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HTS221 MicroPython Driver

MicroPython driver for the STMicroelectronics HTS221 humidity and temperature sensor.

This library is a port of MicroPython_HTS221.

Supported Sensor

Parameter Value
Interface I²C
Default I²C address 0x5F
Device ID 0xBC
Humidity range 0–100 %RH
Humidity accuracy ±3.5 %RH
Temperature range −40 to +120 °C
Temperature accuracy ±0.5 °C

Features

  • I²C communication
  • Device identification (WHO_AM_I)
  • Humidity and temperature measurement
  • One-shot and continuous measurement modes
  • Configurable output data rate (ODR)
  • Configurable averaging
  • Data-ready status flags
  • Power management (on/off, reboot)
  • Factory calibration (automatic)
  • User temperature calibration (offset and two-point)

Basic Usage

from machine import I2C
from hts221 import HTS221

i2c = I2C(1)
sensor = HTS221(i2c)

humidity = sensor.humidity()
temperature = sensor.temperature()

print("Humidity:", humidity, "%")
print("Temperature:", temperature, "°C")

# Read both at once
h, t = sensor.read()

API Reference

Initialization

sensor = HTS221(i2c, address=0x5F)

Device Information

sensor.device_id()

Returns the sensor device ID (WHO_AM_I register, expected 0xBC).

Measurements

  • sensor.temperature() — temperature in °C
  • sensor.humidity() — relative humidity in %
  • sensor.read() — returns (humidity, temperature)
  • sensor.read_one_shot() — triggers a one-shot conversion and returns (humidity, temperature) after a fixed 15 ms delay

Data Readiness

  • sensor.data_ready() — True when both humidity and temperature are available
  • sensor.temperature_ready() — True when temperature is available
  • sensor.humidity_ready() — True when humidity is available

One-Shot Mode

sensor.trigger_one_shot()

Triggers a single conversion with a 15 ms delay. Used internally by read_one_shot().

Configuration

  • sensor.get_odr() — returns current output data rate
  • sensor.set_odr(odr) — set ODR (0 = one-shot, 1 = 1 Hz, 2 = 7 Hz, 3 = 12.5 Hz)
  • sensor.set_continuous(odr) — enable continuous mode. Raises ValueError if odr=0.

Averaging

  • sensor.get_av() — returns current averaging configuration register
  • sensor.set_av(av) — set humidity and temperature averaging (raw register value)

The AV_CONF register controls internal averaging for both channels. Higher values improve noise but increase conversion time. Refer to the HTS221 datasheet for the register encoding.

Power Management

  • sensor.power_on() — enable sensor
  • sensor.power_off() — disable sensor
  • sensor.reboot() — reload factory calibration data from non-volatile memory

Temperature Calibration

# Simple offset correction
sensor.set_temp_offset(-1.2)

# Two-point calibration (gain + offset)
sensor.calibrate_temperature(
    ref_low=0.0,
    measured_low=0.8,
    ref_high=50.0,
    measured_high=48.7,
)

No calibration is required for basic usage — the driver applies factory calibration automatically.

Examples

File Description
humidity.py Basic humidity and temperature reading 
mpremote mount lib/hts221 run lib/hts221/examples/humidity.py

Notes

  • The driver uses factory calibration data stored in the sensor, read automatically at initialization.
  • temperature(), humidity(), and read() poll the sensor's status bits via _ensure_data() to wait for fresh data before returning.
  • read_one_shot() triggers a conversion and waits a fixed 15 ms delay before reading registers (no status polling).
  • In power-down or one-shot mode, calling a measurement method automatically triggers a new conversion.