LCD on Analog Port

[melissa creek]

<font face="Courier New" size=-1>Hi,
Can anyone please solve this. I am trying to run an LCD display off of port a on a 16F873. As far as I know I have disabled the analog and enabled the digital IO on that port but the LCD refuses to initialise.

Any suggestions?
PRE
/*
---------
+5--20-|Vdd |
+5---1-|Mclr |
Gnd---8-|Vss |
Gnd--19-|Vss |
4MHz--10-|Xtal |
4MHz---9-|Xtal |
| |
| 16F873 |
| |
| |
| |
| |
| |
| |
| |
| | ---------
| A0|-15--11-|D4 |
| A1|-16--12-|D5 |
| A2|-17--13-|D6 |
| A3|-18--14-|D7 |
| | | |-3--20K pot (contrast)
| A4|-14---6-|EN |
| A5|-13---4-|RS |
| | | |
| | +5-2-| |
| | Gnd-1-| |
| | Gnd-5-| |
| | | DISPLAY |
--------- ---------
/PRE
*/

#include <16F873.h>
#include <jonsinc.h>
#fuses XT, NOPROTECT, NOPUT, NOWDT, NOBROWNOUT, NOLVP, NOCPD, NOWRT

// LCD STUFF
#define LCD_D0 PIN_A0
#define LCD_D1 PIN_A1
#define LCD_D2 PIN_A2
#define LCD_D3 PIN_A3
#define LCD_EN PIN_A4
#define LCD_RS PIN_A5
#define CLEAR_DISP 0x01
#use delay ( clock=4000000 )
#use standard_io ( A )

// These defines are specifically for a 4x16 line display.
#define LINE_16_1 0x00
#define LINE_16_2 0x40
#define LINE_16_3 0x10
#define LINE_16_4 0x50
// These defines are specifically for a 4x20 line display.
#define LINE_20_1 0x00
#define LINE_20_2 0x40
#define LINE_20_3 0x14
#define LINE_20_4 0x54

// These are prototype statements.
void LCD_SetPosition ( UCHAR cX );
void LCD_PutChar ( UCHAR cX );
void LCD_PutCmd ( UCHAR cX );
void LCD_Init ( void );
void LCD_PulseEnable ( void );
void LCD_SetData ( unsigned int cX );




void main( void )
{

LCD_Init (); // initializes display
LCD_PutCmd ( CLEAR_DISP ); // clears display
LCD_SetPosition ( LINE_16_1 ); // sets cursor at offset 0 in first line
printf ( LCD_PutChar, "Test" ); // displays "Test"
LCD_SetPosition ( LINE_16_2 + 5 ); // sets cursor at offset 5 in second line
printf ( LCD_PutChar, "Test" ); // displays "2nd test"
while ( TRUE ); // halts here
}




// These are the display subroutines.==============================


void LCD_Init ( void )
{
setup_adc(NO_ANALOGS); // make all of port a digital
LCD_SetData ( 0x00 );
delay_ms ( 200 ); // wait enough time after Vdd rise
output_low ( LCD_RS );
LCD_SetData ( 0x03 ); // init with specific nibbles to start 4-bit mode
LCD_PulseEnable();
LCD_PulseEnable();
LCD_PulseEnable();
LCD_SetData ( 0x02 ); // set 4-bit interface
LCD_PulseEnable(); // send dual nibbles hereafter, MSN first
LCD_PutCmd ( 0x2C ); // function set (all lines, 5x7 characters)
LCD_PutCmd ( 0x0C ); // display ON, cursor off, no blink
LCD_PutCmd ( 0x01 ); // clear display
LCD_PutCmd ( 0x06 ); // entry mode set, increment
}

void LCD_SetPosition ( unsigned int cX )
{
// this subroutine works specifically for 4-bit Port A
LCD_SetData ( swap ( cX ) | 0x08 );
LCD_PulseEnable();
LCD_SetData ( swap ( cX ) );
LCD_PulseEnable();
}

