Is it a phone or is it a
computer? We make an odd hybrid device from his Android phone
The computing
power inside a modern smartphone is amazing, especially if you look at in the
context of previous mainframe systems. Cray’s first powerful system was the
Cray-1A. it weighed 5.5 metric tons and could achieve 160 MIPS and 250 floating
point megaflops for those with the $9m to buy it back in 1977. The ARM Corex-A9
used in many of the latest phones can do 2.5 gigaflops and 8000 Dhrystone MIPS
running at 1.5GHz, which is quicker than most of the mainframes that were made
in 80s.
ARM Corex-A9
That’s about the
same power that we had in desktop PCs nine years ago, equivalent to an AMD
Athlon XP 2500+, or close enough. There are people I’m sure still using their
Athlon XP systems as perfectly usable computers, as the mount of power needed
to word process and surf the internet isn’t huge.
AMD Athlon XP 2500+
With so much power
in your pocket, is it possible to turn your smartphone into a useable PC?
Maybe. But before we tackle some of the bigger issues, perhaps first we need to
address getting information into the phone in a slightly more elegant way than
with a tiny touch panel.
Can I use a USB Keyboard or
Mouse?
At first glance
that seems like an impossible dream, not least because when you plug an Android
phone into a PC it acts as a peripheral, where what we want it to do is
function as a USB host. Surely, then, that’s not going to work, ever?
Amazing, it will
work, but under very particular circumstances. What is implemented on some
Android phone USB ports is USB-OTG (On-The-Go), a version of USB where the port
can act as both a host and a peripheral.
USB-OTG
To do this you
need either a special cable, which I found on eBay for $5, or you can actually
butcher some USB parts to make one. I respectfully suggest you pay the nice
eBay vendor, because getting the power line connections wrong could fry the
port, which would make your phone impossible to directly charge among other
issues.
This would all be
just an interesting technical point had Google not put in Android (or at least
the latest versions of Android) the code needed to make a USB keyboard and
mouse work. It also put other interesting code in there too, which makes
external storage, like USB keys and external hard drives work. The only caveat
is that external drives need their own PSU, because the phone won’t provide
enough power to drive them directly.
But before you all
rush off to buy a cable, I’d do some research first, because while the hardware
in my HTC does support OTG, that company, in its less than infinite wisdom,
chose not to bind the code that makes it work into the kernel.
So what are the
limitations of this if it does work for you? Well, the first issue you’ll
encounter is that you’ve only got room for one device, but you can’t get around
this with a USB hub. A powered hub is ideal, and using it you can connect a
mouse and keyboard easily.
‘With so much power in your pocket, is it possible to turn your
smartphone into a useable PC?’
I tried a keyboard
with integrated hub on a OTG enabled phone and it complained it was a ‘high
power USB device’, so it’s critical to have a powered hub for some devices.
You can also
attach flash drives and USB hard drives, as long as they don’t pull too much
power. Most Android phones understand the FAT32 file system, but only a few
custom ROMs have been augmented to understand NTFS so far.
Unfortunately, the
phone I was focusing most of my effort on, the HTC Sensation XE, appears to
have not had this feature enabled, although the Samsung Galaxy S2 that I also
used worked flawlessly with lots of USB devices.
A side note to
this feature is that my research suggests that almost all Samsung Android
phones have working OTG, as do most of Nokia’s better Symbian ones, but at this
time I can’t find a single Microsoft WM7 phone that has it. As for tablets, for
those that don’t have normal USB connectors, the Acer Iconia Tab A200, Sony
Tablet S 3G, Samsung Galaxy Tab and Huawei MediaPad S7-301w all support OTG.
