View source for Dct2000serial

{{Wrongtitle|dct200serial}}
{{Script info
|author=Ian Forde
|short=Serial control of cable boxes in MythTV
|long=Serial control of cable boxes in MythTV
|category=Channel Change Scripts
|name=changechannel.py}}

Serial control of cable boxes in MythTV

Or... "Want to get serial control working on your DCT-2000 cable box?"

= Version History =

See changechannel.py

= Credits =

README Written by Ian Forde ( ian a duckland d org)

Mostly using code from Chris Griffiths ( dct2000 a y-fronts d com ) to do the actual work

Additional cable box functions written by Lonny Selinger

Inspired by Embeem's Tivo serial code

And various snippets of code from around the net. ;)

= Contents =

 changechannel.py
 crcgen.py

= Prerequisites =

# You have to have a Motorola/GI DCT-2000 series box.  DCT-2244, DCT-2224, and so on...
# You have to have firmware version 7.54 or higher on the box.  It's somewhere off of the main menu when using the cable remote.
# Your serial port has to be enabled.
# Python2.2 on your myth backend

Note that if you meet prerequisite #1, but meet only one of 2 and 3, then
you'll need to have your cable provider either a) Upgrade your firmware/enable
your serial port or b) Swap out your cable box.  Be creative in how you
approach them.  And you *don't* have to tell them why you want this...
Especially the serial port bit...

Actually, regarding the serial port bit, I believe they might enable them if
you tell them that you have or are planning to get a Tivo (note that I'm not
*endorsing* that approach...)

In any case, once you meet the prereqs, you can continue.

= Installation =

Okay - Basically, place the two scripts (crcgen.py, changechannel.py) into /usr/local/bin, make sure they are executable, then you're done.

 cp crcgen.py changechannel.py /usr/local/bin
 cd /usr/local/bin
 chown 755 crcgen.py changechannel.py
 # Edit the SERIALPORT variable in changechannel.py to reflect which serial port you'll be using.

If you're using MythTV, you can point it to the external change channel script
provided.  (Here's a hint - it's the one called changechannel.py)

That's it!


= The Code =

{{Code box|crcgen.py|
<pre>
#!/usr/bin/env python

# Chris Griffiths, June 8th 2003 (dct2000@y-fronts.com)
#
# CRC calculator preset for CRC-CCIT suitable for a Motorola DCT2000

# Please see http://rcswww.urz.tu-dresden.de/~sr21/crctester.c
# and http://rcswww.urz.tu-dresden.de/~sr21/crc.html for the 
# original c code to this, a web based crc generator, and
# a description of what these settings do

order = 16;
polynom = 0x1021;
direct = 1;
crcinit = 0x0000;
crcxor = 0x0000;
refin = 1;
refout = 1;


def reflect (crc, bitnum):
	i = 1 << (bitnum-1)
	j = 1
	crcout=0
	while i:
		if (crc & i):
			crcout = crcout | j
		j = j << 1
		i = i >> 1
	
	return crcout

def calcrc(data_bytes):

	crcmask = (((1<<(order-1))-1)<<1)|1;
	crchighbit = 1<<(order-1);

	# compute missing initial CRC value
	if direct:
		crcinit_direct = crcinit;
		crc = crcinit;
		for i in range (order):
			bit = crc & 1;
			if bit:
				crc = crc ^ polynom;
			crc >>= 1;
			if bit:
				 crc = crc | crchighbit;
		crcinit_nondirect = crc;
	else:
		crcinit_nondirect = crcinit
		crc = crcinit
		for i in range (order):
			bit = crc & crchighbit
			crc = crc << 1;
			if bit: 
				crc= crc ^ polynom;
		crc = crc & crcmask;
		crcinit_direct = crc;

	# now compute the crc
	crc = crcinit_direct

	for i in range( len(data_bytes) ):

		c = ord(data_bytes[i])
		if refin:
			c = reflect(c, 8)

		j=0x80;
		while j:
			bit = crc & crchighbit
			crc = crc << 1
			if (c & j):
				bit = bit ^ crchighbit
			if bit:
				crc = crc ^ polynom
			j = j >> 1


	if refout:
		crc=reflect(crc, order)
	crc = crc ^ crcxor
	crc = crc & crcmask

	return crc
</pre>
}}

{{Code box|changechannel.py|
<pre>
#!/usr/bin/env python
#
# Chris Griffiths, June 8th 2003 (dct2000@y-fronts.com)
#
# Simple program to send remote control sequences via serial port to a
# motorola dct2000
# It does not respect sequence numbers, nor check the returned codes for
# success or failure
#
# Modified by Ian Forde (ian@duckland.org) (Sometime in early 2003 - I don't
# remember when...)
#
# Modified by Lonny Selinger to support additional dct2000 functions
#
#	Version history
#		0.87: Added an EXIT_KEY code to make the dct2000 osd go away
#			as quickly as possible, since I don't know how to disable
#			it yet!
#		0.86: Removed the debugging flag.  That's my responsibility,
#			not everyone else's!
#		0.85: Added a debugging flag
#		      Cleaned up the channel code determination by removing
#			a whole bunch of 'if' statements and the corresponding
#			variable names.
#		      Eliminated the need for a separate shell script by
#			including channel number length normalizing into the
#			script.
#		      Turned off flow control
#		      Created a variable for setting the serial port
#		      Fixed a bug in the alternate button parsing
#		0.81: Experimental code added by Lonny Selinger for additional
#			functions such as last_channel, mute, favorite, chup,
#			chdown.  Not integrated into Myth yet!
#		0.8:  it works!

