Forum Rule: Always post complete source code & details to reproduce any issue!
Results 1 to 11 of 11

Thread: What type of cable to use

  1. #1

    What type of cable to use

    Hi

    Maby a dumb question but I'm just an newbie on this, but could anyone recommend me a specific cable to use for my Teensy to connect via SPI an so on?

    I've tried to search for a web shop in Europe to order from but without success, mainly do to my lack of knowledge...

    /Hans

  2. #2
    Senior Member+ KurtE's Avatar
    Join Date
    Jan 2014
    Posts
    7,903
    Sorry, not sure what you are asking?

    SPI to connect to what? At least for experimenting, I will often start off with my Teensy plugged into a breadboard, and then use some form of breadboard wires to connect it to whatever devices I am experimenting with.

    My last set of different breadboard connections was with some of these: https://smile.amazon.com/gp/product/B089FZ79CS/

    Not sure how good they are yet, but at least I try to get some fresh ones from time to time.

    But for SPI on my Teensy boards connect to pins 11-13 plus at least one other pin for chip select and of course a ground and most devices will want some form of power.

  3. #3
    Senior Member
    Join Date
    Jul 2020
    Posts
    468
    SPI is for short distances only, same PCB or a nearby module. Thus there's no connector standard for it.

  4. #4
    If you are trying to use an SPI display over a wire, i'm doing the same. I'm using Cat5 ethernet cable and have been able to use cable distance of 20 feet--however my standard setup is around 4 feet in an electrically noisy electric race car. The remote display PCB has a few push buttons for menus and such. i've implemented a Teensy 3.2, an ILI9341 2.4 inch display, custom printed PCB board RJ45 connectors

    A few tricks I'm doing

    1. gnd and MOSI are on one twisted pair -- an absolute must
    2. SCK and Vcc are on another twisted pair -- pretty sure this is a must (I'm mainly trying to wrap key lines around some type of barrier)
    3. inline 100 ohm resistors on the MOSI and SCK lines at the MCU side--I found not really needed but many claim it helps counteract wire capacitance
    4. 4K7 pullups on SCK and MOSI located at the display side
    5. periodically i'll call display.begin() to reset display if any screen anomalies appear

  5. #5
    Hi

    Yes, having some weird issues when running FT5206_touchScreen.ino from the Teensuino library.

    Sometimes the screen work properly but if restarted it don't work. I think the connections are ok and now I suspect the poor cable I'm using between the Teensy and the display.

    The display is the ER-TFTM070-5. Have measured all connection also with a multimeter.

  6. #6
    If you could be more specific on what doesn't work we might be able to help you out.

  7. #7
    Oh sorry, it's the touch that's the problem. It wont work intermittently. I'm soldering in new cable as you suggested right know.

    Have connected as https://github.com/sumotoy/RA8875/wi...ion-and-wiring.

  8. #8
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Posts
    23,027
    Normally SPI isn't used over cables. It's really meant for connecting chips together on a circuit board over relatively short distance.

  9. #9
    Senior Member+ MichaelMeissner's Avatar
    Join Date
    Nov 2012
    Location
    Ayer Massachussetts
    Posts
    3,881
    Note, if the touch system uses the same SPI bus as the display, you might need to add pull-up resistors on the two CS pins (display & touch):


    Particularly if you are running a Teensy 4.0 or 4.1, you might also need to adjust the SPI bus speed, since the faster Teensys might run too fast for the display. I've had two displays on the same SPI bus (running the uncanny eyes program) that initially I needed to dial down the speed to prevent glitching when I moved from a Teensy 3.2 to a Teensy 3.6. Adding the pull-up resistors allowed me to increase the SPI clock speed, but there was a point where I couldn't run it any faster. I have several displays from different vendors, and the speeds were slightly different for each manufacturer. Once I did the testing, I just set the speed to match the slowest display I had on hand.

  10. #10
    Thank you all for your valuable input!


    @Paul
    I really want to use my Teensy in my little project with a display, so do you have any other suggestions?
    I would gladly pay someone to do a circuit board that connects to my display and Teensy like buydisplay.com seems to have for Arduino. Looks like plug and play.
    I'm more into the coding than build electrinics part together.

    Again, many thanks for your fast respons.

  11. #11
    Junior Member
    Join Date
    Sep 2020
    Posts
    4
    I'm using Cat5 ethernet cable and have been able to use cable distance of 20 feet--however my standard setup is around 4 feet in an electrically noisy electric race car. The remote display PCB has a few push buttons for menus and such. i've implemented a Teensy 3.2, an ILI9341 2.4 inch display, custom printed PCB board RJ45 connectors
    @ KrisKasprzak
    About your solution with the RJ45 connectors, any chance you have it online to look at it? I think That is the sort of thing I need, Im also with a ILI9341 but with ribbon cable, and works sometimes... hope to fix it using all your recommendations... in fact, counting cables, following what you say, I get the 13 connections without IRQ pin to 9, what do you do with the +1 on the 8 lines on the ethernet cable? Im gonna do MOSI-GND, SCK-Vin, 3.3-CS, MISO-T-CS, but the DC?
    Last edited by leacolumbi; Yesterday at 08:47 PM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •