Ask Slashdot: Why Buy a Raspberry Pi When I Have a Perfectly Good Cellphone?

scorp1us writes "I've been looking into getting a Raspberry Pi, but I end up needing a case, a display, and some way to power it, and wanting some degree of portability. It seems to me that even the most outdated cellphone has far superior features (screen, touch screen, Wifi, 3g/4g camera(s), battery etc) in a much better form factor. The only thing that is missing are the digital/analog in/out pins. So why not flip it around and make a USB or bluetooth peripheral board with just the pins? I've been looking for this and can't find any, but does anyone know of any in the corners of the internet? I don't care what phone platform."

Comments

Arduino Uno

[rwa2]

Done in one (pun intended)

Solid, lots of add-on modules, vibrant hacker community. And it has its own programmable processor so if your application permits you don't even have to have it attached to your PC to collect and process data.

Re:Arduino Uno

[girlintraining]

Solid, lots of add-on modules, vibrant hacker community. And it has its own programmable processor so if your application permits you don't even have to have it attached to your PC to collect and process data.

Limited memory, slow I/O, slow processor, can emulate a USB device but can't function at anything resembling modern USB speed... This guy doesn't want another bag on the side, he wants something that gives him a spread of I/O pins and sampling options. And Arduino ain't that -- and he's right, there's nothing on the market that will give him a programmable DAC/ADC paired with a USB controller that can operate at the speeds of the current USB standard (v3).

It's not hard for an electronics engineer to slap some glue logic and a few chips on a homebrew board and do it, but for a hobbyist who just wants to play? Forget it.

Re:Arduino Uno

[SQLGuru]

With an Android phone, you just need this: http://en.wikipedia.org/wiki/USB_On-The-Go

Buy one here: http://hakshop.myshopify.com/products/micro-to-micro-otg (site might be blocked at some work locations as they might think it's hacking related)

Re:Arduino Uno

[rwa2]

I have both... my dad gifted me a Pi B and an Uno. I'm having more fun with the Uno, since it gives you more analog/digital I/O options.

The Pi is certainly more powerful and capable... but anything I try doing with it inevitably leaves me wishing I had dropped a $100 more for an nVidia ION miniITX board that does a much better job pretending to be a "real" PC.

Re:Arduino Uno

[harrkev]

First, a disclaimer. I am not an Arduino expert. I have one and have played around, but am not a pro. Please forgive me if I make a mistake...

The big thing is that Arduino does NOT have Ethernet. Yes, you can add it on. I just built a small project for an internet-controlled power outlet. Raspberry Pi + an SD card (around $40 total) is significantly cheaper than an Arduino plus an Ethernet shield (around $60). Plus, the Pi can be programmed in your choice of languages (Python, Perl, TCL, C++, etc.) while the Arduino . Also, a web server on Pi is just an "apt-get" away. Don't get me wrong. The Arduino has its place too. Lots of IO. analog input, PWM output, etc. But the Pi and Arduino are different beasts with different (but somewhat overlapping) targets.

Now, the concept of using a phone as a general-purpose controller is interesting, if you can overcome the IO problem. If you can find something and cobble it together go for it. However, finding a steady supply of phones would be problematic. I could order a dozen Raspberries or Arduino boards in a moment. Using an old cell phone would require hitting garage sales or thrift stores looking for old phones that actually run something you can use (such an Android). I don't think that you can program older "feature phones." You probably need something with full-blown iOS or Android, and I doubt that an older iOS device is cheaper than a Pi. That leaves Android. If you only need one or two for a particular project, you might be able to swing it. Otherwise, you can't beat a couple of mouse clicks to get a proper development platform delivered to your door for under $50.

Re:Arduino Uno

[cruse.mike]

He needs portability. The missing piece is a USB I/O board that plugs into your phone. Of course this means having a phone that can be the host device and not just the peripheral.

