BB.py

#! /usr/bin/env python3

"""
Program to read in data from the BB wetlabs sensor.
"""

try:
    import serial
except ImportError as message:
    print("Failed to import serial, maybe it is not installed correctly? Error was: {}".format(message))

try:
    import datetime 
except ImportError as message:
    print("Failed to import datetime, maybe it is not installed correctly? Error was: {}".format(message))

try:
    import time
except ImportError as message:
    print("Failed to import time, maybe it is not installed correctly? Error was: {}".format(message))

try:
    from BBX_Sensors import BBX
except ImportError as message:
    print("Failed to import BBX from BBX_Sensors, maybe file is missing? Error was: {}".format(message))

# try:
#     from SQL_queries import BB3_insert 
# except ImportError as message:
#     print("Failed to import BB3_insert from SQL_queries, maybe file is missing? Error was: {}".format(message))

# try:
#     from BBX_Sensors import BBX
# except ImportError as message:
#     print("Failed to import BBX from BBX_Sensors, maybe ile is missing? Error was: {}".format(message))

from dummy_sensors import DummyBBSensor


class BB(BBX):
    """
    The BB sensor class to read in data live while in-situ.

    Reads in a line of data, then after checking a certain number of times to see if there is data, adjust a waiting timer.

    The waiting timer is adjusted to avoid unnecessary CPU usage on the Raspberry Pi.
    """
    def __init__(self, port):
        self.port = port

    def Reading(self):
        """
        Generator function to read in data from the sensor.
        
        Uses a time taken per line read formula to adjust the time to wait between making checks.

        Reads in all the data in the buffer, then splits it up into lines, and processs them individually.
        
        """
        # Initialise values
        leftoverData = ""
        lineOfData = b''
        bitOfData = b''
        numberOfChecksToMake = 10
        timeToSleep = 1
        targetChecksPerLine = 1.3
        targetLinesPerCheck = 1/targetChecksPerLine

        try:
            myPort = '/dev/'+self.port
            ser = serial.Serial(myPort,self.baudRate,timeout=self.timeoutLength)
            #ser = DummyBBSensor()

            while True:  

                lineCount = 0          
                # The number of checks to make 
                for i in range(numberOfChecksToMake):
                    time.sleep(timeToSleep)
                    # This if statement is specific for this sensor, everything else here can be used with other sensors.
                    if ser.in_waiting != 0:
                        bitOfData = ser.read(ser.in_waiting)
                        lineOfData = lineOfData + bitOfData
                        bitOfData = ""
                        # Checking if there is a carrage return and new line in the line, as that is used to signal the end of a reading.
                        if(b"\r\n" in lineOfData):                                 
                            #break up by /r/n              
                            stringLine = lineOfData.decode('utf-8')
                            listOfLines = stringLine.split("\r\n")
                            # If there is more than one item in the list, it may not be full so store the last bit and add it on to the next reading
                            if(len(listOfLines) > 1):
                                listOfLines[0] = leftoverData + listOfLines[0]
                                leftoverData = listOfLines[-1]                  
                                del listOfLines[-1]
                            # If there is something in the list yield the line back to sensor manager
                            if(len(listOfLines) > 0):
                                for singleLine in listOfLines:
                                    lineCount += 1
                                    stringLine = singleLine.split()
                                    yield (stringLine)
                                lineOfData = b"" 
                        else:
                            pass
                
                linesPerCheck = lineCount / numberOfChecksToMake
            
                print("Time of {}s gave us {} lines per check".format(timeToSleep, linesPerCheck ))
                #Formula for new timer.
                newtimeToSleep = timeToSleep * ( targetLinesPerCheck / linesPerCheck )

                timeToSleep = newtimeToSleep
                if(numberOfChecksToMake < 100):
                    numberOfChecksToMake += 10
        
        except ValueError as message:
            print("Did not manage to connect to sensor properly, check your settings. Error was: {}".format(message))
        except serial.SerialException as message:
            print("Did not read data from sensor properly, check your settings. Error was: {}".format(message))