drivers: sensor: Add support for BH1750 ambient light sensor

This commit adds support for BH1750 ambient light sensor.
The driver works using I2C peripheral in one-time mode.

Signed-off-by: Michal morsisko <[email protected]>

Author: morsisko

drivers/sensor/CMakeLists.txt

@@ -9,6 +9,7 @@ add_subdirectory_ifdef(CONFIG_AMG88XX		amg88xx)
 add_subdirectory_ifdef(CONFIG_AMS_AS5600	ams_as5600)
 add_subdirectory_ifdef(CONFIG_AMS_IAQ_CORE	ams_iAQcore)
 add_subdirectory_ifdef(CONFIG_APDS9960		apds9960)
+add_subdirectory_ifdef(CONFIG_BH1750		bh1750)
 add_subdirectory_ifdef(CONFIG_BMA280		bma280)
 add_subdirectory_ifdef(CONFIG_BMC150_MAGN	bmc150_magn)
 add_subdirectory_ifdef(CONFIG_BME280		bme280)

drivers/sensor/Kconfig

@@ -59,6 +59,8 @@ source "drivers/sensor/ams_iAQcore/Kconfig"
 
 source "drivers/sensor/apds9960/Kconfig"
 
+source "drivers/sensor/bh1750/Kconfig"
+
 source "drivers/sensor/bma280/Kconfig"
 
 source "drivers/sensor/bmc150_magn/Kconfig"

drivers/sensor/bh1750/CMakeLists.txt

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+
+zephyr_library_sources(bh1750.c)

drivers/sensor/bh1750/Kconfig

@@ -0,0 +1,12 @@
+# BH1750 ambient light sensor configuration options
+
+# Copyright (c) 2022 Michal Morsisko
+# SPDX-License-Identifier: Apache-2.0
+
+config BH1750
+	bool "BH1750 ambient light sensor"
+	default y
+	depends on DT_HAS_ROHM_BH1750_ENABLED
+	select I2C
+	help
+	  Enable driver for BH1750 ambient light sensor.

