#!/bin/env python

# This python script can be used to change the channel
# of a RCA DirecTV satellite receiver.   I have
# personally used it with my RCA that has a 
# "low speed" dataport on the back.  
#
# Use this script "AS IS".  I make NO garantees.
# If you fry your system, don't blame me.
#
# The tech control information needed to create this script 
# was taken from http://www.pcmx.net/dtvcon/cmds.htm
#
# This script requires pyserial (pyserial.sf.net)
#
# Run as "./channel.py 296"
#
# Version 0.3 by Barry Grussling (webmaster@barrygrussling.com)
#
# Changelog
#
# version 0.3
# Fixed Hex convert bug that made it impossilbe to goto channel 269.
# Rewrite of hex convert function.
# Added on/off abilities
# Other Various fixes
#
# version 0.2
# Added check for pyserial, print message if it is not found.
#
# version 0.1 
# Initial release

import os, sys, math, struct, string, re, time


# -- User Configuration
#Specify your serial port that is hooked to the RCA receiver here
Port = "/dev/ttyS0"

# -- End User Configuration

try:
	import serial
except ImportError:
	print "You must have python serial installed to use this script"
	print "see http://pyserial.sourceforge.net"
	sys.exit(1)


ser = serial.Serial(Port, 9600, timeout=1)

channelfilter = re.compile('\d+')

RCODES = {\
'0xf0': 'Valid command received',\
'0xf1': 'Invalid command received',\
'0xf2': 'Command is being processed',\
'0xf3': 'Timeout waiting for complete command',\
'0xf4': 'Command has completed successfully',\
'0xf5': 'Command has failed',\
'0xfb': 'Illegal character received',\
'0xfd': 'Buffer underflow',\
'0xff': 'Buffer overflow'}

SCODES = {\
'Off': '0xfa01',\
'On':  '0xfa02',\
'SetChannel': '0xfa46'}

Want = {\
'Verbose': 0, \
'Help': 0,\
'NoAutoOn': 0,\
'Off': 0,\
'Chan': 0}

NEEDDATA = '0xf0'
DATAGOOD = '0xf4'
SENDLIMIT = 25

for arg in sys.argv:
	if arg == "-v":
		Want['Verbose'] = 1
	elif arg == "-h":
		Want['Help'] = 1
	elif arg == "-noautoon":
		Want['NoAutoOn'] = 1
	elif arg == "-off":
		Want['Off'] = 1
	elif channelfilter.match(arg):
		Want['Chan'] = 1
		nchannel = arg


if Want['Verbose']:
	for a, b in Want.items():
		print a + ":", b
	print "NChannel:", nchannel


def PrintHelp():
	print "Usage:", sys.argv[0], "[-v] [-h] [-noautoon] [-off] [channel]"
	print "\nOPTIONS:"
	print "-v: Verbose"
	print "-h: Help and Usage"
	print "-noautoon: Don't automatically turn receiver on"
	print "-off: Turn receiver off (channel not needed/omitted)\n\n"
	sys.exit(2)

def SendCommand(command):
	global nchannel, SCODES
	if SCODES.has_key(command):
		sending = SCODES[command]
	else:
		sending = command
	
	if command == 'SetChannel':
		sending = '0xfa46' + string.split(str(hex(int(nchannel))),'x')[1].zfill(4)
	if Want['Verbose']:
		print "Sending command", sending, "due to requested command", command
	SendTillGet(sending, DATAGOOD)

def SendTillGet(send, need):
	global RCODES
	sendtry = 0
	rdata = ''
	Changed = 0
	while(Changed == 0 ):
		if Want['Verbose']:
			print "Sending:", send, "Until we receive", need, "(Try", sendtry, "out of", str(SENDLIMIT) + ")"
		ser.write(struct.pack('>i', eval(send)))
		s = ser.read(70)

		if len(s) == 0:
			rdata = "NULL DATA"
		else:
			rdata = [hex(ord(k)) for k in s]


		for a in rdata:
			if a == need:
				Changed = 1
			if Want['Verbose']:
				print "Received", a, 
				if RCODES.has_key(a):
					print "(" + RCODES[a] + ")"
				else:
					print ""

		sendtry=sendtry+1
		if(sendtry == SENDLIMIT):
			print "Too Many Send Tries without valid responce"
			sendtry = 0
	# If we get here, rdata must have done what we wanted...
	if Want['Verbose']:
		print "Success"
	

if Want['Help']:
	PrintHelp()

if len(sys.argv)==1:
	PrintHelp()

if Want['Off']:
	SendCommand('Off')
	sys.exit(0)

if not Want['NoAutoOn']:
	SendCommand('On')

if Want['Chan']:
	SendCommand('SetChannel')

#ser = serial.Serial(Port, 9600, timeout=1)
#rdata = ["0xf2"] #[hex(ord(k)) for k in s]
#	s = ser.read(5)
ser.close()