adc.cpp
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/****************************************************************************
*
* Copyright (C) 2020 PX4 Development Team. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
#include <board_config.h>
#include <drivers/drv_adc.h>
#include <px4_platform_common/log.h>
#include <fcntl.h>
#include <stdint.h>
#include <unistd.h>
#define ADC_SYSFS_PATH "/sys/bus/iio/devices/iio:device0"
#define ADC_MAX_CHAN 8
int _channels_fd[ADC_MAX_CHAN];
int px4_arch_adc_init(uint32_t base_address)
{
for (int i = 0; i < ADC_MAX_CHAN; i++) {
_channels_fd[i] = -1;
}
return 0;
}
void px4_arch_adc_uninit(uint32_t base_address)
{
for (int i = 0; i < ADC_MAX_CHAN; i++) {
::close(_channels_fd[i]);
_channels_fd[i] = -1;
}
}
uint32_t px4_arch_adc_sample(uint32_t base_address, unsigned channel)
{
if (channel > ADC_MAX_CHAN) {
PX4_ERR("channel %d out of range: %d", channel, ADC_MAX_CHAN);
return UINT32_MAX; // error
}
// open channel if necessary
if (_channels_fd[channel] == -1) {
// ADC_SYSFS_PATH
char channel_path[strlen(ADC_SYSFS_PATH) + 20] {};
if (sprintf(channel_path, "%s/in_voltage%d_raw", ADC_SYSFS_PATH, channel) == -1) {
PX4_ERR("adc channel: %d\n", channel);
return UINT32_MAX; // error
}
_channels_fd[channel] = ::open(channel_path, O_RDONLY);
}
char buffer[10] {};
if (::pread(_channels_fd[channel], buffer, sizeof(buffer), 0) < 0) {
PX4_ERR("read channel %d failed", channel);
return UINT32_MAX; // error
}
return atoi(buffer);
}
float px4_arch_adc_reference_v()
{
return BOARD_ADC_POS_REF_V; // 12-bit 1.8V ADC
}
uint32_t px4_arch_adc_dn_fullcount()
{
return 1 << 12; // 12 bit ADC
}