void LCD_PutChar ( unsigned int cX )
{
// this subroutine works specifically for 4-bit Port A
output_high ( LCD_RS );
LCD_SetData ( swap ( cX ) ); // send high nibble
LCD_PulseEnable();
LCD_SetData ( swap ( cX ) ); // send low nibble
LCD_PulseEnable();
output_low ( LCD_RS );
}

void LCD_PutCmd ( unsigned int cX )
{
// this subroutine works specifically for 4-bit Port A
LCD_SetData ( swap ( cX ) ); // send high nibble
LCD_PulseEnable();
LCD_SetData ( swap ( cX ) ); // send low nibble
LCD_PulseEnable();
}

void LCD_PulseEnable ( void )
{
output_high ( LCD_EN );
delay_us ( 10 );
output_low ( LCD_EN );
delay_ms ( 5 );
}

void LCD_SetData ( unsigned int cX )
{
output_bit ( LCD_D0, cX & 0x01 );
output_bit ( LCD_D1, cX & 0x02 );
output_bit ( LCD_D2, cX & 0x04 );
output_bit ( LCD_D3, cX & 0x08 );
}</font>
___________________________
This message was ported from CCS's old forum
Original Post ID: 11738

[PCM programmer]

:=Hi,
:=Can anyone please solve this. I am trying to run an LCD display off of port a on a 16F873. As far as I know I have disabled the analog and enabled the digital IO on that port but the LCD refuses to initialise.
:=
------------------------------------------------------

The very first question would be, do you have a pull-up
resistor on pin A4 ? That's an open drain output, so
you'll need one. You could use a 4.7K resistor in this
circuit.

Also, your ASCII art doesn't display properly on this board.
You have to use the PRE and /PRE tags.
<a href="http://www.pic-c.com/forum/general/posts/11373.html" TARGET="_blank">http://www.pic-c.com/forum/general/posts/11373.html</a>
You could edit your post, and surround the art with those tags.
___________________________
This message was ported from CCS's old forum
Original Post ID: 11739

[Hans Wedemeyer]

Did you forget to set tris_a for the line that need to be Output. i.e. A4 and A5.

I did not see it in your code, did I miss something.

Don't forget to do that pulup resistor as PCM Programmer advised. 10K is fine.
___________________________
This message was ported from CCS's old forum
Original Post ID: 11748

[melissa creek]

Not sure that resistors are required!! I have had this code working on port A of a 16F84 without pullup resistors and the port doesn't have any internally.

