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LCD Bargraph
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hansknec



Joined: 30 Sep 2004
Posts: 25
Location: Virginia, USA

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LCD Bargraph
PostPosted: Thu May 19, 2005 1:06 pm     Reply with quote

As a user that has been transitioning from PicBasicPro to PIC C, I was surprised to find that there were no canned LCD bargraph routines. (PBP didn't have one either, but the coding was commonly shared) Last year I finalized this code with the help of other users on this and other forums, but forgot to post it. The first file is LCD_bargraph.c and is fully commented. The routine works quite well, but I welcome suggestions for improvements.
Code:

/***LCD_bargraph.c************************************************************
Purpose:  An enhancement to the standard capabilities of LCD.c that enables
          one to pass a value to be bargraphed on a LCD.
Prerequisites:  Must also include LCD.c in main program or add this code
                to your own copy of LCD.c
//****************************************************************************
* void init_user_chars
* Purpose:   Set pointer in LCD memory to CGRAM and load first 8 bytes with
*         user defined characters. This function must be called once before
*         a bargraph is implemented. At exit it resets pointer to line 1,
*/
void init_user_chars(void) {
   // User defined characters are 5 x 7 but remember the cursor on 8
   int8 i;  //counting variable
 // ** setup an array of special characters to form the bars **** 
   // char 0x00 left vertical line of bar
    const char user_char[24] = {0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x00,
   // char 0x01 two units of bar
                          0x14, 0x14, 0x14, 0x14, 0x14, 0x14, 0x14, 0x00,
   // char 0x02 three units of bar (full bar)
                          0x15, 0x15, 0x15, 0x15, 0x15, 0x15, 0x15, 0x00};

   lcd_send_byte(0,64); // Sets ram address to beginning of CGRAM area

   for (i=0; i<24;i++)  // fill in CGRAM with the data from array above.
      lcd_send_byte(1,user_char[i]);

   lcd_gotoxy(1,1); // Resets address to top line / position 1
}

/******************************************************************************
*     void bargraph(int8 percent)
*  Purpose:  This function generates the bar graph indicator.
*  Written for a 2 X 16 Intelligent LCD Display with HD44780 type controller.
*  It expects a 0 to 48 value input to generate 0 to full width bar.
*  B_Wdth could be modified for larger LCD's.
*/
void bargraph(BYTE percent) {
//' ** Declare Variables **
   int16 Bar_Val;        // Value to be graphed.
   int Bars;          // Number of full ||| bars to draw.
   int Balance;      //   Balance left after all |||s are drawn.
   int i;           // counting variable
//' ** Declare Constants **
   int const B_Wdth = 16;             // Max width in characters of bar.
   int const Maxbar = B_Wdth * 3;   //   Max bar counts.
// meat of code **
   Bars = percent/3;        // how many full bars to print?
   Balance = percent%3;    // are partial bars required?
   lcd_gotoxy(1,2);       // go to beginning of line 2
  for (i=0; i<Bars;i++)
   lcd_send_byte(1,0x02);  // print the bars
  switch (Balance) {
      case 0: break;
      case 1: lcd_send_byte(1, 0x00);
              break;
      case 2: lcd_send_byte(1, 0x01);
              break; }
}



The second file is a simple sample of a PIC16F877 running the code and displaying its ADC value to the LCD.
Enjoy...

Code:

/*  bargraph_test.c  *******************************************************
Authors:  John Hansknecht and Daniel Charles
Purpose:  This program demonstrates the use of the LCD_bargraph.c in a real
          application.  A PIC16F877 is set up to write to a 2X16 LCD and read
          an incoming voltage on an ADC input pin.  The ADC value is written
          on the top line and the bottom line displays it in bargraph mode.
*/         
#include <16F877.h>
#device adc=10
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=4000000)
#include <LCD.c>
//#include <LABX1LCD.C>  // Our own special file with a different port pinout
#include <LCD_bargraph.c>

long value;
int A;
void main() {
   setup_adc_ports(RA0_ANALOG);
   setup_adc(ADC_CLOCK_INTERNAL);
   lcd_init();
   delay_ms(2000);
   init_user_chars();    // loads special characters into LCD CGRAM for bargraph
   set_adc_channel(0);
   delay_us(10);

   while(1)
   {
      value=read_adc(); //read the ADC
      delay_ms(20);     //pause so we don't blur the LCD display     
      A=value/21;       //calculate the full scale for our bar
      lcd_putc('\f');   //clear the LCD
      printf(lcd_putc, "value = %lu \n",value); //Print top line with ADC value
      bargraph(A);      //print line 2 with the bargraph output.
   }
}
jruibarroso



