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drivers: sensor: mb7040: add support for MB7040 ultrasonic sensor
This commit adds a new driver for the MaxBotix MB7040 ultrasonic rangefinder. The driver uses I2C communication to read range data from the sensor and exposes it via the Zephyr sensor API. Tested on an esp32-s3 board using I2C bus. Verified readings at multiple distances to confirm accuracy. Signed-off-by : Sabrina Simkhovich <sabrinasimkhovich@gmail.com>
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‎drivers/sensor/mb7040/CMakeLists.txt

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# SPDX-License-Identifier: Apache-2.0
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zephyr_library()
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zephyr_library_sources(mb7040.c)

‎drivers/sensor/mb7040/Kconfig

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# MB7040 ultrasonic sensor config
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# Copyright 2025 Sabrina Simkhovich <sabrinasimkhovich@gmail.com>
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# SPDX-License-Identifier: Apache-2.0
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config MB7040
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bool "MB7040 ultrasonic distance sensor"
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default y
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depends on DT_HAS_MAXBOTIX_MB7040_ENABLED
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select I2C
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help
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Enable driver for MB7040 distance sensor.
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config MB7040_DELAY_MS
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int "Delay in milliseconds to wait for distance measurment"
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default 100
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depends on MB7040
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help
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Default delay if status-gpio is not defined