Thanks


:=Hi,
:=Can anyone please solve this. I am trying to run an LCD display off of port a on a 16F873. As far as I know I have disabled the analog and enabled the digital IO on that port but the LCD refuses to initialise.
:=
:=Any suggestions?
:=
:=/*
:= ---------
:= +5--20-|Vdd |
:= +5---1-|Mclr |
:= Gnd---8-|Vss |
:= Gnd--19-|Vss |
:= 4MHz--10-|Xtal |
:= 4MHz---9-|Xtal |
:= | |
:= | 16F873 |
:= | |
:= | |
:= | |
:= | |
:= | |
:= | |
:= | |
:= | | ---------
:= | A0|-15--11-|D4 |
:= | A1|-16--12-|D5 |
:= | A2|-17--13-|D6 |
:= | A3|-18--14-|D7 |
:= | | | |-3--20K pot (contrast)
:= | A4|-14---6-|EN |
:= | A5|-13---4-|RS |
:= | | | |
:= | | +5-2-| |
:= | | Gnd-1-| |
:= | | Gnd-5-| |
:= | | | DISPLAY |
:= --------- ---------
:=
:=*/
:=
:=#include <16F873.h>
:=#include <jonsinc.h>
:=#fuses XT, NOPROTECT, NOPUT, NOWDT, NOBROWNOUT, NOLVP, NOCPD, NOWRT
:=
:=// LCD STUFF
:=#define LCD_D0 PIN_A0
:=#define LCD_D1 PIN_A1
:=#define LCD_D2 PIN_A2
:=#define LCD_D3 PIN_A3
:=#define LCD_EN PIN_A4
:=#define LCD_RS PIN_A5
:=#define CLEAR_DISP 0x01
:=#use delay ( clock=4000000 )
:=#use standard_io ( A )
:=
:=// These defines are specifically for a 4x16 line display.
:=#define LINE_16_1 0x00
:=#define LINE_16_2 0x40
:=#define LINE_16_3 0x10
:=#define LINE_16_4 0x50
:=// These defines are specifically for a 4x20 line display.
:=#define LINE_20_1 0x00
:=#define LINE_20_2 0x40
:=#define LINE_20_3 0x14
:=#define LINE_20_4 0x54
:=
:=// These are prototype statements.
:=void LCD_SetPosition ( UCHAR cX );
:=void LCD_PutChar ( UCHAR cX );
:=void LCD_PutCmd ( UCHAR cX );
:=void LCD_Init ( void );
:=void LCD_PulseEnable ( void );
:=void LCD_SetData ( unsigned int cX );
:=
:=
:=
:=
:=void main( void )
:= {
:=
:= LCD_Init (); // initializes display
:= LCD_PutCmd ( CLEAR_DISP ); // clears display
:= LCD_SetPosition ( LINE_16_1 ); // sets cursor at offset 0 in first line
:= printf ( LCD_PutChar, "Test" ); // displays "Test"
:= LCD_SetPosition ( LINE_16_2 + 5 ); // sets cursor at offset 5 in second line
:= printf ( LCD_PutChar, "Test" ); // displays "2nd test"
:= while ( TRUE ); // halts here
:= }
:=
:=
:=
:=
:=// These are the display subroutines.==============================
:=
:=
:=void LCD_Init ( void )
:= {
:= setup_adc(NO_ANALOGS); // make all of port a digital
:= LCD_SetData ( 0x00 );
:= delay_ms ( 200 ); // wait enough time after Vdd rise
:= output_low ( LCD_RS );
:= LCD_SetData ( 0x03 ); // init with specific nibbles to start 4-bit mode
:= LCD_PulseEnable();
:= LCD_PulseEnable();
:= LCD_PulseEnable();
:= LCD_SetData ( 0x02 ); // set 4-bit interface
:= LCD_PulseEnable(); // send dual nibbles hereafter, MSN first
:= LCD_PutCmd ( 0x2C ); // function set (all lines, 5x7 characters)
:= LCD_PutCmd ( 0x0C ); // display ON, cursor off, no blink
:= LCD_PutCmd ( 0x01 ); // clear display
:= LCD_PutCmd ( 0x06 ); // entry mode set, increment
:= }
:=
:=void LCD_SetPosition ( unsigned int cX )
:= {
:= // this subroutine works specifically for 4-bit Port A
:= LCD_SetData ( swap ( cX ) | 0x08 );
:= LCD_PulseEnable();
:= LCD_SetData ( swap ( cX ) );
:= LCD_PulseEnable();
:= }
:=
:=void LCD_PutChar ( unsigned int cX )
:= {
:= // this subroutine works specifically for 4-bit Port A
:= output_high ( LCD_RS );
:= LCD_SetData ( swap ( cX ) ); // send high nibble
:= LCD_PulseEnable();
:= LCD_SetData ( swap ( cX ) ); // send low nibble
:= LCD_PulseEnable();
:= output_low ( LCD_RS );
:= }
:=
:=void LCD_PutCmd ( unsigned int cX )
:= {
:= // this subroutine works specifically for 4-bit Port A
:= LCD_SetData ( swap ( cX ) ); // send high nibble
:= LCD_PulseEnable();
:= LCD_SetData ( swap ( cX ) ); // send low nibble
:= LCD_PulseEnable();
:= }
:=
:=void LCD_PulseEnable ( void )
:= {
:= output_high ( LCD_EN );
:= delay_us ( 10 );
:= output_low ( LCD_EN );
:= delay_ms ( 5 );
:= }
:=
:=void LCD_SetData ( unsigned int cX )
:= {
:= output_bit ( LCD_D0, cX & 0x01 );
:= output_bit ( LCD_D1, cX & 0x02 );
:= output_bit ( LCD_D2, cX & 0x04 );
:= output_bit ( LCD_D3, cX & 0x08 );
:= }
___________________________
This message was ported from CCS's old forum
Original Post ID: 11766

