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mcp3427.hpp
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mcp3427.hpp
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#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/i2c-dev.h>
#include <iostream>
#include <boost/exception/all.hpp>
#include <boost/shared_ptr.hpp>
class mcp3427 {
int file_i2c;
unsigned char buffer[4];
int channel, rx_channel;
int continuous_mode;
int bit_mode;
int pga_bits;
int rx_val;
double rx_val_d;
const double c_lsb = 62.5e-6;
bool rx_ready;
bool ready = false;
public:
mcp3427(std::string bus, int addr);
void config(int channel, int continuous_mode, int bit_mode, int pga_bits);
int config(char word);
int config_write();
int get(int channel);
int getbuffer();
void print_rx_buffer();
double get_float(int channel);
operator bool() {return this->ready;}
};
mcp3427::mcp3427(std::string bus, int addr)
{
if(addr == 0)
return;
//char *filename = (char*)"/dev/i2c-1";
char *filename;
//filename = bus;
if ((file_i2c = open(bus.c_str(), O_RDWR)) < 0)
{
BOOST_THROW_EXCEPTION(std::runtime_error("Failed to open i2c bus"));
}
int length;
if (ioctl(file_i2c, I2C_SLAVE, addr) < 0)
{
BOOST_THROW_EXCEPTION(std::runtime_error("Failed to acquire bus access and/or talk to slave.\n"));
}
//----- WRITE BYTES -----
char word = 0x98; // 1 00 1 10 00
// 1 = no effect
// 00 = channel 0
// 1 = continuous conversion mode
// 10 = 16 bit mode
// 00 = x1 PGA
config(word);
config(0, 1, 2, 0);
this->ready = true;
}
void mcp3427::config(int channel, int continuous_mode, int bit_mode, int pga_bits)
{
this->channel = channel;
this->continuous_mode = continuous_mode;
this->bit_mode = bit_mode;
this->pga_bits = pga_bits;
}
int mcp3427::config_write()
{
return this->config(
((char)channel << 5) |
((char)continuous_mode << 4) |
((char)bit_mode << 2) |
((char)pga_bits & 0x3)
);
}
int mcp3427::config(char word)
{
if (write(this->file_i2c, &word, 1) != 1)
{
BOOST_THROW_EXCEPTION(std::runtime_error("Failed to write to i2c bus"));
}
return 1;
}
int mcp3427::getbuffer()
{
if (read(this->file_i2c, this->buffer, 3) != 3)
{
BOOST_THROW_EXCEPTION(std::runtime_error("Failed to read i2c bus"));
}
rx_channel = ((buffer[2] >> 5) & 0x3);
rx_val = ((int)(buffer[0]))<<8 | (int)buffer[1];
if(rx_val & 0x8000){
rx_val ^= 0xFFFF;
rx_val += 1;
rx_val *= -1;
}
rx_val_d = ((double)rx_val) * c_lsb;
rx_ready = (buffer[2] & 0x80) == 0;
return 1;
}
void mcp3427::print_rx_buffer()
{
for(int x=0;x<3;x++){
printf("0x%X ", buffer[x]);
}
}
int mcp3427::get(int channel)
{
if(this->channel != channel){
this->channel = channel;
config_write();
}
do{
if (this->getbuffer())
{
if(rx_channel == channel && rx_ready)
return this->rx_val;
}
} while(rx_channel != channel || !rx_ready);
return 0;
}
double mcp3427::get_float(int channel)
{
get(channel);
return rx_val_d;
}