Pic : RS232 communication

RS232 communication on PIC

I will make the remote controller device by using XBEE. Before that, PC and PIC communication is tested.

18f2320 is used.

RX/TX port are used and TRISCbits.RC7 is set to be input I/O and TRISCbits.RC6 is set to output one. Also TRISCbits.RC6 is set to high.

Please check below setting is set correctly.

• SPEN (RCSTA<7>) bit must be set (= 1)

• TRISC<7> bit must be set (= 1)

• TRISC<6> bit must be cleared (= 0)

Below program needs windows' hyper terminal input.

10MHz clock is multiplied by config. HSPLL so clock is 40MHz.

Then, baud rate is 115.2kHz. 

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

//main program

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

#include <p18f2320.h>

#include <i2c.h>

#include <usart.h>

#include "i2cLCD.h"

#include "wait.h"

#pragma config OSC=HSPLL, FSCM=OFF, IESO=OFF, PWRT=ON

#pragma config BOR=ON, BORV=27, WDT=OFF, WDTPS=1024

#pragma config MCLRE=ON, PBAD=DIG, CCP2MX=C1

#pragma config STVR=OFF, LVP=OFF, DEBUG=OFF

#pragma config CP0=OFF, CP1=OFF, CP2=OFF, CP3=OFF, CPB=OFF

#pragma config CPD=OFF, WRT0=OFF, WRT1=OFF, WRT2=OFF, WRT3=OFF

#pragma config WRTB=OFF, WRTC=OFF, WRTD=OFF, EBTR0=OFF

#pragma config EBTR1=OFF, EBTR2=OFF, EBTR3=OFF, EBTRB=OFF

void main(void)

{

char test[]="AQM0802A";

char inputFromPC[] = "From PC";

char inputMsg[]="\r\nInput 5 characteristic= ";

char bufLcd[10]={0,0,0,0,0,0,0,0,0,0};

//I2C initialization

TRISC = 0x18;

SSPADD = 24; //MCLK40MHz / (4*(SSPAD+1)) = 400khz

  SSPCON1 = 0b00101000;

wait_ms(100);

lcdIni();

lcdCommand(LCD_1ST_LINE);

lcdPrintSting(test);

wait_ms(200);

lcdCommand(LCD_CLEAR);

//USART

TRISC |= 0x80;

LATC = 0x40; 

RCSTAbits.SPEN=1;

OpenUSART(USART_TX_INT_OFF & USART_RX_INT_OFF &

USART_ASYNCH_MODE & USART_EIGHT_BIT &

USART_CONT_RX & USART_BRGH_HIGH,21);

while(1)

{

putsUSART(inputMsg);

getsUSART(bufLcd,5);

lcdCommand(LCD_CLEAR);

wait_ms(2);

lcdCommand(LCD_1ST_LINE);

lcdPrintSting(inputFromPC);

lcdCommand(LCD_2ND_LINE);

lcdPrintSting(bufLcd);

}

}

Pic : LCD AQM0802A driving

Driving AQM0802A LCD

I have bought AQM0802A which can be driven by the I2C bus.

Driving voltage is 3.3V so PIC is also driven by 3.3V for connecting by I2C.

Below is the example code of driving the LCD.

This ic has the function of continuous sending, but below code is only sending each byte every time. 

Sending each byte needs slave address, control byte and data byte.

By setting control byte, clear, changing cursor and etc can be implemented like SD1602 display.

This ic only needs 2 wire from Pic so we can use lots of port comparing with SD1602.

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

i2cLCD.h

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

#ifndef I2C_FUNCTION

#define I2C_FUNCTION

#define SLV_ADDR 0x7C

#define LCD_CLEAR 0x01

#define LCD_1ST_LINE 0x80

#define LCD_2ND_LINE 0xC0

int lcdCommand(char cmd);

int lcdIni(void);

int lcdByteWrite(unsigned char cmd, unsigned char data);

int lcdPrintSting(char* str);

#endif

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

i2c functions

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

#include <p18f2320.h>

#include <delays.h>

#include <i2c.h>

#include "i2cLCD.h"

#include "wait.h"

int lcdPrintSting(char* str)

{

char byteRsOn=0x40;

//Send buffer data

while(*str!=0x00)

{

lcdByteWrite(byteRsOn, *str);

str++;

}

return 0;

}

int lcdCommand(char cmd)

{

lcdByteWrite(0x00, cmd);

return 0;

}

int lcdIni(void)

{

OpenI2C(MASTER,SLEW_OFF);

//Function set

lcdByteWrite(0x00, 0x38);

wait_ms(1);

//Function set, IS=1

lcdByteWrite(0x00, 0x39);

wait_ms(1);

//Internal osc freq. setting

lcdByteWrite(0x00, 0x14);

wait_ms(1);

//Contrast set

lcdByteWrite(0x00, 0x70);

wait_ms(1);

//Power/ICON/Contrast control

lcdByteWrite(0x00, 0x56);

wait_ms(1);

//Follower control

lcdByteWrite(0x00, 0x6C);

wait_ms(300);

//Function set

lcdByteWrite(0x00, 0x38);

wait_ms(1);

//Dispaly on/off control

lcdByteWrite(0x00, 0x0C);

wait_ms(1);

//Clear dispaly

lcdByteWrite(0x00, 0x01);

wait_ms(2);

    return 0;

}

int lcdByteWrite(unsigned char cmd, unsigned char data)

{

//Start Condition

    IdleI2C();

    StartI2C();

    while(SSPCON2bits.SEN){;}

        

//Write Slave Address wtih Write mode

    if(WriteI2C(SLV_ADDR)<0){return -1;}

IdleI2C();

    //Send control byte

    if(WriteI2C(cmd)<0){return -2;}

IdleI2C();

//Write data

if(WriteI2C(data)<0){return -3;}

//Send Stop

IdleI2C();

    StopI2C();

while(SSPCON2bits.PEN);

Delay10TCYx(4);

    

return 0;

}

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

//main: 10MHz external OSC is used

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

void main(void)

{

char test[]="AQM0802A";

  //I2C initialization

TRISC = 0x18;

SSPADD = 24; //MCLK40MHz / (4*(SSPAD+1)) = 400khz

  SSPCON1 = 0b00101000;

wait_ms(100);

lcdIni();

lcdCommand(LCD_1ST_LINE);

lcdPrintSting(test);

lcdCommand(LCD_2ND_LINE);

lcdPrintSting(test);

while(1)

{

}