Overview
The Wireless Electronic Fridge TAG
The idea is simple and a little playful: you type a message on your phone, and that message shows up on a small display stuck to the fridge with a magnet — no wires, no cloud account required to understand, just a clean end-to-end wireless link from pocket to kitchen.
What is IT
It's a short-range wireless display node:
- The user enters text on a phone (app or web page)
- The text is sent over a wireless link to a small controller mounted behind a magnetic front panel.
- The controller drives a display so the message is visible at a glance on the fridge
That's the whole loop. What makes it a good project is that every layer is learnable: a radio/network
Hardware
- E-ink LED
- Raspberry Pi
- Phone APP with CORDOVA
Software
- CORDOVA part with html coding for pubsub service
<!DOCTYPE html>
<html>
<!--
-->
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, user-scalable=no
initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0" />
<title>eSticker</title>
<style>
[url=home.php?mod=space&uid=568594]@import[/url] 'ui/css/evothings-app.css';
</style>
<script src="cordova.js"></script>
<script src="libs/jquery/jquery.js"></script>
<script src="libs/evothings/evothings.js"></script>
<script src="libs/evothings/ui/ui.js"></script>
<script src="libs/evothings/arduinoble/arduinoble.js"></script>
<script src="libs/pubnub.4.18.0.js"></script>
<!-- or <script src="https://cdn.pubnub.com/sdk/javascript/pubnub.4.18.0.js"></script> -->
</head>
<body><!-- enables low-delay CSS transitions. -->
<header>
<button class="back">
<img src="./ui/images/arrow-left.svg" />
</button>
<img class="logotype" src="./ui/images/logoesticker.png" alt="eSticker" />
<!--<button class="menu"><img src="ui/images/menu.svg" /></button>-->
</header>
<h1>eSticker</h1>
<p id="info">Initializing...</p>
<!--
<button class="yellow wide">CONNECT</button>
//New empty Keys
pubnub = new PubNub({
publishKey: 'pub-c-218bb0fd-bdb4-45c6-a1c4-77d7674c8caf',
subscribeKey: 'sub-c-383e74cc-d0e3-11e7-b07a-4e4fd9aca72d'
})
-->
<br />
<input type="text" id="txtag" value="input text...">
<button class="green wide big">Sent Text</button>
<br />
<button class="red wide big">Clear Text</button>
<script>
// Application object.
var app = {}
var pubnub = new PubNub({
subscribeKey: 'sub-c-81c369ca-5ba6-11e7-a298-xxxxxxxxxxx', // always required
publishKey: 'pub-c-6a7a7381-128c-4d9b-b3af-xxxxxxxxxxxxxx' // only required if publishing
});
// Function PublishMessage.
function publishMessage(txMessage) {
console.log("Since we're publishing on subscribe connectEvent, we're sure we'll receive the following publish.");
var publishConfig = {
channel : "flood_alarm_signal",
message : txMessage
}
pubnub.publish(publishConfig, function(status, response) {
console.log(status, response);
})
};
// Connected device.
app.device = null;
var count=0;
// Add listener and subscribing
pubnub.addListener({
status: function(statusEvent) {
if (statusEvent.category === "PNConnectedCategory") {
publishMessage("PNConnected!");
}
},
message: function(message) {
console.log("New Message!!", message);
count=count+1;
//app.showMessage(message.message);
app.showMessage(message.message);
},
presence: function(presenceEvent) {
// handle presence
}
});
pubnub.subscribe({
channels: ['flood_alarm_signal']
});
// Turn on LED.
app.sentTX = function()
{
var txSent=new Uint8Array();
txSent=document.getElementById('txtag').value;
app.device && app.device.writeDataArray(new Uint8Array([txSent]), '19b10001-e8f2-537e-4f6c-d104768a1214');
var txMessage = txSent;
publishMessage(txMessage) ;
//app.showMessage(txMessage.text);
}
// Turn off LED.
app.clearTX = function()
{
document.getElementById('txtag').value = " ";
app.device && app.device.writeDataArray(new Uint8Array([0]), '19b10001-e8f2-537e-4f6c-d104768a1214');
}
app.showMessage = function(info)
{
document.getElementById('info').innerHTML = info
};
// Called when BLE and other native functions are available.