Joined: 07 Jan 2006
Posts: 64
Location: Braga

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PostPosted: Sat Jan 21, 2006 6:10 am     Reply with quote

I used this code and I had one problem:

Each time I power up the pic the display shows a diferent symbol for the bargraph. Do you know why this happens ? Thank you.
picmicroman



Joined: 21 Jan 2006
Posts: 1
Location: USA

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PostPosted: Sun Jan 22, 2006 12:01 am     Reply with quote

Hi

Thanks for the great code in deed. I have not tried yet, I need to know if its possible to use this code with HD44780 LCDs and LCD.C file,

Thanks
jruibarroso



Joined: 07 Jan 2006
Posts: 64
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PostPosted: Sun Jan 22, 2006 3:49 am     Reply with quote

i used with HD44780 LCDs and LCD.C and works fine for me !!! Thank you
jruibarroso



Joined: 07 Jan 2006
Posts: 64
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PostPosted: Sun Jan 22, 2006 3:51 am     Reply with quote

i ask you hansknec if you can give me some clues how can i have a array of some graphics made by me, and print then during the program on LCD

Ex.:

printf(lcd_putc, "Some text\n");
lcd_gotoxy(1,2);
printf(lcd_putc, mygraphic[x] );


Thank you ALL !!
akokyaw



Joined: 11 Feb 2005
Posts: 24

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Modification of bargraph
PostPosted: Fri Jun 02, 2006 9:53 am     Reply with quote

Hi,
I have modified the bargraph that posted by hansknec. The code will clear first bar of every character while value of bar is down, as follows:
Code:
/***LCD_bargraph.c************************************************************
Purpose:  An enhancement to the standard capabilities of LCD.c that enables
          one to pass a value to be bargraphed on a LCD.
Prerequisites:  Must also include LCD.c in main program or add this code
                to your own copy of LCD.c
//****************************************************************************
* void init_user_chars
* Purpose:   Set pointer in LCD memory to CGRAM and load first 8 bytes with
*         user defined characters. This function must be called once before
*         a bargraph is implemented. At exit it resets pointer to line 1,
*/
void init_user_chars(void) {
   // User defined characters are 5 x 7 but remember the cursor on 8
   int8 i;  //counting variable
 // ** setup an array of special characters to form the bars ****
   // char 0x00 no bar
    const char user_char[32] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
   // char 0x01 left vertical line of bar
                          0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x00,
   // char 0x02 two units of bar
                          0x14, 0x14, 0x14, 0x14, 0x14, 0x14, 0x14, 0x00,
   // char 0x03 three units of bar (full bar)
                          0x15, 0x15, 0x15, 0x15, 0x15, 0x15, 0x15, 0x00};

   lcd_send_byte(0,64); // Sets ram address to beginning of CGRAM area

   for (i=0; i<32;i++)  // fill in CGRAM with the data from array above.
      lcd_send_byte(1,user_char[i]);

   lcd_gotoxy(1,1); // Resets address to top line / position 1
}

/******************************************************************************
*     void bargraph(int8 percent)
*  Purpose:  This function generates the bar graph indicator.
*  Written for a 2 X 16 Intelligent LCD Display with HD44780 type controller.
*  It expects a 0 to 48 value input to generate 0 to full width bar.
*  B_Wdth could be modified for larger LCD's.
*/
void bargraph(BYTE percent) {
//' ** Declare Variables **
   int16 Bar_Val;        // Value to be graphed.
   int Bars;       // Number of full ||| bars to draw.
   int Balance;      //   Balance left after all |||s are drawn.
   int i;           // counting variable
//' ** Declare Constants **
   int const B_Wdth = 40;             // Max width in characters of bar.
   int const Maxbar = B_Wdth * 3;   //   Max bar counts.
// meat of code **
   Bars = percent/3;        // how many full bars to print?
   Balance = percent%3;    // are partial bars required?
   lcd_gotoxy(1,2);       // go to beginning of line 4
  for (i=0; i<Bars;i++)
   lcd_send_byte(1,0x03);  // print the bars
  switch (Balance) {
      case 0: lcd_send_byte(1, 0x00);
              break;
      case 1: lcd_send_byte(1, 0x01);
              break;
      case 2: lcd_send_byte(1, 0x02);
              break; }
}


