Merge pull request #255 from CarlsonCustoms/add-shtc3-waveshare-sensors

Add SHTC3 and Waveshare UPS HAT (D) sensor plug-ins
This commit is contained in:
Lloyd
2026-05-19 11:12:04 +01:00
committed by GitHub
2 changed files with 258 additions and 0 deletions
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"""
SHTC3 temperature and humidity sensor plug-in (RAK1901 WisBlock sensor).
Requires: pip install smbus2
The SHTC3 uses 16-bit command words and requires a raw I2C read (no register
byte prefix), so smbus2.i2c_rdwr is used instead of the standard SMBus API.
Config example:
- type: shtc3
name: "ambient"
enabled: true
auto_install_packages: false
settings:
i2c_address: 0x70 # SHTC3 fixed I2C address
bus_number: 1 # I2C bus number (1 for Raspberry Pi default)
"""
from __future__ import annotations
import time
from typing import Any, Dict, Optional
from .base import SensorBase
from .registry import SensorRegistry
# SHTC3 two-byte command words
_CMD_WAKE = [0x35, 0x17]
_CMD_MEAS = [0x7C, 0xA2] # T-first, normal power mode
_CMD_SLEEP = [0xB0, 0x98]
@SensorRegistry.register("shtc3")
class SHTC3Sensor(SensorBase):
sensor_type = "shtc3"
def __init__(self, name: str, config: Optional[Dict[str, Any]] = None, log=None):
super().__init__(name=name, config=config, log=log)
self.i2c_address = int(self.settings.get("i2c_address", 0x70))
self.bus_number = int(self.settings.get("bus_number", 1))
self.available = False
if not self.ensure_python_modules([("smbus2", "smbus2")]):
return
try:
import smbus2 # type: ignore[import-not-found]
self._smbus2 = smbus2
# Verify sensor is reachable: wake then immediately sleep
bus = smbus2.SMBus(self.bus_number)
try:
bus.i2c_rdwr(smbus2.i2c_msg.write(self.i2c_address, _CMD_WAKE))
time.sleep(0.002)
bus.i2c_rdwr(smbus2.i2c_msg.write(self.i2c_address, _CMD_SLEEP))
finally:
bus.close()
self.available = True
self.log.info(
"SHTC3 initialized (addr=0x%02X, bus=%d)",
self.i2c_address,
self.bus_number,
)
except Exception as exc:
self.log.warning(
"SHTC3 init failed (addr=0x%02X, bus=%d): %s",
self.i2c_address,
self.bus_number,
exc,
)
self.available = False
def _read(self) -> Dict[str, Any]:
"""Read temperature and humidity from SHTC3."""
if not self.available:
raise RuntimeError("SHTC3 device not available")
smbus2 = self._smbus2
bus = smbus2.SMBus(self.bus_number)
try:
bus.i2c_rdwr(smbus2.i2c_msg.write(self.i2c_address, _CMD_WAKE))
time.sleep(0.002)
bus.i2c_rdwr(smbus2.i2c_msg.write(self.i2c_address, _CMD_MEAS))
time.sleep(0.02) # measurement takes ~12 ms in normal power mode
r = smbus2.i2c_msg.read(self.i2c_address, 6)
bus.i2c_rdwr(r)
data = list(r)
bus.i2c_rdwr(smbus2.i2c_msg.write(self.i2c_address, _CMD_SLEEP))
# Bytes: T_MSB, T_LSB, T_CRC, RH_MSB, RH_LSB, RH_CRC
t_raw = (data[0] << 8) | data[1]
rh_raw = (data[3] << 8) | data[4]
temp_c = round(-45.0 + 175.0 * t_raw / 65536.0, 2)
temp_f = round(temp_c * 9.0 / 5.0 + 32.0, 2)
rh = round(100.0 * rh_raw / 65536.0, 2)
return {
"temperature_c": temp_c,
"temperature_f": temp_f,
"humidity_pct": rh,
}
except Exception as exc:
raise RuntimeError(f"SHTC3 read failed: {exc}") from exc
finally:
bus.close()
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"""
Waveshare UPS HAT (D) battery monitor plug-in — INA219 at I2C 0x43.
Reads a single 21700 Li-ion cell via INA219. Reports voltage, current,
power, battery percent, and charge state.
