temphum: support multiple temp/relhum sensors

Makefile

@@ -10,7 +10,7 @@ endif
 PROGRAMS = admin_bot inverter_bot pump_bot sensors_bot
 PROGRAMS += inverter_mqtt_receiver inverter_mqtt_sender
 PROGRAMS += sensors_mqtt_receiver sensors_mqtt_sender
-PROGRAMS += si7021d
+PROGRAMS += temphumd
 PROGRAMS += gpiorelayd
 PROGRAMS += gpiosensord
 #PROGRAMS += web_api

src/home/temphum/__init__.py

@@ -0,0 +1,18 @@
+from .base import SensorType, TempHumSensor
+from .si7021 import Si7021
+from .dht12 import DHT12
+
+__all__ = [
+    'SensorType',
+    'TempHumSensor',
+    'create_sensor'
+]
+
+
+def create_sensor(type: SensorType, bus: int) -> TempHumSensor:
+    if type == SensorType.Si7021:
+        return Si7021(bus)
+    elif type == SensorType.DHT12:
+        return DHT12(bus)
+    else:
+        raise ValueError('unexpected sensor type')

src/home/temphum/base.py

@@ -0,0 +1,25 @@
+import smbus
+
+from abc import abstractmethod, ABC
+from enum import Enum
+
+
+class TempHumSensor:
+    @abstractmethod
+    def humidity(self) -> float:
+        pass
+
+    @abstractmethod
+    def temperature(self) -> float:
+        pass
+
+
+class I2CTempHumSensor(TempHumSensor, ABC):
+    def __init__(self, bus: int):
+        super().__init__()
+        self.bus = smbus.SMBus(bus)
+
+
+class SensorType(Enum):
+    Si7021 = 'si7021'
+    DHT12 = 'dht12'

src/home/temphum/dht12.py

@@ -0,0 +1,22 @@
+from .base import I2CTempHumSensor
+
+
+class DHT12(I2CTempHumSensor):
+    i2c_addr = 0x5C
+        
+    def _measure(self):
+        raw = self.bus.read_i2c_block_data(self.i2c_addr, 0, 5)
+        if (raw[0] + raw[1] + raw[2] + raw[3]) & 0xff != raw[4]:
+            raise ValueError("checksum error")
+        return raw
+
+    def temperature(self) -> float:
+        raw = self._measure()
+        temp = raw[2] + (raw[3] & 0x7f) * 0.1
+        if raw[3] & 0x80:
+            temp *= -1
+        return temp
+
+    def humidity(self) -> float:
+        raw = self._measure()
+        return raw[0] + raw[1] * 0.1

src/home/temphum/si7021.py

@@ -0,0 +1,13 @@
+from .base import I2CTempHumSensor
+
+
+class Si7021(I2CTempHumSensor):
+    i2c_addr = 0x40
+
+    def temperature(self) -> float:
+        raw = self.bus.read_i2c_block_data(self.i2c_addr, 0xE3, 2)
+        return 175.72 * (raw[0] << 8 | raw[1]) / 65536.0 - 46.85
+
+    def humidity(self) -> float:
+        raw = self.bus.read_i2c_block_data(self.i2c_addr, 0xE5, 2)
+        return 125.0 * (raw[0] << 8 | raw[1]) / 65536.0 - 6.0

src/temphum.py

@@ -0,0 +1,19 @@
+from argparse import ArgumentParser
+from home.temphum import SensorType, create_sensor
+
+
+if __name__ == '__main__':
+    parser = ArgumentParser()
+    parser.add_argument('-t', '--type', choices=[item.value for item in SensorType],
+                        required=True,
+                        help='Sensor type')
+    parser.add_argument('-b', '--bus', type=int, default=0,
+                        help='I2C bus number')
+    arg = parser.parse_args()
+
+    sensor = create_sensor(SensorType(arg.type), arg.bus)
+    temp = sensor.temperature()
+    hum = sensor.humidity()
+
+    print(f'temperature: {temp}')
+    print(f'rel. humidity: {hum}')

src/temphumd.py

@@ -1,29 +1,26 @@
 #!/usr/bin/env python3
-import smbus
-import argparse
 import asyncio
 import json
 import logging
 
+from typing import Optional
+
 from home.config import config
 from home.util import parse_addr
+from home.temphum import SensorType, create_sensor, TempHumSensor
 
 logger = logging.getLogger(__name__)
-bus = None
+sensor: Optional[TempHumSensor] = None
 lock = asyncio.Lock()
 delay = 0.01
 
 
-async def si7021_read():
+async def get_measurements():
     async with lock:
         await asyncio.sleep(delay)
 
-        # these are still blocking... meh
-        raw = bus.read_i2c_block_data(0x40, 0xE3, 2)
-        temp = 175.72 * (raw[0] << 8 | raw[1]) / 65536.0 - 46.85
-
-        raw = bus.read_i2c_block_data(0x40, 0xE5, 2)
-        rh = 125.0 * (raw[0] << 8 | raw[1]) / 65536.0 - 6.0
+        temp = sensor.temperature()
+        rh = sensor.humidity()
 
         return rh, temp
 
@@ -41,7 +38,7 @@ async def handle_client(reader, writer):
 
         if request == 'read':
             try:
-                rh, temp = await asyncio.wait_for(si7021_read(), timeout=3)
+                rh, temp = await asyncio.wait_for(get_measurements(), timeout=3)
                 data = dict(humidity=rh, temp=temp)
             except asyncio.TimeoutError as e:
                 logger.exception(e)
@@ -68,12 +65,14 @@ async def run_server(host, port):
 if __name__ == '__main__':
     config.load()
 
-    host, port = parse_addr(config['server']['listen'])
+    if 'measure_delay' in config['sensor']:
+        delay = float(config['sensor']['measure_delay'])
 
-    delay = float(config['smbus']['delay'])
-    bus = smbus.SMBus(int(config['smbus']['bus']))
+    sensor = create_sensor(SensorType(config['sensor']['type']),
+                           int(config['sensor']['bus']))
 
     try:
+        host, port = parse_addr(config['server']['listen'])
         asyncio.run(run_server(host, port))
     except KeyboardInterrupt:
         logging.info('Exiting...')

systemd/sensors_mqtt_sender.service

@@ -1,6 +1,6 @@
 [Unit]
 Description=Sensors MQTT sender
-After=si7021d.service
+After=temphumd.service
 
 [Service]
 User=user

systemd/si7021d.service

@@ -1,10 +0,0 @@
-[Unit]
-Description=si7021 daemon
-After=network-online.target
-
-[Service]
-Restart=on-failure
-ExecStart=/home/user/homekit/src/si7021d.py --config /etc/si7021d.toml
-
-[Install]
-WantedBy=multi-user.target

systemd/temphumd.service

@@ -0,0 +1,10 @@
+[Unit]
+Description=temperature and humidity daemon
+After=network-online.target
+
+[Service]
+Restart=on-failure
+ExecStart=/home/user/homekit/src/temphumd.py --config /etc/temphumd.toml
+
+[Install]
+WantedBy=multi-user.target