feat: intercom for Raspberry 4 and below (GPIO library)

.gitignore

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+.idea/

README.md

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+# Intercom
+
+Comunicación VoIP entre dos raspberrys.
+
+## How to
+
+1. Copiar Raspbian Lite en el SD usando Balena Etcher.
+2. Crear un archivo en la partición boot con el nombre ssh para activar SSHD.
+3. Loguear en el raspberry (pass por defecto: raspberry) y ejecutar:
+   sudo systemctl enable ssh
+   sudo apt install libopus-dev build-essential libasound2-dev libogg-dev python3-gpiozero python3-pip
+   sudo pip3 install pyyaml
+   wget http://holdenc.altervista.org/parole/downloads/parole-010beta4.tgz
+   tar xf parole-010beta4.tgz
+   cd parole-010beta4/
+   make
+   sudo cp parole /usr/bin/
+4. Crear /etc/systemd/system/parole.service y activarlo.
+   sudo chown root:root /etc/systemd/system/parole.service
+   sudo systemctl enable parole
+5. Crear /etc/systemd/system/intercom.service y activarlo.
+   sudo chown root:root /etc/systemd/system/intercom.service
+   sudo systemctl enable intercom
+6. Añadir intercom en /etc/hosts
+7. Copiar intercom.py e intercom.yml en la home. Editar intercom.yml
+
+CONFIGURAR ALSA?

