One wire in PIC16F84A

[BêBop]

Chảo Briantk,
I agree with namqn, that the 'f84 is not the best choice. It is old, and has no USART, etc. etc. Next time try a 16F628A, or a 16F88. You can free up some pins by using a 2 wire LCD interface, though. Take a look at this site for the hardware:
http://www.rentron.com/Myke1.htm

He gives examples in assembly, and somewhere I have source in ccs C to run it. I will try and find my source if you wish to go this route. I'm quite busy these days as I will move back to Canada in 3 weeks, but I'll watch this forum to see if you are interested.

Regards

[briantk_1988]

Thanks so much. It must be the best that you can provide me with the source in CCS C. I hope you can post it soon

Regards

Br

[BêBop]

Chảo,
I hope this works, but if you have any questions, I'll keep watching here...
first the driver

////////////////////////////////////////////////////////////////////////////
//// Library for a 2 wire LCD interface using an 74hc174		////
////									////
////									////
////////////////////////////////////////////////////////////////////////////

#ifndef LCD_clk
#define LCD_data 	PIN_B2
#define LCD_clk		PIN_B1
#endif

void LCDInit(void)	{		//  Initialize the LCD I/O Pins

	Dlay = RTC +20;
	while (Dlay != RTC);

	LCDNybble(0x003, 0);  // send init command
	Dlay = RTC + 6;			// wait > 5 mSec for
	while (Dlay != RTC);	// LCD to accept cmd

	LCDNybble(0x003, 0);  // send init command
	Dlay = RTC + 1;			// wait > 160 uSec for
	while (Dlay != RTC);	// LCD to accept cmd

	LCDNybble(0x003, 0);  // send init command
	Dlay = RTC + 1;			// wait > 160 uSec for
	while (Dlay != RTC);	// LCD to accept cmd

	LCDNybble(0x002, 0);  // send init command	0000 0010
	Dlay = RTC + 6;			// wait > 5 msec for
	while (Dlay != RTC);	// LCD to accept cmd

	LCDByte(0x028, 0);		// step 6, set operating	0010 1000

	LCDByte(0x008, 0);		// step 7, display off		0000 1000

	LCDByte(0x001, 0);		// step 8, clear display	0000 0001

	LCDByte(0x006, 0);		// step 9, shift		0000 0110

	LCDByte(0x00E, 0);		// step 10, display on		0000 1110

}  //  End LCDInit

void LCDNybble(char Nybble, char RS) { 		//  Send Nybble to LCD

	int i; // removed unsigned from before int

	output_low(PIN_B2);	//Data = 0; // Clear the '174 
	for (i = 0; i < 6; i++) { 		// Repeat for six bits 
		//Clock = 1; Clock = 0; 	// Write the "0"s into the '174 
		output_high(PIN_B1);
		output_low(PIN_B1);
		}   //  endfor 

	//Data = 1; 				// Output the "AND" Value 
	output_high(PIN_B2);
	//Clock = 1; Clock = 0;
	output_high(PIN_B1);
	output_low(PIN_B1);
//	Data = RS; 				// Output the RS Bit Value 
	if (RS>0)output_high(PIN_B2);
		else output_low(PIN_B2);
	//Clock = 1; Clock = 0; 
		output_high(PIN_B1);
		output_low(PIN_B1);

	for (i = 0; i < 4; i++) { 		// Output the Nybble 
		if ((Nybble & 0x008) != 0) 
		//	Data = 1; 		// Output the High Order Bit
			output_high(PIN_B2);
		else 
			//Data = 0; 
			output_low(PIN_B2);
		//Clock = 1; Clock = 0; 		// Strobe the Clock 
		output_high(PIN_B1);
		output_low(PIN_B1);

		Nybble = Nybble << 1; 		// Shift up Nybble for Next Byte 
		}  //  endfor

//	Data = 1; Data = 0; 			// Toggle the "E" Clock Bit 
	output_high(PIN_B2);
	output_low(PIN_B2);
}  //  End LCDNybble 

void LCDByte(char myByte, char RS) {	 //  Send Byte to LCD	
	int LBDlay;

	LCDNybble((myByte >> 4) & 0x00F, RS);	//  Send High Nybble

	LCDNybble(myByte & 0x00F, RS);		//  Send Low Nybble

	if ((myByte < 4) && (RS == 0))  // type of instruction
		LBDlay = RTC + 6;
	else
		LBDlay = RTC + 2;

	while (LBDlay != RTC); // command to complete wait
}  //  End LCDByte

void send_c(char myByte) {	 		//  Send Byte to LCD	
	int LBDlay;
	char RS = 1;

	LCDNybble((myByte >> 4) & 0x00F, RS);	//  Send High Nybble

	LCDNybble(myByte & 0x00F, RS);		//  Send Low Nybble

	if ((myByte < 4) && (RS == 0))  	// type of instruction
		LBDlay = RTC + 6;
	else
		LBDlay = RTC + 2;

	while (LBDlay != RTC); 			// command to complete wait
}  //  End send_c

void SecondLine(void) {
	LCDByte(0xC0, 0);
	} // end SecondLine

void Home(void) {
	LCDByte(0x02, 0);
	} // end Home

void ClearLCD(void) {
	LCDByte(0x01, 0);
	} // end ClearLCD

then a test program

#if defined(__PCM__)
#include <16F84A.h>
#fuses HS,NOWDT,NOPROTECT
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_B6, rcv=PIN_B7)
#endif

#include "LCDHG.C"
#include <STDIO.h>
#include <string.h>

#define CDCLK Pin_B1

//#define LCDDAT Pin_B2

void main() {
	int x, y, c;
	x = 0x01;
	y = 0x01;
	c = 0x55;
//	char *c;// = "H";
//	char string[20];
	//c="H";

	lcd_init();
	lcd_gotoxy(x, y);

	lcd_putc("\f");
	lcd_putc(0x55);

	while(1) {
	;
	} // end while
}