drivers/sensor/bh1750/bh1750.c

@@ -0,0 +1,222 @@
+/*
+ * Copyright (c) 2022, Michal Morsisko
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT rohm_bh1750
+
+#include <zephyr/drivers/sensor.h>
+#include <zephyr/drivers/i2c.h>
+#include <zephyr/logging/log.h>
+#include <zephyr/kernel.h>
+#include <zephyr/devicetree.h>
+#include <zephyr/sys/byteorder.h>
+#include <zephyr/sys/__assert.h>
+
+LOG_MODULE_REGISTER(BH1750, CONFIG_SENSOR_LOG_LEVEL);
+
+#define BH1750_CONTINUOUS_HIGH_RES_MODE                 0x10
+#define BH1750_CONTINUOUS_HIGH_RES_MODE_2               0x11
+#define BH1750_CONTINUOUS_LOW_RES_MODE                  0x13
+#define BH1750_ONE_TIME_HIGH_RES_MODE                   0x20
+#define BH1750_ONE_TIME_HIGH_RES_MODE_2                 0x21
+#define BH1750_ONE_TIME_LOW_RES_MODE                    0x23
+#define BH1750_MTREG_HIGH_BYTE                          0x40
+#define BH1750_MTREG_LOW_BYTE                           0x60
+#define BH1750_MTREG_HIGH_BYTE_MASK                     0xE0
+#define BH1750_MTREG_LOW_BYTE_MASK                      0x1F
+
+#define BH1750_DEFAULT_MTREG                            69U
+#define BH1750_LOW_RES_MODE_MAX_WAIT                    24U
+#define BH1750_HIGH_RES_MODE_MAX_WAIT                   180U
+#define BH1750_LOW_RES_MODE_TYPICAL_WAIT                16U
+#define BH1750_HIGH_RES_MODE_TYPICAL_WAIT               120U
+
+#define BH1750_LOW_RES_DTS_ENUM                         0U
+#define BH1750_HIGH_RES_DTS_ENUM                        1U
+#define BH1750_HIGH_RES_2_DTS_ENUM                      2U
+
+struct bh1750_dev_config {
+	struct i2c_dt_spec bus;
+	uint8_t resolution;
+	uint8_t mtreg;
+};
+
+struct bh1750_data {
+	uint16_t sample;
+};
+
+static int bh1750_opcode_read(const struct device *dev, uint8_t opcode,
+			      uint16_t *val)
+{
+	const struct bh1750_dev_config *cfg = dev->config;
+	int rc;
+
+	rc = i2c_burst_read_dt(&cfg->bus, opcode, (uint8_t *)val, 2);
+	if (rc < 0) {
+		return rc;
+	}
+
+	*val = sys_be16_to_cpu(*val);
+	return 0;
+}
+
+static int bh1750_opcode_write(const struct device *dev, uint8_t opcode)
+{
+	const struct bh1750_dev_config *cfg = dev->config;
+
+	return i2c_write_dt(&cfg->bus, &opcode, 1);
+}
+
+static int bh1750_mtreg_write(const struct device *dev, uint8_t mtreg)
+{
+	int rc;
+	uint8_t high_byte = mtreg & BH1750_MTREG_HIGH_BYTE_MASK;
+	uint8_t low_byte = mtreg & BH1750_MTREG_LOW_BYTE_MASK;
+
+	rc = bh1750_opcode_write(dev, BH1750_MTREG_HIGH_BYTE | (high_byte >> 5));
+	if (rc < 0) {
+		LOG_ERR("%s, Failed to write high byte of mtreg!",
+			dev->name);
+		return rc;
+	}
+
+	rc = bh1750_opcode_write(dev, BH1750_MTREG_LOW_BYTE | low_byte);
+	if (rc < 0) {
+		LOG_ERR("%s, Failed to write low byte of mtreg!",
+			dev->name);
+		return rc;
+	}
+
+	return 0;
+}
+
+static uint8_t bh1750_get_mode_from_dts_device(const struct device *dev)
+{
+	const struct bh1750_dev_config *cfg = dev->config;
+
+	if (cfg->resolution == BH1750_HIGH_RES_2_DTS_ENUM) {
+		return BH1750_ONE_TIME_HIGH_RES_MODE_2;
+	} else if (cfg->resolution == BH1750_HIGH_RES_DTS_ENUM) {
+		return BH1750_ONE_TIME_HIGH_RES_MODE;
+	} else {
+		return BH1750_ONE_TIME_LOW_RES_MODE;
+	}
+}
+
+static int bh1750_get_wait_time_from_dts_device(const struct device *dev)
+{
+	const struct bh1750_dev_config *cfg = dev->config;
+
+	if (cfg->resolution == BH1750_HIGH_RES_2_DTS_ENUM) {
+		return BH1750_HIGH_RES_MODE_MAX_WAIT;
+	} else if (cfg->resolution == BH1750_HIGH_RES_DTS_ENUM) {
+		return BH1750_HIGH_RES_MODE_MAX_WAIT;
+	} else {
+		return BH1750_LOW_RES_MODE_MAX_WAIT;
+	}
+}
+
+static int bh1750_sample_fetch(const struct device *dev,
+			       enum sensor_channel chan)
+{
+	const struct bh1750_dev_config *cfg = dev->config;
+	struct bh1750_data *drv_data = dev->data;
+	const int max_wait = bh1750_get_wait_time_from_dts_device(dev);
+	const uint8_t mode = bh1750_get_mode_from_dts_device(dev);
+	int rc;
+	int wait_time;
+
+	if (chan != SENSOR_CHAN_ALL &&
+	    chan != SENSOR_CHAN_LIGHT) {
+		return -ENOTSUP;
+	}
+
+	/* Start the measurement */
+	rc = bh1750_opcode_write(dev, mode);
+	if (rc < 0) {
+		LOG_ERR("%s, Failed to start measurement!",
+			dev->name);
+		return rc;
+	}
+
+	/* Calculate measurement time */
+	wait_time = (max_wait * (cfg->mtreg * 10000 / BH1750_DEFAULT_MTREG)) / 10000;
+
+	/* Wait for the measurement to be stored in the sensor memory */
+	k_msleep(wait_time);
+
+	/* Fetch result */
+	rc = bh1750_opcode_read(dev, mode, &drv_data->sample);
+	if (rc < 0) {
+		LOG_ERR("%s: Failed to read measurement result!",
+			dev->name);
+		return rc;
+	}
+
+	return 0;
+}
+
+static int bh1750_channel_get(const struct device *dev,
+			      enum sensor_channel chan,
+			      struct sensor_value *val)
+{
+	const struct bh1750_dev_config *cfg = dev->config;
+	struct bh1750_data *drv_data = dev->data;
+	uint32_t tmp;
+
+	if (chan != SENSOR_CHAN_ALL &&
+	    chan != SENSOR_CHAN_LIGHT) {
+		return -ENOTSUP;
+	}
+
+	/* See datasheet (Technical note 11046EDT01), page 11
+	 * https://www.mouser.com/datasheet/2/348/Rohm_11162017_ROHMS34826-1-1279292.pdf
+	 * for more information how to convert raw sample to lx
+	 */
+	tmp = (drv_data->sample * 1000 / 12) * (BH1750_DEFAULT_MTREG * 100 / cfg->mtreg);
+
+	if (cfg->resolution == BH1750_HIGH_RES_2_DTS_ENUM) {
+		tmp /= 2;
+	}
+
+	val->val1 = tmp / 10000;
+	val->val2 = (tmp % 10000) * 100;
+
+	return 0;
+}
+
+static const struct sensor_driver_api bh1750_driver_api = {
+	.sample_fetch = bh1750_sample_fetch,
+	.channel_get = bh1750_channel_get
+};
+
+static int bh1750_init(const struct device *dev)
+{
+	const struct bh1750_dev_config *cfg = dev->config;
+
+	if (!device_is_ready(cfg->bus.bus)) {
+		LOG_ERR("I2C dev %s not ready", cfg->bus.bus->name);
+		return -ENODEV;
+	}
+
+	if (cfg->mtreg != BH1750_DEFAULT_MTREG) {
+		bh1750_mtreg_write(dev, cfg->mtreg);
+	}
+
+	return 0;
+}
+
+#define DEFINE_BH1750(_num)							       \
+	static struct bh1750_data bh1750_data_##_num;				       \
+	static const struct bh1750_dev_config bh1750_config_##_num = {		       \
+		.bus = I2C_DT_SPEC_INST_GET(_num),				       \
+		.mtreg = DT_INST_PROP(_num, mtreg),				       \
+		.resolution = DT_INST_PROP(_num, resolution)			       \
+	};									       \
+	SENSOR_DEVICE_DT_INST_DEFINE(_num, bh1750_init, NULL,				       \
+			      &bh1750_data_##_num, &bh1750_config_##_num, POST_KERNEL, \
+			      CONFIG_SENSOR_INIT_PRIORITY, &bh1750_driver_api);
+
+DT_INST_FOREACH_STATUS_OKAY(DEFINE_BH1750)

