add real time plotting functionality

src/flow_meter.py

@@ -7,7 +7,8 @@
 class FlowMeter(object):
     """
     This class represents the flowmeter device and handles its I/O with the APIs provided by manufacturer
-    Sensirion."""
+    Sensirion.
+    """
     def __init__(self, port='/dev/ttyUSB0', baudrate=460800, slave_address=2):
         """
         Initialize connection to the flow meter and other configurations.
@@ -22,13 +23,69 @@ def __init__(self, port='/dev/ttyUSB0', baudrate=460800, slave_address=2):
         self.port = ShdlcSerialPort(port=port, baudrate=baudrate) # setup serial port
         self.device = Sfc5xxxShdlcDevice(ShdlcConnection(self.port), slave_address=slave_address)
         self.device.activate_calibration(3) # specify calibration file index in list; default now on Helium (3)
-        # set units
-        self.unit = Sfc5xxxMediumUnit(
+        # set default units
+        self._unit = Sfc5xxxMediumUnit(
             Sfc5xxxUnitPrefix.ONE,
             Sfc5xxxUnit.STANDARD_LITER,
             Sfc5xxxUnitTimeBase.MINUTE
         )
-        self.device.set_user_defined_medium_unit(self.unit)
+        self.device.set_user_defined_medium_unit(self._unit)
+
+
+    def set_units(self, prefix, unit, time_base):
+        """
+        Set units of output for the flow rate readings. The Sensirion driver has a set of conventions for
+        naming the units, and you can use the get_unit_convention() method to view the valid units.
+
+        Parameters
+        ----------
+        prefix : str
+            String literal of the unit prefix (MILLI, MICRO, KILO, etc.) Name has to match exactly with names of
+            the Sfx5xxxUnitPrefix enumerator items.
+        prefix : str
+            String literal of the medium units (STANDARD_LITER, BAR, etc.) Name has to match exactly with names of
+            the Sfx5xxxUnit enumerator items.
+        prefix : str
+            String literal of the unit time base (MILLISECOND, MINUTE, etc.) Name has to match exactly with names of
+            the Sfx5xxxUnitTimeBase enumerator items.
+        """
+        _prefix = None
+        _unit = None
+        _time_base = None
+        for item in Sfc5xxxUnitPrefix:
+            if item.name == prefix : _prefix = item
+        if _prefix == None : raise KeyError('Invalid unit prefix. Refer to get_unit_convention() for prefix names')
+        for item in Sfc5xxxUnit:
+            if item.name == unit : _unit = item
+        if _unit == None : raise KeyError('Invalid unit. Refer to get_unit_convention() for unit names')
+        for item in Sfc5xxxUnitTimeBase:
+            if item.name == time_base : _time_base = item
+        if _time_base == None : raise KeyError('Invalid time base. Refer to get_unit_convention() for time base names')
+
+        units = Sfc5xxxMediumUnit(_prefix, _unit, _time_base)
+        self.device.set_user_defined_medium_unit(units)
+
+
+    def get_unit_convention(self, category):
+        """
+        A helper method for getting available units for flow meter readings. You can use the 'name' string literals
+        to access and set units in the set_units() method.
+
+        Parameters
+        ----------
+        category : str
+            Category of units you want to view. Available options are 'prefix', 'unit', and 'time_base'.
+        """
+        if category == 'prefix':
+            for item in Sfc5xxxUnitPrefix:
+                print('name: ', item.name, ', description: ', item.description)
+        elif category == 'unit':
+            for item in Sfc5xxxUnit:
+                print('name: ', item.name, ', description: ', item.description)
+        elif category == 'time_base':
+            for item in Sfc5xxxUnitTimeBase:
+                print('name: ', item.name, ', description: ', item.description)
+        else: raise KeyError('Invalid unit category. Choose from prefix, unit, and time_base to view available units')
 
 
     def set_baudrate(self, baudrate):
@@ -54,7 +111,7 @@ def get_reading(self, duration):
         # dump what's already inside the buffer. this is only useful for low overhead
         #buffer = self.device.read_measured_value_buffer(Sfc5xxxScaling.USER_DEFINED)
         while len(reading) <= duration * 1000: # flow meter reads at 1kHz
-            buffer = self.device.read_measured_value_buffer(Sfc5xxxScaling.USER_DEFINED)
+            buffer = self.device.read_measured_value_buffer(Sfc5xxxScaling.USER_DEFINED, max_reads=2)
             #print(buffer.sampling_time) # the only "time" returned from read buffer command
             reading.extend(buffer.values)
         return reading
@@ -72,52 +129,4 @@ def get_reading_single_cycle(self, duration):
             reading.append(val)
         return reading
 
