or they are too long...

    I have had better luck with them plugged into a socket on my own board, where they make reasonably good contact.

    With some of these boards I have had better luck if I hook up an IO pin to the RESET pin of the display, and have the code do a reset operation.

    Sometimes I have had better luck when I go into the settings and lower the MAX SPI SPeed.

  14. #14
    Hi KurtE

    I have very short cable from the Teensy to the screen, about 50 mm, and connected as in the sumotoy wiki.

    Yesterday I lowered the SPI speed and now it's looking ok for my purposes.

    Did also a test connected in the car with good results.

    Many thanks for your input.

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