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If you want to use a RPi for most of the display stuff, you could still use a microcontroller for getting sensor data and relay it to the RPi over I2C or serial or something. It could be as simple as timing pulses from a Hall effect sensor and reporting the interval between the last two pulses (or some smoothed function thereof). The microcontroller code would be very simple, and the RPi wouldn't need to do the timing itself, just calculations on the sensor data. Cars are electrically noisy and it sounds like you will be running cables all over the car so you might want to think about electrically protecting the various bits as well, from both electrical interference and power surges.
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Jul 16, 2014 07:20
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I presume they don't allow it for the map; I can't imagine they are opposed to using it for readings of distance, heading, or for logging purposes. Either way, reading the speedometer output is still significantly easier than dealing with all the previously mentioned problems. If it's just outputting to an old led display then the arduino is enough.
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Jul 16, 2014 08:02
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TVarmy posted:I was wondering if there are any good really small, inexpensive and low powered boards like the Raspberry Pi but instead of focusing on GPIO or graphics, the board instead had better I/O and processor performance and compatibility with SATA hard drives? x86 would be nice since I've had a lot of fun with the pi, but having to deal with the issues of compiling code to a less popular platform made for a few more troubles than I'd like. I'd like to have something like a Pi that'd work better for stuff like NAS, Usenet, playing with a LAMP stack, Take a look at this one; http://cubieboard.org/2013/10/30/cubieboard3-cubietruck-is-all-ready/ It's ARM based, dual-core, reasonabily prized and has the features you are interested in.
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Jul 16, 2014 10:49
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I'd like to get a simple true/false 1/0 output from a raspberry pi to an arduino and am trying to figure out the best way to do this. Can I simply connect a GPIO pin directly from the pi to an arduino and output a 3.3v high/low to an input on the arduino? Is this safe? Or is it necessary to use a relay?
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Jul 27, 2014 14:36
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Ideally, you'd want a logic level converter. They're cheap and simple and work both ways, and you can get them with plenty of channels. Howver, if you're SURE you're not going to be going from arduino -> pi and will only ever go pi -> arduino, I believe that yes, you can technically hook it up directly, as the pi's HIGH is high enough to trigger the arduino's HIGH. If you ever go the other way, though, you could damage your pi.
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Jul 27, 2014 16:09
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Just make sure to never program the arduino while connected with anything that might set the pin to high. Tho the pi might be protected anyway.
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Jul 27, 2014 18:34
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Bad Munki posted:Ideally, you'd want a logic level converter. They're cheap and simple and work both ways, and you can get them with plenty of channels. If he is just going to interface ONE pin, using a logic converter is probably overkill. Wouldn't a simple voltage divider do the job?
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Jul 27, 2014 18:35
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Amberskin posted:If he is just going to interface ONE pin, using a logic converter is probably overkill. Wouldn't a simple voltage divider do the job? I don't think that would work? Like, going from pi->arduino, you need all the voltage you can get, but if you go from arduino to pi you need to reduce it. So, not reducing it in all cases, and certainly not in the direction he wants to go. Oh, you know what would be the simplest solution: just slap in a diode going from the pi to the arduino. Then you don't even have to worry about it during programming or if you accidentally write to that pin or anything. Obviously, that solution ONLY works if you're only communicating from the pi to the arduino. Doing the same in the other direction would, of course, damage the pi. Still, having a little 4-channel converter is SUPER handy and only costs a few bucks. Bad Munki fucked around with this message at 19:30 on Jul 27, 2014 |
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Jul 27, 2014 19:28
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Adding a diode will drop the voltage a little bit (like half a volt), so be careful it might get too low for the Arduino to detect as a high signal. Worth a shot to see what works though.
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Jul 27, 2014 19:36
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mod sassinator posted:Adding a diode will drop the voltage a little bit (like half a volt), so be careful it might get too low for the Arduino to detect as a high signal. Worth a shot to see what works though. Is that really a normal voltage drop on diodes?
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Jul 27, 2014 19:44
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Standard silicon diodes have a forward voltage drop of around 0.6 - 0.7 volts.Amberskin posted:If he is just going to interface ONE pin, using a logic converter is probably overkill. Wouldn't a simple voltage divider do the job? It depends on the amount of current that the pins will source/sink. If they are high impedance then a voltage divider won't really work.
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Jul 27, 2014 20:13
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Perfect, thanks for the tips!
