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adcreader.cpp
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adcreader.cpp
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#include "adcreader.h"
#include <QDebug>
#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
#define MAX_SAMPLES 65536
ADCreader::ADCreader()
{
int ret = 0;
// set up ringbuffer
samples = new int[MAX_SAMPLES];
// pointer for incoming data
pIn = samples;
// pointer for outgoing data
pOut = samples;
// SPI constants
static const char *device = "/dev/spidev0.0";
mode = SPI_CPHA | SPI_CPOL;
bits = 8;
speed = 50000;
delay = 10;
drdy_GPIO = 22;
// open SPI device
fd = open(device, O_RDWR);
if (fd < 0)
pabort("can't open device");
/*
* spi mode
*/
ret = ioctl(fd, SPI_IOC_WR_MODE, &mode);
if (ret == -1)
pabort("can't set spi mode");
ret = ioctl(fd, SPI_IOC_RD_MODE, &mode);
if (ret == -1)
pabort("can't get spi mode");
/*
* bits per word
*/
ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);
if (ret == -1)
pabort("can't set bits per word");
ret = ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits);
if (ret == -1)
pabort("can't get bits per word");
/*
* max speed hz
*/
ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);
if (ret == -1)
pabort("can't set max speed hz");
ret = ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed);
if (ret == -1)
pabort("can't get max speed hz");
fprintf(stderr, "spi mode: %d\n", mode);
fprintf(stderr, "bits per word: %d\n", bits);
fprintf(stderr, "max speed: %d Hz (%d KHz)\n", speed, speed/1000);
// enable master clock for the AD
// divisor results in roughly 4.9MHz
// this also inits the general purpose IO
gz_clock_ena(GZ_CLK_5MHz,5);
// enables sysfs entry for the GPIO pin
gpio_export(drdy_GPIO);
// set to input
gpio_set_dir(drdy_GPIO,0);
// set interrupt detection to falling edge
gpio_set_edge(drdy_GPIO,"falling");
// get a file descriptor for the GPIO pin
sysfs_fd = gpio_fd_open(drdy_GPIO);
// resets the AD7705 so that it expects a write to the communication register
writeReset(fd);
writeReg(fd,0x00);
// tell the AD7705 that the next write will be to the clock register
writeReg(fd,0x20);
// write 00001110 : CLOCKDIV=1,CLK=1,expects 4.9152MHz input clock
writeReg(fd,0x0E);
// tell the AD7705 that the next write will be the setup register
writeReg(fd,0x10);
// intiates a self calibration and then after that starts converting
writeReg(fd,0x44);
}
void ADCreader::writeReset(int fd)
{
int ret;
uint8_t tx1[5] = {0xff,0xff,0xff,0xff,0xff};
uint8_t rx1[5] = {0};
struct spi_ioc_transfer tr;
memset(&tr,0,sizeof(struct spi_ioc_transfer));
tr.tx_buf = (unsigned long)tx1;
tr.rx_buf = (unsigned long)rx1;
tr.len = sizeof(tx1);
ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
if (ret < 1) {
printf("\nerr=%d when trying to reset. \n",ret);
pabort("Can't send spi message");
}
}
void ADCreader::writeReg(int fd, uint8_t v)
{
int ret;
uint8_t tx1[1];
tx1[0] = v;
uint8_t rx1[1] = {0};
struct spi_ioc_transfer tr;
memset(&tr,0,sizeof(struct spi_ioc_transfer));
tr.tx_buf = (unsigned long)tx1;
tr.rx_buf = (unsigned long)rx1;
tr.len = sizeof(tx1);
ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
if (ret < 1)
pabort("can't send spi message");
}
uint8_t ADCreader::readReg(int fd)
{
int ret;
uint8_t tx1[1];
tx1[0] = 0;
uint8_t rx1[1] = {0};
struct spi_ioc_transfer tr;
memset(&tr,0,sizeof(struct spi_ioc_transfer));
tr.tx_buf = (unsigned long)tx1;
tr.rx_buf = (unsigned long)rx1;
tr.len = sizeof(tx1);
ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
if (ret < 1)
pabort("can't send spi message");
return rx1[0];
}
int ADCreader::readData(int fd)
{
int ret;
uint8_t tx1[2] = {0,0};
uint8_t rx1[2] = {0,0};
struct spi_ioc_transfer tr;
memset(&tr,0,sizeof(struct spi_ioc_transfer));
tr.tx_buf = (unsigned long)tx1;
tr.rx_buf = (unsigned long)rx1;
tr.len = sizeof(tx1);
ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
if (ret < 1){
printf("\n can't send spi message, ret = %d\n",ret);
exit(1);
}
return (rx1[0]<<8)|(rx1[1]);
}
void ADCreader::run()
{
running = true;
while (running) {
//ask for a read from the comms register
writeReg(fd,0x08);
int x = readReg(fd);
//check for the data ready bit to be low - /DRDY is glitchy on the board! use this instead
if (!(x & 0x80)){
// tell the AD7705 to read the data register (16 bits)
writeReg(fd,0x38);
// read the data register by performing two 8 bit reads
int value = readData(fd)-0x8000;
*pIn = value;
if (pIn == (&samples[MAX_SAMPLES-1]))
pIn = samples;
else
pIn++;
}
}
close(fd);
gpio_fd_close(sysfs_fd);
}
int ADCreader::getSample()
{
assert(pOut!=pIn);
int value = *pOut;
if (pOut == (&samples[MAX_SAMPLES-1]))
pOut = samples;
else
pOut++;
return value;
}
int ADCreader::hasSample()
{
return (pOut!=pIn);
}
void ADCreader::quit()
{
running = false;
exit(0);
}
void ADCreader::pabort(const char *s)
{
perror(s);
abort();
}