LCD not displaying anything at all ST7066 LCD Sitronix

[amateur_24]

Hi
This LCD is compatible with the HD4780 however it won't display anything at all. I'm using a 20 MHZ crystal which is running at 20 - 20.02 MHZ. I setup the avr to use an high frequency external crystal with highest startup.

I'm using a library from Peter Fleury Home page Peter Fleury's Home Page.

I've tried grounding the RS,RW and enable lines but it still won't display anything. i Have double checked my wiring. I'm using a atmega16P chip.

Right now all I have is black squares on the top row and 2nd to last row when I turn the contrast. I did turn the contrast down but I don't see anything.

The library is only 4 bit so I used the last 4 bits on the lcd i.e. d4-d7
It's a 20*4 row LCD.

https://www.electro-tech-online.com/custompdfs/2011/03/0900766b80f25f62.pdf


#define XTAL 20000000 /**< clock frequency in Hz, used to calculate delay timer */

/**
 * @name  Definition for LCD controller type
 * Use 0 for HD44780 controller, change to 1 for displays with KS0073 controller.
 */
#define LCD_CONTROLLER_KS0073 0  /**< Use 0 for HD44780 controller, 1 for KS0073 controller */

/** 
 *  @name  Definitions for Display Size 
 *  Change these definitions to adapt setting to your display
 */
#define LCD_LINES           4     /**< number of visible lines of the display */
#define LCD_DISP_LENGTH    20     /**< visibles characters per line of the display */
#define LCD_LINE_LENGTH  0x16     /**< internal line length of the display    */
#define LCD_START_LINE1  0x00     /**< DDRAM address of first char of line 1 */
#define LCD_START_LINE2  0x40     /**< DDRAM address of first char of line 2 */
#define LCD_START_LINE3  0x14     /**< DDRAM address of first char of line 3 */
#define LCD_START_LINE4  0x54     /**< DDRAM address of first char of line 4 */
#define LCD_WRAP_LINES      0     /**< 0: no wrap, 1: wrap at end of visibile line */


#define LCD_IO_MODE      1         /**< 0: memory mapped mode, 1: IO port mode */
#if LCD_IO_MODE
/**
 *  @name Definitions for 4-bit IO mode
 *  Change LCD_PORT if you want to use a different port for the LCD pins.
 *
 *  The four LCD data lines and the three control lines RS, RW, E can be on the 
 *  same port or on different ports. 
 *  Change LCD_RS_PORT, LCD_RW_PORT, LCD_E_PORT if you want the control lines on
 *  different ports. 
 *
 *  Normally the four data lines should be mapped to bit 0..3 on one port, but it
 *  is possible to connect these data lines in different order or even on different
 *  ports by adapting the LCD_DATAx_PORT and LCD_DATAx_PIN definitions.
 *  
 */
#define LCD_PORT         PORTC        /**< port for the LCD lines   */
#define LCD_DATA0_PORT   LCD_PORT     /**< port for 4bit data bit 0 */
#define LCD_DATA1_PORT   LCD_PORT     /**< port for 4bit data bit 1 */
#define LCD_DATA2_PORT   LCD_PORT     /**< port for 4bit data bit 2 */
#define LCD_DATA3_PORT   LCD_PORT     /**< port for 4bit data bit 3 */
#define LCD_DATA0_PIN    0            /**< pin for 4bit data bit 0  */
#define LCD_DATA1_PIN    1            /**< pin for 4bit data bit 1  */
#define LCD_DATA2_PIN    2            /**< pin for 4bit data bit 2  */
#define LCD_DATA3_PIN    3            /**< pin for 4bit data bit 3  */
#define LCD_RS_PORT      PORTD     /**< port for RS line         */
#define LCD_RS_PIN       4            /**< pin  for RS line         */
#define LCD_RW_PORT      PORTD     /**< port for RW line         */
#define LCD_RW_PIN       5            /**< pin  for RW line         */
#define LCD_E_PORT       PORTD     /**< port for Enable line     */
#define LCD_E_PIN        6            /**< pin  for Enable line     */

The firmware is the example that come with the library

 

[Gobbledok]

They can be finicky things, these LCD screens.

Unless the LCD Screen is initialised properly, all you will see is the black squares you are seeing.

The most likely reason (after you have checked your port settings) is the timing is too fast for the controller.

You could lower your oscillator frequency without changing #define XTAL 20000000. Hopefully with the larger delays it should get it going.


Edit to add: You could probably just increase #define XTAL 20000000 to do the same thing.

 

[amateur_24]

How do i ensure i have set the internal length properly?

 

[3lectrokid]

that code doesn't do anything. It defines some pins etc but does not actually set any pins high or low so it won't get initialised

 

[amateur_24]

Thanks. Alot guys I have it working now!! It was because when I cable tied the data pin cables, it overlapped as I pulled the tie tight. Hence the wires weren't in the right order. I randomly decided to do continuity check. That's how I discovered the wires weren't matching to the corrosponding pin on the lcd. LOOOOL. Don't know how many bloody hours this cost me!!!!!! I know for next time then hey lol.
Continuty check is the man!!! It also confirmed my soldering isn't as dodgy as it used to be.

 

[3lectrokid]

well done. I hope the rest of your project goes well