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jet_pack234
Joined: 11 Feb 2005
Posts: 11
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| Powertip LCD with 16F84A |
 Posted: Mon Sep 19, 2005 11:10 am |
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Hi,
This is driving me crazy! Aim: to use a 16 by 2 powertip LCD module for in write mode to display a character.
Have studied the data sheet for many hours and played with my code but just cant get this going.
When I power up I get one row of solid blue boxes. My initialisation routine is called and I get two rows of very light blue boxes. Does this mean its initialised - I thought i would see a cursor or something. At no point during initialisation does the lcd turn on/off so I think there is something wrong with the initialisation routine.
Can anyone see if there is anything wrong with my code?
I have made timings quite long (since there is no maximum time according to the datasheet) so that I can see what is happening on a scope.
Someone must have written something similar in ccs.
Grateful for any help!!
Code below should send the letter 'M'
| Code: |
/////////////////////////////////////////////////////////////////////////
//// 16*2 LCD Display Driver ////
//// ////
//// Matt Holmes ////
/////////////////////////////////////////////////////////////////////////
#include <16f84a.h>
#include <stdio.h>
#include <stdlib.h>
#fuses XT,NOWDT,NOPUT,NOPROTECT
#use delay (clock=4000000) // Clock Frequency 4 MHz
#define RS PIN_A0 // Define portA pins
#define RW PIN_A1
#define EN PIN_A2
#define DB0 PIN_B0 // Define portB pins
#define DB1 PIN_B1
#define DB2 PIN_B2
#define DB3 PIN_B3
#define DB4 PIN_B4
#define DB5 PIN_B5
#define DB6 PIN_B6
#define DB7 PIN_B7
/////////////////////////////////////////////////////////////////////////
// Subroutine: Enable data transmission
/////////////////////////////////////////////////////////////////////////
Enable()
{
output_high(EN);
delay_ms(10);
output_low(EN);
//delay_us(1);
delay_ms(10);
}
/////////////////////////////////////////////////////////////////////////
// Subroutine: Write Character to LCD screen
/////////////////////////////////////////////////////////////////////////
Write_Data(int Character)
{
OUTPUT_B(Character);
output_high(RS); // Select data register for write
output_low(RW); // Write mode
Enable();
}
/////////////////////////////////////////////////////////////////////////
// Subroutine: Initialisation procedure for power up
/////////////////////////////////////////////////////////////////////////
Initialisation (int N_Lines, int Font)
{
delay_ms(20);
output_low(RS); //Select instruction register for write
output_low(RW);
OUTPUT_B(0b00110000);
Enable();
Delay_ms(1000);
OUTPUT_B(0b00110000);
Enable();
Delay_ms(1000);
OUTPUT_B(0b00110000);
Enable();
if (N_Lines=2){
output_high(DB3);
}else{
output_low(DB3);
}
if (Font=1){
output_high(DB2);
}else{
output_low(DB2);
}
Enable();
Delay_ms(3000);
OUTPUT_B(0b00001000); //Display off
Enable();
Delay_ms(3000);
OUTPUT_B(0b00000001); //Display on
Enable();
Delay_ms(3000);
OUTPUT_B(0b00000110);
Enable();
}
/////////////////////////////////////////////////////////////////////////
void main()
{
// Define Port i/o settings
SET_TRIS_A(0b00000000); // Set PortA as output
SET_TRIS_B(0b00000000); // Set PortB as output
OUTPUT_B(0b00000000);
OUTPUT_A(0b00000000);
Delay_ms(500);
Initialisation(1,1); // (int N_Lines, int Font) N_Lines = Number of lines (1 or 2), Font = Font style (0=5*7 or 1=5*10)
Delay_ms(1000);
Write_Data(77);
while (TRUE) { // Continuous loop through
// Writes letter 'M'
Delay_ms(20);
}
return;
}
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Sep 20, 2005 6:53 pm |
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My suggestion is don't try to re-invent the wheel. Use the CCS driver
and it will work. Also, for 16x2 LCDs, no one uses the 8-bit data bus.
The upper 4-bits are used. This saves valuable pins on your PIC for
other uses. Here's a page that has a schematic that shows how
to connect the LCD to your PIC, when using the CCS driver on Port B.
http://academic1.bellevue.edu/robots/16f84lcd.html
Remember that the CCS driver, LCD.C, must be configured to use
Port B. Do this by placing the #define statement shown below
in the line above the #include statement for the LCD driver file.
Example:
#define use_portb_lcd TRUE
#include <lcd.c> |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Tue Sep 20, 2005 10:07 pm |
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| PCM programmer wrote: | | no one uses the 8-bit data bus. |
Somebody does  |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Sep 20, 2005 11:11 pm |
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Yes, I knew I took a risk in saying that.  |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Wed Sep 21, 2005 6:07 am |
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I probably will not use all 8 in future designs unless I have an 8 bit data bus going to other IC's  |
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Guest
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| Posted: Wed Sep 21, 2005 11:52 am |
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| Ok thanks for your help will try it out. Still would like to know why my code doesnt work though!!! |
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