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by joep
Mon Dec 19, 2011 3:00 pm
Forum: Other projects
Topic: Do I need a gertboard to run a servo
Replies: 47
Views: 12636

Re: Do I need a gertboard to run a servo

<r>Although this is a bit beyond the scope of the OP's question, my favorite approach has always been to use a USB connected AVR (like the teensy: <URL url="http://www.pjrc.com/teensy/index.html">http://www.pjrc.com/teensy/index.html</URL>). It is flashed to appear as a serial device to any connecte...
by joep
Mon Dec 19, 2011 12:59 pm
Forum: Other projects
Topic: Do I need a gertboard to run a servo
Replies: 47
Views: 12636

Re: Do I need a gertboard to run a servo

<t>Beware that controlling a real servo requires you to generate a 50Hz square wave with variable duty cycle. It is not a simple GPIO on/off circuit.<br/> <br/> I thought the RPi had PWM available on some of the pins? I guess the software to control it won't be available through the generic GPIO dri...
by joep
Mon Dec 19, 2011 12:03 pm
Forum: Other projects
Topic: Do I need a gertboard to run a servo
Replies: 47
Views: 12636

Re: Do I need a gertboard to run a servo

<r>I wouldn't think it would be a problem to control the servo directly from one of the Pi's PWM GPIOs. Most servos require about 100ma or so but I'm not entirely sure if the 3.3 volts would need to be shifted up to 5V. Haven't tried it myself.<br/> <br/> The servo motor requires its own power sourc...
by joep
Sun Dec 18, 2011 4:15 pm
Forum: Other projects
Topic: Cases for the Raspberry Pi
Replies: 866
Views: 399013

Re: Cases for the Raspberry Pi

I was planning on using some variation of a bar soap box, e.g.,

http://www.amazon.com/Donovan-.....pd_sbs_a_2
by joep
Fri Dec 16, 2011 8:36 pm
Forum: Other projects
Topic: Raspberry PI with an arduino...
Replies: 26
Views: 16250

Re: Raspberry PI with an arduino...

I'm planning on building an remote procedure call system over the SPI so that for example one could simply issue a call on the RPi and execute functions on the Arduino to do things like set outputs, read the A/Ds, input buttons or keypads, etc. Multiple Arduinos could be attached and addressed.
by joep
Thu Dec 15, 2011 2:02 pm
Forum: Other projects
Topic: Break out board (GPIO, SPI, I2C, and UART)
Replies: 189
Views: 40612

Re: Break out board (GPIO, SPI, I2C, and UART)

<t>Gert:<br/> <br/> I'd like to turn an RPi into a multifunction piece of test equipment (scope/frequency counter/signal analyzer/etc.) for schools to teach electronics (with interface and display software on another device --- pad, phone, etc). Do you think the hardware on your board will accommoda...
by joep
Fri Dec 09, 2011 11:58 am
Forum: Other projects
Topic: Raspberry Pi Sunshine
Replies: 42
Views: 7432

Re: Raspberry Pi Sunshine

<r>Are you concerned about the micro usb connector using too much physical space?<br/> <br/> Otherwise, I'd just buy a micro usb -> usb connector for $1, cut the usb connector off and solder on a barrel connector to plug directly into your passive power splitter. <URL url="http://www.firefold.com/8-...
by joep
Fri Dec 09, 2011 12:06 am
Forum: Other projects
Topic: Raspberry Pi Sunshine
Replies: 42
Views: 7432

Re: Raspberry Pi Sunshine

I am planning to inject 5V directly rather than 12V. There are plenty of 5V wall warts for USB charging etc.

My distances are obviously a bit further than yours. I was concerned 5v would drop too much, especially since I want to power a little more than just the RPi itself.
by joep
Thu Dec 08, 2011 4:14 pm
Forum: Other projects
Topic: Raspberry Pi Sunshine
Replies: 42
Views: 7432

Re: Raspberry Pi Sunshine

<r>In fact, the power question is probably the least of my worries. I'm really keen to understand the serial port answers though.<br/> <br/> I believe there are USB->RS485 cables you can pick up fairly cheap. Seems like a better and faster solution than doing it yourself, although it will probably c...
by joep
Thu Dec 08, 2011 2:43 pm
Forum: Other projects
Topic: Raspberry Pi Sunshine
Replies: 42
Views: 7432

Re: Raspberry Pi Sunshine

<t>The inverter switches itself off when the sun goes down, and there is nowhere clean to get 5V from so I am considering powering it over ethernet. I have read that this is an oft requested feature, and that it can't be done at the moment. I also note from the photos of the PCBs that the Ethernet R...
by joep
Tue Dec 06, 2011 10:19 pm
Forum: Other projects
Topic: GPU API question(s)
Replies: 6
Views: 1525

Re: GPU API question(s)

<t>I have been turning over the idea of a software emulator of the RPi board. The ARM part is not a big deal. The biggest question is in regard to the GPU. I understand that the code and hardware details won't be released for it, but will the API be of sufficient detail and granularity that one coul...
by joep
Mon Dec 05, 2011 10:38 pm
Forum: Other projects
Topic: Simple OS from scratch
Replies: 27
Views: 6986

Re: Simple OS from scratch

<t>Oh, yes! They talked about MINIX 3 on the Raspberry PI!, too.<br/> <br/> I actually ported MINIX to the Macintosh back in the 90s sometime (it was called MacMINIX). I've been thinking about doing it again ever since I read about the RPi. I suspect the only real obstacle is waiting for all the tec...
by joep
Mon Dec 05, 2011 9:12 pm
Forum: Other projects
Topic: Simple OS from scratch
Replies: 27
Views: 6986

Re: Simple OS from scratch

MINIX is a highly modular, message passage OS written entirely in C to teach operating systems principles (and, btw, the inspiration for linux), so it might be of interest to some people here.

http://www.minix3.org/
by joep
Sat Dec 03, 2011 3:31 pm
Forum: General discussion
Topic: How does R-Pi boot?
Replies: 21
Views: 3419

Re: How does R-Pi boot?

Is any sort of boot loader being worked on? It would be the thing that gets loaded by the GPU blob, and from there you could boot from another partition of the SD card, net, a usb disk, i2c, or whatever.
by joep
Fri Dec 02, 2011 3:04 pm
Forum: General discussion
Topic: I2C programming
Replies: 25
Views: 15566

Re: I2C programming

Does anyone know if the I2C on this processor supports high speed mode?
by joep
Tue Nov 29, 2011 3:20 pm
Forum: General discussion
Topic: I2C programming
Replies: 25
Views: 15566

Re: I2C programming

I've done a fair amount linux/unix/minix driver work, and I have some I2C experience, so I'd be willing to look at it as well, but it depends on how accessible the hardware details are going to be.
by joep
Sat Nov 26, 2011 4:37 pm
Forum: Other projects
Topic: video digitizer
Replies: 7
Views: 2915

Re: video digitizer

<t>Hi There,<br/> <br/> Just discovered the RP and am looking forward to getting one. My apologies if this has been discussed already, but I am interested in finding and/or building a compatible video digitizing card.<br/> <br/> I envision the card to have an input (composite/RCA/HDMI/whatever) and ...

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