Where's your wheelie bin? (iOS #1)

"I tell people I bin on 'olidays, but I wheelie bin in gaol!" Sorry, my sense of humour. It's funny to me. It's Australian humour, sorry if you don't get it.

I wheelie bin working in the land of iOS. I've been ploughing through the book Beginning iOS 5 Development (Exploring the SDK) by Dave Mark, Jack Nutting and Jeff LaMarche and I'm nearly finished. So am I off the Arduino reservation? Well yes, and no.

I'm dreaming about having Arduino devices be my 'real world' minions and having iOS (and Android, eventually) applications be the 'command and control' applications. I'd like to be able to turn off the light from my phone. I want to have a completely renewable-powered house that reports to me when it's running low on juice (electricity) and asks me before it powers down the PC in the study. It's my idea of the 'Internet of things': things that are intelligent, measure their environment and themselves, inform their owners, and then do the owner's bidding. If you're thinking Ninja Blocks, you're on the right track.

I've yet to be convinced Ninja Blocks can do what I want. If they do, I'll utilise them. If not, I'll forge my own path. The next small step is to have small, solar-powered XBee mesh network nodes that report their own power state to the mesh and otherwise do nothing. I figure this is a 'basic right' of embedded devices - to source their own power, and know their own state of charge. Without this, devices can just drop off the planet with no notice. This just won't do.

I feel like this is basic - from first principles. If you have a battery, you should be able to say when you're going to shut down. Better than that, you should be able to report your state of charge, then more intelligent decisions can be made based on when a node might black out; and change its behaviour (maybe put it to sleep). If a node can master its own power usage it's then useful to do other things, but not before.

I'd like to:
  1. Build XBee mesh network nodes that are self-powered and report their state of charge to the mesh.
  2. Build a router so that devices are logging state of charge to the Internet.
  3. Build the above that log instantaneous power consumption/charge including maximum power point (MPP) for photo-voltaic (PV) charged devices.
  4. Build sun-tracking nodes that self-align to ensure maximum PV charging.
I envision I'll build devices with small Li-ion batteries and solar panels on two-axis mechanisms operated by servos. These I might position in the yard on poles so the kids don't tamper with them and I can monitor their operation. It'll be a weird way of landscaping, but I think they'll be functional as well as a conversation starter; a bit like man-made sunflowers. Right now it's back to learning iOS. It has a purpose related to Arduinos, I promise.

[That is all]


  1. I recently purchased a GPRS/GSM shield for arduino Mega and connected an external power supply to the mega, not to the shield. The power supply was capable of delivering only upto 1A. I also connected a duck antenna to the shield. However, this antenna was a WiFi antenna, not a GPRS/GSM antenna. I inserted a SIM and uploaded the program to send SMS messages. The arduino and the shield powered and the LEDs were on. No message were delivered to the phone. I checked the serial monitor. It was blank. After several attempts by reloading the program, the shield suddenly went off (LED was off). I smelled like somethings burning. The transistors near power socket on the arduino and the 5100B module on the shield were very hot. I disconnected power and removed the shield from arduino board. I checked the arduino board and it works fine. Then I connected the shied to a regulated lab power supply capable of delivering large current. I set the supply voltage to 4V before connecting. To my surprise, the volt meter on the power supply showed much lower value than 4V and the current value increased well passing 3A, more like a short circuit. When I removed the sm5100B module from the shield, the voltage is back to normal and the current is lowered. The LEDs on the board are on. It seems like the module has been damaged. Please share your thoughts on this.


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