app.onDeviceReady = function()
{
app.showMessage('Touch the connect button to begin.');
};
app.connect = function()
{
evothings.arduinoble.close();
app.showMessage('Connecting...');
evothings.arduinoble.connect(
'TAG', // Advertised name of BLE device.
function(device)
{
app.device = device;
app.showMessage('Connected! Touch buttons to turn LED on/off.');
},
function(errorCode)
{
app.showMessage('Connect error: ' + errorCode + '.');
});
};
document.addEventListener(
'deviceready',
function() { evothings.scriptsLoaded(app.onDeviceReady) },
false);
</script>
</body>
</html>
This is how it appears in ANDROID phone
- codes in python running on Raspberry Pi and driver for Waveshare E-link LCD
##
# @filename : main.cpp
# @brief : 1.54inch e-paper display demo
##
import epd1in54
import time
import Image
import ImageDraw
import ImageFont
from pubnub.callbacks import SubscribeCallback
from pubnub.enums import PNStatusCategory
from pubnub.pnconfiguration import PNConfiguration
from pubnub.pubnub import PubNub
pnconfig = PNConfiguration()
pnconfig.subscribe_key = 'sub-c-81c369ca-5ba6-11e7-a298-xxxxxxxxxxxxxx'
pnconfig.publish_key = 'pub-c-xxxxxxxxxxxxxxxxxxxxxxxxxx'
pubnub = PubNub(pnconfig)
def main():
epd = epd1in54.EPD()
epd.init(epd.lut_full_update)
image = Image.new('1', (epd1in54.EPD_WIDTH, epd1in54.EPD_HEIGHT), 255) # 255: clear the frame
draw = ImageDraw.Draw(image)
font = ImageFont.truetype('/usr/share/fonts/truetype/freefont/FreeMonoBold.ttf', 24)
draw.rectangle((0, 10, 200, 34), fill = 0)
epd.clear_frame_memory(0xFF)
epd.set_frame_memory(image, 0, 0)
epd.display_frame()
epd.delay_ms(2000)
# for partial update
epd.init(epd.lut_partial_update)
image = Image.open('/home/pi/zTag/python/monocolor.bmp')
epd.set_frame_memory(image, 0, 0)
epd.display_frame()
epd.set_frame_memory(image, 0, 0)
epd.display_frame()
time_image = Image.new('1', (96, 48), 255) # 255: clear the frame
draw = ImageDraw.Draw(time_image)
font = ImageFont.truetype('/usr/share/fonts/truetype/freefont/FreeMonoBold.ttf', 32)
image_width, image_height = time_image.size
def indisplay(txdata):
draw.rectangle((0, 0, 96, 48), fill = 255)
draw.text((0, 0), txdata, font = font, fill = 0)
epd.set_frame_memory(time_image.rotate(90), 80, 80)
epd.display_frame()
# Pubnub start...
def my_publish_callback(envelope, status):
if not status.is_error():
pass
else:
pass
class MySubscribeCallback(SubscribeCallback):
def presence(self, pubnub, presence):
pass
def status(self, pubnub, status):
# print("Status category", status.category)
if status.category == PNStatusCategory.PNUnexpectedDisconnectCategory:
pass
elif status.category == PNStatusCategory.PNConnectedCategory:
pubnub.publish().channel("flood_alarm_signal").message("Hi...").async(my_publish_callback)
elif status.category == PNStatusCategory.PNReconnectedCategory:
pass
def message(self, pubnub, message):
txdata=message.message
#jdata=json.dumps(txdata)
print(txdata)
indisplay(txdata)
pubnub.add_listener(MySubscribeCallback())
pubnub.subscribe().channels('flood_alarm_signal').execute()
- pubsub service behind the bar
The API dey and registered service shall be use in the program both in mobile APP and raspberry PI part, as broker
RUNING the APP
- Start the app in raspberry PI
runing
python main.py
- Input text such as 'cool', it appears in phone app
- On The Wireless Electronic Fridge Tag as well
z-wave part is not passed in testing, but the UI still keep it
- put it into one case and stick magnet as back
b--a----c----k 
Summary
This is one demo project on how to delivery short message across different platform, in this case , mix wifi and bluetooth service together. Simple as it is, it is prototype for IoT service with Center MSG broker, ede view and remote control.