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interfacing 7 segment lcd

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parthaarathi

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7 segment lcd

Hello friends,

I know how to interface the 16x2 lcd but i have to interface the 4-digit 7 segment lcd to my project .Since sufficient material is not available on that one.Please someone could help me regarding that one.


Thank U
 

7 segment lcd display

The datasheet from the manufacturer maybe :p
 
7 segment lcd driver

which processor are u using?

If you are using 8051 then

**broken link removed**
(This one using shift register)

**broken link removed**
(This one 7219)

**broken link removed**
(and this one directly)

Regards
Nandhu
 
seven segment lcd

Thank u for ur information and i am using atmel avr microcontroller.I will see the information if i got any doubt i will post in the forum.

Added after 3 minutes:

what ever the information given by u is abt 7 segment led not the seven segment lcd.
 

lcd 7 segment

You need an LCD driver.
 
seven segment display lcd

Hi,

I am not getting any electrical information on 7 segment lcd.I am only getting the mechanical details.

thank u
 

7-segment lcd

is it like small clock display ?

if so , you need driver, and reduced voltage logic , and flash xor gate clk circuit ,,

i am not have all information right now , ok.
 

lcd seven segment display

Sorry i could only understand the first line could u please brief me once again what ur telling.

Thank U
 

lcd 7 segment driver

here is the picture , i think you are using
 

int to 7 segment with avr

parthaarathi said:
i am using atmel avr microcontroller.
Click to expand...

There is a special version of the Atmel AVR uC available with build-in LCD driver. You want to use this one, an external driver will be more expensive and consume more space. Look for ATMega169.

There is even an evaluation board available for this Atmel uC (STK502). It is an add-on for the STK500.

CU
 

7 seg lcd

Hello,

special LCD drivers are necessary for multiplexed LCD, 3 and 4 digit 7-segment are usually non-multiplexed. They can be driven by processor port-pins, or any I/O expansion available in your system. Basically you need a pin for each segment and one additional for the backplane. Unused segments can be shorted to backplane or stay unconnected. Your software must care that the driving voltage is DC free, otherwise the display would be damaged by electrolysis after short operation. This means simply generating a 50 % duty cycle square wave, driving each segment either in phase with the backplane (off) or out of phase (on). Frequency isn't critical 30 to 100 Hz are usual, I think. I would have to look into my sources what I used.

I was using e. g. a 3 digit LCD at an Analog ADuC836. Open drain port pins on this processor could be used with a weak pullup (e. g. 10 k). I append a schematic to illustrate.

Regards,

Frank
 
driving 7-segment lcd

Check this app. note from Dallas.
DS89C450 used to drive the 7 segment LCD display directly.
 
7segment lcd

Hello friends,

Thank u for all the replys but i have one doubt why 4 digit seven segment lcd has 2 common planes and why it is not possible to drive the lcd through dc current(i am confused with ac current) if i do that thing what will happen ? and also could any one provide information on how much current the single segment will consume.

Thank U
 

avr 7 segment lcd

Hello,

LCD display doesn't draw any current, it's a capacitive load to the driver. It must not be driven by DC, or will be damaged due to electrolysis. I'm surprized about your display having 2 backplanes, that's uncommon to my opinion. Does it have individual contacts for each segment? Then the 2 backplane contacts could be simply tight together (or are already internally connected). If it has less contacts, it utilizes some kind of multiplex scheme.

Regards,
Frank
 
lcd 7 segments

Unless u give the exact part no or make you can't get the information needed.

Please post your requirement in detail, which will help others to help you.

atleast post a photograph of what ur using?

Regards
Nandhu
 

driving lcd 7 segment

Hello friends,

I am uploading the data sheet.
 

7 segment lcd interface

Here it is

I just found it by searching in google

Best of luck

Regards
Nandhu
 
lcd 7segment

Hello,

it's as I guessed: A standard non-multiplexed LCD. You can drive it e. g. directly from uP port pins, if your processor has enough of that. Supplementing the circuit recently posted, I show some lines of code used to drive the LCD.

The following code writes a 3 digit number to buffer variables
Code: 
char bcd2seg7 (unsigned char b) {
	char seg7 [10] = {0x3f,0x06,0x5b,0x4f,0x66,0x6d,
			  0x7c,0x07,0x7f,0x67 };
	if (b<10) return seg7[b];
	switch (b) {
		case 0xff: 
			return 0x40; // minus
			break;
		default:
			return 0;    
	}
}

void update_lcd (int nLCD) {
	if (nLCD>999) nLCD=999;
	else if (nLCD<-99) nLCD=-99;
 	if (nLCD<0) {
		lcd_bcd[0]=0xff;
		nLCD=-nLCD;
	}
	else lcd_bcd[0]=nLCD / 100;

	if (lcd_bcd[0]==0) lcd_bcd[0] = 10; // zero supress 
	lcd_bcd[1]=(nLCD % 100) / 10;	  	
	lcd_bcd[2]=nLCD % 10;
	EA	= 0;
	p0 = bcd2seg7(lcd_bcd[2]);
	p3 = bcd2seg7(lcd_bcd[1]) << 1;
	p2 = bcd2seg7(lcd_bcd[0]) | (p3 & 2) <<6; 
	EA	= 1;
}
In timer interrupt (64 Hz frequency), the buffer variable is written to port with alternating phase to guarantee a DC free drive voltage
Code: 
if (tic_128 & 2) {
	P0 = ~p0 & ~0x80;
	P2 = ~p2;
	P3 = ~p3 | 3;
}
else {
	P0 = p0 | 0x80;
	P2 = p2;
	P3 = p3 | 3;
}
Regards,

Frank
 
7 segment lcd with driver

Hello friends,

Thank u for all the suggetions given by u.I will use all information provided u and once again i thank u.If any problem i will come back here.

Thank U
 

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