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 It seems to me that even the most outdated cellphone has far superior features (screen, touch screen, Wifi, 3g/4g camera(s), battery etc) in a much better form factor.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

[chrylis]

Of course nothing's going to operate at USB v3 Super-Speed. You'd have to be running custom FPGA hardware to get anywhere close. On the other hand, the IOIO seems to be about as close to what the submitter wants as is practical with cheap hardware.

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.

Re:Arduino Uno

[Joce640k]

an Arduino plus an Ethernet shield (around $60).

You can get it for a lot less than $60 of you don't buy official Arduino hardware.

eg. A $6 Arduino clone: http://www.ebay.com/sch/i.html?_nkw=arduino+pro+mini plus a $12 W5100 module: http://www.ebay.com/itm/111025516885

(or use a $4 Ethernet module if you don't need the official Arduino Ethernet library: http://www.ebay.com/sch/i.html?_nkw=arduino+ENC28J60 )

if you can overcome the IO problem

You can build an Arduino USB I/O controller for about $1.25 with a Tiny85 plus a copy of v-usb

Android development kit

[Tim the Gecko]

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

Re:Android development kit

[chrylis]

The OTG is the latest IOIO. Ytai is still working on crazily trying to pack even more features on the thing (apparently, his goal is to fit in every single sort of IO that the ATmega is capable of), but the OTG is the current state-of-the-art.

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.

Peripheral boards

[RabidReindeer]

"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."

I think this might be adaptable. Although its original intent was as an XBee interface, the catalog explicitly states it can be used for USB-to-TTL. Presumably by tapping the points where the ZBee's GPIO pins break out:

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2159285_-1

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!

It's also fine if you have an iPhone

[SuperKendall]

A lot of people especially in the Americas and western Europe carry an iPhone, for which development of accessory hardware is far more expensive.

Only if you plan to sell it. If it's for personal development, just jailbreak the phone and connect to the serial port pins of the dock connector as per this SO post.

Obviously anyone looking to build custom hardware can handle the simple task required to hook up to it.

Optionally of course, you can do anything you like with Bluetooth LE without any licensing from Apple - and commercial apps are allowed to do BTLE communications in the background because of the low power consumption. That's what I would start with as an approach unless you need more bandwidth for some reason.

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.

Rasberi Pi != cellhone

[davydagger]

1. price- no cell phone is that cheap
2. better documented hardware with FOSS drivers.(NO cellphone has FOSS drivers, or firmware). In fact its hard if not impossible getting firmware extracted, or proprietary binary drivers for a general purpose OS for your cell phone.

Its not like desktop OSs, where you can just download the latest nvidia or ATI drivers for linux from the vendor

3. Cell phones are made for android which is NOT a General Purpose OS, and can be restrictive.

4. Rasberri PI by default boots from an SD card, making running whatever OS you want, without hacking easy. There is also no need to root it.

5. the Rasberri PI also has hostmode USB ports, for plugging devices in, your phone most likely does not, if your lucky OTG.

6. There are other ARM protoboards and dev boards that are not the PI which have ARM class CPUs. Most of them run any OS you put on them. RasPI is not the first nor will be the last.

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.

Ask better questions, get better answers

[inglorion_on_the_net]

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

Because you can install your own operating system on your Raspberry Pi, but not on your cellphone?

Because you want to support the Raspberry Pi foundation?

There are many possible answers.

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.

If the combination of those is what you're looking for, then maybe you want a cellphone. Why are you comparing a cellphone against a Raspberry Pi?

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.

What are you going to do with it? How are you planning to do it? You don't care what phone platform? Don't you at least want one that you can run your own code on? Preferably with enough privileges that you can actually drive your shiny peripheral?

Here's the thing: Tell us what you're trying to do, and maybe we can help you, possibly by giving some recommendations for hardware to work with.

As it stands, your question is more flamebait than helpful. You're stating that you think even outdated cellphones are superior to a devices that some of us really like, without stating what purpose you think cellphones are superior for. That gives us little opportunity to be helpful, and plenty of opportunity to feel slighted.

headphone GPIO or exposed i2c/spi?

[Miamicanes]

Does anybody know of any widely-available Android phone that directly exposes 2 or more GPIO pins via some usable-connection point, like the headphone jack or Samsung USB port pins (via some officially-nondocumented WDC USB crossbar-chip setting or resistor value)?

I know some phones expose a UART (with nonstandard levels) on the headphone jack (Original G1) and repurposed usb pins (original Galaxy S?), but I've never come across a real reverse-engineered schematic for the HTC HeroC, Samsung Galaxy S/Epic4g, Motorola Photon (as if it would matter, since the evil bastards permalocked the bootloader & ruined it), or Krait/US-variety Galaxy S3 that shows what's sitting between the headphone jack & SoC and what the jack is physically wired to inside.

The big prize: if the 3 headphone jack pins (plus gnd) are connected to real gpio pins (normally tristated, or even directly-driving/sampling the headset)... THEN bitbanged SPI becomes possible. A real UART is a distant second consolation prize, moving up a notch if it can do Atmel-like 1mbps and/or 9-bit serial. I2C would be cool, but I won't hold my breath. DMA-able ADC (== mic) and DAC (== audio out) would be nice IF they aren't forcibly intercepted by a codec chip that can ONLY do mp3 &| audio-bitrate P[W|C]M.

As others have noted, IOIO is great, but USB limits you in some serious ways if you're trying to do raw realtime bitbanging. The main problem with USB is that it basically forces you to move your realtime logic to dedicated hardware at the other end of a USB cable (like ioio, or an AVR-based ADP. A Raspberry Pi gives you directly-bitbangable gpio. AFAIK, no Android phone does.

Re:Works for some, not for all

[grouchomarxist]

Redpark has gone through the MFi program so we don't have to.

I mentioned this in a different post, but if you want to experiment with iOS accessories you can get the Redpark TTL Cable for iOS. More information here: http://www.redpark.com/c2ttl.html

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)

Re:Received an iPhone as a gift

[Joce640k]

Not everybody who uses an iPhone chose an iPhone. What should somebody who received an iPhone as a gift do?

Sell it on eBay?

Re:Received an iPhone as a gift

[tehcyder]

Shouldn't the precious snowflake just be fucking grateful their doting parents have given them an over-priced unnecessasry toy?