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LCD.c
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LCD.c
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/*
This program was modified from LCD code originally created by John Bibin. I'm not trying to claim any undeserved
credit for the setup of the LCD code, but I did change quiet a bit and made it what it is.
All the comments are my own.
Author: Roznerd http://roznerd.blogspot.com/
AVR: ATtiny2313 with internal clock set at 4MHz and CLKDIV8 Fuse deactivated so delays are timely
Compiler: AVRStudio 4.17 build 666 + WinAVR GCC 20090313
LCD: JHD162A 16x2 H44780 Character LCD on 5v used in 8 bit mode
Size: When burned to my ATtiny2313 it takes up 22% of my flash
Purpose:
Display "SCORE = 0" and using a momentary switch to gnd on ext. interrupt INT1
to iterate the counter variable and refresh the screen very quickly so the display
"instantly" shows the value of the variable
When the counter reaches 10, Display "A Winner Is You!" for ~3-5 seconds and reset the counter and clear the display.
Layout: PORTB is setup to handle the 8 data pins of the LCD. Some of PORTD is handling the control pins of the LCD. The backlight is handled on the breadboard. INT1 is used to trigger the ISR for the counter.
*/
#include "LCD.h"
/*------------------------------------------------------------------
----------------TEST FUNCTION--------------------------------------
-----------------------------------------------------------------*/
void test(void) {
int len, i; // set up length variable and index for topstring
char topstring[] = { "This is a test" }; // this is the string that will be written on the top row
char bottomstring[] = { "This is line 2" }; // this is the string that will be written on the bottom row
Init_Lcd(); // Run Init_Lcd function which sets up LCD with your preferences
len = strlen(topstring); // measure the length of topstring using strlen() and store the into in len1 variable
{ // lets write topstring to the LCD
for (i = 0; i < len; i++) // the for loop steps through the string sending each letter
Lcd_Send(topstring[i]); // the Lcd_Send function is run for the given letter of the topstring at index i
}
delay(50); // a quick delay in ms to allow LCD to display the value for a little bit before refreshing
len = strlen(bottomstring); // measure length of the bottom string using strlen() from string.h
Set_Cursor(0xC0); //set cursor to the beginning of the second line
for (i = 0; i < len; i++) {
Lcd_Send(bottomstring[i]); // Display the winner string on the LCD
}
delay(5000); // wait 5000ms so you can enjoy the feeling of victory
Clear_LCD();
} // end test
/*----------------------------------------------------------------
-----------------SEND A CHARACTER TO LCD-------------------------
-----------------------------------------------------------------*/
void Lcd_Send(unsigned char a)
// by now you have see most of my comments regarding these lines of code because they were used above
// nothing really changes here except we have a function which has a character input, which means you
// feed in characters from your strings using a for loops and it will clock them into the LCD
{
cli(); //disable interrupts
Select_DataRegister; // Sets R/S pin on LCD HI so the LCD knows we are giving it characters, not instructions
Write_Lcd; // R/W pin of LCD is set low so LCD knows we are writing to it, not reading from
Data_Lcd(a); // put ASCII hex code for the given letter/character out on PORTB for the LCD data pins. The ASCII hex codes are handled in the compiler, nice!
Set_Enable; // Sets the Enable pin HI on the LCD to clock in the data presented to the Data pins
delay(1); // delay 1 ms to let things settle
Clear_Enable; // Clears Enable by seting it back low.
delay(1); // delay 1 ms to let things settle
sei(); // re-enable interrupts
}
void Set_Cursor(unsigned char position)
{
/*
Possible locations:
-------------------
Top Display Row |80|81|82|83|84|85|86|87|88|89|8A|8B|8C|8D|8E|8F|
Bottom Display Row |C0|C1|C2|C3|C4|C5|C6|C7|C8|C9|CA|CB|CC|CD|CE|CF|
*/
cli(); // Disable interrupts
Select_InstructionRegister; // Sets R/S pin on LCD low so the LCD knows we are giving it instructions, not characters
Write_Lcd; // R/W pin of LCD is set low so LCD knows we are writing to it, not reading from
Data_Lcd(position); // have the AVR push a cursor location for the LCD out of PORTB to the LCD's data pins - this will move the cursor to the 88 position to overwrite previous number
Set_Enable; // Sets the Enable pin HI on the LCD to clock in the data presented to the Data pins
delay(1); // delay 1 ms to let things settle
Clear_Enable; // Clears Enable by seting it back low.
delay(1); // delay 1 ms to let things settle
sei(); // re-enable interrupts
}
void Clear_LCD(void)
{
cli(); // Disable interrupts
Select_InstructionRegister; // Sets R/S pin on LCD low so the LCD knows we are giving it instructions, not characters
Write_Lcd; // R/W pin of LCD is set low so LCD knows we are writing to it, not reading from
Data_Lcd(0x01); // this is the command for completely clearing the display and returning the cursor to the home location
Set_Enable; // Sets the Enable pin HI on the LCD to clock in the data presented to the Data pins
delay(1); // delay 1 ms to let things settle
Clear_Enable; // Clears Enable by seting it back low.
delay(1); // delay 1 ms to let things settle
sei(); // re-enable interrupts
}
/*----------------------------------------------------------------
-----------------FUNCTIONS TO INITIALIZE PORTS--------------------
Initialize the naming for the ports and set up output register
-----------------------------------------------------------------*/
void Init_Ports(void) {
DATA_DDR = 0XFF; //Setting data port for output
CONTROL_DDR = CONTROL_MASK; //setting selected pins of control port for output
CONTROL_PORT &= ~(_BV(Enable_Pin) | _BV(RegSelect_Pin )
| _BV(ReadWrite_Pin)); //setting values to 0 at starting
}
void lcdInit(void) {
Init_Ports(); // configure the ports
Init_Lcd(); // initialize the LCD
delay(100); // wait for the LCD to boot up
}
/*------------FUNCTION TO INITIATE LCD -----------------------------
Initializes the LCD with the instruction commands we want to use for writing
to the display. You can do alot here, but you want to avoid having to clear the
display too frequenlty because it can cause flicker, its better over over write.
There's alot of cool stuff you can mess with here.
Check out these 2 sites for more instruction code
http://www.dinceraydin.com/lcd/commands.htm
http://ouwehand.net/~peter/lcd/lcd0.shtml
-----------------------------------------------------------------*/
void Init_Lcd(void) {
char init[4];
int i;
init[0] = 0x0C; // turn off cursor - 0x0E blinking underline - 0x0F blinking block
init[1] = 0x38; // Use LCD in 8bit mode with both lines of the display
init[2] = 0x06; // entry mode set - increment cursor position to write left to right with no character shifting
init[3] = 0x80; // home ddram position 0x80 - 0x8F
// Top Display Row |80|81|82|83|84|85|86|87|88|89|8A|8B|8C|8D|8E|8F|
//Bottom Display Row |C0|C1|C2|C3|C4|C5|C6|C7|C8|C9|CA|CB|CC|CD|CE|CF|
cli(); // disable interrupts
Select_InstructionRegister;
Write_Lcd;
for (i = 0; i < 4; i++) // same story, set LCD in instruction mode and clock in command data
{
Data_Lcd(init[i]);
Set_Enable;
delay(1);
Clear_Enable;
delay(1);
} // end for
sei(); // re-enable interrupts
} //end function