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JawnV6 posted:I don't see what magic an FPGA brings you. Reprogrammable silicon.
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Dec 16, 2013 20:43
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evol262 posted:Reprogrammable silicon. A CPU is just as reprogrammable though.
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Dec 16, 2013 20:45
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... ok, perhaps some clarification is in order. I am very familiar with FPGA's and their uses and capabilities. I am questioning, for this specific problem space, what they're bringing to the table when I can find what seems to be complete solutions on other, boring and traditional, computing substrates.
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Dec 16, 2013 20:46
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mod sassinator posted:A CPU is just as reprogrammable though. It is most assuredly not until you can dump VHDL on it and turn your Haswell into a DAC, SPARC-alike, change pinouts on the fly, or anything else you can do with a FPGA. Even Atmel and other embedded CPUs are still limited in flexibility.
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Dec 16, 2013 21:13
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Tbqh a CNC controller isn't exactly rocket science.
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Dec 16, 2013 22:27
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evol262 posted:It is most assuredly not until you can dump VHDL on it and turn your Haswell into a DAC, SPARC-alike, change pinouts on the fly, or anything else you can do with a FPGA. Even Atmel and other embedded CPUs are still limited in flexibility. Sure... but if you're just moving a router bit around on a plane, why do you need to change the digital logic?
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Dec 16, 2013 22:36
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mod sassinator posted:Sure... but if you're just moving a router bit around on a plane, why do you need to change the digital logic? The only real advantage is resiliency if you want a single-board solution in an extremely hazardous environment. So essentially nil, but I'm not all that familiar with CNC itself, and it's entirely possible that reprogrammable logic is helpful for interfacing with commercial CNC equipment.
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Dec 16, 2013 22:46
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evol262 posted:The only real advantage is resiliency if you want a single-board solution in an extremely hazardous environment. So essentially nil, but I'm not all that familiar with CNC itself, and it's entirely possible that reprogrammable logic is helpful for interfacing with commercial CNC equipment. I'm really unimpressed that you came in here to explain FPGA 101 without bothering to check the domain-specific solution I recommended for the informed questioner. Short answer: Reprogrammable logic really doesn't help. The biggest problem is sourcing a few amps to drive the servos and and any FPGA is going to have similar limits to a micro. (fake edit: nah, virtex7 claims 14mA DC pin output where even a cheap ATmega can handle 40mA) If you really can't be assed to google the specific board I recommended that already solves exactly this problem here are the technical specs. Surprise surprise, parsing assumed-correct gcode just takes a Atmel ATxmega192A3.
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Dec 16, 2013 22:57
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JawnV6 posted:I'm really unimpressed that you came in here to explain FPGA 101 without bothering to check the domain-specific solution I recommended for the informed questioner. This utterly misses the point, and the technical limitations of FPGAs regarding pin output limitations are trivially solved. Flatly, FPGAs are useful for prototyping something that you want to get fabricated, and neither TinyG nor any given microcontroller solution is appropriate for that class of problems. I didn't come in here to "explain FPGA 101". I'm asserting that parsing assumed-correct GCode and (maybe) talking DNC is not the sum of the problem domain of CNC. The point of asserting that I don't work with CNC is not to say that "I'm here to explain FPGAs to you, because I don't get CNC", it's that I'm not sure of the future problems on CNC compatibility and proprietary protocols, but the uptake of MESA cards should tell you a lot about problems the RPi kit is trying to solve.
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Dec 16, 2013 23:21
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Pretty sure CNC control and FPGAs don't intersect why are we even talking about this?
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Dec 17, 2013 00:51
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JawnV6 posted:... ok, perhaps some clarification is in order. I am very familiar with FPGA's and their uses and capabilities. Accurately driving a CNC machine at decent speed (as well as many robotics applications) requires tight real-time control, something that FPGAs are way better at than a traditional CPU (I hear ARM CPUs in particular don't do so great with real-time control).
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Dec 17, 2013 03:11
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Cockmaster posted:(I hear ARM CPUs in particular don't do so great with real-time control). Nope, they don't. That's why LIRC needs to be used for IR output via GPIO. The pi on it's own cannot handle the timing.
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Dec 17, 2013 15:31
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Cockmaster posted:(I hear ARM CPUs in particular don't do so great with real-time control). That has nothing to do with the CPU itself, and everything to do with the software running on it. Linux isn't built for hard real-time operation.
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Dec 17, 2013 15:44
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Zuph posted:That has nothing to do with the CPU itself, and everything to do with the software running on it. Linux isn't built for hard real-time operation. "What is CONFIG_PREEMPT_RT?" It's not VxWorks or QNX, but it's passable.
