PIC Vietnam - One wire in PIC16F84A

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One wire in PIC16F84A

Hi everyone,

I'm just a new "apprentice" in this field. I'm contemporarily learning how to transfer data from one PIC16F84A to the other one, including how to receive the data, of course. I can read and understand MPAsm, Mikro Basic and CCS C quite well; so, if you know about this, you can help me in the aforementioned language. Thank you in advance.

B

Trích:

Nguyên văn bởi briantk_1988

Hi briantk,

There are many ways to do what you want, using different interface protocols and standards. Unfortunately, PIC16F84A doesn't give you much power to do a lot of stuff in implementing those protocols and standards.

So, could you be more specific on what you are trying to do?
What sort of data are you transferring?
How fast would you like your data to be transferred?
Have you got any idea about the interface protocol/standard?

Cheers,

Thanks a lot for replying me.

I'm trying to make a simple calculator. As far as I am concerned, an LCD display requires 6 pins from the microcontroler, a simplest keypad needs 8 more pins --> we need at least 14 IO pins which is impossible for an PIC16F84A. Unfortunately, since I haven't a clue about microcontroler before, I just though everything was the same which made me I got the PIC16F84A. Now, I'm thinking that I might use one PIC6F84A for the keypad and then use one wire interface to transmiss the information to the other one which will manipulate the data and then display in the LCD. I did read the onewire example in MikroBasic but it's not satifiable, for the example is just for getting data from a themometer (DS1820). Furthermore, I think that I don't need a very high speed to do this task. Also, I'm just a novice, I have a very humble idea about interface protocol/standard. So, if anyone have any idea about what i gotta do, I'm very grateful to know.

Thanks in advance

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

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

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

Code:

////////////////////////////////////////////////////////////////////////////

//// 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

Code:

#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

}