121 lines
3.7 KiB
C
121 lines
3.7 KiB
C
/*
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* Copyright (c) 2024 Benedikt Schmidt <benediktibk@gmail.com>
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#define DT_DRV_COMPAT onnn_nct75
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#include <zephyr/drivers/i2c.h>
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#include <zephyr/drivers/sensor.h>
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#include <zephyr/logging/log.h>
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#include <zephyr/sys/byteorder.h>
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#include <zephyr/sys/util.h>
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LOG_MODULE_REGISTER(NCT75, CONFIG_SENSOR_LOG_LEVEL);
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#define NCT75REGISTER_STOREDTEMPERATUREVALUE 0x00
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#define NCT75REGISTER_CONFIGURATION 0x01
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#define NCT75REGISTER_ONESHOT 0x04
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#define NCT75_CONFIGURATION_ONESHOTMODE_POS 5
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#define NCT75_TEMPERATURE_CONVERSION_TIME_US 48500
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#define NCT75_TEMPERATURE_CONVERSION_WAIT_TIME_US (NCT75_TEMPERATURE_CONVERSION_TIME_US + 1000)
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struct nct75_config {
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struct i2c_dt_spec i2c;
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};
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struct nct75_data {
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/* temperature in 1e-6 °C */
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int64_t value;
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};
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static int nct75_sample_fetch(const struct device *dev, enum sensor_channel chan)
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{
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const struct nct75_config *config = dev->config;
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struct nct75_data *data = dev->data;
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int result;
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uint8_t write_buffer = 0;
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uint16_t read_buffer;
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int16_t raw_value;
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__ASSERT_NO_MSG(chan == SENSOR_CHAN_ALL);
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result = i2c_reg_write_byte_dt(&config->i2c, NCT75REGISTER_ONESHOT, 0);
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if (result != 0) {
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LOG_ERR("%s: unable to trigger temperature one shot measurement", dev->name);
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return result;
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}
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k_sleep(K_USEC(NCT75_TEMPERATURE_CONVERSION_WAIT_TIME_US));
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write_buffer = NCT75REGISTER_STOREDTEMPERATUREVALUE;
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result = i2c_write_read_dt(&config->i2c, &write_buffer, sizeof(write_buffer), &read_buffer,
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sizeof(read_buffer));
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if (result != 0) {
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LOG_ERR("%s: unable to read temperature", dev->name);
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return result;
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}
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raw_value = arithmetic_shift_right(sys_be16_to_cpu(read_buffer), 4);
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data->value = (raw_value * 1000 * 1000) * 100 / 0x640;
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return 0;
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}
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static int nct75_channel_get(const struct device *dev, enum sensor_channel chan,
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struct sensor_value *val)
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{
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struct nct75_data *data = dev->data;
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if (chan != SENSOR_CHAN_AMBIENT_TEMP) {
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LOG_ERR("%s: requesting unsupported channel %i", dev->name, chan);
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return -ENOTSUP;
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}
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val->val1 = data->value / (1000 * 1000);
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val->val2 = data->value - val->val1 * 1000 * 1000;
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return 0;
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}
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static const struct sensor_driver_api nct75_api = {
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.sample_fetch = nct75_sample_fetch,
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.channel_get = nct75_channel_get,
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};
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static int nct75_init(const struct device *dev)
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{
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const struct nct75_config *config = dev->config;
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uint8_t configuration_register_value = BIT(NCT75_CONFIGURATION_ONESHOTMODE_POS);
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int result;
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if (!i2c_is_ready_dt(&config->i2c)) {
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LOG_ERR("I2C device not ready");
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return -ENODEV;
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}
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result = i2c_reg_write_byte_dt(&config->i2c, NCT75REGISTER_CONFIGURATION,
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configuration_register_value);
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if (result != 0) {
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LOG_ERR("%s: unable to configure temperature sensor", dev->name);
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return result;
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}
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return 0;
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}
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#define NCT75_INIT(inst) \
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static const struct nct75_config nct75_##inst##_config = { \
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.i2c = I2C_DT_SPEC_INST_GET(inst), \
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}; \
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\
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static struct nct75_data nct75_##inst##_data; \
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\
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SENSOR_DEVICE_DT_INST_DEFINE(inst, nct75_init, NULL, &nct75_##inst##_data, \
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&nct75_##inst##_config, POST_KERNEL, \
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CONFIG_SENSOR_INIT_PRIORITY, &nct75_api);
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DT_INST_FOREACH_STATUS_OKAY(NCT75_INIT);
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