112 lines
3.0 KiB
C
112 lines
3.0 KiB
C
/*
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* Copyright (c) 2016 Intel Corporation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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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_TEMPERATURE_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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/* thermistor Nominal B-Constant */
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#if defined(CONFIG_GROVE_TEMPERATURE_SENSOR_V1_0)
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#define B_CONST 3975
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#elif defined(CONFIG_GROVE_TEMPERATURE_SENSOR_V1_X)
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#define B_CONST 4250
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#endif
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struct gts_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 gts_sample_fetch(struct device *dev, enum sensor_channel chan)
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{
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struct gts_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 gts_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 gts_data *drv_data = dev->driver_data;
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uint16_t analog_val;
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double 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 degrees Celisus
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* is taken from the sensor reference page:
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* http://www.seeedstudio.com/wiki/Grove_-_Temperature_Sensor
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*/
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dval = 1 / (log(1023.0 / analog_val - 1.0) / B_CONST +
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1 / 298.15) - 273.15;
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val->type = SENSOR_VALUE_TYPE_INT_PLUS_MICRO;
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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 gts_api = {
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.sample_fetch = >s_sample_fetch,
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.channel_get = >s_channel_get,
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};
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static int gts_init(struct device *dev)
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{
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struct gts_data *drv_data = dev->driver_data;
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drv_data->adc = device_get_binding(
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CONFIG_GROVE_TEMPERATURE_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 =
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CONFIG_GROVE_TEMPERATURE_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 = >s_api;
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return 0;
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}
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static struct gts_data gts_data;
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DEVICE_INIT(gts_dev, CONFIG_GROVE_TEMPERATURE_SENSOR_NAME, >s_init, >s_data,
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NULL, POST_KERNEL, CONFIG_SENSOR_INIT_PRIORITY);
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