lcd162.c

/*-------------------------------------------------------------------
  File name: "lcd162.c"

  Driver for "LCD Keypad Shield" alphanumeric display.
  Display controller = HD44780U (LCD-II).

  Max. uC clock frequency = 16 MHz (Tclk = 62,5 ns)

  Connection : PORTx (4 bit mode) :
  [LCD]        [Portx]
  RS   ------  PH 5
  RW   ------  GND
  E    ------  PH 6
  DB4  ------  PG 5
  DB5  ------  PE 3
  DB6  ------  PH 3
  DB7  ------  PH 4

  Henning Hargaard, February 5, 2018
---------------------------------------------------------------------*/

#define F_CPU 16000000
// ADC values for button presses
#define BUTTON_SELECT 540
#define BUTTON_LEFT 308
#define BUTTON_UP 50
#define BUTTON_DOWN 155
#define BUTTON_RIGHT 0
#define NO_KEY_PRESSED 1000

#include <avr/io.h>
#include <util/delay.h>
// Enabling us to use macro _NOP() to insert the NOP instruction
#include <avr/cpufunc.h>
#include "lcd162.h"

// library function itoa() is needed
#include <stdlib.h>

//*********************** PRIVATE (static) operations *********************
static void waitBusy()
{
  _delay_ms(2);
}

static void pulse_E()
{
  PORTH = PORTH | (1<<6);   // Enable E (PH6)

  // min 230ns delay
  _NOP();
  _NOP();
  _NOP();
  _NOP();

  PORTH = PORTH & ~(1<<6);  // Disable E (PH6)

  // Fit cycle time
  _NOP();
  _NOP();
}

// Sets the display data pins according to the 4 lower bits of data
static void set4DataPins(unsigned char data)
{
  PORTH = (PORTH & 0b11100111) | ((data<<1) & 0b00011000);
  PORTE = (PORTE & 0b11110111) | ((data<<2) & 0b00001000);
  PORTG = (PORTG & 0b11011111) | ((data<<5) & 0b00100000);
}

static void sendInstruction(unsigned char data)
{
    unsigned char msb_data = (data>>4);
    waitBusy(); // To make sure that previous tasks are done

    // Send MS 4 bits
    PORTH &= 0b10010000;    // RS and E low for instructions
    set4DataPins(msb_data);
    pulse_E();

    set4DataPins(data);
    pulse_E();
}

static void sendData(unsigned char data)
{
    unsigned char msb_data = (data>>4);
    waitBusy(); // To make sure that previous tasks are done
    PORTH = PORTH | (1<<5); // Enable RS for data
    PORTH = PORTH & ~(1<<6); // E=0 to enable E pulse

    set4DataPins(msb_data);
    pulse_E();

    set4DataPins(data);
    pulse_E();
    _delay_us(0.5);
    PORTH = PORTH & ~(1<<5);    // Disable RS
}

//*********************** PUBLIC functions *****************************

// Initializes the display, blanks it and sets "current display position"
// at the upper line, leftmost character (cursor invisible)
// Reference: Page 46 in the HD44780 data sheet
void LCDInit()
{
  // Initializing the used port
  DDRH |= 0b01111000;  // Outputs
  DDRE |= 0b00001000;
  DDRG |= 0b00100000;
  DDRF |= 0b00000001;   // Keys as input


  // Wait 50 ms (min. 15 ms demanded according to the data sheet)
  _delay_ms(50);
  // Function set (still 8 bit interface)
  PORTG |= 0b00100000;
  PORTE |= 0b00001000;
  pulse_E();

  // Wait 10 ms (min. 4,1 ms demanded according to the data sheet)
  _delay_ms(10);
  // Function set (still 8 bit interface)
  pulse_E();

  // Wait 10 ms (min. 100 us demanded according to the data sheet)
  _delay_ms(10);
  // Function set (still 8 bit interface)
  pulse_E();

