AVR microcontroller IIC experiment-EEWORLD

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//Chip ATMEGA16 crystal oscillator 8mhz

#include

#define uchar unsigned char

#define uint unsigned int

//-----------------------------

uchar str1[]={"IIC TEST"};

//---------------------------

void delay(uint k) //delay function

{

uint i,j;

for(i=0;i

for(j=0;j<1140;j++);

}

#include "1602.h" //1602 library functions

//-------Key input point settings-------

#define s1 (PIND&0x10) //Variable value increase key

#define s2 (PIND&0x20) // variable value reduction key

#define s3 (PIND&0x40) //storage key

#define s4 (PIND&0x80) //Read key

//-------------------

#define TWINT 7 //interrupt flag

#define TWEN 2 //Interrupt

#define TWSTA 5 //Start status bit

#define TWSTO 4 //Stop status bit

//-----TWI status definition, MT master mode transmission, MR master mode reception

#define START 0x08 //Start

#define RE_START 0x10 // Restart

#define MT_SLA_ACK 0x18 //Host response

#define MT_SLA_NOACK 0x20 // Host does not respond

#define MT_DATA_ACK 0x28 //Host responds after data transmission

#define MT_DATA_NOACK 0x30 // Host does not respond after data transmission

#define MR_SLA_ACK 0x40 //Slave response

#define MR_SLA_NOACK 0x48 //Slave no response

#define MR_DATA_ACK 0x50 //Slave data response

#define MR_DATA_NOACK 0x58 //Slave data no response

//-------------------------

#define start() (TWCR=(1<

#define stop() (TWCR=(1<

#define wait() {while(!(TWCR&(1<

#define testack() (TWSR&0xf8) //TWI status detection, shield pre-scaling bit

#define setack() (TWCR|(1<

#define setnoack() (TWCR&=~(1<

#define twi() (TWCR=(1<

#define writebit(x) {TWDR=(x);TWCR=(1<

//------I/0 port settings------------

void portinit()

{

PORT=0xff;

DDRA=0xff;

PORTB=0xff;

DDRB=0xff;

PORTC=0xff;

DDRC=0xff;

PORTD=0xff;

DDRD=0x00;

}

//-----------Read data function----------

uchar iicread(uchar address)

{

flying tempo;

start();

wait();

if(testack()!=START) return 0;

writebit(0xa0);

wait();

if(testack()!=MT_SLA_ACK) return 0;

writebit(address);

wait();

if(testack()!=MT_DATA_ACK) return 0;

start();

wait();

if(testack()!=RE_START) return 0;

writebit(0xa1);

wait();

if(testack()!=MR_SLA_ACK) return 0;

twi();

wait();

if(testack()!=MR_DATA_NOACK) return 0;

temp=TWDR;

stop();

return temp;

}

//---------------Write data function----------------

uchar iicwrite(uchar address,uchar data)

{

start();

wait();

if(testack()!=START) return 1;

writebit(0xa0);

wait();

if(testack()!=MT_SLA_ACK) return 1;

writebit(address);

wait();

if(testack()!=MT_DATA_ACK) return 1;

writebit(data);

wait();

if(testack()!=MT_DATA_ACK) return 1;

stop();

delay(10);

return 0;

}

void main()

{

uchar val=0; //data value variable

portinit();

delay(200);

heat();

delay(200);

display(2,0,str1);

delay(200);

while(1)

{

displayz(5,1,val/10+0x30);

displayz(6,1,val%10+0x30);

delay(10);

if(s1==0) //value increase key

{

delay(100); //Software delay 100ms to prevent key jitter

if(s1==0)

{

val++;

if(val>30)val=0;

}

if(s2==0) //value decrease key

{

delay(100);

if(s2==0)

{

val--;

if(val<1)val=40;

}

if(s3==0) //value storage key

{

delay(100);

if(s3==0)

{

iicwrite(70,val);

}

if(s4==0) //value read key

{

delay(100);

if(s4==0)

{

val=iicread(70);

}

[page]

//-------------------1602.h--------------------

//------------1602.h-------------

#define RS1 PORTB_Bit0=1

#define RS0 PORTB_Bit0=0

#define RW1 PORTB_Bit1=1

#define RW0 PORTB_Bit1=0

#define EN1 PORTB_Bit2=1

#define EN0 PORTB_Bit2=0

#define DATAPORT PORTA

#define busy 0x80

void wait()

{

fly shaft;

DATAPORT=0xff;

RS0;

RW1;

__no_operation();

EN1;

__no_operation();

DDRA=0x00;

val=PINA;

while(val&busy)val=PINA;

EN0;

DDRA=0xff;

}

void writecmd(uchar w)

{

wait();

RS0;

RW0;

__no_operation();

DATAPORT=in;

__no_operation();

EN1;

__no_operation();

EN0;

}

void writedata(uchar data)

{

wait();

RS1;

RW0;

__no_operation();

DATAPORT=data;

__no_operation();

EN1;

__no_operation();

EN0;

}

void delay_nms(uint k)

{

uint i,j;

for(i=0;i

for(j=0;j<1140;j++);

}

void init()

{

delay_nms(15);

writecmd(0x38);

delay_nms(5);

writecmd(0x38);

delay_nms(5);

writecmd(0x38);

writecmd(0x80);

writecmd(0x01);

writecmd(0x06);

writecmd(0x0c);

}

void display(fly x,fly y,fly *p)

{

fly add=0x80;

y=y&0x01;

x=x&0x0f;

if(y)add=add+0x40;

writecmd(add+x);

while(*p!='')

{

writedata(*p++);

}

void displayz(fly x,fly y,fly k)

{

fly add=0x80;

y=y&0x01;

x=x&0x0f;

if(y)add=add+0x40;

writecmd(add+x);

writedata(k);

}

Keywords：AVR Reference address：AVR microcontroller IIC experiment

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