src/adafruit_blinka/microcontroller/raspi_23/pulseio/PulseIn.py

   1 import array
   2 import time
   3 import subprocess
   4 import os, signal
   5 import traceback
   6 import signal
   7 import sysv_ipc
   8 import atexit
   9 import random
  10
  11 DEBUG = False
  12 queues = []
  13 procs = []
  14
  15 # The message queues live outside of python space, and must be formally cleaned!
  16 def final():
  17     if DEBUG:
  18         print("Cleaning up message queues", queues)
  19         print("Cleaning up processes", procs)
  20     for q in queues:
  21         q.remove()
  22     for proc in procs:
  23         proc.terminate()
  24 atexit.register(final)
  25
  26 class PulseIn:
  27     def __init__(self, pin, maxlen=2, idle_state=False):
  28         self._pin = pin
  29         self._maxlen = maxlen
  30         self._idle_state = idle_state
  31         self._queue_key = random.randint(1, 9999)
  32         try:
  33             self._mq = sysv_ipc.MessageQueue(None, flags=sysv_ipc.IPC_CREX)
  34             if DEBUG:
  35                 print("Message Queue Key: ", self._mq.key)
  36             queues.append(self._mq)
  37         except sysv_ipc.ExistentialError:
  38             raise RuntimeError("Message queue creation failed")
  39
  40         cmd = ["/home/pi/libgpiod_pulsein/src/libgpiod_pulsein",
  41                "--pulses", str(maxlen),
  42                "--queue", str(self._mq.key)]
  43         if not idle_state:
  44             cmd.append("-i")
  45         cmd.append("gpiochip0")
  46         cmd.append(str(pin))
  47         if DEBUG:
  48             print(cmd)
  49
  50         self._process = subprocess.Popen(cmd)
  51         procs.append(self._process)
  52
  53         # wait for it to start up
  54         if DEBUG:
  55             print("Waiting for startup success message from subprocess")
  56         message = self._mq.receive(type=2)
  57         if message[0] != b'!':
  58             raise RuntimeError("Could not establish message queue with subprocess")
  59
  60
  61     def deinit(self):
  62         # Clean up after ourselves
  63         self._process.terminate()
  64         procs.remove(self._process)
  65         self._mq.remove()
  66         queues.remove(self._mq)
  67
  68     def __enter__(self):
  69         return self
  70
  71     def __exit__(self, exc_type, exc_value, tb):
  72         self.deinit()
  73
  74     def resume(self, trigger_duration=0):
  75         if trigger_duration != 0:
  76             self._mq.send("t%d" % trigger_duration, True, type=1)
  77         else:
  78             self._mq.send("r", True, type=1)
  79
  80     def pause(self):
  81         self._mq.send("p", True, type=1)
  82
  83     def clear(self):
  84         self._mq.send("c", True, type=1)
  85
  86     def popleft(self):
  87         self._mq.send("^", True, type=1)
  88         message = self._mq.receive(type=2)
  89         reply = int(message[0].decode('utf-8'))
  90         if reply == -1:
  91             reply = None
  92         return reply
  93
  94     def __len__(self):
  95         self._mq.send("l", True, type=1)
  96         message = self._mq.receive(type=2)
  97         return int(message[0].decode('utf-8'))