drivers: sensor: ens210: Implement AMS ens210 Sensor

Implementation of AMS (Austria Micro Systems) ENS210 temperature and
relative humidity sensor.

Signed-off-by: Alexander Wachter <alexander.wachter@student.tugraz.at>

drivers/sensor/CMakeLists.txt

@@ -15,6 +15,7 @@ add_subdirectory_ifdef(CONFIG_BMI160		bmi160)
 add_subdirectory_ifdef(CONFIG_BMM150		bmm150)
 add_subdirectory_ifdef(CONFIG_CCS811		ccs811)
 add_subdirectory_ifdef(CONFIG_DHT			dht)
+add_subdirectory_ifdef(CONFIG_ENS210		ens210)
 add_subdirectory_ifdef(CONFIG_FXAS21002		fxas21002)
 add_subdirectory_ifdef(CONFIG_FXOS8700		fxos8700)
 add_subdirectory(grove)

drivers/sensor/Kconfig

@@ -55,6 +55,8 @@ source "drivers/sensor/ccs811/Kconfig"
 
 source "drivers/sensor/dht/Kconfig"
 
+source "drivers/sensor/ens210/Kconfig"
+
 source "drivers/sensor/fxas21002/Kconfig"
 
 source "drivers/sensor/fxos8700/Kconfig"

drivers/sensor/ens210/CMakeLists.txt

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+
+zephyr_library_sources_ifdef(CONFIG_ENS210 ens210.c)

drivers/sensor/ens210/Kconfig

@@ -0,0 +1,35 @@
+# Kconfig - ENS210 Digital Temperature and Humidity sensor configuration options
+
+#
+# Copyright (c) 2018 Alexander Wachter.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+menuconfig ENS210
+	bool "ENS210 Digital Temperature and Humidity sensor"
+	depends on I2C && HAS_DTS_I2C
+	help
+	  Enable driver for ENS210 Digital Temperature and Humidity sensor.
+if ENS210
+
+config ENS210_CRC_CHECK
+	bool "Enable CRC Check"
+	default y
+	help
+	 Check the crc value after data reading.
+
+config ENS210_MAX_STAT_RETRIES
+	int "Number of status read retries"
+	default 4
+	help
+	 Number of retries when status reading failed or device not ready.
+
+config ENS210_MAX_READ_RETRIES
+	int "Number of value reading retries"
+	default 4
+	help
+	 Number of retries when value reading failed, value not valid
+	 or crc not ok.
+
+endif # ENS210