intercom.py

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+import RPi.GPIO as GPIO
+import subprocess
+from threading import Thread
+import socket
+import yaml
+import time
+
+NO_CALL = 0
+INCOMING_CALL = 1
+OUTGOING_CALL = 2
+OP_CALL = 'CALL'.encode()
+OP_HANG = 'HANG'.encode()
+OP_PING = 'PING'.encode()
+OP_OK = 'OK'.encode()
+OP_ERROR = 'ERROR'.encode()
+CHECK_STATUS_INTERVAL = 120
+
+
+class CallManager:
+    state = NO_CALL
+    station = None
+    call_process = None
+
+    def call(self, station):
+        try:
+            self.call_process = subprocess.Popen(['parole', '-c', station['host'], '-d', config['audio device']])
+            s = socket.socket()
+            s.connect((station['host'], station['port']))
+            s.send(OP_CALL)
+            response = s.recv(1024)
+            print('Call notice sent', 'response=', response.decode())
+            s.close()
+            self.state = OUTGOING_CALL
+            self.station = station
+            GPIO.output(station['red led'], GPIO.HIGH)
+        except Exception as e:
+            print('Error al realizar la llamada: ', e)
+            GPIO.output(station['green led'], GPIO.LOW)
+            self.call_process.terminate()
+            self.call_process.communicate()
+
+    def incoming_call(self, station):
+        self.state = INCOMING_CALL
+        self.station = station
+        GPIO.output(station['red led'], GPIO.HIGH)
+
+    def hang(self):
+        print('Hang! self.station', self.station)
+        if self.station is not None:
+            GPIO.output(self.station['red led'], GPIO.LOW)
+        if self.call_process is not None:
+            self.call_process.terminate()
+            self.call_process.communicate()
+        self.state = NO_CALL
+        self.station = None
+
+    def notify_hang(self):
+        if self.station is not None:
+            s = socket.socket()
+            s.connect((self.station['host'], self.station['port']))
+            s.send(OP_HANG)
+            response = s.recv(1024)
+            print('Hang notify sent', 'response=', response.decode())
+            s.close()
+
+
+callManager = CallManager()
+
+
+def getstationbyip(ip):
+    for s in stations:
+        if s['ip'] == ip:
+            return s
+    return None
+
+
+# Escuchamos en port para peticiones de operaciones.
+def listen(call_manager):
+    serversocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    serversocket.bind(('0.0.0.0', port))
+    print('Listening address', socket.gethostname(), 'on port', port)
+    serversocket.listen(5)
+    while True:
+        # accept connections from outside
+        (clientsocket, ip_address) = serversocket.accept()
+        data = clientsocket.recv(1024)
+        print('Connection from', ip_address, 'host=', clientsocket.getpeername(), 'data=', data.decode())
+        station = getstationbyip(ip_address[0])
+
+        if data == OP_HANG:
+            call_manager.hang()
+            clientsocket.send(OP_OK)
+        elif data == OP_CALL:
+            if callManager.state == OUTGOING_CALL or callManager.state == INCOMING_CALL:
+                callManager.hang()
+            call_manager.incoming_call(station)
+            clientsocket.send(OP_OK)
+        elif data == OP_PING:
+            GPIO.output(station['green led'], GPIO.HIGH)
+            clientsocket.send(OP_OK)
+        else:
+            clientsocket.send(OP_ERROR)
+        clientsocket.close()
+
+
+# Comprueba que el otro intercom esta activo.
+def check_status(station):
+    while True:
+        s = socket.socket()
+        try:
+            s.connect((station['host'], station['port']))
+            s.send(OP_PING)
+            if s.recv(1024) == OP_OK:
+                GPIO.output(station['green led'], GPIO.HIGH)
+            else:
+                GPIO.output(station['green led'], GPIO.LOW)
+                GPIO.output(station['red led'], GPIO.LOW)
+        except socket.error:
+            GPIO.output(station['green led'], GPIO.LOW)
+            GPIO.output(station['red led'], GPIO.LOW)
+            print('Check status failed! host=', station['host'])
+        finally:
+            s.close()
+        time.sleep(CHECK_STATUS_INTERVAL)
+
+
+config = yaml.safe_load(open("intercom.yml"))
+port = config['port']
+stations = config['stations']
+GPIO.setmode(GPIO.BCM)
+
+# Start thread to wait for incoming hang petitions.
+thread_listen = Thread(target=listen, args=(callManager,))
+thread_listen.daemon = True
+thread_listen.start()
+
+# Power off leds and start threads to check other intercoms status.
+for _station in stations:
+    _station['ip'] = socket.gethostbyname(_station['host'])
+    GPIO.setup(_station['green led'], GPIO.OUT)
+    GPIO.setup(_station['red led'], GPIO.OUT)
+    GPIO.setup(_station['button'], GPIO.IN, pull_up_down=GPIO.PUD_UP)
+    _station['old button state'] = GPIO.input(_station['button'])
+    _station['button state changed time'] = time.clock_gettime(time.CLOCK_MONOTONIC)
+    _station['button pressed'] = False
+    thread_check = Thread(target=check_status, args=(_station,))
+    thread_check.daemon = True
+    thread_check.start()
+
+# Listen for swith changes.
+try:
+    while True:
+        for _station in stations:
+            new_input_state = GPIO.input(_station['button'])
+            # Al pulsar el interruptor cambia el estado.
+            elapsed_time = time.clock_gettime(time.CLOCK_MONOTONIC) - _station['button state changed time']
+            if new_input_state != _station['old button state'] and elapsed_time > 0.05:
+                if not _station['toogle button']:
+                    _station['button pressed'] = not _station['button pressed']
+                    if _station['button pressed']:
+                        _station['old button state'] = new_input_state
+                        _station['button state changed time'] = time.clock_gettime(time.CLOCK_MONOTONIC)
+                        continue
+                print('Interruptor pulsado callManager.state=', callManager.state, 'elapsed_time', elapsed_time)
+                # Si no hay llamada en curso la hacemos.
+                if callManager.state == NO_CALL:
+                    callManager.call(_station)
+                elif callManager.state == OUTGOING_CALL:
+                    callManager.notify_hang()
+                    callManager.hang()
+                elif callManager.state == INCOMING_CALL:
+                    callManager.notify_hang()
+                    callManager.hang()
+
+                _station['old button state'] = new_input_state
+                _station['button state changed time'] = time.clock_gettime(time.CLOCK_MONOTONIC)
+        time.sleep(0.02)
+finally:
+    GPIO.cleanup()

intercom.service

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+[Unit]
+Description=Intercom
+After=network.target
+
+[Service]
+ExecStart=/usr/bin/python3 -u intercom.py
+WorkingDirectory=/home/pi
+StandardOutput=inherit
+StandardError=inherit
+Restart=always
+User=root
+
+[Install]
+WantedBy=multi-user.target

intercom.yml

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+port: 8111
+audio device: plughw:1,0
+stations:
+  - host: rba
+    port: 8111
+    button: 25
+    toogle button: False
+    red led: 26
+    green led: 12
+  - host: kuku
+    port: 8111
+    button: 18
+    toogle button: False
+    red led: 26
+    green led: 2

parole.service

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+[Unit]
+Description=Parole
+After=network.target
+
+[Service]
+ExecStart=/usr/bin/parole -la -d plughw:1,0
+WorkingDirectory=/home/pi
+StandardOutput=inherit
+StandardError=inherit
+Restart=always
+User=pi
+
+[Install]
+WantedBy=multi-user.target