Random Stuff: Getting data from ADXL345 From USART

A small update on Interfacing ADXL345 with ATmega32, this program will get raw data from ADXL345 working on I2C mode and send the data over USART.

To recieve data to PC over USART see this.
#include<avr/io.h>
#include<inttypes.h>
#include<util/delay.h>
#include<math.h>

#define F_CPU 8000000UL
#define error 0
#define success 1

//USART
void USART_Init( unsigned int baud )
{
    /* Set baud rate */
    UBRRH = (unsigned char)(baud>>8);
    UBRRL = (unsigned char)baud;
    /* Enable transmitter and receiver */
    UCSRB = (1<<TXEN)|(1<<RXEN);
    /* Set frame format: 8data, 2stop bit */
    UCSRC = (1<<URSEL)|(1<<USBS)|(3<<UCSZ0);
}

void USART_Transmit_char(char txdata )
{
    /* Wait for empty transmit buffer */
    while ( !( UCSRA & (1<<UDRE)) )
    ;
    /* Put data into buffer, sends the data */
    UDR = txdata;
}

unsigned char USART_Receive( void )
{
 /* Wait for data to be received */
 while ( !(UCSRA & (1<<RXC)) );
 /* Get and return received data from buffer */
 return UDR;
}

//This function can only send three digit integers.
void USART_Transmit_int(unsigned int i)
{
        unsigned char h,t,o;
        o= (i%10) | 0x30;//ones
        i/=10;
        t= (i%10) | 0x30;//tens
        i=i%100;
        h=(i/10) | 0x30;//hundreds
        USART_Transmit_char(h);
        USART_Transmit_char(t);
        USART_Transmit_char(o);
}
//Can only send xxx.xx type number
void USART_Transmit_float(const float f)
{
        unsigned int v,p;
        long int num;
        num=f*1000;
        p=num%1000;
        num=num/1000;
        v=num;

        USART_Transmit_int(v);
        USART_Transmit_char('.');
        USART_Transmit_int(p);

}

void USART_Transmit(char* txdata)
{
    int i = 0;
    while(txdata[i] != 0x00)
    {
        USART_Transmit_char(txdata[i]);
        i++;
    }

}

//TWI Initialization
void TWI_Init(void)
{
    //set SCL to 400kHz
    TWSR = 0x00;
    TWBR = 0x02;
    //enable TWI
    TWCR = (1<<TWEN);
}

//TWI Start Singnal
void TWI_Start(void)
{
    TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN);
    while ((TWCR & (1<<TWINT)) == 0);
}

//TWI fuction tio retrieve the status
uint8_t TWI_GetStatus(void)
{
    uint8_t status;
    //mask status
    status = TWSR & 0xF8;
    return status;
}

//Write command for TWI
void TWI_Write(uint8_t u8data)
{
    TWDR = u8data;
    TWCR = (1<<TWINT)|(1<<TWEN);
    while ((TWCR & (1<<TWINT)) == 0);
}


//Read NACK for TWI
//Return read data from TWCR
uint8_t TWIReadNACK(void)
{
    TWCR = (1<<TWINT)|(1<<TWEN);
    while ((TWCR & (1<<TWINT)) == 0);
    return TWDR;
}

uint8_t TWIReadACK(void)
{
 TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
 while((TWCR & (1<<TWINT)) == 0);

    return TWDR;
}


//Terminate TWI Interface
void TWI_Stop(void)
{
 TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
 while(TWCR & (1<<TWSTO));
}


//Function to write to ADXL345-Accelerometer
//CS has to be high for ADXL345 to work in I2C mode
//Supports standard 100KHz and fast 400KHz Mode
//ALT address pin grounded implies 0xA6 for write and 0xA7 for read
uint8_t ADXL_write(uint8_t reg, uint8_t data)
{
    TWI_Start();
    if(TWI_GetStatus() != 0x08)
    {
        return error;
    }
    TWI_Write(0b10100110);
    if(TWI_GetStatus() != 0x18)
    {
        return error;
    }
    TWI_Write(reg);
    if(TWI_GetStatus() != 0x28)
    {
        return error;
    }
    TWI_Write(data);
    if(TWI_GetStatus() != 0x28)
    {
        return error;
    }
    TWI_Stop();
    return success;
}

//Write multiple bits to ADXL345
uint8_t ADXL_Multi_write(uint8_t reg, uint8_t data1, uint8_t data2)
{
 TWI_Start();
 if(TWI_GetStatus() != 0x08)
 {
  return error;
 }
 TWI_Write(0b10100110);
 if(TWI_GetStatus() != 0x18)
 {
  return error;
 }
 TWI_Write(data1);
 if(TWI_GetStatus() != 0x28)
 {
  return error;
 }
 TWI_Write(data2);
 if(TWI_GetStatus() != 0x28)
    {
        return error;
    }
    TWI_Stop();
    return success;
}


//Fuction to read data sent from ADXL Accelerometer
uint8_t ADXL_read(uint8_t reg)
{
    uint8_t data;
    TWI_Start();
    if(TWI_GetStatus() != 0x08)
    {
        return error;
    }
    TWI_Write(0b10100110);
    if(TWI_GetStatus() != 0x18)
    {
        return error;
    }
    TWI_Write(reg);
    if(TWI_GetStatus() != 0x28)
    {
        return error;
    }
    TWI_Start();
    if(TWI_GetStatus() != 0x10)
    {
        return error;
    }
    TWI_Write(0b10100111);
    if(TWI_GetStatus() != 0x40)
    {
        return error;
    }
    data = TWIReadNACK();
    if(TWI_GetStatus() != 0x58)
    {
        return error;
    }
    TWI_Stop();
    return data;
}

int main (void)
{
 //initialize USART
 USART_Init(51);
 //USART_Transmit_char('H');
 //initialize TWI
 TWI_Init();
 //Initailze ADXL345
 uint8_t x1,x2,y1,y2,z1,z2;
 //set ADXL to 400 Hz
 ADXL_write(0x2c,0b00001100);
 _delay_ms(100);
 ADXL_write(0x31,0b01000010);
 _delay_ms(100);
 ADXL_write(0x2D,0x00);
 _delay_ms(100);
 ADXL_write(0x2d,0x16);
 _delay_ms(100);
 ADXL_write(0x2d,0x08);
 _delay_ms(100);
 while(1)
 {
  x1 = ADXL_read(0x32);
  x2 = ADXL_read(0x33);
  y1 = ADXL_read(0x34);
  y2 = ADXL_read(0x35);
  z1 = ADXL_read(0x36);
  z2 = ADXL_read(0x37);
  x1 += (x2<<8);
  z1 += (z2<<8);
  y1 += (y2<<8);
  USART_Transmit("x1 =");
  USART_Transmit_int(x1);
  USART_Transmit("y1 =");
  USART_Transmit_int(y1);
  USART_Transmit("z1 =");
  USART_Transmit_int(z1);
  USART_Transmit("\n");
  _delay_ms(100);
 }
}
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Monday, September 28, 2015

Getting data from ADXL345 From USART - ATmega32

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