LCD Interfacing using msp430

By Prabeesh Keezhathra

July 4, 2012 - 3 minutes read - 468 words

There is a pot connect to the ADC of msp430 Ao(pin p1.0). The values of ADC10MEM displayed using LCD.

The Vcc for pot is taken from msp430 launchpad.so maximum voltage is 3.6v.

The msp430 10 bit ADC operates in the range 0 to 3.6V. If the input voltage is 0V,

the ADC generates a 10 bit value:

0 0 0 0 0 0 0 0 0 0

which is numerically equal to 0.

When the input voltage is 3.6V, the ADC

generates a 10 bit pattern:

1 1 1 1 1 1 1 1 1 1

which is numerically equal to 1023.

These values are stored in ADC10MEM.

The Vcc for LCD is given using another power supply of 5v.Because LCD display needed 5v for its functioning.

#include <msp430.h>

#define LCM_DIR P1DIR
#define LCM_OUT P1OUT

#define LCM_PIN_RS BIT2 // P1.2
#define LCM_PIN_EN BIT1 // P1.1
#define LCM_PIN_D7 BIT7 // P1.7
#define LCM_PIN_D6 BIT6 // P1.6
#define LCM_PIN_D5 BIT5 // P1.5
#define LCM_PIN_D4 BIT4 // P1.4
#define LCM_PIN_MASK ((LCM_PIN_RS | LCM_PIN_EN | LCM_PIN_D7 | LCM_PIN_D6 | LCM_PIN_D5 | LCM_PIN_D4))

#define FALSE 0
#define TRUE 1

//msp430 adc

void adc_init()

{
	ADC10CTL0 = ADC10ON | ADC10SHT_2 | SREF_0;
	ADC10CTL1 = INCH_0 | SHS_0 | ADC10DIV_0 | ADC10SSEL_0 | CONSEQ_0 ;
	ADC10AE0 = BIT0;
	ADC10CTL0 |= ENC ;
}

void start_conversion()

{
	ADC10CTL0 |= ADC10SC;
}

unsigned int converting()
{
	return ADC10CTL1 & ADC10BUSY;
}

// MSP430 LCD Code
void PulseLcm()
{	
	// pull EN bit low	
	LCM_OUT &= ~LCM_PIN_EN;
	__delay_cycles(200);
	// pull EN bit high	
	LCM_OUT |= LCM_PIN_EN;
	__delay_cycles(200);
	// pull EN bit low again	
	LCM_OUT &= (~LCM_PIN_EN);
	__delay_cycles(200);
}

void SendByte(char ByteToSend, int IsData)
{
	// clear out all pins	
	LCM_OUT &= (~LCM_PIN_MASK);	
	LCM_OUT |= (ByteToSend & 0xF0);	

	if (IsData == TRUE)
	{
		LCM_OUT |= LCM_PIN_RS;
	}
	else
	{
		LCM_OUT &= ~LCM_PIN_RS;
	}

	PulseLcm();
	LCM_OUT &= (~LCM_PIN_MASK);
	LCM_OUT |= ((ByteToSend & 0x0F) << 4);	

	if (IsData == TRUE)
	{
		LCM_OUT |= LCM_PIN_RS;
	}
	else
	{
		LCM_OUT &= ~LCM_PIN_RS;
	}	

	PulseLcm();
}

void LcmSetCursorPosition(char Row, char Col)
{
	char address;
	// construct address from (Row, Col) pair	

	if (Row == 0)
	{
		address = 0;
	}
	else
	{
		address = 0x40;
	}

	address |= Col;
	SendByte(0x80 | address, FALSE);
}

void ClearLcmScreen()
{
	// Clear display, return home
	SendByte(0x01, FALSE);
	SendByte(0x02, FALSE);
}

void InitializeLcm(void)
{
	LCM_DIR |= LCM_PIN_MASK;
	LCM_OUT &= ~(LCM_PIN_MASK);	
	__delay_cycles(100000);	
	LCM_OUT &= ~LCM_PIN_RS;
	LCM_OUT &= ~LCM_PIN_EN;	
	LCM_OUT = 0x20;
	PulseLcm();	
	SendByte(0x28, FALSE);	
	SendByte(0x0E, FALSE);	
	SendByte(0x06, FALSE);
}

void PrintStr(char *Text)
{
	char *c;
	c = Text;

	while ((c != 0) && (*c != 0))
	{
		SendByte(*c, TRUE);
		c++;
	}
}

void main(void)
{
	adc_init();	
	int i,a;	
	char b[5];	
	WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer	
	InitializeLcm();	

	while(1)
	{	

		start_conversion();	
		while(converting());	
		a = ADC10MEM;	
		itoa(a,b,10);//integer to ASCII	
		ClearLcmScreen();	
		PrintStr(b);	
		for(i=0;i<5000;i++);
	} 
}

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