attenuation-control/source/attenuator/__init__.py

import os
import sys

try:
    from IOPi import IOPi
except ImportError:
    sys.path.append('mock')
    try:
        from IOPi import IOPi
    except ImportError:
        raise ImportError("IOPi not found")

class Pin(object):
    """Abstraction of pin object. Every pin object contains a gpio number and a i2c bus address."""
    bus_address = None
    pin_number = None
    bus = None

    def __init__(self, bus_address, pin_number):
        """Constructor.

        Args:
            bus_address (int): i2c bus address [0x20..0x23].
            pin_number (int): Gpio pin number.
        """
        self.bus_address = bus_address
        self.pin_number = pin_number

class Attenuator(object):
    """Abstraction of ANALOG DEVICES HMC425A digital attenuator"""
    pin = None

    def __init__(self,pin_0_5db, pin_1_0db, pin_2_0db, pin_4_0db, pin_8_0db, pin_16_0db):
        """Constructor.

        Args:
            pin_0_5db (Pin): Pin object to control the 0.5 db gpio
            pin_1_0db (Pin): Pin object to control the 1.0 db gpio
            pin_2_0db (Pin): Pin object to control the 2.0 db gpio
            pin_4_0db (Pin): Pin object to control the 4.0 db gpio
            pin_8_0db (Pin): Pin object to control the 8.0 db gpio
            pin_16_0db (Pin): Pin object to control the 16.0 db gpio
        """
        if type(pin_0_5db) is not Pin:
            raise TypeError("Wrong type for pin_0_5db")
        if type(pin_1_0db) is not Pin:
            raise TypeError("Wrong type for pin_1_0db")
        if type(pin_2_0db) is not Pin:
            raise TypeError("Wrong type for pin_2_0db")
        if type(pin_4_0db) is not Pin:
            raise TypeError("Wrong type for pin_4_0db")
        if type(pin_8_0db) is not Pin:
            raise TypeError("Wrong type for pin_8_0db")
        if type(pin_16_0db) is not Pin:
            raise TypeError("Wrong type for pin_16_0db")

        if pin_0_5db.bus_address not in range(0x20, 0x24):
            raise IndexError('pin_0_0db i2c bus address index out of range')
        if pin_1_0db.bus_address not in range(0x20, 0x24):
            raise IndexError('pin_1_0db i2c bus address index out of range')
        if pin_2_0db.bus_address not in range(0x20, 0x24):
            raise IndexError('pin_2_0db i2c bus address index out of range')
        if pin_4_0db.bus_address not in range(0x20, 0x24):
            raise IndexError('pin_4_0db i2c bus address index out of range')
        if pin_8_0db.bus_address not in range(0x20, 0x24):
            raise IndexError('pin_8_0db i2c bus address index out of range')
        if pin_16_0db.bus_address not in range(0x20, 0x24):
            raise IndexError('pin_16_0db i2c bus address index out of range')

        if pin_0_5db.pin_number not in range(1, 17):
            raise IndexError('pin_0_5db pin number index out of range')
        if pin_1_0db.pin_number not in range(1, 17):
            raise IndexError('pin_1_0db pin number index out of range')
        if pin_2_0db.pin_number not in range(1, 17):
            raise IndexError('pin_2_0db pin number index out of range')
        if pin_4_0db.pin_number not in range(1, 17):
            raise IndexError('pin_4_0db pin number index out of range')
        if pin_8_0db.pin_number not in range(1, 17):
            raise IndexError('pin_8_0db pin number index out of range')
        if pin_16_0db.pin_number not in range(1, 17):
            raise IndexError('pin_16_0db pin number index out of range')

        self.pin = [pin_0_5db, pin_1_0db, pin_2_0db, pin_4_0db, pin_8_0db, pin_16_0db]

        for pin in self.pin:
            pin.bus = IOPi(pin.bus_address)
            pin.bus.set_pin_direction(pin.pin_number, 0)
            pin.bus.write_pin(pin.pin_number, 0)

    def set_attenuation(self, attenuation):
        """Set attenuation.

        Args:
            attenuation (float): Value of attenuation to be set [0..31.5]
        """
        if attenuation < 0:
            attenuation = 0
        elif attenuation > 31.5:
            attenuation = 31.5

        max_single_value = 16 * 2
        attenuation *= 2
        switch_pin = [1 for i in range(6)]
        index = 5

        while index >= 0:
            if attenuation - max_single_value >= 0:
                attenuation -= max_single_value
                switch_pin[index] = 0
            max_single_value /= 2
            index -= 1

        for i in range(0, len(switch_pin)):
            bus = IOPi(self.pin[i].bus_address)
            bus.write_pin(self.pin[i].pin_number, switch_pin[i])