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samples: sensor: add sample for SHT4X
Add a new sample specifically for the SHT4X sensor. Signed-off-by: Jakub Wasilewski <jwasilewski@internships.antmicro.com> Signed-off-by: Filip Kokosinski <fkokosinski@antmicro.com>
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‎samples/sensor/sht4x/CMakeLists.txt

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# Copyright (c) 2025 Antmicro <www.antmicro.com>
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# SPDX-License-Identifier: Apache-2.0
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cmake_minimum_required(VERSION 3.20.0)
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find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
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project(sht4x)
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FILE(GLOB app_sources src/*.c)
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target_sources(app PRIVATE ${app_sources})

‎samples/sensor/sht4x/Kconfig

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# Copyright (c) 2025 Antmicro <www.antmicro.com>
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# SPDX-License-Identifier: Apache-2.0
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mainmenu "SHT4X sample application"
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config APP_USE_HEATER
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bool "Use the Heater on the SHT4X"
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help
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Maximum duty cycle for using the heater is 5%
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config APP_HEATER_HUMIDITY_THRESH
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int "RH [%] threshold above which the heater will be activated"
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range 0 99
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default 65
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depends on APP_USE_HEATER
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config APP_HEATER_PULSE_POWER
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int "Heater Power Setting"
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range 0 2
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default 2
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depends on APP_USE_HEATER
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help
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0 -> High power heater pulse -> ~200 mW @3.3V
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1 -> Medium power heater pulse -> ~110 mW @3.3V
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2 -> Low power heater pulse -> ~20 mW @3.3V
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config APP_HEATER_PULSE_DURATION_LONG
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bool "Use long pulse duration Heater setting"
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default y
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depends on APP_USE_HEATER
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help
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Say 'Y' if you want to use the long pulse duration setting. This sets the pulse time to
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1.1s. Say 'N' if you want to use the short pulse duration setting, which sets the pulse
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time to 0.11s.
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source "Kconfig.zephyr"

‎samples/sensor/sht4x/README.rst

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.. _sht4x:
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SHT4X: High Accuracy Digital I2C Humidity Sensor
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#################################################
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Description
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***********
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This sample application periodically reads the ambient temperature and humidity
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from an SHT4X device. The result is written to the console.
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The SHT4X sensor has an optional heater that can be useful for specific
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environments or applications (refer to the datasheet for more information).
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To utilize the heater, check the Kconfig options for this application.
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References
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**********
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- `SHT4X sensor <https://sensirion.com/products/catalog/SHT45>`_
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Wiring
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******
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This sample uses the SHT4X sensor controlled via the I2C interface.
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Connect Supply: **VDD**, **GND** and Interface: **SDA**, **SCL**.
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The supply voltage can be in the 1.7V to 3.6V range.
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Depending on the baseboard used, the **SDA** and **SCL** lines may require Pull-Up
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resistors.
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Building and Running
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********************
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This project outputs sensor data to the console. It requires an SHT4X
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sensor. It should work with any platform featuring an I2C peripheral
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interface. This example includes a device tree overlay
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for the :zephyr:board:`blackpill_f411ce` board.
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.. zephyr-app-commands::
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:zephyr-app: samples/sensor/sht4x
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:board: blackpill_f411ce
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:goals: build flash
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Sample Output
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=============
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.. code-block:: console
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*** Booting Zephyr OS build v2.6.0-rc1-315-g50d8d1187138 ***
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SHT4X: 23.64 Temp. [C] ; 30.74 RH [%]
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SHT4X: 23.66 Temp. [C] ; 32.16 RH [%]
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SHT4X: 23.63 Temp. [C] ; 30.83 RH [%]
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The datasheet states that the sensor measures temperature and humidity in degrees Celsius
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and percent relative humidity respectively.