drivers/sensor/ens210/ens210.c

@@ -0,0 +1,262 @@
+/*
+ * Copyright (c) 2018 Alexander Wachter.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <device.h>
+#include <i2c.h>
+#include <kernel.h>
+#include <misc/byteorder.h>
+#include <misc/util.h>
+#include <sensor.h>
+#include <misc/__assert.h>
+#include <logging/log.h>
+#include "ens210.h"
+
+#define LOG_LEVEL CONFIG_SENSOR_LOG_LEVEL
+LOG_MODULE_REGISTER(ENS210);
+
+#ifdef ENS210_CRC_CHECK
+u32_t ens210_crc7(u32_t bitstream)
+{
+	u32_t polynomial = (ENS210_CRC7_POLY << (ENS210_CRC7_DATA_WIDTH - 1));
+	u32_t bit = ENS210_CRC7_DATA_MSB << ENS210_CRC7_WIDTH;
+	u32_t val = (bitstream << ENS210_CRC7_WIDTH) | ENS210_CRC7_IVEC;
+
+	while (bit & (ENS210_CRC7_DATA_MASK << ENS210_CRC7_WIDTH)) {
+		if (bit & val) {
+			val ^= polynomial;
+		}
+
+		bit >>= 1;
+		polynomial >>= 1;
+	}
+
+	return val;
+}
+#endif /*ENS210_CRC_CHECK*/
+
+static int ens210_sample_fetch(struct device *dev, enum sensor_channel chan)
+{
+	struct ens210_data *drv_data = dev->driver_data;
+	struct ens210_value_data data[2];
+	int ret, cnt;
+
+#ifdef ENS210_CRC_CHECK
+	u32_t temp_valid, humidity_valid;
+#endif /*ENS210_CRC_CHECK*/
+
+	__ASSERT_NO_MSG(chan == SENSOR_CHAN_ALL);
+
+	for (cnt = 0; cnt <= CONFIG_ENS210_MAX_READ_RETRIES; cnt++) {
+		ret =  i2c_burst_read(drv_data->i2c, DT_AMS_ENS210_0_BASE_ADDRESS,
+				ENS210_REG_T_VAL, (u8_t *)&data, sizeof(data));
+		if (ret < 0) {
+			LOG_ERR("Failed to read data");
+			continue;
+		}
+
+		if (!data[0].valid) {
+			LOG_WRN("Temperature not valid");
+			continue;
+		}
+
+		if (!data[1].valid) {
+			LOG_WRN("Humidity not valid");
+			continue;
+		}
+
+#ifdef ENS210_CRC_CHECK
+		temp_valid =      data[0].val |
+				  (data[0].valid << (sizeof(data[0].val) * 8));
+		humidity_valid =  data[1].val |
+				  (data[1].valid << (sizeof(data[1].val) * 8));
+
+		if (ens210_crc7(temp_valid) != data[0].crc7) {
+			LOG_WRN("Temperature CRC error");
+			continue;
+		}
+
+		if (ens210_crc7(humidity_valid) != data[1].crc7) {
+			LOG_WRN("Humidity CRC error");
+			continue;
+		}
+#endif /*ENS210_CRC_CHECK*/
+
+		drv_data->temp = data[0];
+		drv_data->humidity = data[1];
+
+		return 0;
+	}
+
+	return -EIO;
+}
+
+static int ens210_channel_get(struct device *dev,
+			      enum sensor_channel chan,
+			      struct sensor_value *val)
+{
+	struct ens210_data *drv_data = dev->driver_data;
+	s32_t temp_frac;
+	s32_t humidity_frac;
+
+	switch (chan) {
+	case SENSOR_CHAN_AMBIENT_TEMP:
+		/* Temperature is in 1/64 Kelvin. Subtract 273.15 for Celsius */
+		temp_frac = sys_le16_to_cpu(drv_data->temp.val) * (1000000 / 64);
+		temp_frac -= 273150000;
+
+		val->val1 = temp_frac / 1000000;
+		val->val2 = temp_frac - val->val1;
+		break;
+	case  SENSOR_CHAN_HUMIDITY:
+		humidity_frac = sys_le16_to_cpu(drv_data->humidity.val) *
+				(1000000 / 512);
+		val->val1 = humidity_frac / 1000000;
+		val->val2 = humidity_frac - val->val1;
+
+		break;
+	default:
+		return -ENOTSUP;
+	}
+
+	return 0;
+}
+
+static int ens210_sys_reset(struct device *i2c_dev)
+{
+	const struct ens210_sys_ctrl sys_ctrl = {.low_power = 0, .reset = 1};
+	int ret;
+
+	ret = i2c_reg_write_byte(i2c_dev, DT_AMS_ENS210_0_BASE_ADDRESS,
