Problem with PIC24F LCD code

[natmag]

I am trying my to implement a simple program such that my PIC24F displays a string of characters on my LCD screen. Unfortunately, nothing is being written on screen and on debugging it seems that PORTA and PORTB pins never change from their initial 0 state. Cannot understand why this is happening :S

Am using the Microstick to program my PIC24FV16KM202 together with the following code:

 /* Delay Function being used throughout the program */
void delay(int num)
{
    int i =0;
    for (i=0; i<num; i++)
    {
        ;
    }
}

/* LCD_command function to send a command to LCD */
void LCD_command(unsigned char c)
{
    LCD_rs = 0; /* Disable register select */
    LCD_rw = 0; /* Disable Read/Write */
    LCD_en = 1; /* Enable */
    delay(200);
    LCD_data = c; /* Write Command on LCD pin */
    delay(200);
    LCD_en = 0; /* Disable */
}

/* Function to Initialize LCD */
void Init_LCD(void)
{
    LCD_rs = 0;
    LCD_rw = 0;
    delay(800);
    LCD_en = 1;
    delay(500);
    LCD_en = 0;
    delay(500);
    LCD_en = 1;
    delay(500);
    LCD_en = 0;
    LCD_command(0x38); /*Function Set: 2 Line, 8-bits, 5x7 dots*/
    LCD_command(0x08); /*Display Off*/
    LCD_command(0x0F); /*Display On, Cursor On*/
    LCD_command(0x06); /*Entry Mode*/
    LCD_command(0x80); /*Entry Mode DDRAM address*/
}

/* Function to clear the LCD Screen */
void Clear_LCD(void)
{
    LCD_rs = 0;
    LCD_command(0x1); /* Clear Command */
    delay(800);
}
/* Function to write a character onto LCD */
void Write_char_LCD(unsigned char c)
{
    LCD_rw = 0;
    LCD_rs = 1;
    LCD_en = 1;
    delay(200);
    LCD_data = c; /* c is the character to be written */
    delay(200);
    LCD_en = 0;
}

/* Function to write a string of characters on LCD */
void Write_string_LCD(const char *s)
{
    LCD_rs = 1;
    while(*s)
    {
        Write_char_LCD(*s++); /* Write each character in string, one at a time */
    }
}



int main(void)
{
    unsigned int i;
    
    // Set up output pin for LED
    
    TRISB = 0x0000;
    TRISAbits.TRISA0 = 0;
    TRISAbits.TRISA1 = 0;
    TRISAbits.TRISA2 = 0;
    TRISAbits.TRISA3 = 0;
    
    PORTAbits.RA1 = 0;
    PORTAbits.RA2 = 0;
    PORTAbits.RA3 = 0;

    OSCCONbits.COSC = 0x7;
    OSCCONbits.NOSC = 0x7;
    CLKDIVbits.RCDIV = 0x6;

    Init_LCD();
    Clear_LCD();

    while(1)
    {

        Write_string_LCD("***pH Meter***");
        delay(100);


        // To make the LED blink visibly, we have to wait a while between toggling

        // the LED pin.
        for(i = 0; i < 65535; i++)
        {
            Nop();
            Nop();
            Nop();
            Nop();
        }
        

        // Toggle the LED output pin to alternate between the LED being on and off
        LATAbits.LATA0 ^= 1;
    }
}

Please help :S

 

[Vizier87]

Hi,
Actually you can also cut the chase and use libraries and the command will be like:

Lcd_Disp(0,1,"Hello!");

I think your compiler should also have a library for this. I presume you're using the Hitachi 16x2 LCD display, are you?

 

[natmag]

Yes i am using the Hitachi 16x2 LCD display.
Ill try using that command Thnx.

What is baffling me is why on debugging nothing is being written in the registers. For instance if I write

TRISBbits.RB1 = 0;

PORTBbits.RB1 = 1;

The value of RB1 doesnt change :S

 

[Vizier87]

Well you can toggle the pins via LED can you? I'd test if the pins respond to a simple program first if I were you.

 

[misterT]

Are you able to blink the LED in the real hardware? Maybe there is a bug in the simulator.

EDIT: Just like Vizier said.. make a simple LED blinkin program to test the hardware.

 

[natmag]

Im using the MPLAB C16 compiler and it doesnt have such a library to allow the use of the command Lcd_Disp(0,1,"Hello!");

 

[natmag]

The LED blinks in hardware but the LCD doesnot initialize and display the string of characters

 

[Ian Rogers]

RB1 has analogue input capability.... AD1CHS register needs to be set / unset..

 

[natmag]

Thanks that solved my problem

 

[misterT]

RB1 has analogue input capability.... AD1CHS register needs to be set / unset..

I think it would be strange if the analog input is enabled by default on reset. All IO pins on a microcontroller should be digital inputs (tristate) by default.. that is my opinion.

 

[Ian Rogers]

Pics always are.... You have to turn them off....

 

[misterT]

Pics always are.... You have to turn them off....

I haven't worked with pics for a long time and that was unexpected to me.. just shows that you really need to read the datasheet.

 

[Vizier87]

I haven't worked with pics for a long time and that was unexpected to me.. just shows that you really need to read the datasheet.

Yup but as I used MikroC before this, initialization on a pin basis is rare for me.

 

[Vizier87]

Im using the MPLAB C16 compiler and it doesnt have such a library to allow the use of the command Lcd_Disp(0,1,"Hello!");

Ouch... no libraries... are you sure? writing your own function for display takes a bit more time then. Oh well you did manage to display the basics though, did you?

 

[natmag]

Not as yet, it seems that when i try to initalise the LCD using the command function

void LCD_command(unsigned char c)
{
    LCD_rs = 0; /* Disable register select */
    LCD_rw = 0; /* Disable Read/Write */
    LCD_en = 1; /* Enable */
    delay(200);
    PORTB = c; /* Write Command on LCD pin */
    delay(200);
    LCD_en = 0; /* Disable */
}

and the character input c has a value of 0x38,the value 0x8 is being written on PORTB eventhough the whole port is set as a digital output

 

[Ian Rogers]

Im using the MPLAB C16 compiler and it doesnt have such a library to allow the use of the command Lcd_Disp(0,1,"Hello!");

Are you sure!!! The C30 compiler is for 16 bit chips.... The old C16 compiler hasn't been around for ages...

The C30 has oodles of libraries.....