Retro Space Invaders Gmail Notifier

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A couple of weeks ago I was in our local Boots chemist. They were clearing out all the Christmas gifts at 75% off. I saw this Space Invaders alarm clock reduced to around £3 ($5) and had to have it, even though I had no use for another alarm clock. (Btw, even though Boots are now sold out, the same clock is available from Play, IWOOT, Menkind and others.)

The challenge was… what to do with it?

In the end I decided to turn it into an ambient device, connected to the internet and capable of alerting me when things happen. Right now I’ve got it firing up with a new message arrives in my Gmail inbox, but really it could do anything – flag up Twitter replies, indicate the chance of rain or even, paired with one of my previous projects, act as an additional ringer for the doorbell. I’ve added a row of LEDs (three red, three yellow) to give it some more feedback options.

Every time I get a new email the clock moves from side to side and does the classic Space Invaders sound, then lights one of the LEDs to give me an idea of how many unread messages there are. There’s loads more that could be done with it, but I was happy just turning it into something more useful without destroying it in the process.

If you want to make one yourself, here’s what I did…

I used an Arduino to give the clock some more logic. I didn’t want to alter the external appearance of the clock and space was incredibly tight inside, so I used an Arduino Nano clone that I had lying around.

Update: I’ve since written a post with a parts list and some setup instructions that may be useful to read in conjunction with this.

First step was to get the components working on a breadboard. I ran 6 LEDs off the Arduino’s digital pins and added an opto-isolator to another digital pin to act as a switch. I knew the Arduino wouldn’t be able to drive the clock’s motor straight off an IO pin, so my plan was to simply trigger the clock’s handy ‘demo’ button from the pin and deliver the main clock/motor power from the direct 5V pin on Arduino.

Here’s the wiring layout that I ended up with…

The original power source for the clock was 3 AA batteries producing around 4.5v. I was planning to power the clock directly over USB – I figured 5V was close enough – so the battery compartment provided the perfect space to house the additional components. Unfortunately the battery box wasn’t quite deep enough for the Nano, so my first job was to cut out the battery recess with a craft knife. I left a small lip on the bottom edge to support the additional components and to retain the original motor mounting point.

With a bit of breadboard trimming (with a hacksaw… quick and nasty!) I was able to fit it into the clock…

Next step, the Arduino sketch. The code is currently dead simple: listen to the serial input and if it’s a number, light that many LEDs; if the new number is higher than the old number (i.e. you’ve got new emails, not just cleared out old ones) then also close the ‘demo’ switch to activate the sound and movement. Here’s the finished code.

int ser = 0; // for incoming serial data
int prevCount = 0;
int timer = 100;

void setup() {
 for (int thisPin = 2; thisPin <= 13; thisPin++) {
 pinMode(thisPin, OUTPUT);
 }
 Serial.begin(9600); // opens serial port, sets data rate to 9600 bps
}

void loop() {

 if (Serial.available() > 0) {
 // read the incoming byte:
 ser = Serial.read();

if (ser >= 48 && ser <= 58) {
 int newCount = ser - 48;
 if (newCount > 0 && newCount > prevCount) {
 digitalWrite(12, HIGH);
 delay(100);
 digitalWrite(12, LOW);
 delay(1500);
 digitalWrite(12, HIGH);
 delay(500);
 digitalWrite(12, LOW);
 }
 prevCount = newCount;
 } else {
 digitalWrite(13, HIGH);
 delay(100);
 digitalWrite(13,LOW);
 }
 }

for (int thisPin = 3; thisPin <= 11; thisPin++) {
 digitalWrite(thisPin, LOW);
 }

int topPin = prevCount + 2;

for (int thisPin = 3; thisPin <= topPin; thisPin++) {
 if(thisPin <= 5) {
 digitalWrite(thisPin, HIGH);
 } else {
 digitalWrite(thisPin+3, HIGH); // Because I left a gap in the digital pins
 }
 }
}

The last step was to write a quick script to poll Gmail and get the number of unread messages. I’ve tried lots of different languages for Arduino serial control in the past – Perl, PHP and DOS shell scripts – but every time it’s been a little bit flakey, at least under Windows. Flash Actionscript is pretty reliable using Serproxy, but that was overkill for this project. So in the end I decided to give Python a go. It was a good choice – reliable and really quick to implement. Here’s the code…

import serial
import time
import imaplib

ser = serial.Serial('COM6', 9600)
time.sleep(2)

while True:
 obj = imaplib.IMAP4_SSL('imap.gmail.com','993')
 obj.login('GMAIL_USER_HERE','PASSWORD_HERE')
 obj.select()
 obj.search(None,'UnSeen')
 count = len(obj.search(None, 'UnSeen')[1][0].split())

if(count > 9):
 ser.write(':')
 else:
 ser.write(count)

time.sleep(120)

ser.close()

The only bit that had me scratching my head was Arduino’s trick of resetting every time the serial line is opened. The Nano takes around 1.5 seconds to restart, meaning it would always miss the first mail notification. A wee sleep command fixed that.

And that’s about it. Three hours and around £12 of components (including the Nano clone) to turn an alarm clock into a Gmail notifier.

Future scope

There are still lots of free pins on the Nano, so plenty of scope for expansion. A light sensor could be a useful addition so it doesn’t trigger when the room lights are off, and maybe a knock sensor so it could be set to ‘snooze’ with a quick tap. Apart from that, most other mods would be software-based. I might make the three red LEDs linked to Gmail and the yellow ones linked to Twitter.

If you decide to make one of your own please let me know. And if you make any improvements to the software, please share!

Update: The response to this hack has been phenomenal – thanks for all your emails and feedback. Here are some of the mainstream sources that have picked up on it.

• Make Magazine: Space Invaders Gmail Notifier
• Engadget: Arduino hack turns Space Invaders alarm into Gmail Notifier
• Ubergizmo: Space Invaders Gmail notifier
• Technabob: Space Invaders Alarm Clock Becomes a Gmail Notifier
• Engadget Espanol
• How-To Geek

On Twitter:

• The Gmail Team
• Massimo Banzi (co-father of Arduino)

On YouTube:

• Someone has successfully copied my hack