HD-C0216CIZ-FSW-FBW-3V3 requires bit banging????

I have a HD-C0216CIZ-FSW-FBW-3V3 on an Arduino Uno with 4.7k pullup resistors to a 3.3V plane (same as VDD) for the I2C bus. I'm having trouble getting the display to actually show characters.
When I ran an example I found on these forums that used bit-banging on the I2C bus, that worked fine. However, when I instead attempt to use an I2C library to have that controlled by hardware, it isn't working correctly. I even modified the example to use the embeded I2C rather than bit-baning

********************************THIS WORKS************************************

unsigned char text1[]={"NEWHAVEN Display"};
unsigned char text2[]={"2x16 LCD Module "};
unsigned char text3[]={0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f};
unsigned char text4[]={0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f};
/*****************************************************/
#define SDO A4            //Serial data
#define SCLK A5            //Serial clock
#define RESET 13             //RESETET
/*****************************************************/
const char Slave = 0x7C;
const char Comsend = 0x00;
const char Datasend = 0x40;
const char Line2 = 0xC0;
/*****************************************************/

/*****************************************************/
void I2C_out(unsigned char j)       //I2C Output
{
  int n;
  unsigned char d;
  d=j;
  for(n=0;n<8;n++){
    if((d&0x80)==0x80)
    digitalWrite(SDO, HIGH);
    else
    digitalWrite(SDO, LOW);
    d=(d<<1);
    digitalWrite(SCLK, LOW);
    digitalWrite(SCLK, HIGH);
    digitalWrite(SCLK, LOW);
    }
  digitalWrite(SCLK, HIGH);
  while(SDO==HIGH){
    digitalWrite(SCLK, LOW);
    digitalWrite(SCLK, HIGH);
    }
  digitalWrite(SCLK, LOW);
}
/*****************************************************/
void I2C_Start()
{
  digitalWrite(SCLK, HIGH);
  digitalWrite(SDO, HIGH);
  digitalWrite(SDO, LOW);
  digitalWrite(SCLK, LOW);
}
/*****************************************************/
void I2C_Stop()
{
  digitalWrite(SDO, LOW);
  digitalWrite(SCLK, LOW);
  digitalWrite(SCLK, HIGH);
  digitalWrite(SCLK, HIGH);
}
/*****************************************************/
void Show(unsigned char *text) // Display text
{
  int n, d;
  d=0x00;
  I2C_Start();
  I2C_out(Slave);
  I2C_out(Datasend);
  for(n=0;n<16;n++){
    I2C_out(*text);
    ++text;
    }
  I2C_Stop();
}
/*****************************************************/
void nextline(void)  // Move to Line 2
{
  I2C_Start();
  I2C_out(Slave);
  I2C_out(Comsend);
  I2C_out(Line2);
  I2C_Stop();
}
void CGRAM (void)
{
  I2C_Start();
  I2C_out(Slave);
  I2C_out(Comsend);
  I2C_out(0x38);    //go to instructino table 0
  I2C_out(0x40);    //Set CGRAM addRESETs to 0x00
  I2C_Stop();
  delay(10);
 
  I2C_Start();
  I2C_out(Slave);
  I2C_out(Datasend);
  I2C_out(0x00);    //write to first CGRAM addRESETs
  I2C_out(0x1E);
  I2C_out(0x18);
  I2C_out(0x14);
  I2C_out(0x12);
  I2C_out(0x01);
  I2C_out(0x00);
  I2C_out(0x00);    //8 bytes per character
  I2C_out(0x00);
  //continue writing to remaining CGRAM if desired
  I2C_Stop();
}
/****************************************************
*           Initialization For ST7032i              *
*****************************************************/
void init_LCD()
{
  I2C_Start();
  I2C_out(Slave);
  I2C_out(Comsend);
  I2C_out(0x38);
  //delay(10);
  I2C_out(0x39);
  //delay(10);
  I2C_out(0x14);
  I2C_out(0x78);
  I2C_out(0x5D);
  I2C_out(0x6D);
  I2C_out(0x0C);
  I2C_out(0x01);
  I2C_out(0x06);
  //delay(10);
  I2C_Stop();
 
  //CGRAM();      //define CGRAM
 
  I2C_Start();
  I2C_out(Slave);
  I2C_out(Comsend);
  I2C_out(0x39);   
  I2C_out(0x01);    //go back Home
  I2C_Stop();
  //delay(10);
}
/*****************************************************/
/*****************************************************/


void setup() {
  pinMode(RESET, OUTPUT);
  pinMode(SDO, OUTPUT);
  pinMode(SCLK, OUTPUT);
  digitalWrite(RESET, LOW);
  delay(10);
  digitalWrite(RESET, HIGH);
  delay(100);

}

void loop() {
  init_LCD();
  //delay(2);
  Show(text1);
  nextline();
  Show(text2);
  delay(25000);
  while(1){
    digitalWrite(SDO, HIGH);
    delay(1000);
  }
       

}

****************************************THIS DOESN'T WORK********************************

#include <Wire.h>

unsigned char text1[]={"NEWHAVEN Display"};
unsigned char text2[]={"2x16 LCD Module "};
unsigned char text3[]={0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f};
unsigned char text4[]={0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f};
/*****************************************************/
#define SDO A4            //Serial data
#define SCLK A5            //Serial clock
#define RESET 13             //RESETET
/*****************************************************/
const char Slave = 0x7C;
const char Comsend = 0x00;
const char Datasend = 0x40;
const char Line2 = 0xC0;
/*****************************************************/

