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Need help on Samsung VFD LCD Display 20T202DA2JA

 
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lambali



Joined: 12 Aug 2011
Posts: 1

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Need help on Samsung VFD LCD Display 20T202DA2JA
PostPosted: Fri Aug 12, 2011 8:25 am     Reply with quote
Hi;
I have Samsung 5 pin 20x2 VFD. It use SPI communication.

[url="I bought on eBay"] http://cgi.ebay.com/20X2-Serial-SAMSUNG-VFD-LCD-Module-Display-20T202DA2JA-/190409174276?pt=LH_DefaultDomain_0&hash=item2c55456d04 [/url]

Seller Test code not running CCS C and pic 16F876:
Code:

//M68 8bit-4bit interface

#include <AT89X51.H>

#define STB  P2_1
#define SCLK P2_4
#define SDATA P2_0

unsigned char bdata data_byte;
sbit bit7=data_byte^7;
sbit bit6=data_byte^6;
sbit bit5=data_byte^5;
sbit bit4=data_byte^4;
sbit bit3=data_byte^3;
sbit bit2=data_byte^2;
sbit bit1=data_byte^1;
sbit bit0=data_byte^0;

unsigned char i,j,k;

unsigned char code UDF[13][8]=
{
 0xff,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
 0x00,0xff,0x00,0x00,0x00,0x00,0x00,0x00,
 0x00,0x00,0xff,0x00,0x00,0x00,0x00,0x00,
 0x00,0x00,0x00,0xff,0x00,0x00,0x00,0x00,
 0x00,0x00,0x00,0x00,0xff,0x00,0x00,0x00,
 0x00,0x00,0x00,0x00,0x00,0xff,0x00,0x00,
 0x00,0x00,0x00,0x00,0x00,0x00,0xff,0x00,
 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xff,
 0x10,0x10,0x10,0x10,0x10,0x10,0x10,0x10,
 0x08,0x08,0x08,0x08,0x08,0x08,0x08,0x08,
 0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x04,
 0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,
 0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,
};

unsigned char code Seril_Demo_Line1[]={
' ',' ',' ',' ','V','F','D','-','D','I','S','P','L','A','Y',' ',' ',' ',' ',' ',
};
unsigned char code Seril_Demo_Line2[]={
'M','O','D','E',':','S','E','R','I','A','L','-','D','E','M','O',' ',' ',' ',' ',
};



void delay(unsigned int t)
{
 while(t--);
}

void code_send(unsigned char display_data_byte)
{
 data_byte=display_data_byte;

 SDATA=bit7; SCLK=0; SCLK=1;
 SDATA=bit6; SCLK=0; SCLK=1;
 SDATA=bit5; SCLK=0; SCLK=1;
 SDATA=bit4; SCLK=0; SCLK=1;
 SDATA=bit3; SCLK=0; SCLK=1;
 SDATA=bit2; SCLK=0; SCLK=1;
 SDATA=bit1; SCLK=0; SCLK=1;
 SDATA=bit0; SCLK=0; SCLK=1;
 
 delay(1);           //delay 40us at least, according to the SPEC 
}

void S_data_send(unsigned char temp_1)
{
 STB=0;
 code_send(0xfa);
 code_send(temp_1);
 STB=1;
}

void S_COM_send(unsigned char temp_2)
{
 STB=0;
 code_send(0xf8);
 code_send(temp_2);
 STB=1;
}

void main(void)
{
 S_COM_send(0x01);   //clear all display and set DD-RAM address 0 in address counter
 S_COM_send(0x02);   //move cursor to the original position
 S_COM_send(0x06);   //set the cursor direction increment and cursor shift enabled
 S_COM_send(0x38);   //set 8bit operation,2 line display and 100% brightness level
 S_COM_send(0x80);   //set cursor to the first position of 1st line
 S_COM_send(0x0c);   //set display on,cursor on,blinking off
 delay(10);

 for(j=0;j<13;j++)
 {
 /*********************************/
 
  S_COM_send(0x40);  //CGRAM ADDRESS SETTING

  for(k=0;k<8;k++)
  {
   S_data_send(UDF[j][k]);
  }
 /*********************************/

  S_COM_send(0x80);  //DDRAM ADDRESS SETTING

  for(i=0;i<80;i++)
  {
   S_data_send(0x00);
  }
 /*********************************/
 
  delay(20000);
 }


 S_COM_send(0x80);
 for(i=0;i<20;i++)
 {
  S_data_send(Seril_Demo_Line1[i]);
 }

 S_COM_send(0xc0);
 for(i=0;i<20;i++)
 {
  S_data_send(Seril_Demo_Line2[i]);
 }
 delay(50000);
 delay(50000);
 delay(50000);
 delay(50000);
 delay(50000);
 delay(50000);
 delay(50000);
 delay(50000);
 delay(50000);
 delay(50000);

 /*********************************/

 S_COM_send(0x80);  //DDRAM ADDRESS SETTING

 for(i=0;i<20;i++)
 {
  S_data_send(0x2a);
  S_data_send(0x20);
 }
 for(i=0;i<20;i++)
 {
  S_data_send(0x20);
  S_data_send(0x2a);
 }
 delay(50000);
 delay(50000);
 /*********************************/

 S_COM_send(0x80);  //DDRAM ADDRESS SETTING

 for(i=0;i<20;i++)
 {
  S_data_send(0x20);
  S_data_send(0x2a);
 }
 for(i=0;i<20;i++)
 {
  S_data_send(0x2a);
  S_data_send(0x20);
 }
 delay(50000);
 delay(50000);
 /*********************************/

 S_COM_send(0x40);  //CGRAM ADDRESS SETTING

 for(k=0;k<8;k++)
 {
  S_data_send(0xff);
 }
 
 S_COM_send(0x80);  //DDRAM ADDRESS SETTING

 for(i=0;i<80;i++)
 {
  S_data_send(0x00);
 }

 while(1);
}


Help me pls. Who have working code, sharing pls.
Excuse me my bad english.
Regards.
asmallri



Joined: 12 Aug 2004
Posts: 1635
Location: Perth, Australia

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PostPosted: Fri Aug 12, 2011 9:25 am     Reply with quote
The code is obviously delay sensitive.

I do not know what the CCS compiler does but some compilers, when faced with this:

Code:
while(x--);


will optimize this code out completely. So no delay.

CCS had delay_us() and delay_ms() functions which will be far more accurate. Don't forget to the the #delay(clock=...) directive.
_________________
Regards, Andrew

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