import serial		# pyserial (http://pyserial.sourceforge.net/)
import crcgen		# CRC generator - preset to generate CCITT polynomial crc's
import time			# std python lib
import sys

# define the serial port
SERIALPORT='/dev/ttyS1'

# define button codes:
ONOFF='\x0A'
CHAN_UP='\x0B'
CHAN_DOWN='\x0C'
VOLUME_UP='\x0D'
VOLUME_DOWN='\x0E'
MUTE='\x0F'
MUSIC='\x10'
SELECT_OK='\x11'
ENTER='\x11'
EXIT_KEY='\x12'
LAST_CHANNEL='\x13'
SWITCH_AB='\x14'
FAVORITE='\x15'
PPV_KEY='\x16'
A_KEY='\x17'
P_F='\x18'
MENU='\x19'
OUTPUT_CHAN='\x1C'
FAST_FORWARD='\x1D'
REVERSE='\x1E'
PAUSE='\x1F'
BROWSE='\x22'
CANCEL='\x23'
LOCK='\x24'
LIST='\x25'
THEME='\x26'
GUIDE='\x30'
RECORD='\x31'
HELP='\x32'
INFO='\x33'
UP='\x34'
DOWN='\x35'
LEFT='\x36'
RIGHT='\x37'
DAY_PLUS='\x38'
DAY_MINUS='\x39'
PAGE_PLUS='\x3A'
PAGE_MINUS='\x3B'
B_KEY='\x27'
C_KEY='\x28'

# This function below was blatantly lifted from:
#         http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52660

def IsAllDigits( str ):
        """ Is the given string composed entirely of digits? """
        return all(letter.isdigit() for letter in str)

def debug(ctrl_str):
	for hexChar in ctrl_str:
		print "%#x" % ord(hexChar),
	print '\n'

def word2str(val):
	return chr((val & 0xFF00) / 256) + chr(val & 0x00FF)

def get_response(ser):
	#response = ''
	#byte = ser.read()
	#while byte:
	#	response = response + byte
	#	byte = ser.read()

	byte = ser.read()
	response = byte
	byte = ser.read()
	while byte:
		response += byte
		byte = ser.read(7)
	#print "length of response is ",len(response)
	return response

def calc_code(payload=""):
	#
	# code is 10 78 ll ll ss 40 pp pp cc 10 03
	# where ss = seq num, pp pp = payload (for a remote keypress first byte is 22), cc = crc
	# It seems the sequence number can be ignored - so long as we send this double sequence before it - 
	# this is what embleem was using with the last sequence being the on/off keypress
	#
	# It also looks like we can only send one keypress at a time - although correct use of sequence number
	# be get that working
	#
	code = '\x78' + word2str(len(payload)+2) + '\x10\x40' + payload
	crc = crcgen.calcrc(code)
	code = "\x10\x70\x00\x02\x03\x40\xc8\x27\x10\x03\x10\x78\x00\x03\x03\x40\x00\x68\x96\x10\x03" + '\x10' + code + word2str(crc) + '\x10\x03'
	return code

def send_to_unit(ser, key_presses):
	#
	# Send each keypress, then get the returned status from the box (and subsequently ignore it)
	# You have to read the return code, otherwise the next send with fail
	#
	for key in key_presses:
		ser.write(calc_code('\x22' + key))
		get_response(ser)

cmdarg = sys.argv[1]

# added an extra code block to handle a few more options that
# can be passed to remote.py.
# options: last_channel(), mute(), favorite(), chan_up(),
# chan_down() .... for now anyway
#
# Lonny Selinger

if not IsAllDigits(cmdarg):
	if cmdarg in ("l", "m", "f", "u", "d"):
		BUTNKEY=''
		if cmdarg == "l" :
			BUTNKEY=LAST_CHANNEL
		elif cmdarg == "m" :
			BUTNKEY=MUTE
		elif cmdarg == "f" :
			BUTNKEY=FAVORITE
		elif cmdarg == "u" :
			BUTNKEY=CHAN_UP
		elif cmdarg == "d" :
			BUTNKEY=CHAN_DOWN
		serCon = serial.Serial(SERIALPORT,baudrate=9600, bytesize=serial.EIGHTBITS,  parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE, timeout=1, xonxoff=0, rtscts=0,)
		send_to_unit(serCon, BUTNKEY)
else:
	if len(cmdarg) > 3:
		print "too many chars!"
	else:
		chanset=cmdarg.rjust(3, '0')

	CHANCODE=''.join(chr(int(c)) for c in chanset)

	serCon = serial.Serial(SERIALPORT,baudrate=9600, bytesize=serial.EIGHTBITS,  parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE, timeout=1, xonxoff=0, rtscts=0,)
	send_to_unit(serCon, CHANCODE)
	send_to_unit(serCon, EXIT_KEY)
</pre>
}}

{{Code box|Makefile|
<pre>
PREFIX = /usr/local
BINPATH = ${PREFIX}/bin

all:

install:
	install -m 0755 changechannel.py ${BINPATH}
	install -m 0755 crcgen.py ${BINPATH}

uninstall:
	rm -f ${BINPATH}/changechannel.py
	rm -f ${BINPATH}/crcgen.py
</pre>
}}


[[Category:Channel_Change_Scripts]]