‎drivers/sensor/mb7040/mb7040.c

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/*
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* Copyright (c) 2025 Sabrina Simkhovich <sabrinasimkhovich@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 maxbotix_mb7040
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#include <zephyr/kernel.h>
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#include <zephyr/drivers/sensor.h>
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#include <zephyr/drivers/i2c.h>
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#include <zephyr/device.h>
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#include <zephyr/devicetree.h>
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#include <zephyr/logging/log.h>
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#include <zephyr/drivers/gpio.h>
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#define RANGE_CMD 0x51
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#define MB7040_HAS_STATUS_GPIO DT_ANY_INST_HAS_PROP_STATUS_OKAY(status_gpios)
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LOG_MODULE_REGISTER(mb7040, LOG_LEVEL_DBG);
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struct mb7040_data {
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uint16_t distance_cm;
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struct k_sem read_sem;
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#if MB7040_HAS_STATUS_GPIO
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struct gpio_callback gpio_cb;
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#endif
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};
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struct mb7040_config {
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struct i2c_dt_spec i2c;
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#if MB7040_HAS_STATUS_GPIO
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struct gpio_dt_spec status_gpio;
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#endif
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};
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#if MB7040_HAS_STATUS_GPIO
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static void status_gpio_callback(const struct device *dev, struct gpio_callback *cb, uint32_t pins)
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{
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struct mb7040_data *data = CONTAINER_OF(cb, struct mb7040_data, gpio_cb);
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k_sem_give(&data->read_sem);
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}
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#endif
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static int mb7040_sample_fetch(const struct device *dev, enum sensor_channel chan)
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{
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const struct mb7040_config *cfg = (struct mb7040_config *)dev->config;
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struct mb7040_data *data = (struct mb7040_data *)dev->data;
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uint8_t cmd = RANGE_CMD;
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int ret;
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uint8_t read_data[2];
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if (chan != SENSOR_CHAN_DISTANCE && chan != SENSOR_CHAN_ALL) {
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LOG_ERR("Sensor only supports distance");
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return -EINVAL;
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}
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k_sem_reset(&data->read_sem);
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#if MB7040_HAS_STATUS_GPIO
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/* Enable interrupt before writing */
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ret = gpio_pin_interrupt_configure_dt(&cfg->status_gpio, GPIO_INT_EDGE_FALLING);
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if (ret != 0) {
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LOG_ERR("Failed to configure interrupt: %d", ret);
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return ret;
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}
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#endif
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/* Write range command to sensor */
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ret = i2c_write_dt(&cfg->i2c, &cmd, 1);
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if (ret != 0) {
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LOG_ERR("I2C write failed with error %d", ret);
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return ret;
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}
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ret = k_sem_take(&data->read_sem, K_MSEC(CONFIG_MB7040_DELAY_MS));
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if (ret != 0) {
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if (ret == -EAGAIN) {
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LOG_ERR("Semaphore take timed out");
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return -ETIMEDOUT;
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} else {
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LOG_ERR("Semaphore take failed with error %d", ret);
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return ret;
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}
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}
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#if MB7040_HAS_STATUS_GPIO
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gpio_pin_interrupt_configure_dt(&cfg->status_gpio, GPIO_INT_DISABLE);
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#endif
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/* Small wait due to devie specific i2c timings */
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k_msleep(10);
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ret = i2c_read_dt(&cfg->i2c, read_data, 2);
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if (ret != 0) {
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LOG_ERR("I2C read failed with error %d", ret);
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return ret;
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}
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/* Convert MSB/LSB to distance in cm */
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data->distance_cm = (read_data[0] << 8) | read_data[1];
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return 0;
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}
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static int mb7040_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 mb7040_data *data = (struct mb7040_data *)dev->data;
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if (chan != SENSOR_CHAN_DISTANCE && SENSOR_CHAN_ALL != chan) {
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LOG_ERR("Sensor only supports distance");
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return -EINVAL;
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}
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val->val1 = data->distance_cm;
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val->val2 = 0;
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return 0;
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}
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static DEVICE_API(sensor, mb7040_api) = {
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.sample_fetch = mb7040_sample_fetch,
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.channel_get = mb7040_channel_get,
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};
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static int mb7040_init(const struct device *dev)
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{
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const struct mb7040_config *cfg = (struct mb7040_config *)dev->config;
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struct mb7040_data *data = (struct mb7040_data *)dev->data;
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k_sem_init(&data->read_sem, 0, 1);
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if (!i2c_is_ready_dt(&cfg->i2c)) {
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LOG_ERR("I2C not ready!");
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return -ENODEV;
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}
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/* Initialize status GPIO if present */
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#if MB7040_HAS_STATUS_GPIO
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if (!gpio_is_ready_dt(&cfg->status_gpio)) {
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LOG_ERR("Status GPIO not ready");
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return -ENODEV;
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}
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int ret = gpio_pin_configure_dt(&cfg->status_gpio, GPIO_INPUT);
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if (ret < 0) {
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LOG_ERR("Failed to configure status GPIO: %d", ret);
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return ret;
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}
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gpio_init_callback(&data->gpio_cb, status_gpio_callback, BIT(cfg->status_gpio.pin));
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ret = gpio_add_callback(cfg->status_gpio.port, &data->gpio_cb);
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if (ret < 0) {
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LOG_ERR("Failed to add GPIO callback: %d", ret);
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return ret;
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}
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LOG_INF("MB7040 initialized with status GPIO");
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#else
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LOG_INF("MB7040 initialized");
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#endif
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return 0;
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}
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#define MB7040_DEFINE(inst) \
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static struct mb7040_data mb7040_data_##inst = { \
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.distance_cm = 0, \
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}; \
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\
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static const struct mb7040_config mb7040_config_##inst = { \
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.i2c = I2C_DT_SPEC_INST_GET(inst), \
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IF_ENABLED(DT_INST_NODE_HAS_PROP(inst, status_gpios), \
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(.status_gpio = GPIO_DT_SPEC_INST_GET(inst, status_gpios),)) }; \
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\
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SENSOR_DEVICE_DT_INST_DEFINE(inst, mb7040_init, NULL, &mb7040_data_##inst, \
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&mb7040_config_##inst, POST_KERNEL, \
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CONFIG_SENSOR_INIT_PRIORITY, &mb7040_api);
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DT_INST_FOREACH_STATUS_OKAY(MB7040_DEFINE)

‎dts/bindings/sensor/maxbotix,mb7040.yaml

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description: MB7040 ultrasonic distance sensor
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compatible: "maxbotix,mb7040"
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include: [sensor-device.yaml, i2c-device.yaml]
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on-bus: i2c
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properties:
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reg:
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description: I2C address of the MB7040 sensor. Zephyr expects 7-bit addressing and handles shifting internally.
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required: true
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status-gpios:
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type: phandle-array
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description: GPIO pin connected to Pin 2 (Address Announce/Status) to monitor sensor state. Pin is high during range reading and low when ready for I2C communication.

‎tests/drivers/build_all/sensor/i2c.dtsi

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compatible = "rohm,bh1730";
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reg = <0xb4>;
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};
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test_i2c_mb7040: mb7040@b5 {
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compatible = "maxbotix,mb7040";
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reg = <0xb5>;
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};

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