LCD i2C hello for Mbed 5

Questions » LCD i2C hello for Mbed 5

5 years, 2 months ago.

I'm trying to find a Mbed 5 program that uses i2c to run a HD44780 20x4 LCD display or the like.

Does anyone know of such a program/Library?

I tried some i2cLCD hello programs but most of the work with Mbed OS-2 and I was unsuccessful in translating them to OS-5. I'm using NUCLEO F767ZI board.

Thank you.

1 Answer

5 years, 2 months ago.

Hi Greg,

The library is able to be imported to a Mbed OS 5 program, so you can import the Text LCD library.

https://os.mbed.com/users/wim/code/TextLCD/

And create a Mbed OS 5 program to use it in your main.cpp, like below.

/* Hello World! for the TextLCD Enhanced Library*/
 
#include "mbed.h"
#include "TextLCD.h"
 
// Host PC Communication channels
Serial pc(USBTX, USBRX); // tx, rx
 
// I2C Communication
I2C i2c_lcd(PB_9,PB_8); // SDA, SCL
//I2C i2c_lcd(p28,p27); // SDA, SCL
 
// SPI Communication
//SPI spi_lcd(p5, NC, p7); // MOSI, MISO, SCLK
 
// LCD instantiation 
//TextLCD lcd(p15, p16, p17, p18, p19, p20, TextLCD::LCD20x2);        // 4bit bus: rs, e, d4-d7
TextLCD_I2C lcd(&i2c_lcd, 0x40, TextLCD::LCD20x4);                  // I2C exp: I2C bus, PCF8574 Slaveaddress, LCD Type
//TextLCD_I2C lcd(&i2c_lcd, 0x42, TextLCD::LCD16x2, TextLCD::WS0010); // I2C exp: I2C bus, PCF8574 Slaveaddress, LCD Type, Ctrl Type
//TextLCD_I2C lcd(&spi_lcd, p8, TextLCD::LCD24x4D);                   // I2C exp: SPI bus, CS pin, LCD Type
//TextLCD_SPI_N lcd(&spi_lcd, p8, p9, TextLCD::LCD16x2, NC, TextLCD::ST7032_3V3); // SPI native: SPI bus, CS pin, RS pin, LCDType=LCD16x2, BL=NC, LCDTCtrl=ST7032
//TextLCD_I2C_N lcd(&i2c_lcd, ST7032_SA, TextLCD::LCD16x2, NC, TextLCD::ST7032_3V3); // I2C native: I2C bus, slaveaddress, LCDType=LCD16x2, BL=NC, LCDTCtrl=ST7032 =Ok
//TextLCD_I2C_N lcd(&i2c_lcd, SSD1803_SA1, TextLCD::LCD20x4D, NC, TextLCD::SSD1803_3V3); // I2C native: I2C bus, slaveaddress, LCDType=LCD20x4D, BL=NC, LCDTCtrl=SSD1803 =Ok
 
int main() {   
  Timer t;
 
  pc.printf("TextLCD Enhanced Test. Columns=%d, Rows=%d\n\r", lcd.columns(), lcd.rows());
    
  for (int row=0; row<lcd.rows(); row++) {
    int col=0;
      
    pc.printf("MemAddr(Col=%d, Row=%d)=0x%02X\n\r", col, row, lcd.getAddress(col, row));      
//    lcd.putc('-');
    lcd.putc('0' + row);      
      
    for (col=1; col<lcd.columns()-1; col++) {    
      lcd.putc('*');
    }
 
    pc.printf("MemAddr(Col=%d, Row=%d)=0x%02X\n\r", col, row, lcd.getAddress(col, row));      
    lcd.putc('+');       
  }    
 
// Fill screen again and time it
  t.start();
 
  for (int row=0; row<lcd.rows(); row++) {
    int col=0;
      
    lcd.putc('0' + row);      
      
    for (col=1; col<lcd.columns()-1; col++) {    
      lcd.putc('*');
    }
 
    lcd.putc('+');       
  }    
  t.stop();    
  pc.printf("All my hard work took %f sec\r\n", t.read());          
 
// Show cursor as blinking character
   lcd.setCursor(TextLCD::CurOff_BlkOn);
 
// Set and show user defined characters. A maximum of 8 UDCs are supported by the HD44780.
// They are defined by a 5x7 bitpattern. 
  lcd.setUDC(0, (char *) udc_0);  // Show |>
  lcd.putc(0);    
  lcd.setUDC(1, (char *) udc_1);  // Show <|
  lcd.putc(1);    
    
  pc.printf("Bye now\r\n");          
}

This code refers from

https://os.mbed.com/users/wim/code/TextLCD_HelloWorld2/

I don't have the boards on hand so I am not able to test, but you can still refer to it. Note, make sure the pin connection is correct.

Regards, Desmond

Hello, I would like to run a program that would allow me to send a text to an LCD via an HD44780 i2C interface. I’m using a NUCLEO-F767ZI, with the online compiler, and can compile small programs that I wrote, but when I compile many programs LIKE TextLCD Hello World, I get a fail.

Here is what I’ve done step by step; 1.Import PROGRAM https://os.mbed.com/users/wim/code/TextLCD/ Hello World[04 Dec 2010] 2. Import LIBRARY https://os.mbed.com/users/wim/code/TextLCD/ Hello World [02 Jan 2014] 3. Compile ERROR: - Compiler Error 230 Syntax error(s) in Assembly. I believe I’m using online 5.13.4 but I don’t know how to verify the version. I must be doing something wrong. Can anyone help, or am I doomed?

posted by Greg Arikian 04 Sep 2019

Hi Greg,

I would suggest you to create a new program or import other Mbed OS 5 program, and re-write the main code, and import the TextLCD library, I've tried this way, and it compiles.

Don't just import TextLCD Hello World, it's a very old project.

Hope this helps.

Regards, Desmond

posted by Desmond Chen 05 Sep 2019

Greg Arikian

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