Using an Android phone as a Roomware Server

Posted on June 8, 2010


By: Peter Kaptein, June 8, 2010

Yesterday another thought crossed my mind, thinking about Roomware. It is a process of adding up different insights.

Reducing energy use

One of the biggest issues on running local installations of Roomware is energy-consumption. Say you have a house monitored by different sensors, with one of the purposes to monitor the energy use to save energy on the long run.

The most energy-efficient machines now are Netbooks and Thin clients based on the same principle and hardware. They consume about 2 to 7 Watts right now (2010).

The phone is a computer

Current phones like the Android are more and more becoming mini-computers with the option to make phone calls as well.

They have a keyboard (on screen or via hardware), WiFi, Bluetooth and USB connectivity and (in the case of Anroid) run some sort of Unix underneath, with Java as the main programming language.

Low energy use, low pricing

The energy consumption of a phone is less than that of a netbook, as the battery is clearly less powerful as well and uptime should be at least a day. Also, if you focus on the low end of the market, the price per phone can be low as well. Around $300 for a new model  or even down to $200.

It is hard to define the amount of energy consumption when the phone is running processes. The batteries included are usually something like 1400 mAh (which indicated it can provide 1,4 Ampere for one hour). Active use (talking / calling) is something like 240 minutes average. So we might take that as a starting point. 240 minutes / 60 equals 4 hours. So divide the battery life by 4 and you get the amount of Amperes used: 1400 mAh / 4 hours = 350 mA. Times the voltage of the battery equals Watts: 350 mA x 3.7 Volts = 1.2 Watt.

USB and devices

I have not yet looked at the possibilities to use the USB port of the Android phone to actively communicate to – let’s say – an Arduino or XBee device. But no doubt – with some hacking involved – you can use the same serial communicator used on the PC.

Posted in: 4: Concepts, Roomware