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Dec 17, 2013 15:58
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Cockmaster posted:Accurately driving a CNC machine at decent speed (as well as many robotics applications) requires tight real-time control, something that FPGAs are way better at than a traditional CPU (I hear ARM CPUs in particular don't do so great with real-time control). Care to take a gander at the CPU based CNC controller board I've posted a couple times about and maybe critique that instead of echoing seemingly baseless assertions? It's a shipping product and if they're blatantly lying through their teeth it would be nice to know.
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Dec 17, 2013 17:51
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evol262 posted:This utterly misses the point, and the technical limitations of FPGAs regarding pin output limitations are trivially solved. Considering you know the requirements chip you have to drive, the pin output limitations of a microcontroller are borderline trivial. Sure, on a FPGA you can just hook it up to pin x, and on a uC you have to hook it up to pin 8, oh well, the board will be routed slightly differently. Once it's built, it's not like the driver chip is going to change where it's i/o is. And if you move to a different driver, you'd probably have to reroute anyway. The real reason for the rise of the MESA cards is that the parallel ports, even in industrial computing, are going away and people want an ever increasing amount of i/o data directly into the computer. And for this, yes the parallel capabilities of a FPGA is a great tool. But then you're talking to a PCIe or PCI bus. With the LOGi, the best you're going to see is SPI bus speeds. The non internal bus mesa cards are really just there to support the line and make it look complete. Using the USB one for example will always be hobbled by the fact that USB has huge latency. It'd still be fine for low speed or non synchronous applications. Its the same reason why just about all USB cnc controllers have an onboard interpreter. Different paradigm. But really, I think bringing up the MESA cards actually explains a lot about your perspective. You're more talking about building more or less arbitrary systems about of much higher level components. If you've already used 30 of your available 35 channels connecting to random stuff, and all you have is a random assortment of pins, and you need a clock, you absolutely need to be able to call one of the last available pins as a clock for the next thing. Or have I mischaracterized your problem? Going back to the LOGi for a moment. I can see it being a useful GPIO expander and preprocessor, but at the same time, the RPi is a slow machine with a slow bus and doesn't really need the help of a high speed data adapter to swamp it. The beaglebone has more computing power, and is closer to the fast computer + bus + i/o on the bus model. Except it still has a slow bus. It also has plenty of native i/o. Still, to take an ocilloscope as an example, plenty of them are a fpga + an ARM, and you end up with more than the sum of the parts. For motion in particular the RPi could probably use it to get enough i/o to drive a bunch of channels, but I can't help but think that a board with collection of bog standard i2c gpio expanders and motor drivers wouldn't be the more economical solution. It is unfair to compare a general purpose device to an optimized solution though.
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Dec 17, 2013 20:15
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Aurium posted:Considering you know the requirements chip you have to drive, the pin output limitations of a microcontroller are borderline trivial. Sure, on a FPGA you can just hook it up to pin x, and on a uC you have to hook it up to pin 8, oh well, the board will be routed slightly differently. Once it's built, it's not like the driver chip is going to change where it's i/o is. And if you move to a different driver, you'd probably have to reroute anyway.
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Dec 17, 2013 20:30
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I've ordered a whole bunch of Raspberry Pis to deploy in kiosks. They work fine for the most part, but there are a few which stay stuck on that colourful screen on startup and don't proceed to boot. Power cycling gets them started up once in a few tries but they're more stuck than not. Is there anything simple that I can do to try and sort these out or do I just RMA all of the ones that are doing this?
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Dec 18, 2013 09:18
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Yeah probably RMA (unless using a different sdcard helps). The only time I have seen that happen is running 1ghz overclocks at stock volts, and even then, only on samples that overclock poorly (the "made in UK" ones in my experience).
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Dec 19, 2013 08:48
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So apparently you can build a joystick using two hall effect sensors, three if you want a throttle, a magnet, and an arduino and the unojoy library, but only has 6 input pins. Looks like the Adruino Leonardo has 12 analog inputs but only supports keyboard and mouse with no Unojoy support Actually what'd I'd like is a netduino with unojoy support but that's probably not happening. Looks like between the Arduino Uno, Sensors and Magnet I'd be about $40 out the door? $30 for an Uno seems steep but maybe I've been spoiled by cheap "hacker" bits/mini computers like the Pi for $35 and Beaglebone Black for $45...
