93 lines
2.2 KiB
C
93 lines
2.2 KiB
C
/*
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* Copyright (c) 2016 Intel Corporation
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <adc.h>
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#include <device.h>
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#include <math.h>
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#include <sensor.h>
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#include <zephyr.h>
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#define SYS_LOG_DOMAIN "GROVE_LIGHT_SENSOR"
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#define SYS_LOG_LEVEL CONFIG_SYS_LOG_GROVE_LEVEL
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#include <logging/sys_log.h>
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struct gls_data {
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struct device *adc;
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struct adc_seq_entry sample;
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struct adc_seq_table adc_table;
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uint8_t adc_buffer[4];
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};
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static int gls_sample_fetch(struct device *dev, enum sensor_channel chan)
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{
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struct gls_data *drv_data = dev->driver_data;
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return adc_read(drv_data->adc, &drv_data->adc_table);
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}
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static int gls_channel_get(struct device *dev,
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enum sensor_channel chan,
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struct sensor_value *val)
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{
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struct gls_data *drv_data = dev->driver_data;
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uint16_t analog_val;
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double ldr_val, dval;
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/* rescale sample from 12bit (Zephyr) to 10bit (Grove) */
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analog_val = ((uint16_t)drv_data->adc_buffer[1] << 8) |
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drv_data->adc_buffer[0];
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analog_val = analog_val >> 2;
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/*
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* The formula for converting the analog value to lux is taken from
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* the UPM project:
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* https://github.com/intel-iot-devkit/upm/blob/master/src/grove/grove.cxx#L161
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*/
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ldr_val = (1023.0 - analog_val) * 10.0 / analog_val;
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dval = 10000.0 / pow(ldr_val * 15.0, 4.0/3.0);
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val->val1 = (int32_t)dval;
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val->val2 = ((int32_t)(dval * 1000000)) % 1000000;
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return 0;
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}
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static const struct sensor_driver_api gls_api = {
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.sample_fetch = &gls_sample_fetch,
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.channel_get = &gls_channel_get,
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};
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static int gls_init(struct device *dev)
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{
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struct gls_data *drv_data = dev->driver_data;
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drv_data->adc =
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device_get_binding(CONFIG_GROVE_LIGHT_SENSOR_ADC_DEV_NAME);
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if (drv_data->adc == NULL) {
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SYS_LOG_ERR("Failed to get ADC device.");
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return -EINVAL;
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}
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drv_data->sample.sampling_delay = 12;
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drv_data->sample.channel_id = CONFIG_GROVE_LIGHT_SENSOR_ADC_CHANNEL;
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drv_data->sample.buffer = drv_data->adc_buffer;
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drv_data->sample.buffer_length = 4;
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drv_data->adc_table.entries = &drv_data->sample;
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drv_data->adc_table.num_entries = 1;
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adc_enable(drv_data->adc);
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dev->driver_api = &gls_api;
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return 0;
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}
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static struct gls_data gls_data;
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DEVICE_INIT(gls_dev, CONFIG_GROVE_LIGHT_SENSOR_NAME, &gls_init, &gls_data,
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NULL, POST_KERNEL, CONFIG_SENSOR_INIT_PRIORITY);
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