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Jul 27, 2014 21:29
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I'm not an electrical engineer but it was my impression that you'd also want a pull down resistor after the diode to keep the pin on the arduino from floating? And wouldn't the data sheet for the atmega the chip is based on say what it considers at minimum a high signal? Could a pair of transistors in a not gate be triggered by the pi to pull down a pin on the arduino? If it's a full board arduino, you could just use usb and the serial interface without much fuss on the pi's end. TVarmy fucked around with this message at 23:37 on Jul 27, 2014 |
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Jul 27, 2014 23:33
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ATMegas should have internal pulldowns (or maybe pull-ups?) This thread is getting kinda over-engineery and funny. I like it.
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Jul 28, 2014 02:09
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TVarmy posted:I'm not an electrical engineer but it was my impression that you'd also want a pull down resistor after the diode to keep the pin on the arduino from floating? You can init the arduino with INPUT_PULLUP to connect the internal resistor.
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Jul 28, 2014 04:59
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What's the "correct" way send a high-signal to the arduino with minimal components, anyway? A transistor and 5V from somewhere?
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Jul 28, 2014 12:51
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Computer viking posted:What's the "correct" way send a high-signal to the arduino with minimal components, anyway? A transistor and 5V from somewhere? Why would you need a transistor if the input is a 5v switch or similar?
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Jul 28, 2014 14:26
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As a way to step up the voltage if your signal is a bit too low to trigger the 5V logic, but you have 5V at hand - or is that an inappropriate/silly way to do it? (I do, obviously, have very little idea what I'm talking about.) Computer viking fucked around with this message at 13:34 on Jul 29, 2014 |
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Jul 29, 2014 13:30
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Computer viking posted:As a way to step up the voltage if your signal is a bit too low to trigger the 5V logic, but you have 5V at hand - or is that an inappropriate/silly way to do it? Well all I'm saying is, that the minimum component way, would be to use 5V on the switching circuit if you can.
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Jul 29, 2014 13:52
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SEKCobra posted:Well all I'm saying is, that the minimum component way, would be to use 5V on the switching circuit if you can. Ha, yes - I guess "a wire" is about as minimal as you'll get.  (In the case of the Pi I guess you're stuck at 3.3V, though.)
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Jul 29, 2014 13:57
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Computer viking posted:What's the "correct" way send a high-signal to the arduino with minimal components, anyway? A transistor and 5V from somewhere? If you want to make it out of discrete components, a transistor, a pull up resistor, and a current limiting base resistor (if you're using a bipolar) is typical. The typical configuration will give you inverted logic, so you'd either deal with that, or add a second assembly to reinvert it. A level shifter IC, such as the TXB0102, would probably be better still. It'd be more flexible and less prone for error.
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Jul 29, 2014 15:28
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Does anyone know where I could find someone who can tell me if the way I am getting hot air through a tube is gonna work or overheat my setup?
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Jul 29, 2014 18:50
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Anyone know if I should expect to have any trouble with these servos and a raspi B+? http://www.amazon.com/HOSSEN%C2%AE-...&keywords=servo I just ask because I've literally never messed with servos before, not sure what to expect or look out for. So far as I can tell, they're just...servos. They look like they're pretty weak but that's fine: I'm just planning on using them to do things like aim my picam.
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Jul 30, 2014 15:38
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How's Retropie these days? I would like to use it with a wired Xbox 360 controller, assuming there isn't a better supported image. Also, what systems are worth emulating on it? It seems to have a lot of support on paper, but not much description of what works for actual gameplay. It even has a Wii emulator, but I'm getting the impression that it can barely play PSX games.
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Jul 30, 2014 16:24
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Bad Munki posted:Anyone know if I should expect to have any trouble with these servos and a raspi B+? http://www.amazon.com/HOSSEN%C2%AE-...&keywords=servo I would get a PWM servo driver if you're going to drive that many servos: https://www.adafruit.com/products/815 The reason is that the Pi doesn't have a lot of hardware PWM pins (just 1) and although you can do PWM in software it's not super reliable and could make the servos shake or jitter. Using a servo driver board like that one is great because it will handle generating the PWM signal needed to move the servos. The board will also let you distribute power from a better power supply to all those servos. You definitely don't want to power that many servos from the Pi's 5V line--really only maybe 1 servo can be powered from it.
