133 lines
3.3 KiB
C
133 lines
3.3 KiB
C
/*
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* Copyright (c) 2020 Christian Hirsch
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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 maxim_max31855
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#include <zephyr/kernel.h>
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#include <zephyr/drivers/sensor.h>
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#include <zephyr/init.h>
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#include <zephyr/drivers/gpio.h>
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#include <zephyr/sys/byteorder.h>
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#include <zephyr/sys/__assert.h>
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#include <zephyr/drivers/spi.h>
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#include <zephyr/logging/log.h>
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#include <zephyr/types.h>
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#include <zephyr/device.h>
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#define THERMOCOUPLE_TEMPERATURE_POS 18
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#define INTERNAL_TEMPERATURE_POS 4
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#define THERMOCOUPLE_SIGN_BITS 0xffff2000
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#define INTERNAL_SIGN_BITS 0xfffff800
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#define THERMOCOUPLE_RESOLUTION 25
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#define INTERNAL_RESOLUTION 625
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LOG_MODULE_REGISTER(MAX31855, CONFIG_SENSOR_LOG_LEVEL);
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struct max31855_config {
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struct spi_dt_spec spi;
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};
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struct max31855_data {
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uint32_t sample;
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};
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static int max31855_sample_fetch(const struct device *dev, enum sensor_channel chan)
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{
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struct max31855_data *data = dev->data;
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const struct max31855_config *config = dev->config;
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int ret;
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__ASSERT_NO_MSG(chan == SENSOR_CHAN_ALL);
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struct spi_buf rx_buf = {
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.buf = &(data->sample),
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.len = sizeof(data->sample),
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};
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const struct spi_buf_set rx = {.buffers = &rx_buf, .count = 1};
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ret = spi_read_dt(&config->spi, &rx);
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if (ret < 0) {
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LOG_ERR("max31855_read FAIL %d", ret);
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return ret;
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}
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return 0;
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}
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static int max31855_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 max31855_data *data = dev->data;
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uint32_t temp = sys_be32_to_cpu(data->sample);
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if (temp & BIT(16)) {
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return -EIO;
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}
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switch (chan) {
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case SENSOR_CHAN_AMBIENT_TEMP:
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temp = (temp >> THERMOCOUPLE_TEMPERATURE_POS) & 0x3fff;
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/* if sign bit is set, make value negative */
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if (temp & BIT(14)) {
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temp |= THERMOCOUPLE_SIGN_BITS;
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}
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temp = temp * THERMOCOUPLE_RESOLUTION;
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val->val1 = temp / 100;
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val->val2 = (temp - val->val1 * 100) * 10000;
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break;
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case SENSOR_CHAN_DIE_TEMP:
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temp = (temp >> INTERNAL_TEMPERATURE_POS) & 0xfff;
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/* if sign bit is set, make value negative */
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if (temp & BIT(12)) {
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temp |= INTERNAL_SIGN_BITS;
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}
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temp = temp * INTERNAL_RESOLUTION;
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val->val1 = temp / 10000;
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val->val2 = (temp - val->val1 * 10000) * 100;
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break;
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default:
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return -ENOTSUP;
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}
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return 0;
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}
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static const struct sensor_driver_api max31855_api = {
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.sample_fetch = max31855_sample_fetch,
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.channel_get = max31855_channel_get,
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};
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static int max31855_init(const struct device *dev)
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{
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const struct max31855_config *config = dev->config;
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if (!spi_is_ready_dt(&config->spi)) {
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LOG_ERR("SPI bus is not ready");
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return -ENODEV;
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}
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return 0;
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}
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#define MAX31855_INIT(n) \
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static struct max31855_data max31855_data_##n; \
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static const struct max31855_config max31855_config_##n = { \
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.spi = SPI_DT_SPEC_INST_GET(n, SPI_OP_MODE_MASTER | SPI_WORD_SET(8U), 0U), \
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}; \
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SENSOR_DEVICE_DT_INST_DEFINE(n, &max31855_init, NULL, &max31855_data_##n, \
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&max31855_config_##n, POST_KERNEL, \
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CONFIG_SENSOR_INIT_PRIORITY, &max31855_api);
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DT_INST_FOREACH_STATUS_OKAY(MAX31855_INIT)
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