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// Read analog values from Linux IIO device
//
// Copyright (C) 2017 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include <fcntl.h> // open
#include <stdio.h> // snprintf
#include <stdlib.h> // atoi
#include <unistd.h> // read
#include "command.h" // shutdown
#include "gpio.h" // gpio_adc_setup
#include "internal.h" // report_errno
#include "sched.h" // sched_shutdown
DECL_CONSTANT("ADC_MAX", 4095); // Assume 12bit adc
#define ANALOG_START (1<<8)
DECL_ENUMERATION_RANGE("pin", "analog0", ANALOG_START, 8);
#define IIO_PATH "/sys/bus/iio/devices/iio:device0/in_voltage%d_raw"
struct gpio_adc
gpio_adc_setup(uint32_t pin)
{
char fname[256];
snprintf(fname, sizeof(fname), IIO_PATH, pin-ANALOG_START);
int fd = open(fname, O_RDONLY|O_CLOEXEC);
if (fd < 0) {
report_errno("analog open", fd);
goto fail;
}
int ret = set_non_blocking(fd);
if (ret < 0)
goto fail;
return (struct gpio_adc){ .fd = fd };
fail:
if (fd >= 0)
close(fd);
shutdown("Unable to open adc device");
}
uint32_t
gpio_adc_sample(struct gpio_adc g)
{
return 0;
}
uint16_t
gpio_adc_read(struct gpio_adc g)
{
char buf[64];
int ret = pread(g.fd, buf, sizeof(buf)-1, 0);
if (ret <= 0) {
report_errno("analog read", ret);
try_shutdown("Error on analog read");
return 0;
}
buf[ret] = '\0';
return atoi(buf);
}
void
gpio_adc_cancel_sample(struct gpio_adc g)
{
}
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