+				 ENS210_REG_SYS_CTRL, *(u8_t *)&sys_ctrl);
+	if (ret < 0) {
+		LOG_ERR("Failed to set SYS_CTRL to 0x%x", *(u8_t *)&sys_ctrl);
+	}
+	return ret;
+}
+
+static int ens210_sys_enable(struct device *i2c_dev)
+{
+	const struct ens210_sys_ctrl sys_ctrl = {.low_power = 0, .reset = 0};
+	int ret;
+
+	ret = i2c_reg_write_byte(i2c_dev, DT_AMS_ENS210_0_BASE_ADDRESS,
+				 ENS210_REG_SYS_CTRL, *(u8_t *)&sys_ctrl);
+	if (ret < 0) {
+		LOG_ERR("Failed to set SYS_CTRL to 0x%x", *(u8_t *)&sys_ctrl);
+	}
+	return ret;
+}
+
+static int ens210_wait_boot(struct device *i2c_dev)
+{
+	int cnt;
+	int ret;
+	struct ens210_sys_stat sys_stat;
+
+	for (cnt = 0; cnt <= CONFIG_ENS210_MAX_STAT_RETRIES; cnt++) {
+		ret =  i2c_reg_read_byte(i2c_dev, DT_AMS_ENS210_0_BASE_ADDRESS,
+					 ENS210_REG_SYS_STAT,
+					 (u8_t *)&sys_stat);
+
+		if (ret < 0) {
+			k_sleep(1);
+			continue;
+		}
+
+		if (sys_stat.sys_active) {
+			return 0;
+		}
+
+		if (cnt == 0) {
+			ens210_sys_reset(i2c_dev);
+		}
+
+		ens210_sys_enable(i2c_dev);
+
+		k_sleep(2);
+	}
+
+	if (ret < 0) {
+		LOG_ERR("Failed to read SYS_STATE");
+	}
+
+
+	LOG_ERR("Sensor is not in active state");
+	return -EIO;
+}
+
+static const struct sensor_driver_api en210_driver_api = {
+	.sample_fetch = ens210_sample_fetch,
+	.channel_get = ens210_channel_get,
+};
+
+static int ens210_init(struct device *dev)
+{
+	struct ens210_data *drv_data = dev->driver_data;
+	const struct ens210_sens_run sense_run = {
+		.t_run = 1,
+		.h_run = 1
+	};
+	const struct ens210_sens_start sense_start = {
+		.t_start = 1,
+		.h_start = 1
+	};
+	int ret;
+	u16_t part_id;
+
+	drv_data->i2c = device_get_binding(DT_AMS_ENS210_0_BUS_NAME);
+	if (drv_data->i2c == NULL) {
+		LOG_ERR("Failed to get pointer to %s device!",
+			    DT_AMS_ENS210_0_BUS_NAME);
+		return -EINVAL;
+	}
+
+	/* Wait until the device is ready. */
+	ret = ens210_wait_boot(drv_data->i2c);
+	if (ret < 0) {
+		return -EIO;
+	}
+
+	/* Check Hardware ID. This is only possible after device is ready */
+	ret =  i2c_burst_read(drv_data->i2c, DT_AMS_ENS210_0_BASE_ADDRESS,
+			      ENS210_REG_PART_ID, (u8_t *)&part_id,
+			      sizeof(part_id));
+	if (ret < 0) {
+		LOG_ERR("Failed to read Part ID register");
+		return -EIO;
+	}
+
+	if (part_id != ENS210_PART_ID) {
+		LOG_ERR("Part ID does not match. Want 0x%x, got 0x%x",
+			    ENS210_PART_ID, part_id);
+		return -EIO;
+	}
+
+	/* Set continuous measurement */
+	ret = i2c_reg_write_byte(drv_data->i2c, DT_AMS_ENS210_0_BASE_ADDRESS,
+				 ENS210_REG_SENS_RUN, *(u8_t *)&sense_run);
+	if (ret < 0) {
+		LOG_ERR("Failed to set SENS_RUN to 0x%x",
+			    *(u8_t *)&sense_run);
+		return -EIO;
+	}
+
+	/* Start measuring */
+	ret = i2c_reg_write_byte(drv_data->i2c, DT_AMS_ENS210_0_BASE_ADDRESS,
+				 ENS210_REG_SENS_START, *(u8_t *)&sense_start);
+	if (ret < 0) {
+		LOG_ERR("Failed to set SENS_START to 0x%x",
+			    *(u8_t *)&sense_start);
+		return -EIO;
+	}
+	return 0;
+}
+
+static struct ens210_data ens210_driver;
+
+DEVICE_AND_API_INIT(ens210, DT_AMS_ENS210_0_LABEL, ens210_init, &ens210_driver,
+		    NULL, POST_KERNEL, CONFIG_SENSOR_INIT_PRIORITY,
+		    &en210_driver_api);