blob: f7320caaa7c7b9c6471ca77a42fe3bd98264b504 [file] [log] [blame]
/*
* Copyright (c) 2021 Teslabs Engineering S.L.
*
* SPDX-License-Identifier: Apache-2.0
*/
#define DT_DRV_COMPAT maxim_max6675
#include <zephyr/drivers/sensor.h>
#include <zephyr/drivers/spi.h>
#include <zephyr/sys/byteorder.h>
#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(max6675, CONFIG_SENSOR_LOG_LEVEL);
/** Thermocouple input bit (goes high if thermocouple is disconnected). */
#define THERMOCOUPLE_INPUT BIT(2)
/** Temperature position. */
#define TEMPERATURE_POS 3U
/** Temperature resolution (cDeg/LSB). */
#define TEMPERATURE_RES 25U
struct max6675_config {
struct spi_dt_spec spi;
};
struct max6675_data {
uint16_t sample;
};
static int max6675_sample_fetch(const struct device *dev,
enum sensor_channel chan)
{
struct max6675_data *data = dev->data;
const struct max6675_config *config = dev->config;
int ret;
uint8_t buf_rx[2];
const struct spi_buf rx_buf = {
.buf = buf_rx,
.len = ARRAY_SIZE(buf_rx)
};
const struct spi_buf_set rx_bufs = {
.buffers = &rx_buf,
.count = 1U
};
if (chan != SENSOR_CHAN_ALL && chan != SENSOR_CHAN_AMBIENT_TEMP) {
return -ENOTSUP;
}
ret = spi_read_dt(&config->spi, &rx_bufs);
if (ret < 0) {
return ret;
}
data->sample = sys_get_be16(buf_rx);
if (data->sample & THERMOCOUPLE_INPUT) {
LOG_INF("Thermocouple not connected");
return -ENOENT;
}
return 0;
}
static int max6675_channel_get(const struct device *dev, enum sensor_channel chan,
struct sensor_value *val)
{
struct max6675_data *data = dev->data;
int32_t temperature;
if (chan != SENSOR_CHAN_AMBIENT_TEMP) {
return -ENOTSUP;
}
temperature = (data->sample >> TEMPERATURE_POS) * TEMPERATURE_RES;
val->val1 = temperature / 100;
val->val2 = (temperature - val->val1 * 100) * 10000;
return 0;
}
static const struct sensor_driver_api max6675_api = {
.sample_fetch = &max6675_sample_fetch,
.channel_get = &max6675_channel_get,
};
static int max6675_init(const struct device *dev)
{
const struct max6675_config *config = dev->config;
if (!spi_is_ready_dt(&config->spi)) {
LOG_ERR("SPI bus is not ready");
return -ENODEV;
}
return 0;
}
#define MAX6675_INIT(n) \
static struct max6675_data max6675_data_##n; \
static const struct max6675_config max6675_config_##n = { \
.spi = SPI_DT_SPEC_INST_GET(n, \
SPI_OP_MODE_MASTER | \
SPI_WORD_SET(8U), \
0U), \
}; \
SENSOR_DEVICE_DT_INST_DEFINE(n, &max6675_init, NULL, \
&max6675_data_##n, &max6675_config_##n, \
POST_KERNEL, CONFIG_SENSOR_INIT_PRIORITY, \
&max6675_api);
DT_INST_FOREACH_STATUS_OKAY(MAX6675_INIT)