aml_relay.py

#!/usr/bin/env python

import time, serial

"""
This is the Relay object that controls communication between
the computer and the Arduino controlling the relays in the AML.
"""
class Relay(object):
    
    def __init__(self, port='/dev/tty.usbmodem14241'):
        self.port = port
        self.start_serial(self.port)
        # Power on the relays by default
        self.connectMotors()


    #Open a port for serial communication. 
    def start_serial(self, port):
        # Configure the serial connections for Arduino
        try:
            self.ser = serial.Serial(
                    port=port,
                    baudrate=9600,
                    parity=serial.PARITY_NONE,
                    bytesize=serial.EIGHTBITS,
                    stopbits=serial.STOPBITS_ONE,
                    timeout=None  # blocking
            )
            time.sleep(2)  # Wait for Arudino to restart
        except:
            print("Couldn't connect to the AML relay serial...")
        
        
    def write(self, command):
        self.ser.write(command)
        time.sleep(.01)
         
    def close_serial(self):
        self.ser.close()

    # Not used
    def read(self):
            out = None
            # Flush buffer of old data
            while self.ser.inWaiting() > 0:
                self.ser.read()
            while True:
                data = str(self.ser.read())
                # Wait for next new measurement
                if data == '\n' and out == None:
                    out = []
                elif data != '\n' and out != None:
                    out.append(data)
                elif data == '\n' and out != None:
                    out.append(data)
                    break
            return int(''.join(out)[:-2])


    # Not used
    def write_and_read(self, command):
        self.write(command)
        return self.read()
        
    # Send commands to Arduino
    def connectMotors(self):
        self.write('t') 
        time.sleep(1)
        
    def disconnectMotors(self):
        self.write('f') 
        time.sleep(1)