‎samples/sensor/sht4x/boards/blackpill_f411ce.overlay

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/*
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* Copyright (c) 2025 Antmicro <www.antmicro.com>
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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&i2c1 {
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status = "okay";
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clock-frequency = <I2C_BITRATE_FAST>;
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sht4x@44 {
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status = "okay";
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compatible = "sensirion,sht4x";
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reg = <0x44>;
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repeatability = <2>;
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};
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};

‎samples/sensor/sht4x/prj.conf

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# Copyright (c) 2025 Antmicro <www.antmicro.com>
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# SPDX-License-Identifier: Apache-2.0
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CONFIG_CBPRINTF_FP_SUPPORT=y
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CONFIG_I2C=y
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CONFIG_SENSOR=y
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CONFIG_PM_DEVICE=y
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CONFIG_LOG=y
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CONFIG_SENSOR_LOG_LEVEL_DBG=y

‎samples/sensor/sht4x/sample.yaml

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# Copyright (c) 2025 Antmicro <www.antmicro.com>
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# SPDX-License-Identifier: Apache-2.0
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sample:
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name: SHT4X Sensor Sample
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tests:
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sample.sensor.sht4x:
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build_only: true
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platform_allow:
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- blackpill_f411ce
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- myra_sip_baseboard
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tags:
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- sensors

‎samples/sensor/sht4x/src/main.c

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/*
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* Copyright (c) 2025 Antmicro <www.antmicro.com>
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/kernel.h>
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#include <zephyr/device.h>
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#include <zephyr/drivers/sensor.h>
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#include <stdio.h>
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#include <zephyr/drivers/sensor/sht4x.h>
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#if !DT_HAS_COMPAT_STATUS_OKAY(sensirion_sht4x)
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#error "No sensirion,sht4x compatible node found in the device tree"
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#endif
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int main(void)
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{
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const struct device *const sht = DEVICE_DT_GET_ANY(sensirion_sht4x);
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struct sensor_value temp, hum;
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if (!device_is_ready(sht)) {
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printf("Device %s is not ready.\n", sht->name);
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return 0;
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}
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#if CONFIG_APP_USE_HEATER
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struct sensor_value heater_p;
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struct sensor_value heater_d;
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heater_p.val1 = CONFIG_APP_HEATER_PULSE_POWER;
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heater_d.val1 = !!CONFIG_APP_HEATER_PULSE_DURATION_LONG;
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sensor_attr_set(sht, SENSOR_CHAN_ALL, SENSOR_ATTR_SHT4X_HEATER_POWER, &heater_p);
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sensor_attr_set(sht, SENSOR_CHAN_ALL, SENSOR_ATTR_SHT4X_HEATER_DURATION, &heater_d);
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#endif
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while (true) {
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if (sensor_sample_fetch(sht)) {
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printf("Failed to fetch sample from SHT4X device\n");
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return 0;
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}
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sensor_channel_get(sht, SENSOR_CHAN_AMBIENT_TEMP, &temp);
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sensor_channel_get(sht, SENSOR_CHAN_HUMIDITY, &hum);
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#if CONFIG_APP_USE_HEATER
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/*
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* Conditions in which it makes sense to activate the heater
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* are application/environment specific.
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*
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* The heater should not be used above SHT4X_HEATER_MAX_TEMP (65 °C)
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* as stated in the datasheet.
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*
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* The temperature data will not be updated here for obvious reasons.
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**/
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if (hum.val1 > CONFIG_APP_HEATER_HUMIDITY_THRESH &&
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temp.val1 < SHT4X_HEATER_MAX_TEMP) {
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printf("Activating heater.\n");
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if (sht4x_fetch_with_heater(sht)) {
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printf("Failed to fetch sample from SHT4X device\n");
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return 0;
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}
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sensor_channel_get(sht, SENSOR_CHAN_HUMIDITY, &hum);
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}
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#endif
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printf("SHT4X: %.2f Temp. [C] ; %0.2f RH [%%]\n", sensor_value_to_double(&temp),
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sensor_value_to_double(&hum));
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#if CONFIG_APP_USE_HEATER && !CONFIG_APP_HEATER_PULSE_DURATION
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k_sleep(K_MSEC(20000));
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#else
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k_sleep(K_MSEC(2000));
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#endif
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}
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}

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