NHD-C0220Biz and Arduino/Teensy3.1

jpatrick62

• April 24, 2015 09:07

Hello, the I2C connection between the C0220Biz and my Teensy3.1 locks up when it is first initialized. Other I2c devices work fine, so I'll assume i am doing something wrong at initialization. Is there a library that will work for a teensy3.1 and a C0220Biz? It looks as if the address is 0x78. I have all the hardware connections as peer the Pin description and wiring diagram, and my supply voltage to vdd is 3.3 regulated.

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  Michael_L

  • April 25, 2015 09:07

  I'm sorry but unfortunately we do not have a library for the display with the teensy mcu.  What we do have is the example code provided on our website, here: https://newhavendisplay.com/content/app_notes/NHD-C0220BiZ.txt
  If you come across any libraries for the teensy that are designed to drive an ST7036 display controller, they should work for our display.
  As for your other question, is the display the only device present on the i2c bus when it is locking up?  Have you tried using 10kOhm pull-ups?

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  jpatrick62

  • April 27, 2015 09:07

  As for your other question, is the display the only device present on the i2c bus when it is locking up? 
  Yes, it is the only I2C device on the bus
  
  Have you tried using 10kOhm pull-ups?
  No, but I'll do that - presently we have 47K ohm pull-ups  believe...

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  jpatrick62

  • April 27, 2015 10:07

  Actually we presently have 21K ohm pull-ups, but I'll try to swap them out.

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  jpatrick62

  • May 07, 2015 10:07

  I have swapped the pullups to 10K and then 2K, still no luck - I2C does not enumerate. I used another LCD I2C Backpack and it did work on I2C as well as other I2C devices so I know it's not the mp itself. I just want to ensure I have the proper connections - so as I look down on the LCD display, the mechanical drawing seems to indicate the connections from left to right are 8(c1-), 7(c1+), 6(Vout), 5(VDD), 4(VSS), 3(SDA), 2(SCL), 1(RST). However page 4 would seem to indicate the opposite.

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  jpatrick62

  • May 07, 2015 13:07

  One more thing - a bit odd I should think...I can get the I2C bus to enumerate only when 3.3 volt supply is removed.

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  Paul_B

  • May 08, 2015 10:07

  Hello,
  
  There are no discrepancies between the mechanical drawing pin connection (page 3) and pin description / wiring diagram (page 4).
  
  Below is some example code for that display written for the Arduino:

  #include <Wire.h>
  
  int RES = 22;
  int ASDA = 20;
  int ASCL = 21;
  
  unsigned char text1[]={"  Newhaven Display  "};
  unsigned char text2[]={" Clear Display Test "};
  unsigned char text3[]={"    COG  Display    "};
  unsigned char text4[]={"  2x20  Characters  "};
  
  const char slave2w = 0x3C;  //3E for CiZ (0x7C shifted over 1 bit)  //3C for BiZ (0x78 shifted over 1 bit)
  const char comsend = 0x00;
  const char datasend = 0x40;
  const char line2 = 0xC0;
  
  void show(unsigned char *text)
  {
    int n, d;
    d=0x00;
    Wire.beginTransmission(slave2w);
    Wire.write(datasend);
    for(n=0;n<20;n++)
    {
      Wire.write(*text);
      ++text;
    }
    Wire.endTransmission();
  }
  
  void nextline(void)
  {
    Wire.beginTransmission(slave2w);
    Wire.write(comsend);
    Wire.write(line2);
    Wire.endTransmission();
  }
  
  void cleardisplay(void)
  {
    Wire.beginTransmission(slave2w);
    Wire.write(comsend);
    Wire.write(0x01);
    Wire.endTransmission();
  }
  
  void CiZ_init()
  {
    Wire.beginTransmission(slave2w);
    Wire.write(comsend);
    Wire.write(0x39);
    delay(1);
    Wire.write(0x14);
    Wire.write(0x70);
    Wire.write(0x5E);
    Wire.write(0x6D);
    Wire.write(0x0C);
    Wire.write(0x01);
    Wire.write(0x06);
    Wire.endTransmission();
  }
  
  void setup()
  {
    pinMode(RES, OUTPUT);
    pinMode(ASCL, OUTPUT);
    pinMode(ASDA, OUTPUT);
    digitalWrite(RES, HIGH);
    //delay(10);
    //digitalWrite(ASCL, LOW);
    //digitalWrite(ASDA, LOW);
    //delay(10);
    Wire.begin();
    delay(10);
    CiZ_init();
    delay(5);
  }
  
  void loop()
  {
    show(text1);
    nextline();
    show(text2);
    delay(1500);
    cleardisplay();
    delay(2);
  
    show(text3);
    nextline();
    show(text4);
    delay(1500);
    cleardisplay();
    delay(2);
  }

  Please triple check your wiring and follow along with the code listed above.
  
  Thanks!

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  jpatrick62

  • May 12, 2015 10:07

  OK, I tried our 2nd  NHD-C0220Biz unit and it worked fine. So the issue with the first unit was that it was defective, it would not enumerate on the I2C bus at all.  
  Used a 9K pull up on the working unit, that seems fine.

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  Paul_B

  • May 13, 2015 10:07

  Hello,
  
  I'm sorry to hear about the issue you encountered. We have a set quality control process that is followed for every part so I'm not sure how this one got through, but we will make a note to double-check this type of issue during our QC inspections. I apologize for the inconvenience.
  
  Please contact:
  
  quality@newhavendisplay.com
  
  Thanks!

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