Requires: pip install smbus2
Config example:
- type: waveshare_ups_d
name: "battery"
enabled: true
auto_install_packages: false
settings:
i2c_address: 0x43 # Waveshare UPS HAT (D) fixed address
bus_number: 1 # I2C bus number (1 for Raspberry Pi default)
"""
from __future__ import annotations
import time
from typing import Any, Dict, Optional
from .base import SensorBase
from .registry import SensorRegistry
# INA219 register addresses
_REG_CONFIG = 0x00
_REG_SHUNT = 0x01
_REG_BUS = 0x02
_REG_POWER = 0x03
_REG_CURRENT = 0x04
_REG_CAL = 0x05
# 32V range, ±320mV gain, 128-sample averaging, continuous shunt+bus
_CONFIG_VALUE = 0x3FFF
# Waveshare UPS HAT (D) calibration — 0.01Ω shunt (per Waveshare sample code)
# current_lsb ≈ 0.1524 mA/LSB, power_lsb = current_lsb × 20
_CAL_VALUE = 26868
_CURRENT_LSB = 0.0001524 # A per LSB
_POWER_LSB = _CURRENT_LSB * 20.0 # W per LSB
def _voltage_to_percent(v: float) -> int:
"""Piecewise linear SoC estimate for a single 21700 Li-ion cell (3.04.2 V)."""
if v >= 4.20: return 100
if v >= 4.00: return int(85 + (v - 4.00) / 0.20 * 15)
if v >= 3.80: return int(60 + (v - 3.80) / 0.20 * 25)
if v >= 3.70: return int(40 + (v - 3.70) / 0.10 * 20)
if v >= 3.50: return int(15 + (v - 3.50) / 0.20 * 25)
if v >= 3.00: return int( (v - 3.00) / 0.50 * 15)
return 0
@SensorRegistry.register("waveshare_ups_d")
class WaveshareUpsDSensor(SensorBase):
sensor_type = "waveshare_ups_d"
def __init__(self, name: str, config: Optional[Dict[str, Any]] = None, log=None):
super().__init__(name=name, config=config, log=log)
self.i2c_address = int(self.settings.get("i2c_address", 0x43))
self.bus_number = int(self.settings.get("bus_number", 1))
self.available = False
if not self.ensure_python_modules([("smbus2", "smbus2")]):
return
try:
import smbus2 # type: ignore[import-not-found]
self._smbus2 = smbus2
bus = smbus2.SMBus(self.bus_number)
try:
self._write(bus, _REG_CONFIG, _CONFIG_VALUE)
self._write(bus, _REG_CAL, _CAL_VALUE)
# 128-sample averaging takes ~68 ms; wait for first conversion
time.sleep(0.15)
finally:
bus.close()
self.available = True
self.log.info(
"Waveshare UPS HAT (D) INA219 initialized (addr=0x%02X, bus=%d)",
self.i2c_address,
self.bus_number,
)
except Exception as exc:
self.log.warning(
"Waveshare UPS HAT (D) init failed (addr=0x%02X, bus=%d): %s",
self.i2c_address,
self.bus_number,
exc,
)
def _write(self, bus, reg: int, val: int) -> None:
bus.write_i2c_block_data(
self.i2c_address, reg, [(val >> 8) & 0xFF, val & 0xFF]
)
def _read_u(self, bus, reg: int) -> int:
d = bus.read_i2c_block_data(self.i2c_address, reg, 2)
return (d[0] << 8) | d[1]
def _read_s(self, bus, reg: int) -> int:
v = self._read_u(bus, reg)
return v - 0x10000 if v & 0x8000 else v
def _read(self) -> Dict[str, Any]:
"""Read voltage, current, power, and derived battery state."""
if not self.available:
raise RuntimeError("Waveshare UPS HAT (D) not available")
try:
bus = self._smbus2.SMBus(self.bus_number)
try:
# Re-apply calibration in case of external reset
self._write(bus, _REG_CAL, _CAL_VALUE)
bus_v = (self._read_u(bus, _REG_BUS) >> 3) * 4 / 1000.0
shunt_mv = self._read_s(bus, _REG_SHUNT) * 0.01
current_ma = self._read_s(bus, _REG_CURRENT) * _CURRENT_LSB * 1000.0
power_mw = self._read_u(bus, _REG_POWER) * _POWER_LSB * 1000.0
finally:
bus.close()
pct = _voltage_to_percent(bus_v)
# HAT (D) sign convention: negative = charging, positive = discharging
if current_ma < -50:
state = "charging"
elif current_ma > 50:
state = "discharging"
else:
state = "idle"
return {
"bus_voltage_v": round(bus_v, 3),
"shunt_voltage_mv": round(shunt_mv, 2),
"current_ma": round(current_ma, 1),
"power_mw": round(power_mw, 1),
"battery_percent": pct,
"charge_state": state,
}
except Exception as exc:
raise RuntimeError(f"Waveshare UPS HAT (D) read failed: {exc}") from exc