dts/bindings/sensor/rohm,bh1750.yaml

@@ -0,0 +1,37 @@
+# Copyright (c) 2022, Michal Morsisko
+# SPDX-License-Identifier: Apache-2.0
+
+description: Rohm BH1750 ambient light sensor.
+
+compatible: "rohm,bh1750"
+
+include: [sensor-device.yaml, i2c-device.yaml]
+
+properties:
+  resolution:
+    type: int
+    default: 1
+    description: |
+      Resolution of the measurement result
+      0 = low resolution
+      1 = high resolution
+      2 = high resolution 2
+      The default mode number 1 is mentioned
+      in the datasheet as recommended by the
+      sensor manufacturer. One should pick
+      other mode, if higher or lower resolution
+      is desired.
+    enum:
+      - 0
+      - 1
+      - 2
+  mtreg:
+    type: int
+    default: 69
+    description: |
+      Duration of single measurement process.
+      The greater the value, the longer the duration
+      and greater accuracy. After sensor power-on
+      mtreg register is set to default value of
+      this property (chosen by sensor manufacturer): 69.
+      Valid values are in range 31-254 (inclusive).

tests/drivers/build_all/sensor/i2c.dtsi

@@ -646,3 +646,8 @@ test_i2c_as5600: as5600@64 {
 	compatible = "ams,as5600";
 	reg = <0x64>;
 };
+
+test_i2c_bh1750: bh1750@65 {
+	compatible = "rohm,bh1750";
+	reg = <0x65>;
+};