Connections of LM16202 LCD display with Atmega32 microcontroller

[Sumanta Kumar Show]

Hi, I am trying to interface LAMPEX LM16202 16×2 LCD display with ATmega32. But I have doubt about few pin connections which are as follows – 

1) pin3 – Vo – Contrast Adjustment

2) pin4 – RS – H/L Register Select Signal

3) pin5 – R/W – H/L Read/Write Signal

4) pin6 – E – H ? L Enable Signal

5) pin15 – A/Vee – + 4.2V for LED/Negative Voltage Output (Can we apply 5 volt supply here?)

6) pin16 – K – Power Supply for B/L (OV)

Can anyone please give me some informations regarding the above connections.


Sumanta

[AJISH ALFRED]

Hi Sumanta,

 

1) pin3, contrast control

 

You can connect the variable of a preset not less than 10K to pin3. Other two pins of preset should be connected to VCC and GND.

 

5) pin15, anode (A) of backlight led.

 

You can give GND here

 

6) pin16, cathode (K) of backlight led.

 

You can give VCC directly to this pin (because in the datasheet an internal resistance is shown), but better through a resistor not less than 1K.

 

Answers for 2), 3), 4)

 

I’ve searched a few minutes, but couldn’t find a good datasheet of your lcd. Do one thing, try to find out which is the controller used in the lcd, and search for the datasheet of the controller. You will get a lot of informations.

If your lcd have commonly found KS0070B, then all the answers to the questions 2, 3, and 4 are in the following timing diagram. Try to understand it properly

 

wysiwyg_imageupload:4758:

[AJISH ALFRED]

 

Normally for the lcds we use,

 

RS—->0

---

>instruction R/W

            1

---

>data R/W

 

R/W—>0

---

>data/instruction Write

            1

---

>data Read

 

How to Enable:

 

Set enable pin low

              |

Set the 8 or 4 bit data/instruction on D0 to D7

              |

Set the enable pin high

              |

Keep the enable pin high for a time delay

              |

Set the enable pin low

[Anonymous]

Hi to all,

 

             I am trying to do programming for display in LCD display. The program is as below –

 

 

// Program to display a single alphabet ‘A’ on LCD 

/*

LCD data transfer through 8 bit mode

Writing a single letter A on LCD

 

LCD DATA port—-PORT A

ctrl port

---

PORT B

rs

---

PB0

rw

---

PB1

en

---

PB2

*/

 

#include<avr/io.h>

#include<util/delay.h>

#ifndef F_CPU

#define F_CPU 16000000UL

#endif

 

#define LCD_DATA PORTA // LCD data port

#define ctrl PORTB

#define en PB2 // enable signal

#define rw PB1 // read/write signal

#define rs PB0 // register select signal

 

void LCD_cmd(unsigned char cmd);

void init_LCD(void);

void LCD_write(unsigned char data);

 

 

int main()

{

DDRA=0xff; // making LCD_DATA port as output port

DDRB=0x07; // making signal as out put

init_LCD(); // initialization of LCD

_delay_ms(50); // delay of 50 milli seconds

//LCD_write(‘B’); // call a function to write A on LCD

LCD_string();

return 0;

}

 

void init_LCD(void)

{

LCD_cmd(0x38); // initialization of 16X2 LCD in 8bit mode

_delay_ms(1);

 

LCD_cmd(0x01); // clear LCD

_delay_ms(1);

 

LCD_cmd(0x0E); // cursor ON

_delay_ms(1);

 

LCD_cmd(0x80); // —8 go to first line and –0 is for 0th position

_delay_ms(1);

return;

}

 

void LCD_cmd(unsigned char cmd)

{

LCD_DATA=cmd;

ctrl =(0<<rs)|(0<<rw)|(1<<en); // RS and RW as LOW and EN as HIGH

_delay_ms(1);

ctrl =(0<<rs)|(0<<rw)|(0<<en); // RS, RW , LOW and EN as LOW

_delay_ms(50);

return;

}

 

void LCD_write(unsigned char data)

{

LCD_DATA= data;

ctrl = (1<<rs)|(0<<rw)|(1<<en); // RW as LOW and RS, EN as HIGH

_delay_ms(1);

ctrl = (1<<rs)|(0<<rw)|(0<<en); // EN and RW as LOW and RS HIGH

_delay_ms(50); // delay to get things executed

return ;

}

 

void LCD_string(void)

{

unsigned char str[] = “Hi This is Biswajit Manna”;

int i;

for(i=0;i<16; i++)

{

LCD_DATA = str;

ctrl = (1<<rs)|(0<<rw)|(1<<en); // RW as LOW and RS, EN as HIGH

_delay_ms(1);

ctrl = (1<<rs)|(0<<rw)|(0<<en); // EN and RW as LOW and RS HIGH

_delay_ms(50); // delay to get things executed

}

if (i==16)

{

 

LCD_cmd(0xC0); // —C go to 2nd line and –0 is for 0th position

_delay_ms(1);

for (i=16;i<sizeof str;i++)

{

LCD_DATA = str;

ctrl = (1<<rs)|(0<<rw)|(1<<en); // RW as LOW and RS, EN as HIGH

_delay_ms(1);

ctrl = (1<<rs)|(0<<rw)|(0<<en); // EN and RW as LOW and RS HIGH

_delay_ms(50); // delay to get things executed

}

}

return;

}

 

 

 

Tell me if there is anything wrong in the program. Some display is coming in the LCD but not in accordance with the string specified in the program. Yours help will be highly appreciated.

[AJISH ALFRED]

 

Hi Sumanta,

 

I haven’t gone deeply through your code, but I found these,

 

Increase the delay for enable, try some 5ms.

Globally declare LCD_string(void); It dosen’t matter, but a standard.

You can hardwire the R/W pin to ground. Since you are writing only, no need to drive it through your code.

 

Its not clear what kind of problem you are facing. Are you getting junk values only?

[Author]

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