I designed and built several I/O devices like this for myself, well to sell to other people really. The I/O mix for one of my boards is a follows: 4 "Universal" inputs (0-20VDC, Thermistor, 0-20mA, Binary state and 32 bit counter) 4 12VDC @200mA binary outputs 4 One-Wire sensor bus ports (Dallas/Maxim temperature sensors etc) 2 0-10VDC analog outputs RS485 port for multidrop network comms, i.e. Modbus/Bacnet etc CAN port for I/O expansion (multiple boards acting as one on a CAN network) USB device port for either firmware update (mass storage) or USB CDC serial comm port for config, direct I/O control Powered by 12VDC or 24VAC NXP Cortex M3 32 bit processor @120MHZ Primarily intended for building automation but still general purpose enough for many other things. I use then for lawn watering, door bell control, lighting. Has a basic expression parser for interpreted basic logic. Expressions can be stored in flash as can dynamically created user variables. Expressions can also be nested and scheduled for some level of automated behaviour. Everything is accessible via the USB serial connection. The problem is that even my cost for a board like this is many times the price of the cheapest Raspberry PI. But then having very little real world I/O (and large volumes) is how you can achieve a price like that. Anyway, if a phone can interact with a USB CDC device then it could control one of my boards. I am going to have to try that out myself now.

Android development kit

[Tim the Gecko]

How about this? - http://www.adafruit.com/products/885 - IOIO Mint - Portable Android Development Kit

Depends on use-case

[StealthHunter]

If your use-case is "leave attached to my TV" then a Pi makes a lot of sense. If you want to have a resilient case, be portable, have a small screen attached, etc, then maybe a phone makes more sense.

You might not need one, but...

[mr_goodwin]

I'd have had trouble doing this with a cellphone:

https://www.youtube.com/watch?v=m_c9cxoM8tg

Part of the usefulness of the Pi is *because* it lacks those things; you have the option of adding what suits your application.

Because you need your phone as the remote.

[tuppe666]

I'm not sure why the comparison with a cellphone. Currently I'm using it as XBMC and using my Android phone as the remote. It was a toss up between the Pi and the ultra cheap AndroidTV dongles that are kicking around (Why I think AppleTV is dead on arrival), and overall I couldn't be happier stupid setup errors aside [power supply too weak on the pi to power the usb; couldn't get wifi working on the minimal distribution?] Otherwise its incredible, and using the phone as a remote control has changes my life.

There are a few compromises with the pi [512 memory & missing sata] otherwise I'm overjoyed with the source. Killer feature, you mess up you wipe your card and your good to go.

The bottom line is your old phone is less versatile with less support, but its great at being a phone...which if its the task you want go ahead. Otherwise its such an incredible strange question.

Better choices than a Raspberry Pi.

[hamster_nz]

You should look at the other ARM boards out there e.g. pcDuino. More memory, more I/O, onboard flash, Linux or Android.

However there are some things that you can do with a micro-controller that can not be done with a full OS - e.g. bit-banging I/O to one-wire temperature sensors. I've even used a full USB 1.1. HID driver implemented completely in software, which would be impossible with an full OS running!

Re: Pearls before swine?

[Anonymous Coward]

If you can't figure out that the asker has already figured that out that they're not the Pi's target market, and isn't questioning the Pi's utility for its target market, you're not insightful.

You're a fanboy. Go play with your Pi.

Re:Received an iPhone as a gift

[Microlith]

Sell it and buy something they can use as they see fit? I hear Apple fans gibber on constantly about the resale value of their devices, so you should be able to get a good price I suppose.

Re:Pearls before swine?

[Nemyst]

And this, dear friends, is why geeks are often considered to be antisocial.

Re:People often fail to understand why the Arduino

[Joce640k]

People often fail to understand why the Arduino is so fucking popular. It is NOT because it has the most powerful processor. It is NOT because it has the most pins. It is NOT because it is the easiest to develop for. It is NOT because it is the most standardized.

This.

Just yesterday I had an 'argument' with a guy over how Arduino is dead because such-and-such a chip is way more powerful than AVR (AVR=the chips in Arduinos), how it has hundreds of MegaHertz and Megabytes and all that stuff.

I simply don't care! I don't need a board that has 512Mb of RAM and runs Linux just to light up a few LEDs (even with a motion sensor!). I need something that works well enough, can drive a LED directly from an I/O pin (5V outputs, tada!) and has a huge online community with thousands of web pages/blogs/forums to browse, plus source code to download.

PS: Can you build your own dime-sized clone of that fancy ARM board for $1.50? I can do it with Arduino... (ATtiny85)