Ask Slashdot: Why Buy a Raspberry Pi When I Have a Perfectly Good Cellphone? 273
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 It seems to me that even the most outdated cellphone has far superior features (screen, touch screen, Wifi, 3g/4g camera(s), battery etc) in a much better form factor.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."
You might not need one, but... (Score:5, Interesting)
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 (Score:4, Interesting)
"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 It seems to me that even the most outdated cellphone has far superior features (screen, touch screen, Wifi, 3g/4g camera(s), battery etc) in a much better form factor.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 [jameco.com]
Because you need your phone as the remote. (Score:5, Interesting)
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.
Re:Arduino Uno (Score:5, Interesting)
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.
headphone GPIO or exposed i2c/spi? (Score:4, Interesting)
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 (Score:4, Interesting)
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 [makershed.com]. More information here: http://www.redpark.com/c2ttl.html [redpark.com]
Re:Arduino Uno (Score:4, Interesting)
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.