/*****************************************************/
void I2C_out(unsigned char j)       //I2C Output
{
  Wire.write(j);
/*
  int n;
  unsigned char d;
  d=j;
  for(n=0;n<8;n++){
    if((d&0x80)==0x80)
    digitalWrite(SDO, HIGH);
    else
    digitalWrite(SDO, LOW);
    d=(d<<1);
    digitalWrite(SCLK, LOW);
    digitalWrite(SCLK, HIGH);
    digitalWrite(SCLK, LOW);
    }
  digitalWrite(SCLK, HIGH);
  while(SDO==HIGH){
    digitalWrite(SCLK, LOW);
    digitalWrite(SCLK, HIGH);
    }
  digitalWrite(SCLK, LOW);
  */
}
/*****************************************************/
void I2C_Start()
{
  Wire.beginTransmission(Slave);
  /*
  digitalWrite(SCLK, HIGH);
  digitalWrite(SDO, HIGH);
  digitalWrite(SDO, LOW);
  digitalWrite(SCLK, LOW);
  */
}
/*****************************************************/
void I2C_Stop()
{
  Wire.endTransmission();
  /*
  digitalWrite(SDO, LOW);
  digitalWrite(SCLK, LOW);
  digitalWrite(SCLK, HIGH);
  digitalWrite(SCLK, HIGH);
  */
}
/*****************************************************/
void Show(unsigned char *text) // Display text
{
  int n, d;
  d=0x00;
  I2C_Start();
  //I2C_out(Slave);
  I2C_out(Datasend);
  for(n=0;n<16;n++){
    I2C_out(*text);
    ++text;
    }
  I2C_Stop();
}
/*****************************************************/
void nextline(void)  // Move to Line 2
{
  I2C_Start();
  //I2C_out(Slave);
  I2C_out(Comsend);
  I2C_out(Line2);
  I2C_Stop();
}
void CGRAM (void)
{
  I2C_Start();
  //I2C_out(Slave);
  I2C_out(Comsend);
  I2C_out(0x38);    //go to instructino table 0
  I2C_out(0x40);    //Set CGRAM addRESETs to 0x00
  I2C_Stop();
  delay(10);
 
  I2C_Start();
  //I2C_out(Slave);
  I2C_out(Datasend);
  I2C_out(0x00);    //write to first CGRAM addRESETs
  I2C_out(0x1E);
  I2C_out(0x18);
  I2C_out(0x14);
  I2C_out(0x12);
  I2C_out(0x01);
  I2C_out(0x00);
  I2C_out(0x00);    //8 bytes per character
  I2C_out(0x00);
  //continue writing to remaining CGRAM if desired
  I2C_Stop();
}
/****************************************************
*           Initialization For ST7032i              *
*****************************************************/
void init_LCD()
{
  I2C_Start();
  //I2C_out(Slave);
  I2C_out(Comsend);
  I2C_out(0x38);
  //delay(10);
  I2C_out(0x39);
  //delay(10);
  I2C_out(0x14);
  I2C_out(0x78);
  I2C_out(0x5D);
  I2C_out(0x6D);
  I2C_out(0x0C);
  I2C_out(0x01);
  I2C_out(0x06);
  //delay(10);
  I2C_Stop();
 
  //CGRAM();      //define CGRAM
 
  I2C_Start();
  //I2C_out(Slave);
  I2C_out(Comsend);
  I2C_out(0x39);   
  I2C_out(0x01);    //go back Home
  I2C_Stop();
  //delay(10);
}
/*****************************************************/
/*****************************************************/


void setup() {
  Wire.begin();
  pinMode(RESET, OUTPUT);
  //pinMode(SDO, OUTPUT);
  //pinMode(SCLK, OUTPUT);
  digitalWrite(RESET, LOW);
  delay(10);
  digitalWrite(RESET, HIGH);
  delay(100);

}

void loop() {
  init_LCD();
  delay(2);
  Show(text1);
  nextline();
  Show(text2);
  delay(25000);
  while(1){
    digitalWrite(SDO, HIGH);
    delay(1000);
  }
       

}

zDispUser

June 01, 2019 08:07

I believe I figured it out. Posting my findings to hopefully save someone else from the headache I just went through. The problem here is an inconsistency in I2C addressing.

The example I posted, as well as as the datasheet for the display state that the slave address is 0x7C. Normally, an I2C slave address is only 7-bits, and then an 8th Read/Write bit is appended to the end (1 for read, 0 for write). However, when looking carefully at the example and the datasheet, the slave address is actually 8 bits and includes the read/write bit within it.

Standard I2C libraries, when starting communication, will accept a 7-bit address, then bit shift left by 1 position, then append the Read/Write bit. So when using the "Wire.h" library in Arduino, when I call Wire.beginTransmission(0x7C), what ends up actually happening is the library starts by sending 0xF8 out on to the bus. (If I sent a Wire.requestFrom(0x7C, 3), it would start by sending 0xF9 onto the bus cause it appends a 1-read bit at the end).

So in short, in order to get standard I2C libraries to use this display, the actual slave that should be used is 0x3E. When I modiefied the non-working example above to instead use

const char Slave = 0x3E;

, it began working the same as the working example.

Though I do have a caveat to add. It seems that the SDO line must be kept low in order to actually display the characters. Otherwise you just get black boxes. I can work around this, but it's just an additional annoyance to deal with.

Ted M.

NHD Staff

June 12, 2019 08:07

Thanks for posting your solution as it may assist others with a similar issue.

Best Regards,

HD-C0216CIZ-FSW-FBW-3V3 requires bit banging????

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