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20x2 LCD driver (chinese type)

 
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wangine



Joined: 07 Jul 2009
Posts: 98
Location: Curtea de Arges, Romania

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20x2 LCD driver (chinese type)
PostPosted: Fri Nov 20, 2015 10:47 am     Reply with quote

This driver is based on PCM_p modified driver
https://www.ccsinfo.com/forum/viewtopic.php?t=24661
and an original driver based on a 32 bit ARM controller (i say chinese because the top comment with all description is in chinese and even with google translate i didn't understand too much). The driver has separate functions for all commands (except 2), i didn't find it yet. The controller for LCD is a ST7066u with modified character page. Also the datasheet don't exist. I left the original PCM_p driver intact, without any modifications, i just put the rest of the functions on the bottom, in that you way can call _LCD_putc() and lcd_putc() in same driver, difference is on _LCD_puts()
Code:

// Flex_LCD420.c

// These pins are for my Microchip PicDem2-Plus board,
// which I used to test this driver.
// An external 20x4 LCD is connected to these pins.
// Change these pins to match your own board's connections.
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Clear and home
#define LCD_CLR_DISP   0x01   // Clear screen, home cursor, unshift display
#define LCD_RETURN_HOME   0x02   // Home cursor, unshift display
// commands
// Display on/off, cursor on/off, blinking char at cursor position
#define LCD_DISP_OFF 0x08 // Display off
#define LCD_DISP_ON 0x0C // Display on, cursor off
#define LCD_DISP_ON_BLINK 0x0D // Display on, cursor off, blink char
#define LCD_DISP_ON_CURSOR 0x0E // Display on, cursor on
#define LCD_DISP_ON_CURSOR_BLINK 0x0F // Display on, cursor on, blink char
// Move cursor/shift display
#define LCD_MOVE_CURSOR_LEFT 0x10 // Move cursor left (decrement)
#define LCD_MOVE_CURSOR_RIGHT 0x14 // Move cursor right (increment)
#define LCD_MOVE_DISP_LEFT 0x18 // Shift display left
#define LCD_MOVE_DISP_RIGHT 0x1C // Shift display right

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#define LCD_DB4   PIN_D4
#define LCD_DB5   PIN_D5
#define LCD_DB6   PIN_D6
#define LCD_DB7   PIN_D7

#define LCD_RS    PIN_D1
#define LCD_RW    PIN_D2
#define LCD_E     PIN_D3   

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#define USE_RW_PIN   1     


// These are the line addresses for most 4x20 LCDs.
#define LCD_LINE_1_ADDRESS 0x00
#define LCD_LINE_2_ADDRESS 0x40
///#define LCD_LINE_3_ADDRESS 0x14
///#define LCD_LINE_4_ADDRESS 0x54

// These are the line addresses for LCD's which use
// the Hitachi HD66712U controller chip.
 
//#define LCD_LINE_1_ADDRESS 0x00
//#define LCD_LINE_2_ADDRESS 0x20
//#define LCD_LINE_3_ADDRESS 0x40
//#define LCD_LINE_4_ADDRESS 0x60
 


//========================================
/* Local variables */
static unsigned int _lcd_ptr;

/* 8 user defined characters to be loaded into CGRAM (used for bar graph) */
static const unsigned char UserFont[8][8] = {
  { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 },
  { 0x10,0x10,0x10,0x10,0x10,0x10,0x10,0x10 },
  { 0x18,0x18,0x18,0x18,0x18,0x18,0x18,0x18 },
  { 0x1C,0x1C,0x1C,0x1C,0x1C,0x1C,0x1C,0x1C },
  { 0x1E,0x1E,0x1E,0x1E,0x1E,0x1E,0x1E,0x1E },
  { 0x1F,0x1F,0x1F,0x1F,0x1F,0x1F,0x1F,0x1F },
  { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 },
  { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 }
};
//========================================

#define lcd_type 2   // 0=5x7, 1=5x10, 2=2 lines(or more)

int8 lcd_line;

int8 const LCD_INIT_STRING[4] =
{
 0x20 | (lcd_type << 2),  // Set mode: 4-bit, 2+ lines, 5x8 dots
 0xc,                     // Display on
 1,                       // Clear display
 6                        // Increment cursor
 };
                             

//-------------------------------------
void lcd_send_nibble(int8 nibble)
{
// Note:  !! converts an integer expression
// to a boolean (1 or 0).
 output_bit(LCD_DB4, !!(nibble & 1));
 output_bit(LCD_DB5, !!(nibble & 2)); 
 output_bit(LCD_DB6, !!(nibble & 4));   
 output_bit(LCD_DB7, !!(nibble & 8));   

 delay_cycles(1); 
 output_high(LCD_E);
 delay_us(2);
 output_low(LCD_E);
}

//-----------------------------------
// This sub-routine is only called by lcd_read_byte().
// It's not a stand-alone routine.  For example, the
// R/W signal is set high by lcd_read_byte() before
// this routine is called.     