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Dec 21, 2013 05:54
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If you treat an Arduino as a less-powerful computer than a Pi, then yeah, it doesn't seem worth it. Think of it more as instead of having a cheap computer that can do everything kinda well, it's a development package to make as many $2 chips as you want do one thing really well and have guilt-free permanent deployment. From that perspective, the Arduino is actually really good value for money.
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Dec 21, 2013 06:19
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Hadlock posted:So apparently you can build a joystick using two hall effect sensors, three if you want a throttle, a magnet, and an arduino and the unojoy library, but only has 6 input pins. Did you see the leonardo port, LeoJoy?
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Dec 21, 2013 07:05
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JawnV6 posted:Care to take a gander at the CPU based CNC controller board I've posted a couple times about and maybe critique that instead of echoing seemingly baseless assertions? It's a shipping product and if they're blatantly lying through their teeth it would be nice to know. I'm sure the TinyG would work well for most of the hobbyist CNC machines and 3D printers currently out there. The main advantage of an FPGA is that it has the potential to easily allow for more advanced machines (5 axis mills, upgrading stepper motors to servos). It'd be especially useful for reading encoders - one quardrature encoder requires two interrupt lines to be read by a CPU, and most CPUs have a limited number of them. A decent FPGA could be set up to keep track of as many encoders as one could possibly need.
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Dec 21, 2013 14:22
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Hadlock posted:So apparently you can build a joystick using two hall effect sensors, three if you want a throttle, a magnet, and an arduino and the unojoy library, but only has 6 input pins. You could go with a clone Arduino Uno board like the SainSmart Uno for under $20. I've never used one with the unojoy library but it should be compatible for all intents and purposes.
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Dec 21, 2013 15:06
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Where are the good beagle bone project videos
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Dec 24, 2013 06:07
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I got the beagle bone (the fact that I just needed a USBto hook to my computer. And I got a $~50 electronics basic kit with a breadboard etc. I want to start making baby's first stuff like making an LED blink, etc etcetera. I got the book "getting started with beaglebone". Anyone know of other good resources. There's the book from the beaglebone website but it's $40 and i suspect it's over my head.
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Dec 24, 2013 16:23
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Adafruit has some tutorials to check out: http://learn.adafruit.com/category/beaglebone Also if you're totally new to electronics, this is a good book: http://www.amazon.com/Make-Electronics-Discovery-Charles-Platt/dp/0596153740
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Dec 24, 2013 18:52
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Cockmaster posted:I'm sure the TinyG would work well for most of the hobbyist CNC machines and 3D printers currently out there. The main advantage of an FPGA is that it has the potential to easily allow for more advanced machines (5 axis mills, upgrading stepper motors to servos). You'd really be surprised how many people applying for embedded positions can't come up with the word quadrature.
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Dec 24, 2013 19:23
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mod sassinator posted:Adafruit has some tutorials to check out: http://learn.adafruit.com/category/beaglebone Sick, thanks.
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Dec 24, 2013 21:28
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Set up my first RetroPie today for some fun with the family for the holidays. Runs great. As for my main Pi, I'm still trying to find more things I can do with it. Currently, it hosts my personal website, is a minidlna server, and has a few controls via GPIO (IR for TV/stereo/AC/Heat, controls 2 RF controllers for remote sockets/light switches, and controls my buzzer to get into my condo building (that was fun to get cleared)). I also keep the camera module up to check in on my cat (or to stream when we get crazy snow). Any other ideas? I should also note that all of the home automation is almost finished set up with an Android app for control from anywhere, using Google's API for security. Also, for BeagleBone Black people out there, what is the best route to get wifi working with them? My research project uses Raspberry Pis, so I have an army of 60+ of them, but I recently got the same shield I use for the BBB, but getting wifi to work has been a pain. I'd probably have more luck switching to a Debian-based OS just due to my familiarity with it compared to Arch.
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Dec 24, 2013 22:05
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peepsalot posted:Are there any pi-like low cost boards out there now with a bit more CPU/RAM suitable for GUI desktop stuff. Beaglebone black? Anything else? Looking for a nice little embedded box for a simple public web browser terminal. Seems the pi really struggles on this sort of thing. http://cubieboard.org I've got the cubietruck: dual core Cortex-A7 at 1GHz, 2GB of RAM, gigabit ethernet, SATA drive interface. The drawback is the software: it comes with a crappy version of Android installed, and the current version of Cubian (the debian-based distro for the cubies) does not work well with the cubietruck. I have installed lubuntu on mine, and I have got now a decent system running. Ah, and the price tag is a little bit higher (89 USD, case included). Of course, I use my cubi (as well as one of my raspies) as a headless machine where I run retrocomputing stuff (basically VAX, PDP11 and S/370 stuff), so i can't tell if it would work as a desktop computer.
