Forum Rule: Always post complete source code & details to reproduce any issue!
Results 1 to 6 of 6

Thread: Before I break somethng

  1. #1
    Junior Member
    Join Date
    Dec 2019
    Posts
    5

    Before I break somethng

    Finally getting started on my project, The basic sensors I was worried about appear to work, but will need a little tweaking.
    However I want to use a nextion display. I have a couple NX3224T024_011 variants here which I am going to use for testing, maybe the final project but not sure as yet.
    However they run on 5v (as they all seems to according to their website). While I can feed the display with 5v, but I am concerned that the data line coming back from the display will over volt the teensy 4.0, and damage it.
    I have some zenner diodes here that I could use as protection, is this a good idea or will it adversely affect the data signal, is needed at all?

    Further to this is the 3.3v from the teensy output enough to send data to the nextion?

    I can't help but think that the answer is there somewhere, I have just missed or overlooked it.

  2. #2
    Senior Member
    Join Date
    Oct 2015
    Location
    Roma (IT, EU)
    Posts
    336
    A level (fast) shifter may be the right solution.
    Zeners are tricky and introduce a parasite capacitance which may smooth out signals.

  3. #3
    Senior Member+ MichaelMeissner's Avatar
    Join Date
    Nov 2012
    Location
    Ayer Massachussetts
    Posts
    3,744
    Quote Originally Posted by orac View Post
    Finally getting started on my project, The basic sensors I was worried about appear to work, but will need a little tweaking.
    However I want to use a nextion display. I have a couple NX3224T024_011 variants here which I am going to use for testing, maybe the final project but not sure as yet.
    However they run on 5v (as they all seems to according to their website). While I can feed the display with 5v, but I am concerned that the data line coming back from the display will over volt the teensy 4.0, and damage it.
    I have some zenner diodes here that I could use as protection, is this a good idea or will it adversely affect the data signal, is needed at all?

    Further to this is the 3.3v from the teensy output enough to send data to the nextion?

    I can't help but think that the answer is there somewhere, I have just missed or overlooked it.
    I don't know much about the Nextion, but I did look it up. It mentions that it supports the Raspberry Pi. Since the Pi similarly requires 3.3v processing, you might be able to see what things are needed to hook up a PI.

    Given it appears to use a serial connection, one way to do it would be to use a bi-directional level shifter on the TX/RX pins (and connect VIN to the power). One I've used in the past for I2C level shifting is:

    • https://www.pololu.com/product/2595
    • Hook up HV to VIN (and also hook VIN to the display);
    • Hook up H1 to the TX pin on the display;
    • Hook up H2 to the RX pin on the display;
    • Hook up LV to 3.3v;
    • Hook up L1 to pin 1;
    • Hook up L2 to pin 0 (or maybe you need to hook up L1 to pin 0 and L2 to pin 1);
    • Hook up ground to the display's ground;
    • Use Serial1 to talk to the display (or use one of the other serial ports).

  4. #4
    Senior Member
    Join Date
    Feb 2016
    Location
    Australia
    Posts
    267
    All the nextion displays I’ve ever used specs said 3.3V on their website for data lines.... hold on... google,first result,electrical characteristics...says 3.3v. I think u safe unless you got some clone.

  5. #5
    Junior Member
    Join Date
    Dec 2019
    Posts
    5
    Thanks guys, noticed in the early hours of this morning that vcc should be 5v, but the data lines are typically around 3-3.2v

  6. #6
    Senior Member
    Join Date
    Aug 2019
    Location
    southwest USA
    Posts
    112
    Quote Originally Posted by orac View Post
    Finally getting started on my project, The basic sensors I was worried about appear to work, but will need a little tweaking.
    However I want to use a nextion display. I have a couple NX3224T024_011 variants here which I am going to use for testing, maybe the final project but not sure as yet.
    However they run on 5v (as they all seems to according to their website). While I can feed the display with 5v, but I am concerned that the data line coming back from the display will over volt the teensy 4.0, and damage it.
    I have some zenner diodes here that I could use as protection, is this a good idea or will it adversely affect the data signal, is needed at all?

    Further to this is the 3.3v from the teensy output enough to send data to the nextion?

    I can't help but think that the answer is there somewhere, I have just missed or overlooked it.
    look for vin low (max) and vin high (min) for the data input pin

Posting Permissions

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