dispenser_select.py

#!/usr/bin/env python

import sys
import os
from time import sleep
#from bartendro.error import I2CIOError

ROUTER_BUS              = 1
ROUTER_ADDRESS          = 4
ROUTER_SELECT_CMD_BEGIN = 0
ROUTER_CMD_SYNC_ON      = 251
ROUTER_CMD_SYNC_OFF     = 252
ROUTER_CMD_PING         = 253
ROUTER_CMD_COUNT        = 254
ROUTER_CMD_RESET        = 255


try:
    import smbus
    smbus_missing = 0
except ImportError, e:
    if e.message != 'No module named smbus':
        raise
    smbus_missing = 1

class DispenserSelect(object):
    '''This object interacts with the bartendro router controller to select dispensers'''

    def __init__(self, max_dispensers, software_only):
        self.software_only = software_only
        self.max_dispensers = max_dispensers
        self.router = None
        self.num_dispensers = 3
        self.selected = 255 

    def reset(self):
        if self.software_only: return
        self.router.write_byte(ROUTER_ADDRESS, ROUTER_CMD_RESET)
        sleep(.15)

    def select(self, dispenser):
        if self.software_only: return

        # NOTE: This code used to only send the select message if the dispenser changed.
        # but tracking which dispenser was last selected across many web server threads
        # is an extra pain I dont care to handle now. For now we'll just set the dispenser
        # for each packet we send.
        if dispenser < self.max_dispensers:
            self.selected = dispenser
            self.router.write_byte(ROUTER_ADDRESS, dispenser)
            sleep(.01)

    def sync(self, state):
        if self.software_only: return
        if (state):
            self.router.write_byte(ROUTER_ADDRESS, ROUTER_CMD_SYNC_ON)
        else:
            self.router.write_byte(ROUTER_ADDRESS, ROUTER_CMD_SYNC_OFF)

    def count(self):
        return self.num_dispensers

    def open(self):
        '''Open the i2c connection to the router'''

        if self.software_only: return

        if smbus_missing:
            print "error: You must install the smbus module!"
            sys.exit(-1)

        print "Opening I2C bus to router"
        self.router = smbus.SMBus(ROUTER_BUS)

        print "Done."

if __name__ == "__main__":
    ds = DispenserSelect(15, 0)
    ds.open()
    ds.reset()