-# below is the standalone implementation of flow meter reading for reference
-'''
-with ShdlcSerialPort(port='/dev/ttyUSB0', baudrate=460800) as port:   
-    device = Sfc5xxxShdlcDevice(ShdlcConnection(port), slave_address=2)
-
-    # select calibration
-    print('activate calibration...')
-    device.activate_calibration(3)
-
-    # set units
-    unit = Sfc5xxxMediumUnit(
-        Sfc5xxxUnitPrefix.ONE,
-        Sfc5xxxUnit.STANDARD_LITER,
-        Sfc5xxxUnitTimeBase.MINUTE
-    )
-
-    device.set_user_defined_medium_unit(unit)
-
-    # read flow value for 10s
-    # try with single value reading
-    print('start acquiring...')
-
-    # an implementation with buffer reading
-    read_time = []
-    reading = []
-    t = time.time()
-    buffer = device.read_measured_value_buffer(Sfc5xxxScaling.USER_DEFINED) # dump what's already inside the buffer
-    while len(reading) <= 3000:
-        buffer = device.read_measured_value_buffer(Sfc5xxxScaling.USER_DEFINED)
-        reading.extend(buffer.values)
-        if buffer.lost_values != 0:
-            print('lost values detected!')
-        #read_time.extend([t * 0.001 for t in range(counter, counter + len(buffer.values))])
-        #print(buffer.lost_values)
-    print('execution time:', time.time()-t)
-
-
-    output = open('flow_reading.txt', 'w', encoding='utf-8')
-    #output_time = open('sampling_time.txt', 'w', encoding='utf-8')
-    for r in reading:
-        output.write(str(r))
-        output.write("\n")
-    #for t in read_time:
-        #output_time.write(str(t))
-        #output_time.write("\n")
-    print('success')
-    output.close()
-    #output_time.close()
-'''
+

src/kernel.py

@@ -1,6 +1,7 @@
 import numpy as np
+import matplotlib.pyplot as plt
 import RPi.GPIO as GPIO
-import time
+import time, os, shutil
 #from wavegen_control import wavegen_control
 from flow_meter import FlowMeter
 #from input import generate_pulse
@@ -37,38 +38,75 @@ def __init__(self, gpio_channel) -> None:
 
    # def burst_mode(self, ncycles):
        # self.wavegen.burst(enable=True, ncycles=ncycles, phase=0)
+
+    def check_disk_space(required_space_mb, path="/"):
+        """
+        Check if there is enough disk space available.
+
+        Parameters
+        ----------
+        required_space_mb : float
+            The required space in megabytes.
+        path : str, optional
+            The path to check the disk space of. Default is root.
 
+        Returns
+        -------
+        bool
+            True if there is enough space, False otherwise.
+        """
+        total, used, free = shutil.disk_usage(path)
+        free_mb = free / 1024**2  # Convert bytes to MB
+        return free_mb >= required_space_mb
 
-    def acquire(self, duration, acquisition_limit=100):
+    def acquire(self, path, duration):
         """
         Acquire flow rate measurements from the flow meter for a fixed duration at trigger.
         Currently an upper limit of the number of acquisitions is in place.
 
         Parameters
         ----------
-        duration : Duration of a single acquisition in seconds. This should not exceed the period of
-        plasma discharge to avoid malfunctioning.
-        acquisition_limit : Maximum number of acquisition the command can perform.
+        path : str
+            Path to the diectory that stores acquired data.
+        duration : float
+            Duration of a single acquisition in seconds. This should not exceed the period of
+            plasma discharge to avoid malfunctioning.
         """
         shot_counts = 0
+        data_folder = path
+
+        plt.ion()
+        fig, ax = plt.subplots()
+        line, = ax.plot(np.zeros(int(duration*1000)))
+        ax.set_title('real time flow rate')
+        ax.set_ylabel('flow rate ('+self.flow_meter._unit.__str__()+')')
+        t = time.time()
         try:
-            while shot_counts <= acquisition_limit:
+            while True:
+                if not self.check_disk_space(5, data_folder):  # Check for at least 5 MB of free space
+                    print("Insufficient disk space. Please free up space to continue.")
+                    break
+
+                file_path = os.path.join(data_folder, f'output_{shot_counts}.csv')
+
                 print('waiting for signals...')
                 GPIO.wait_for_edge(self.gpio_channel, GPIO.RISING) # stop the code until receiving a trigger
-                #time.sleep(.1)
-                t = time.time()
-                #readings = np.array(self.flow_meter.get_reading(duration))
-                readings = np.array(self.flow_meter.get_reading_single_cycle(duration))
-                #readings = np.array(self.flow_meter.get_single_buffer())
-                np.savetxt(f'/home/pi/flow_meter/data/output_single_cycle_{shot_counts}.csv', readings)
+                readings = np.array(self.flow_meter.get_reading(duration))
+
+                np.savetxt(file_path, readings)
                 print('shot count {}'.format(shot_counts))
                 print(f'shot interval {time.time()-t}')
+                t = time.time()
+
+                line.set_ydata(readings[:int(duration*1000)])
+                ax.set_ylim(0,max(readings)*1.2)
+                fig.canvas.draw()
+                fig.canvas.flush_events()
+
                 shot_counts += 1
+
         except KeyboardInterrupt:
-            GPIO.cleanup()
-            print('exit on ctrl-C keyboard interrupt')
-        except:
-            GPIO.cleanup()
-            print('an error occured')
-        print('Maximum number of shot records reached!')
-        GPIO.cleanup()
+            print('exit on Ctrl-C keyboard interrupt')
+        except Exception as e:
+            print('An error occured:\n', e)
+

src/plot.py

@@ -1,5 +1,8 @@
 import numpy as np
 import matplotlib.pyplot as plt
+import matplotlib
+
+#matplotlib.rcParams['backend'] = 'agg'
 
 data = np.loadtxt('/home/pi/flow_meter/data/output_0.csv')
 plt.plot(data)