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Jul 30, 2014 18:34
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For my current project, I'm going to be driving precisely two. But still, I was looking at boards, I just don't want to buy an 8 channel or 16 channel or bigger when I literally just need two. I guess maybe it'd be good to have some growing room if I ever want to put a robot arm on this thing or something, I dunno. e: I like that that board only uses two pins, though. Oh, and I could use it to drive the lights for this thing, was going to have to cook up something for that and forgot about it, so that board may be a really great solution for several problems I have, actually. Bad Munki fucked around with this message at 18:41 on Jul 30, 2014 |
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Jul 30, 2014 18:39
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I've been building a small solar charging kit for my beach stereo (though it'll run happily for 12+ hours on a single battery) and i want to reuse this for powering my raspberri Pi. i plan on powering it by simply butchering an old car usb plug, but since it'll run on battery power only at night, i was wondering if there's any distros for it that are especially lowpower focused? and if any of you have done solar power projects with your PI, feel free to share! i've got a free 200mb monthly mobile broadband plan that i intend to use with it for some really offgrid computing. https://www.dropbox.com/sc/bmsa52xe3lvwcyn/AACDPsNgvc1k4ZvO1z7CugCQa
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Jul 30, 2014 21:45
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Frobbe posted:I've been building a small solar charging kit for my beach stereo (though it'll run happily for 12+ hours on a single battery) and i want to reuse this for powering my raspberri Pi. i plan on powering it by simply butchering an old car usb plug, but since it'll run on battery power only at night, i was wondering if there's any distros for it that are especially lowpower focused? and if any of you have done solar power projects with your PI, feel free to share! i've got a free 200mb monthly mobile broadband plan that i intend to use with it for some really offgrid computing. If you really want good battery life you might look around for a switching power supply/voltage regulator. A lot of cheap 12V USB adapters simply have a linear regulator in them that will more than double the power draw of the RPi. If the Pi draws 1A at 5V, a cheap linear regulator will pull 1A at 12V out of the battery and dissipate the difference as heat. Naffer fucked around with this message at 06:07 on Jul 31, 2014 |
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Jul 31, 2014 06:01
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Naffer posted:If you really want good battery life you might look around for a switching power supply/voltage regulator. A lot of cheap 12V USB adapters simply have a linear regulator in them that will more than double the power draw of the RPi. If the Pi draws 1A at 5V, a cheap linear regulator will pull 1A at 12V out of the battery and dissipate the difference as heat. that sounds right, I've just ordered some 12v to 5v converters off of ebay, one seems perfect for the RPI (or other micro usb powered gizmos). my next task is actually designing a 12v powergrid, it's all easy to wire up a single light or whatever, but having a common ground for a bunch of different devices and all does require some thought.
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Jul 31, 2014 16:24
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Frobbe posted:I've been building a small solar charging kit for my beach stereo (though it'll run happily for 12+ hours on a single battery) and i want to reuse this for powering my raspberri Pi. i plan on powering it by simply butchering an old car usb plug, but since it'll run on battery power only at night, i was wondering if there's any distros for it that are especially lowpower focused? and if any of you have done solar power projects with your PI, feel free to share!
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Jul 31, 2014 21:31
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If any of you folks are in the Louisville, KY area, Ben Nuttall from the Pi foundation will be paying us a visit on August 14th:
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Aug 8, 2014 13:12
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Zuph posted:If any of you folks are in the Louisville, KY area, Ben Nuttall from the Pi foundation will be paying us a visit on August 14th: Sweet this is the second time lvl 1 has snagged a pi foundation member right?
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Aug 8, 2014 20:46
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keyvin posted:Sweet this is the second time lvl 1 has snagged a pi foundation member right? Yup, we got Rob Bishop last year. Hoping to knock it out of the park-- We had almost 90 people show up last time, and people were walking out the door as soon as they stepped in because it was so crowded. This time, we've got space enough for 300.
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Aug 8, 2014 21:01
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This doesn't quite fit in any thread I can find in SH/SC but here goes. Basically what I want to do is use my Pi as a network receiver type thing. I want to be able to create an output audio device in Windows or Linux that connects across the network to the Pi and plays audio through the Pi's speaker connection. Does anyone have any idea how I would go about doing that? Is something like UPnP a good basis for this kind of task?
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Aug 8, 2014 22:19
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http://www.radscan.com/nas.html is what you're looking for.
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Aug 8, 2014 22:24
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You can also setup a Pi as an Airtunes receiver, but that's more convenient if there are OSX or iOS devices involved.
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Aug 8, 2014 22:54
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I've been meaning to check out Pi MusicBox myself. It seems to wrap up a lot of audio playback stuff into a nice headless web-controlled interface.
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Aug 8, 2014 23:21
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I'm using shairport to make a pi in the kitchen show up as an airplay receiver, works great and super easy to setup You really need to get some kind of usb soundcard though, the pi sound output is pretty awful as it comes
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Aug 9, 2014 10:01
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Just ordered the new B+ model from Adafruit! My SD card slot broke on my last Pi, so I'm definitely excited about the B+ using MicroSD instead. Plus more GPIO pins, more USB ports, better power supply, four mounting holes on the board...looks like lots of good improvements, and all for the same price.
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Aug 11, 2014 16:30
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I've been enjoying mine pretty well. Even if the specs didn't change, the improved layout is SO much better.
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Aug 11, 2014 16:46
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