0,0 → 1,140 |
/* compass.c |
* |
* Software to read from the CMPS03 magnetic compass. |
* |
|
#include <errno.h> |
#include <string.h> |
#include <stdio.h> |
#include <stdlib.h> |
#include <unistd.h> |
#include <fcntl.h> |
#include <linux/i2c-dev.h> |
|
/* Note that the documentation for the compass states its address as 0xC0. |
* However, this includes the low bit which specifies read or write. |
* Linux i2c does not include this bit in this address, so the actual |
* address is 0xC0 shifted down, 0x60. |
*/ |
|
#define CMPS_Addr (0xC0>>1) |
#define I2C_SLAVE 0x0B /* Change slave address |
|
/* The important registers on the compass. Internal/test registers omitted. */ |
#define CMPS03_SOFTWARE_REVISION 0x0 |
#define CMPS03_BEARING_BYTE 0x1 |
#define CMPS03_BEARING_WORD_HIGH 0x2 |
#define CMPS03_BEARING_WORD_LOW 0x3 |
#define CMPS03_CALIBRATE_CMD 0xF |
|
void I2C_addr (int Addr) // vybere adresu cidla se kterym se bude komunikovat |
{ |
if (ioctl(file, I2C_SLAVE, Addr) == -1) |
{ |
fprintf(stderr, "Failed to set address to 0x%02x.\n", Addr); |
exit(-5); |
} |
} |
|
int i2c_init() // zinicializuje i2c |
{ |
file = open("/dev/i2c-0", O_RDWR); |
if (file < 0) |
{ |
cerr << "Could not open /dev/i2c-0." << endl; |
return -1; |
} |
return 0; |
} |
|
unsigned char read_azimut_mag() // precte azimut z kompasu |
{ |
char Buf[3]; // promena pro manipulaci s i2c |
|
I2C_addr(CMPS_Addr); |
Buf[0]=1; |
write(file,Buf,1); |
read(file, Buf,1); |
return (Buf[0]-SEVER); |
} |
|
void calib() // kalibrace kompasu |
{ |
char Buf[3]; // promena pro manipulaci s i2c |
|
I2C_addr(CMPS_Addr); |
Buf[0]=15; |
Buf[1]=0xFF; |
write(file,Buf,2); |
} |
|
int main(int argc, char *argv[]) |
{ |
char *end; |
int res,file; |
int error; |
char filename[20] ; |
long funcs; |
|
int heading_byte, heading_word_h, heading_word_l; |
int bearing_long, bearing_degrees; |
|
sprintf(filename,"/dev/i2c-0"); |
file = open(filename,O_RDWR); |
if (errno != 0) |
{ |
switch (errno) |
{ |
case EACCES: |
fprintf(stderr,"Run as root? \n"); |
break; |
default: |
fprintf(stderr,"Error: Could not open file '%s' : %s \n", filename, strerror(errno)); |
break; |
} |
} |
|
if (ioctl(file,I2C_SLAVE,CMPS03_ADDR) < 0) { |
switch (errno) |
{ |
case EBUSY: |
printf("device is busy \n"); |
break; |
|
default: |
printf("Got error: %s \n", strerror(errno)); |
exit(0); |
} |
} |
|
/* Get software revision number */ |
res = read(file, CMPS03_SOFTWARE_REVISION,1); |
if (res < 0) { |
printf("Cannot read software revision level \n"); |
} else { |
printf("Software revision level: %02x \n", res); |
} |
|
/* Loop and read from the compass. */ |
while (1) { |
/* The heading byte is 0-255 for the 360 degrees. */ |
heading_byte = read(file, CMPS03_BEARING_BYTE,1); |
if (heading_byte < 0) { printf("Error reading from compass. \n"); exit(1);} |
|
/* The high resolution heading is given in two registers, and is 10 * the |
* heading in degrees, ie 359.9 degrees reads as 3599. */ |
heading_word_h = read(file, CMPS03_BEARING_WORD_HIGH,1); |
if (heading_word_h < 0) { printf("Error reading from compass. \n"); exit(1);} |
heading_word_l = read(file, CMPS03_BEARING_WORD_LOW,1); |
if (heading_word_l < 0) { printf("Error reading from compass. \n"); exit(1);} |
|
/* Combine the two bytes, and get the heading in degrees. */ |
bearing_long = heading_word_h * 256 + heading_word_l; |
bearing_degrees = bearing_long / 10; |
|
printf("Bearing: %d \n", bearing_degrees); |
|
/* Wait for a while. */ |
usleep(200000); |
} |
} |