I've just got back from a weekend with my parents, where I had lots of fun attempting to get an Arduino Uno to control a cheap set of remote control mains sockets. My dad has a set of 3 of these (
http://www.maplin.co.uk/remote-controlled-mains-socket-set-531547) and has them plugged into desk and pedestal lamps in the living room. Since my last two christmas/birthday presents to him were a Raspberry Pi Model B, and a book about home automation using Arduino, he'd picked up an Arduino starter kit from Amazon, and had bought a second remote control and taken it to pieces, all we needed was some solder and some code.
First step, solder 3 wires onto the remote control extracted from the plastic housing, as per
http://blog.sui.li/2011/04/12/163/, and connect it up to the Arduino's 5V, ground and digital out pins (I chose pin 11).
Next, import the library from
https://code.google.com/p/rc-switch/, then write a quick app to set switch one on and off. Once we'd proved this works, we worked through a quick example using a photodetector, then decided it'd be fun to get this working over the web. Since we didn't have any network connectivity, we roped in the Raspberry Pi to serve a very basic website, and use the Pi's GPIO to signal to the Arduino to turn on the lights. I hope you'll forgive the gross insecurity of the web server, but it's quick and does the job - here's the code:
Python Code:
#! /usr/bin/python
import sys
import RPi.GPIO as GPIO
import BaseHTTPServer
from SimpleHTTPServer import SimpleHTTPRequestHandler
class LightsHandler(SimpleHTTPRequestHandler):
def do_GET(self):
print "handling " + self.path
if ("lightson" in self.path):
self.lights_on()
elif ("lightsoff" in self.path):
self.lights_off()
self.send_response(200,'OK')
def lights_on(self):
print "on"
GPIO.output(18, True)
def lights_off(self):
print "off"
GPIO.output(18, False)
HandlerClass = LightsHandler
ServerClass=BaseHTTPServer.HTTPServer
Protocol="HTTP/1.0"
server_address= ("", 8080)
HandlerClass.protocol_version = Protocol
httpd = ServerClass(server_address, HandlerClass)
sa = httpd.socket.getsockname()
print "serving"
GPIO.setmode(GPIO.BOARD)
GPIO.setup(18, GPIO.OUT)
httpd.serve_forever()
Arduino Code:
#include RCSwitch mySwitch = RCSwitch();int d_raspPiInputPin = 10; int d_transmitterPin = 11;int onboardLedPin = 13;int lightsOn = 0;int delayTimeout = 1000;int delayCommand = 500;int valueFromPi = 0;void setup(){ mySwitch.enableTransmit(d_transmitterPin); pinMode(onboardLedPin, OUTPUT); pinMode(d_raspPiInputPin, INPUT); Serial.begin(9600); }void loop(){ valueFromPi = digitalRead(d_raspPiInputPin); if(valueFromPi == HIGH){ allLightsOn(); } else { allLightsOff(); } delay(delayTimeout);}void allLightsOn() { if (lightsOn == 0) { mySwitch.switchOn(1, 1); delay(delayCommand); mySwitch.switchOn(1, 2); delay(delayCommand); mySwitch.switchOn(1, 3); delay(delayCommand); mySwitch.switchOn(1, 4); delay(delayCommand); lightsOn = 1; } digitalWrite(onboardLedPin, HIGH);}void allLightsOff() { if (lightsOn == 1) { mySwitch.switchOff(1, 1); delay(delayCommand); mySwitch.switchOff(1, 2); delay(delayCommand); mySwitch.switchOff(1, 3); delay(delayCommand); mySwitch.switchOff(1, 4); delay(delayCommand); lightsOn = 0; } digitalWrite(onboardLedPin, LOW);
}
And a photo of the Arduino all wired up:
Notes:
- Don't forget to connect the grounds of the Pi and the Uno together
- We used GPIO 18 on the Pi as a digital output connected to pin 10 on the Uno
- Be careful if you're using the Pi for digital input as it'll only take 3.3 Volts
- We used the onboard LED on the Uno to check that we were sending the right signals to the transmitter
- We needed a short delay between sending commands to the transmitter, otherwise we'd only get some rather than all the lights to respond.
- You'll need to run the python script under sudo to be able to write to the GPIO
