/*
3-21-11
Aaron Weiss, aaron at sparkfun dot com
License: Creative Commons Attribution Share-Alike 3.0
http://creativecommons.org/licenses/by-sa/3.0
v10 Example
-outputs x,y,z acceleration values every 1 ms
-output is driven by a timer overflow interrupt, this allows the user to
more easily add additional code without messing with the timing
-values are in g's
LIS331 Accelerometer Configuration:
4-wire SPI, normal mode, 400Hz
Hardware:
Atmega328p, 3.3V, ext. 8MHz, 38400 baud
Hardware Conections (LIS to Arduino):
LIS331 | Arduino
---------------------
VCC | VCC (3.3V)
CS | pin 10 (PB2)
SCL | pin 13 (PB5)
SA0 | pin 12 (PB4)
SDA | pin 11 (PB3)
GND | pin GND
Note: if you need a higher sampling frequency, you need to run a higher clock,
INT functionality not used
*/
#include <stdlib.h>
#include <stdio.h>
#include <avr/io.h>
#include <avr/pgmspace.h>
#include <avr/interrupt.h>
#define MYUBRR 12 //8MHz, 38400bps
#define sbi(var, mask) ((var) |= (uint8_t)(1 << mask))
#define cbi(var, mask) ((var) &= (uint8_t)~(1 << mask))
#define MOSI 3 //PORTB
#define MISO 4 //PORTB
#define SCK 5 //PORTB
#define CS 2 //PORTB
#define SCALE 0.0007324 //sets g-level (48 fullscale range)/(2^16bits) = SCALE
///============Initialize Prototypes=====================///////////////////////
void ioinit(void); // initializes IO
void UART_Init(unsigned int ubrr);
static int uart_putchar(char c, FILE *stream);
uint8_t uart_getchar(void);
static FILE mystdout = FDEV_SETUP_STREAM(uart_putchar, NULL, _FDEV_SETUP_WRITE);
void delay(uint16_t x); // general purpose delay
/////======SPI functions=================================////////////////////////
void SPI_MasterInit(void);
void SPI_MasterTransmit(uint8_t address);
/////======Main Prototypes================================////////////////////////
void config(void);
uint8_t read(uint8_t addr);
void accel(void);
///===========Global Vars=============================//////////////////////////
volatile double xaccel, yaccel, zaccel;
//=========MAIN================/////////////////////////////////////////////////
ISR(TIMER1_OVF_vect)
{
//every ms the acceleration values are printed
TCNT1 = 55536;//(8/8MHz)*(65536bits-55536)=0.01s
accel(); //update LIS registers
printf("z=%6.2f\n\r", zaccel
); }
int main(void)
{
ioinit(); //Setup IO pins and defaults
SPI_MasterInit();
config();
while(1)
{
//put your code here
}
return (0);
}
void config(void)
{
cbi(PORTB, CS);
delay(1);
SPI_MasterTransmit(0x20); //write to 0x20
SPI_MasterTransmit(0x37); //normal mode, 400Hz, xyz-enabled
delay(1);
sbi(PORTB, CS);
delay(100);
cbi(PORTB, CS);
delay(1);
SPI_MasterTransmit(0x21); //write to 0x21
SPI_MasterTransmit(0x00); //HP filter ON (cuttoff@8MHz) = 0x60, HPfilter OFF = 0x00
delay(1);
sbi(PORTB, CS);
delay(100);
cbi(PORTB, CS);
delay(1);
SPI_MasterTransmit(0x23); //write to 0x23
SPI_MasterTransmit(0x30); //24g
delay(1);
sbi(PORTB, CS);
}
//usage: read('hex address'), e.g. read(0x20), reads CTRL_REG1
//returns the value in the address, e.g. read(0x20) = 0x07, returns the default value of 0x20
