remote_control.py

Most satellite dish actuators send a series of pulses to indicate their position. By counting pulse

#!/usr/bin/python
"""
   Access the postioner.
"""

import os,time,fcntl,sys,struct
import raw_keyboard

outputfifo = os.open("/dev/rtf0", os.O_RDWR|os.O_NONBLOCK)
commandfifo = os.open("/dev/rtf1", os.O_RDWR|os.O_NONBLOCK)
    

def ReadStatus(fifo):
  data = ""
  while len(data) <2:
    try :
      data += os.read(fifo,1)
    except OSError :
      pass
  val = struct.unpack("H",data)[0]
  d = {}
  d["position"] = val & 0x0fff
  d["direction"] = {0:"West",1:"East"}[(val & 0x4000) >> 14]
  d["motor"] = {1:"East",2:"West",3:"Off"}[(val & 0x3000) >> 12]
  return d

def GetStatus() :
    os.write(commandfifo,"q")
    return ReadStatus(outputfifo)
  
def SendCommand(cmnd) :
      os.write(commandfifo,cmnd)
      return ReadStatus(outputfifo)



print "This program is controlled by key presses:"
print "	'w': move west"
print "	'e': move east"
print "	'h': halt"
print "	'q': quit"
print "Current status:",GetStatus()

while True :
  kb = raw_keyboard.Keyboard.getch()
  if kb != "":
    if kb=="q" :
      sys.exit(-1)
    elif kb in ["w","e","h"] :
      print "Writing '%s' to command fifo"%kb
      stat = SendCommand(kb)
      print "Status:",stat
  else :
    stat = GetStatus()
    if stat["motor"]!="Off" :
      print stat