Thank you, hansknec
ako
Mircea



Joined: 12 Jan 2007
Posts: 7
Location: Europe

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PostPosted: Fri Jan 12, 2007 4:33 am     Reply with quote

I think the switch statement can be replaced with only one statement.
Code:
switch (Balance)
{
  case 0: lcd_send_byte(1, 0x00); break;
  case 1: lcd_send_byte(1, 0x01); break;
  case 2: lcd_send_byte(1, 0x02); break;
}


can be replaced with
Code:
lcd_send_byte(1, Balance);
tavioman



Joined: 22 Feb 2006
Posts: 65

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PostPosted: Thu Mar 15, 2007 12:27 pm     Reply with quote

Mircea wrote:
I think the switch statement can be replaced with only one statement.
Code:
switch (Balance)
{
  case 0: lcd_send_byte(1, 0x00); break;
  case 1: lcd_send_byte(1, 0x01); break;
  case 2: lcd_send_byte(1, 0x02); break;
}


can be replaced with
Code:
lcd_send_byte(1, Balance);


Actually the switch statement it's very useful, but without the first case. In a 4 x 20 LCD the first case causes the first character on the following logic line of the LCD to be erased. Not a very cool thing. Smile.

Code:
switch (Balance)
{
  //case 0: lcd_send_byte(1, 0x00); break;
  case 1: lcd_send_byte(1, 0x01); break;
  case 2: lcd_send_byte(1, 0x02); break;
}
Mircea



Joined: 12 Jan 2007
Posts: 7
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PostPosted: Tue May 15, 2007 7:19 am     Reply with quote

tavioman,
why do you think the switch statement cannot be replace with that single statement?
tavioman



Joined: 22 Feb 2006
Posts: 65

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PostPosted: Tue May 15, 2007 7:25 am     Reply with quote

I have explained above.
Tried with the single statement or with the three cases scenario and when the cursor it's at the last position of a line the "0" case it's totally unuseful.
The cursor will jump at the next address( following line ).
I have made a software which uses three bargraphs. When in "case 0" the cursor jumped at the next line messing with my next bargraph.
Experiment and see.
The 0 case it's totally unuseful. When it's 0 I don't need to send anything to the lcd.
Mircea



Joined: 12 Jan 2007
Posts: 7
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PostPosted: Tue May 15, 2007 7:46 am     Reply with quote

I thing you don't understand.
If there is a problem with the value 0 of Balance then you can use something like
Code:
if( Balance ) lcd_send_byte(1, Balance);

But the idea to replace an "entire" switch with a single statement remains!
tavioman



Joined: 22 Feb 2006
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PostPosted: Tue May 15, 2007 7:59 am     Reply with quote

You're right now. My main idea was that when balance is 0 we don't need to sent anything to lcd. Smile
soulraven



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PostPosted: Tue Mar 10, 2009 4:11 am     Reply with quote

I have a problem. When the bargraph is decreased to 0, on the display remains a line from the bargraph.
cyrildavids



Joined: 09 May 2009
Posts: 3

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PostPosted: Sat May 09, 2009 2:20 am     Reply with quote

How do one make the screen display percentage instead of the numbers from 0 to 1022.
i tried making another variable that will take the Value of 'value' and divide it by the maximum number and then multiply it by 100 and every time i did run the program the only value that returns or displays on the screen is 0 for minimum or 100 for maximum.

the code is thus
Code:
while(1)
   {
      value=read_adc(); //read the ADC
   percent= ((value/1022)* 100);
      delay_ms(20);     //pause so we don't blur the LCD display     
      A=value/21;       //calculate the full scale for our bar
      lcd_putc('\f');   //clear the LCD
      printf(lcd_putc, "value = %lu \n",percent); //Print top line with ADC value
      bargraph(A);      //print line 2 with the bargraph output.
   }
cyrildavids



Joined: 09 May 2009
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PostPosted: Sat May 09, 2009 2:29 am     Reply with quote

never mind i got it working
first declare the variable
Code:
long value;
int A , percent;
float div = 10.22;


then in the while loop
Code:
 while(1)
   {
      value=read_adc(); //read the ADC
     percent = value/div ;
      delay_ms(20);     //pause so we don't blur the LCD display     
      A=value/21;       //calculate the full scale for our bar
      lcd_putc('\f');   //clear the LCD
      printf(lcd_putc, "Value= %d \n",percent); //Print top line with ADC value
      bargraph(A);      //print line 2 with the bargraph output.
      
   }
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