uint8_t read(uint8_t addr)
{
uint8_t regbyte;
uint8_t read = 0;
read |= (1<<7);
uint8_t byte = 0;
byte = read | addr;
cbi(PORTB, CS);
delay(1);
SPI_MasterTransmit(byte);
SPI_MasterTransmit(0x00); //must keep clock moving, so tx another byte
regbyte = SPDR;
delay(1);
sbi(PORTB, CS);
return(regbyte);
}
void accel(void)
{
uint16_t xl, xh, yl, yh, zl, zh;
int16_t tempx, tempy, tempz;
cbi(PORTB, CS);
SPI_MasterTransmit(0xe8); //read bit | consecutive measure bit | 0x28 = 0xe8
SPI_MasterTransmit(0x00); //must keep clock moving, so tx another byte
xl = SPDR;
SPI_MasterTransmit(0x00); //must keep clock moving, so tx another byte
xh = SPDR;
SPI_MasterTransmit(0x00); //must keep clock moving, so tx another byte
yl = SPDR;
SPI_MasterTransmit(0x00); //must keep clock moving, so tx another byte
yh = SPDR;
SPI_MasterTransmit(0x00); //must keep clock moving, so tx another byte
zl = SPDR;
SPI_MasterTransmit(0x00); //must keep clock moving, so tx another byte
zh = SPDR;
sbi(PORTB, CS);
tempx = (xl|(xh << 8)); //concatenate low and high bits together, load into signed 16 bit
xaccel = SCALE*tempx; //multiply by scale factor for g-level
tempy = (yl|(yh << 8));
yaccel = SCALE*tempy;
tempz = (zl|(zh << 8));
zaccel = SCALE*tempz;
}
////////////////////////////////////////////////////////////////////////////////
///==============Initializations=======================================/////////
////////////////////////////////////////////////////////////////////////////////
void ioinit (void)
{
//1 = output, 0 = input
DDRB = 0b11101111; //input on PB4 = MISO
DDRD = 0b11110010; //PORTD (RX on PD0)
sbi(PORTB, CS);
UART_Init(MYUBRR);
// Setting Timer 1
// normal mode
TCCR1A = 0x00;
// Set to clk/8
TCCR1B |= (1<<CS11);
//enable overflow interrupt
TIMSK1 |= (1<<TOIE1);
//load timer with a value to optimize for 1 second,
TCNT1 = 55536; //(8/8MHz)*(65536bits-55536)=0.01s
sei(); //turn on global interrupts and enable timer
}
void UART_Init(unsigned int ubrr)
{
int ubrr_new;
// set baud rate
ubrr_new = ubrr;
UBRR0H = ubrr_new>>8;
UBRR0L = ubrr_new;
// Enable receiver and transmitter
UCSR0A = (0<<U2X0); //double UART speed
UCSR0B = (1<<RXEN0)|(1<<TXEN0);
// Set frame format: 8 bit, no parity, 1 stop bit,
UCSR0C = (1<<UCSZ00)|(1<<UCSZ01);
stdout = &mystdout; //Required for printf init
}
static int uart_putchar(char c, FILE *stream)
{
if (c == '\n') uart_putchar('\r', stream);
loop_until_bit_is_set(UCSR0A, UDRE0);
UDR0 = c;
return 0;
}
uint8_t uart_getchar(void)
{
while( !(UCSR0A & (1<<RXC0)) );
return(UDR0);
}
//General short delays
void delay(uint16_t x)
{
uint8_t y;
for ( ; x > 100 ; x--){
for ( y = 0 ; y < 200 ; y++){
asm volatile ("nop");
}
}
}
//==========================//
//
//SPI functions
//
//==========================//
void SPI_MasterInit(void)
{
DDRB = (1<<DDB3)|(1<<DDB5)|(1<<DDB2)|(1<<DDB1);
SPCR = (1<<SPE)|(1<<MSTR)|(1<<CPOL)|(1<<CPHA);
}
void SPI_MasterTransmit(uint8_t address)
{
SPDR = address;
while(!(SPSR & (1<<SPIF)));
}
