Effective temperature reading from multiple sensors

digitemp/device/thermometer.py

@@ -1,5 +1,6 @@
 import time
 import struct
+import warnings
 
 from ..utils import *
 from ..master import UART_Adapter
@@ -77,6 +78,13 @@ def get_temperature(self, attempts=3):
         attempts = attempts if attempts > 1 else 1
         self._reset()
         self._convert_T()
+        return self.read_temperature(attempts=attempts)
+
+    def read_temperature(self, attempts=3):
+        # type: (int) -> float
+        """
+        Read scratchpad memory and calculates the temperature.
+        """
         for i in range(attempts):
             self._reset()
             try:
@@ -90,14 +98,8 @@ def get_temperature(self, attempts=3):
 
     def convert_T_all(self):
         # type: () -> None
-        """
-        This forces all temperature sensors to calculate temperature and set/unset alarm flag.
-        """
-        self.bus.skip_ROM()
-        self.bus.write_byte(0x44)
-        # We do not know if there are any DS18B20 or DS1822 on the line and what are their resolution settings.
-        # So, we just wait max(T_conv) that is 750ms for currently supported devices.
-        time.sleep(self.T_CONV)
+        warnings.warn("deprecated", DeprecationWarning)
+        return self.bus.measure_temperature_all()
 
     # ---[ Function Commands ]----
 

digitemp/master.py

@@ -16,6 +16,7 @@
 For details see:
     Using an UART to Implement a 1-Wire Bus Master (http://www.maximintegrated.com/en/app-notes/index.mvp/id/214)
 """
+import time
 import serial
 import platform
 from .utils import *
@@ -237,7 +238,6 @@ def read_ROM(self):
         # type: () -> bytes
         """
         READ ROM [33h]
-
         This command can only be used when there is one device on the bus. It allows the bus driver to read the
         device's 64-bit ROM code without using the Search ROM procedure. If this command is used when there
         is more than one device present on the bus, a data collision will occur when all the devices attempt to
@@ -255,7 +255,6 @@ def match_ROM(self, rom_code):
         # type: (bytes) -> None
         """
         MATCH ROM [55h]
-
         The match ROM command allows to address a specific device on a multidrop or single-drop bus.
         Only the device that exactly matches the 64-bit ROM code sequence will respond to the function command
         issued by the master; all other devices on the bus will wait for a reset pulse.
@@ -267,6 +266,7 @@ def match_ROM(self, rom_code):
     def skip_ROM(self):
         # type: () -> None
         """
+        SKIP ROM [CCh]
         The master can use this command to address all devices on the bus simultaneously without sending out
         any ROM code information.
         """
@@ -330,6 +330,17 @@ def search(current_rom=None):
 
         return complete_roms
 
+    def measure_temperature_all(self):
+        # type: () -> None
+        """
+        This forces all temperature sensors to calculate temperature and set/unset alarm flag.
+        """
+        self.skip_ROM()
+        self.write_byte(0x44)
+        # We do not know if there are any DS18B20 or DS1822 on the line and what are their resolution settings.
+        # So, we just wait max(T_conv) that is 750ms for currently supported devices.
+        time.sleep(0.75)
+
     # ---[ Helper Functions ]----
 
     def get_connected_ROMs(self):

examples/read_sensors_effective.py

@@ -0,0 +1,37 @@
+import time
+from digitemp.master import UART_Adapter
+from digitemp.device import TemperatureSensor
+from digitemp.exceptions import OneWireException
+
+bus = UART_Adapter('/dev/ttyS0')
+
+sensors = []
+for rom in bus.get_connected_ROMs():
+    try:
+        sensors.append(TemperatureSensor(bus, rom))
+    except OneWireException:
+        pass
+
+print(55 * "=")
+for sensor in sensors:
+    sensor.info()
+    print(55 * "=")
+
+# Instead of calling sensor.get_temperature() for each sensor we call bus.measure_temperature_all() once
+# and then do sensor.read_temperature() for each sensor.
+
+try:
+    while True:
+        measurements = []
+        bus.measure_temperature_all()
+        for sensor in sensors:
+            try:
+                measurements.append("%3.02fºC" % sensor.read_temperature())
+            except OneWireException:
+                measurements.append("  error")
+        print("   ".join(measurements))
+        time.sleep(3)
+except KeyboardInterrupt:
+    pass
+finally:
+    bus.close()