NHD-0420CW-AB3 I2C Setup Question

wbaldwin

• February 27, 2016 14:13

I have the NHD-0420CW-AB3 wired up as shown in my diagram (see attachment) but I can not seem to get the I2C interface up.  I am using the following function to scan the I2C Bus.  All other devices on the Bus are found except for the NHD-0420CW-AB3.  Can you tell what I have wrong? 

void ScanI2CBus()
{
byte error, address;
int nDevices;

nDevices = 0;
for (address = 1; address < 127; address++)
{
// The i2c_scanner uses the return value of
// the Write.endTransmission to see if
// a device did acknowledge to the address.
Wire.beginTransmission(address);
error = Wire.endTransmission();

if (error == 0)
{
Serial.print(".....I2C device found at address 0x");

if (address < 16)
Serial.print("0");

Serial.print(address, HEX);
Serial.println("");
nDevices++;
}
else if (error == 4)
{
Serial.print(".....Unknown error at address 0x");
if (address < 16)
Serial.println("0");
Serial.println(address, HEX);
}
}

if (nDevices == 0)
Serial.println(".....No I2C devices found\n");
else
Serial.println(".....done\n");
}

Thanks!

- Will

[attachment deleted by admin]

« Last Edit: February 27, 2016, 04:49:15 PM by Will »

0

• 

  wbaldwin

  • February 27, 2016 23:26

  Ok I solved my own problem.  It was the reset pin...  I didn't tie it HIGH.
  
  I have the display showing me characters!

  0
• 

  Chris O.

  • February 27, 2016 23:31

  O :)

  Quick question?
  Are you running the display on 5 volts or 3.3 volts?

  0
• 

  wbaldwin

  • February 28, 2016 18:52

  Yes 3.3v power and logic (see diagram in previous post).

  0
• 

  Chris O.

  • February 28, 2016 19:39

  I see.
  On my setup i got the REGVDD connected to GND  for  3.3v.
  
    datasheet page 4  https://newhavendisplay.com/content/specs/NHD-0420CW-AB3.pdf 

   

  [REGVDD=0V for 2.8V operation]

  0

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