#ifdef USE_RW_PIN
int8 lcd_read_nibble(void)
{
int8 retval;
// Create bit variables so that we can easily set
// individual bits in the retval variable.
#bit retval_0 = retval.0
#bit retval_1 = retval.1
#bit retval_2 = retval.2
#bit retval_3 = retval.3

retval = 0;
   
output_high(LCD_E);
delay_us(1);

retval_0 = input(LCD_DB4);
retval_1 = input(LCD_DB5);
retval_2 = input(LCD_DB6);
retval_3 = input(LCD_DB7);
 
output_low(LCD_E);
delay_us(1);
   
return(retval);   
}   
#endif

//---------------------------------------
// Read a byte from the LCD and return it.

#ifdef USE_RW_PIN
int8 lcd_read_byte(void) // lcd_rd_stat()
{
int8 low;
int8 high;

output_high(LCD_RW);
delay_cycles(1);

high = lcd_read_nibble();
delay_us(26); //************** 
low = lcd_read_nibble();

return( (high<<4) | low);
}
#endif

//----------------------------------------
// Send a byte to the LCD.
void lcd_send_byte(int8 address, int8 n)
{
output_low(LCD_RS);

#ifdef USE_RW_PIN
while(bit_test(lcd_read_byte(),7)) ;
#else
delay_us(60); 
#endif

if(address)
   output_high(LCD_RS);
else
   output_low(LCD_RS);
     
delay_us(3);  //*********

#ifdef USE_RW_PIN
output_low(LCD_RW);
delay_cycles(1);
#endif

output_low(LCD_E);

lcd_send_nibble(n >> 4);
////delay_us(60);  //*****
lcd_send_nibble(n & 0xf);
}
//----------------------------

void lcd_init(void)
{
int8 i;

lcd_line = 1;

output_low(LCD_RS);

#ifdef USE_RW_PIN
output_low(LCD_RW);
#endif

output_low(LCD_E);

// Some LCDs require 15 ms minimum delay after
// power-up.  Others require 30 ms.  I'm going
// to set it to 35 ms, so it should work with
// all of them.
delay_ms(50);         

for(i=0 ;i < 3; i++)
   {
    lcd_send_nibble(0x03);
    delay_ms(5); //   delay_ms(5);
   }

lcd_send_nibble(0x02);

for(i=0; i < sizeof(LCD_INIT_STRING); i++)
   {
    lcd_send_byte(0, LCD_INIT_STRING[i]);
   
    // If the R/W signal is not used, then
    // the busy bit can't be polled.  One of
    // the init commands takes longer than
    // the hard-coded delay of 50 us, so in
    // that case, lets just do a 5 ms delay
    // after all four of them.
    #ifndef USE_RW_PIN
    delay_ms(5);    //   delay_ms(5);
    #endif
   }

}

//----------------------------

void lcd_gotoxy(int8 x, int8 y)
{
int8 address;


switch(y)
  {
   case 1:
     address = LCD_LINE_1_ADDRESS;
     break;

   case 2:
     address = LCD_LINE_2_ADDRESS;
     break;

//   case 3:
//     address = LCD_LINE_3_ADDRESS;
//     break;
//
//   case 4:
//     address = LCD_LINE_4_ADDRESS;
//     break;

   default:
     address = LCD_LINE_1_ADDRESS;
     break;
     
  }

address += x-1;
lcd_send_byte(0, 0x80 | address);
}

//-----------------------------
void lcd_scroll_right(void)
{
lcd_send_byte(0, 0x1E);
}
//-------------------------

void lcd_scroll_left(void)
{
lcd_send_byte(0, 0x18);
}
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
void lcd_putc(char c)
{
 switch(c)
   {
    case '\f':
      lcd_send_byte(0,1);
      lcd_line = 1;
      delay_ms(2);
      break;
   
    case '\n':
       lcd_gotoxy(1, ++lcd_line);
       break;
   
    case '\b':
       lcd_send_byte(0,0x10);
       break;
   
    default:
       lcd_send_byte(1,c);
       break;
   }
}

//------------------------------
#ifdef USE_RW_PIN
char lcd_getc(int8 x, int8 y)
{
char value;

lcd_gotoxy(x,y);