[PCM programmer]

:=Not sure that resistors are required!! I have had this code working on port A of a 16F84 without pullup resistors and the port doesn't have any internally.
:=

Just put in the resistor.
<a href="http://www.winpicprog.co.uk/pic_tutorial_lcd_board.htm" TARGET="_blank">http://www.winpicprog.co.uk/pic_tutorial_lcd_board.htm</a>
<a href="http://www.piclist.com/techref/microchip/portpins.htm" TARGET="_blank">http://www.piclist.com/techref/microchip/portpins.htm</a>
___________________________
This message was ported from CCS's old forum
Original Post ID: 11769

[Mark]

They are for pin A4 on the 16F873!

:=Not sure that resistors are required!! I have had this code working on port A of a 16F84 without pullup resistors and the port doesn't have any internally.
:=
:=Thanks
:=
:=
:=:=Hi,
:=:=Can anyone please solve this. I am trying to run an LCD display off of port a on a 16F873. As far as I know I have disabled the analog and enabled the digital IO on that port but the LCD refuses to initialise.
:=:=
:=:=Any suggestions?
:=:=
:=:=/*
:=:= ---------
:=:= +5--20-|Vdd |
:=:= +5---1-|Mclr |
:=:= Gnd---8-|Vss |
:=:= Gnd--19-|Vss |
:=:= 4MHz--10-|Xtal |
:=:= 4MHz---9-|Xtal |
:=:= | |
:=:= | 16F873 |
:=:= | |
:=:= | |
:=:= | |
:=:= | |
:=:= | |
:=:= | |
:=:= | |
:=:= | | ---------
:=:= | A0|-15--11-|D4 |
:=:= | A1|-16--12-|D5 |
:=:= | A2|-17--13-|D6 |
:=:= | A3|-18--14-|D7 |
:=:= | | | |-3--20K pot (contrast)
:=:= | A4|-14---6-|EN |
:=:= | A5|-13---4-|RS |
:=:= | | | |
:=:= | | +5-2-| |
:=:= | | Gnd-1-| |
:=:= | | Gnd-5-| |
:=:= | | | DISPLAY |
:=:= --------- ---------
:=:=
:=:=*/
:=:=
:=:=#include <16F873.h>
:=:=#include <jonsinc.h>
:=:=#fuses XT, NOPROTECT, NOPUT, NOWDT, NOBROWNOUT, NOLVP, NOCPD, NOWRT
:=:=
:=:=// LCD STUFF
:=:=#define LCD_D0 PIN_A0
:=:=#define LCD_D1 PIN_A1
:=:=#define LCD_D2 PIN_A2
:=:=#define LCD_D3 PIN_A3
:=:=#define LCD_EN PIN_A4
:=:=#define LCD_RS PIN_A5
:=:=#define CLEAR_DISP 0x01
:=:=#use delay ( clock=4000000 )
:=:=#use standard_io ( A )
:=:=
:=:=// These defines are specifically for a 4x16 line display.
:=:=#define LINE_16_1 0x00
:=:=#define LINE_16_2 0x40
:=:=#define LINE_16_3 0x10
:=:=#define LINE_16_4 0x50
:=:=// These defines are specifically for a 4x20 line display.
:=:=#define LINE_20_1 0x00
:=:=#define LINE_20_2 0x40
:=:=#define LINE_20_3 0x14
:=:=#define LINE_20_4 0x54
:=:=
:=:=// These are prototype statements.
:=:=void LCD_SetPosition ( UCHAR cX );
:=:=void LCD_PutChar ( UCHAR cX );
:=:=void LCD_PutCmd ( UCHAR cX );
:=:=void LCD_Init ( void );
:=:=void LCD_PulseEnable ( void );
:=:=void LCD_SetData ( unsigned int cX );