  // Wait 10 ms (min. 100 us demanded according to the data sheet)
  _delay_ms(10);
  // Function set (now selecting 4 bit interface !)
  PORTG &= 0b11011111;
  pulse_E();

  // Function Set : 4 bit interface, 2 line display, 5x8 dots
  sendInstruction( 0b00101000 );
  // Display, cursor and blinking OFF
  sendInstruction( 0b00001000 );
  // Clear display and set DDRAM adr = 0
  sendInstruction( 0b00000001 );
  // By display writes : Increment cursor / no shift
  sendInstruction( 0b00000110 );
  // Display ON, cursor and blinking OFF
  sendInstruction( 0b00001100 );
}

// Blanks the display and sets "current display position" to
// the upper line, leftmost character
void LCDClear()
{
    sendInstruction(0b00000001);
}

// Sets DDRAM address to character position x and line number y
void LCDGotoXY( unsigned char x, unsigned char y )
{
  // To be implemented
    unsigned char instruction = 0b10000000;
    if (y == 0)
        instruction |= x ;
    else if (y == 1)
        instruction |= (0b11000000 | x);    // Shifted 0x40 as second line starts there

    sendInstruction(instruction);
}

// Display "ch" at "current display position"
void LCDDispChar(char ch)
{
    sendData(ch);
}

// Displays the string "str" starting at "current display position"
void LCDDispString(char* str)
{
    for (uint8_t i = 0; i < strlen(str); i++)
    {
    LCDDispChar(str[i]);
    }
}

// Displays the value of integer "i" at "current display position"
void LCDDispInteger(int i)
{
    char buffer [40];
    itoa(i, buffer, 10);
    LCDDispString(buffer);
}

// Loads one of the 8 user definable characters (UDC) with a dot-pattern,
// pre-defined in an 8 byte array in FLASH memory
void LCDLoadUDC(unsigned char UDCNo, const unsigned char *UDCTab)
{
  // To be implemented
}

// Selects, if the cursor has to be visible, and if the character at
// the cursor position has to blink.
// "cursor" not 0 => visible cursor.
// "blink" not 0 => the character at the cursor position blinks.
void LCDOnOffControl(unsigned char cursor, unsigned char blink)
{
    unsigned char controlBit = 0b00001111;

    if (cursor == 0)
        controlBit &= ~(1<<1);
    if (blink == 0)
        controlBit &= ~(1<<0);

    sendInstruction(controlBit);
}

// Moves the cursor to the left
void LCDCursorLeft()
{
      unsigned char controlBit = 0b00010000;
      sendInstruction(controlBit);
}

// Moves the cursor to the right
void LCDCursorRight()
{
      unsigned char controlBit = 0b00010100;
      sendInstruction(controlBit);
}

// Moves the display text one position to the left
void LCDShiftLeft()
{
    unsigned char controlBit = 0b00011000;
    sendInstruction(controlBit);
}

// Moves the display text one position to the right
void LCDShiftRight()
{
      unsigned char controlBit = 0b00011100;
      sendInstruction(controlBit);
}

// Sets the backlight intensity to "percent" (0-100)
void setBacklight(unsigned char percent)
{
  // To be implemented
}

// Reads the status for the 5 on board keys
// Returns 0, if no key pressed
unsigned char readKeys()
{
    int keyValue = ADCW;

    if (keyValue >= NO_KEY_PRESSED)
        return 0;

    if (keyValue >= BUTTON_SELECT)
    {
        LCDDispString("Select");
        return 1;
    }
    else if (keyValue >= BUTTON_LEFT)
    {
        LCDCursorLeft();
        return 1;
    }
    else if (keyValue >= BUTTON_DOWN)
    {
        LCDDispString("Down");
        return 1;
    }
     else if (keyValue >= BUTTON_UP)
     {
        LCDDispString("Up");
        return 1;
    }
    else if (keyValue >= BUTTON_RIGHT)
    {
        LCDCursorRight();
        return 1;
    }
}