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# binwatch - Tiny binary wristwatch. {{{
#
# Copyright (C) 2010 Nicolas Schodet
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#
# Contact :
#        Web: http://ni.fr.eu.org/
#      Email: <nico at ni.fr.eu.org>
# }}} */
"""RTC control."""
import struct
import dev2.twi

class ProtocolError (RuntimeError):
    pass

class RTC:

    REGS = [
            ('control1', 0xff),
            ('control2', 0xbf),
            ('second', 0xff),
            ('minute', 0x7f),
            ('hour', 0x3f),
            ('day', 0x3f),
            ('weekday', 0x07),
            ('month_century', 0x9f),
            ('year', 0xff),
            ('alarm_minute', 0xff),
            ('alarm_hour', 0xbf),
            ('alarm_day', 0xbf),
            ('alarm_weekday', 0x87),
            ('clkout', 0x83),
            ('timer_control', 0x83),
            ('timer', 0xff),
            ]

    def __init__ (self, address, serial):
        """Initialise and set address and serial object to use."""
        self.address = address
        self.twi = dev2.twi.Twi (serial)

    def init (self):
        s = struct.pack ('<B' + 18 * 'B', 0,
                0x20, 0, # STOP
                0, 0, 0, 0, 0, 0, 0,
                0x80, 0x80, 0x80, 0x80,
                0, 0, 0,
                0, 0) # !STOP
        n = self.twi.send (self.address, s)
        if n != len (s):
            raise ProtocolError ("send init fail")

    def dump (self):
        # Send address.
        s = struct.pack ('<B', 0)
        n = self.twi.send (self.address, s)
        if n != len (s):
            raise ProtocolError ("send address fail")
        # Read all registers.
        r = self.twi.recv (self.address, 16)
        if len (r) != 16:
            raise ProtocolError ("receive fail")
        rl = struct.unpack ('<' + 16 * 'B', r)
        # Format result.
        frl = [ '%s: 0x%02x' % (reg[0], value & reg[1])
                for (reg, value) in zip (self.REGS, rl) ]
        return '\n'.join (frl)

    def _command (self, command, fmt, rfmt, *params):
        """Send a command and check response.
        
         - command: command to send.
         - fmt: command format (see struct).
         - rfmt: response format.
         - params: command parameters.
           
        Will return unpacked response or None on error."""
        s = struct.pack ('<B' + fmt, command, *params)
        n = self.twi.send (self.address, s)
        if n != len (s):
            raise ProtocolError ("send command fail")
        rlen = struct.calcsize ('<B' + rfmt)
        r = self.twi.recv (self.address, rlen)
        if len (r) != rlen:
            raise ProtocolError ("receive ack fail")
        rl = struct.unpack ('<B' + rfmt, r)
        if rl[0] != command:
            raise ProtocolError ("received nack")
        return rl[1:]


def command (args = None):
    """Implement command line interface."""
    # Parse options.
    import optparse
    parser = optparse.OptionParser ()
    parser.add_option ('-i', '--init', action = 'store_true',
            help = "initialise RTC")
    parser.add_option ('-d', '--dump', action = 'store_true',
            help = "dump all registers")
    parser.add_option ('-t', '--tty',
            help = "tty connected to dev2", metavar = 'TTY')
    parser.add_option ('-a', '--address', type = 'int', default = 0xa2,
            help = "define RTC slave address", metavar = 'ADDR')
    (options, extra) = parser.parse_args (args = args)
    if extra:
        parser.error ("extra unused arguments")
    if options.tty is None:
        parser.error ("no tty to open")
    # Apply.
    import serial
    try:
        s = serial.Serial (options.tty)
        rtc = RTC (options.address, s)
        if options.init:
            rtc.init ()
        if options.dump:
            print rtc.dump ()
    except Exception, e:
        import sys
        print >> sys.stderr, e.message
        sys.exit (1)

if __name__ == '__main__':
    command ()