:=:=
:=:=
:=:=
:=:=
:=:=void main( void )
:=:= {
:=:=
:=:= LCD_Init (); // initializes display
:=:= LCD_PutCmd ( CLEAR_DISP ); // clears display
:=:= LCD_SetPosition ( LINE_16_1 ); // sets cursor at offset 0 in first line
:=:= printf ( LCD_PutChar, "Test" ); // displays "Test"
:=:= LCD_SetPosition ( LINE_16_2 + 5 ); // sets cursor at offset 5 in second line
:=:= printf ( LCD_PutChar, "Test" ); // displays "2nd test"
:=:= while ( TRUE ); // halts here
:=:= }
:=:=
:=:=
:=:=
:=:=
:=:=// These are the display subroutines.==============================
:=:=
:=:=
:=:=void LCD_Init ( void )
:=:= {
:=:= setup_adc(NO_ANALOGS); // make all of port a digital
:=:= LCD_SetData ( 0x00 );
:=:= delay_ms ( 200 ); // wait enough time after Vdd rise
:=:= output_low ( LCD_RS );
:=:= LCD_SetData ( 0x03 ); // init with specific nibbles to start 4-bit mode
:=:= LCD_PulseEnable();
:=:= LCD_PulseEnable();
:=:= LCD_PulseEnable();
:=:= LCD_SetData ( 0x02 ); // set 4-bit interface
:=:= LCD_PulseEnable(); // send dual nibbles hereafter, MSN first
:=:= LCD_PutCmd ( 0x2C ); // function set (all lines, 5x7 characters)
:=:= LCD_PutCmd ( 0x0C ); // display ON, cursor off, no blink
:=:= LCD_PutCmd ( 0x01 ); // clear display
:=:= LCD_PutCmd ( 0x06 ); // entry mode set, increment
:=:= }
:=:=
:=:=void LCD_SetPosition ( unsigned int cX )
:=:= {
:=:= // this subroutine works specifically for 4-bit Port A
:=:= LCD_SetData ( swap ( cX ) | 0x08 );
:=:= LCD_PulseEnable();
:=:= LCD_SetData ( swap ( cX ) );
:=:= LCD_PulseEnable();
:=:= }
:=:=
:=:=void LCD_PutChar ( unsigned int cX )
:=:= {
:=:= // this subroutine works specifically for 4-bit Port A
:=:= output_high ( LCD_RS );
:=:= LCD_SetData ( swap ( cX ) ); // send high nibble
:=:= LCD_PulseEnable();
:=:= LCD_SetData ( swap ( cX ) ); // send low nibble
:=:= LCD_PulseEnable();
:=:= output_low ( LCD_RS );
:=:= }
:=:=
:=:=void LCD_PutCmd ( unsigned int cX )
:=:= {
:=:= // this subroutine works specifically for 4-bit Port A
:=:= LCD_SetData ( swap ( cX ) ); // send high nibble
:=:= LCD_PulseEnable();
:=:= LCD_SetData ( swap ( cX ) ); // send low nibble
:=:= LCD_PulseEnable();
:=:= }
:=:=
:=:=void LCD_PulseEnable ( void )
:=:= {
:=:= output_high ( LCD_EN );
:=:= delay_us ( 10 );
:=:= output_low ( LCD_EN );
:=:= delay_ms ( 5 );
:=:= }
:=:=
:=:=void LCD_SetData ( unsigned int cX )
:=:= {
:=:= output_bit ( LCD_D0, cX & 0x01 );
:=:= output_bit ( LCD_D1, cX & 0x02 );
:=:= output_bit ( LCD_D2, cX & 0x04 );
:=:= output_bit ( LCD_D3, cX & 0x08 );
:=:= }
___________________________
This message was ported from CCS's old forum
Original Post ID: 11770