// Wait until busy flag is low.
while(bit_test(lcd_read_byte(),7)); 

output_high(LCD_RS);
value = lcd_read_byte();
output_low(LCD_RS);

return(value);
}
#endif
//// continue CORTEX curiozitate

/*--------------------------- lcd_wr_cmd ------------------------------------*/

static void _lcd_wr_cmd (unsigned int c) {
   /* Write command to LCD controller. */
output_low(LCD_RS);

#ifdef USE_RW_PIN
while(bit_test(lcd_read_byte(),7)) ;
#else
delay_us(60); 
#endif 
   output_low(LCD_RS);     
delay_us(3);  //*********

#ifdef USE_RW_PIN
output_low(LCD_RW);
delay_cycles(1);
#endif

output_low(LCD_E);

lcd_send_nibble(c >> 4);
////delay_us(60);  //*****
lcd_send_nibble(c & 0xf);
}
/*--------------------------- lcd_wr_data -----------------------------------*/

static void _lcd_wr_data (unsigned int d) {
   /* Write data to LCD controller. */
output_low(LCD_RS);

#ifdef USE_RW_PIN
while(bit_test(lcd_read_byte(),7)) ;
#else
delay_us(60); 
#endif 
   output_high(LCD_RS);     
delay_us(3);  //*********

#ifdef USE_RW_PIN
output_low(LCD_RW);
delay_cycles(1);
#endif

output_low(LCD_E);

lcd_send_nibble(d >> 4);
////delay_us(60);  //*****
lcd_send_nibble(d & 0xf);
}
/*--------------------------- LCD_load --------------------------------------*/

void _LCD_load (unsigned char *fp, unsigned int cnt) {
   /* Load user-specific characters into CGRAM */
   unsigned int8 i;

   _lcd_wr_cmd (0x40);                   /* Set CGRAM address counter to 0    */
   for (i = 0; i < cnt; i++, fp++)  {
      _lcd_wr_data (*fp);
   }
}
/*--------------------------- LCD_gotoxy ------------------------------------*/

void _LCD_gotoxy (unsigned int x, unsigned int y) {
   /* Set cursor position on LCD display. Left corner: 1,1, right: 20,2 */
   unsigned int c;

   c = --x;
   if (--y) {
      c |= 0x40;
   }
   _lcd_wr_cmd (c | 0x80);
   _lcd_ptr = y*16 + x;
}
/*--------------------------- LCD_cls ---------------------------------------*/

void _LCD_cls (void) {
   /* Clear LCD display, move cursor to home position. */
   _lcd_wr_cmd (0x01);
   _LCD_gotoxy (1,1);
}
/*--------------------------- LCD_cursor_off------------------------------------*/

void _LCD_cur_off (void) {
   /* Switch off LCD cursor. */
   _lcd_wr_cmd (0x0c);
}
/*--------------------------- LCD_cursor_on------------------------------------*/

void _LCD_cur_on (void) {
   /* Switch on LCD cursor. */
   _lcd_wr_cmd (LCD_DISP_ON_CURSOR);
}
/*--------------------------- LCD_on ------ ---------------------------------*/

void _LCD_on (void) {
   /* Switch on LCD and enable cursor. */
   _lcd_wr_cmd (0x0e);
}
/*--------------------------- LCD_putc --------------------------------------*/

void _LCD_putc (unsigned char c) {
   /* Print a character to LCD at current cursor position. */

   if (_lcd_ptr == 20) {
      _lcd_wr_cmd (0xc0);
   }
   _lcd_wr_data (c);
   _lcd_ptr++;
}
/*--------------------------- LCD_puts --------------------------------------*/

void _LCD_puts (unsigned char *sp) {
   /* Print a string to LCD display. */

   while (*sp) {
      _LCD_putc (*sp++);
   }
}
/*--------------------------- LCD_bargraph ----------------------------------*/

void _LCD_bargraph (unsigned int8 val, unsigned int8 size) {
   /* Print a bargraph to LCD display.  */
   /* - val:  value 0..100 %            */
   /* - size: size of bargraph 1..16    */
   unsigned int i;

   val = val * size / 20;               /* Display matrix 5 x 8 pixels       */
   for (i = 0; i < size; i++) {
      if (val > 5) {
         _LCD_putc (5);
         val -= 5;
      }
      else {
         _LCD_putc (val);
         break;
      }
   }
}
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