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Dec 25, 2013 01:34
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Amberskin posted:http://cubieboard.org It also support Hyp mode.
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Dec 25, 2013 18:20
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Jesus christ, I have never encountered anything as stupid and inane as the Raspberry Pi troubleshooting process. If somebody could help me out here, it would be greatly appreciated. I first got my Pi today and opened it up to install the OS. I decided to roll with Raspbian as it is the recommended choice. It successfully finished and I restarted only to get no video. Pressed 1, 2, 3, 4, and nothing. I'd get a nice color gradient splash screen for a few moments, then my monitor would go to "No Signal" and stay there. I went into the Raspbian IRC for help and was told to format the card and plunk the Raspbian image straight onto it. Well holy loving poo poo guess what, I can't because the initial install partitioned 6.8GB of the 8GB SD card as the loving Ext2 Linux file system. GParted couldn't help me, neither could Ext2 Volume Manager or even Windows' built-in DiskPart or Disk Management. Absolutely NOTHING would fee up that partition for me to image Raspbian directly onto it. After that, I decided to just go back and try the NOOBS lite installer to see if it would fix itself. I would have used the normal NOOBS installer, but it was 2GB and again, I only had a functional 1.17GB to work with. I followed everything exactly as it should be, popped the card back into the Pi, turned it on, and got absolutely nothing. No blinking ACT light, and as a matter of fact, no reaction from the ACT light at all. Didn't flash when the power was plugged in, never indicated that anything was happening, nothing. So right now I'm out $80 (it was a kit) and 5 hours of my Christmas Day with nothing to show for it but pure frustration. I'm about ready to kick the thing down the stairs and cash in the chips.
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Dec 26, 2013 01:28
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http://www.overclock.net/t/1366419/solved-how-can-i-go-about-reclaiming-lost-space-on-sd-card#post_19416298
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Dec 26, 2013 01:33
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FFStudios posted:I went into the Raspbian IRC for help and was told to format the card and plunk the Raspbian image straight onto it. Well holy loving poo poo guess what, I can't because the initial install partitioned 6.8GB of the 8GB SD card as the loving Ext2 Linux file system. GParted couldn't help me, neither could Ext2 Volume Manager or even Windows' built-in DiskPart or Disk Management. Absolutely NOTHING would fee up that partition for me to image Raspbian directly onto it. I'm not sure if I understand the problem. IIRC you must snap the image over the physical device, not the previous partition. The image itself contains two partitions: a small FAT which holds /boot and the / (root) one in ext* (don't remember if it is ext2 or ext3-4). The root partition is just 2GB, once you have booted the card for the first time you wlll be offered the chance to expand that partition to the whole SD (you can do that also ussing the raspi-config utility at any time). EDIT: re-reading your last lines, there is a chance you have got a defective raspi. Check if the SD is firmly inserted: that SD reader is lovely (and be careful with it since it's cheapo plastic and breaks easily). Amberskin fucked around with this message at 02:35 on Dec 26, 2013 |
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Dec 26, 2013 02:26
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I put the micro-SD card in my phone for god knows what reason, and using its built-in format tool it somehow obliterated the Linux partition and restored my 8GB. 
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Dec 26, 2013 02:58
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evol262 posted:It also support Hyp mode. Could you elaborate a little bit on that? I understand HYP mode is related to virtualization (something akin to VT-x), is that right? And more important, is there any way to use that capabilities under linux?
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Dec 26, 2013 19:24
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Amberskin posted:Could you elaborate a little bit on that? I understand HYP mode is related to virtualization (something akin to VT-x), is that right? And more important, is there any way to use that capabilities under linux? It's that exactly -- hardware virt. Needs a modified uboot (easy), and KVM supports it already.
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Dec 26, 2013 20:23
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Out of curiosity is there still an awful wait to get a Pi if you order one these days? I ordered mine in June or July as an early birthday present and it showed up in late September, making it an astutely on time birthday present. But I kind of want the 512mb model and to make the current one into a nice little emulator box.
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Dec 29, 2013 01:18
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Dr. Dos posted:Out of curiosity is there still an awful wait to get a Pi if you order one these days? I ordered mine in June or July as an early birthday present and it showed up in late September, making it an astutely on time birthday present. It probably depends where you're ordering from. A site like Adafruit keeps them in stock and only sells when they're available--you should be able to get one pretty quickly there: http://www.adafruit.com/products/998
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Dec 29, 2013 01:23
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