Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
Hi, Jim, I will ask off-list to reduce noise... :) El 08/04/2012 00:29, Jim Lux escribió: If you need a 64 bit timer core with a bunch of latches and a programmable pulse generator, let me know. We've got one at JPL we're happy to distribute (for free). I take good note. This is the kind of things that comes handy from time to time :) Goddard Space FLight Center has a variety of SpaceWire cores (in VHDL), and we've got a Verilog wrapper for it at JPL. GSF SpW cores are available for free? Or are even available for non-US? One of the things that I plan to do sometime is an SpW implementation, mainly for instrument EGSEs - probably will try in the near future if one of my customers wins a project and contracts us the EGSE. We are currently using SpW cards from Dynamic Engineering, but sincerely I'm not too happy with their support. For internal use, we have a Star Dundee SpW USB brick, but I find that SpW boards from Star Dundee are expensive and only with 3 ports - and we usually need 4 (you know, nominal and redundant I/Fs to both nominal and redundant instruments :) ). There are some "free" SpW ESA cores. The fun part is that they are free except for a 5000 EUR management fee... Best regards, Javier -- Javier Herrero Chief Technology Officer EMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
El 08/04/2012 00:21, Jim Lux escribió: On 4/7/12 10:08 AM, Javier Herrero wrote: El 07/04/2012 16:02, Jim Lux escribió: RTEMS might be just what you need. Kernel, basic OS calls for scheduling, queues, etc. It's nice when you decide you want threading to not have to graft it into a "big loop no-OS" style program. You can use native calls or POSIX style (I like POSIX, because I can develop on Linux and just recompile for the RTEMS target). There's all the usual GDB support as well. Yes, it is starting to seem that would fit my needs for this project very nicely. Device drivers are easy to write for RTEMS, and it has VERY fast ISRs. That's probably one of the big advantages.. I would say that one of the most important for me. Sometimes I've dealed with Xenomai/Adeos and uClinux when Linux latencies and worse, latency uncertainities, but things then start to be a bit complicated... It's a small footprint, stripped down RTOS, but because you can work with POSIX API calls, you can do most of your development in Linux (particuarly things like calibration interfaces and computational stuff) and then it ports very easily when you move it to RTEMS on the target. Looks very good for several of my usual applications, where bare metal sometimes requires too much work, and Linux requires too much footprint :) Also, to support POSIX style is a great advantage. I've had a quick look around www.rtems.org, and I see that it is also ported to Blackfin, so it will also fit my usual ADSP-BF532 based platform. I hope that the learning curve will not be too steep :) Thanks for the info. Best regards, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
On 4/7/12 8:57 AM, Chris Albertson wrote: If you are looking for free soft core CPUs for use in an FPGA then look here: http://opencores.org/projects Look under "processors" for many CPU cores. They also have some Eithernet controllers you'd need. Like all things opencores/sourceforge/etc you need to examine whats out there... We've used a SDRAM controller from opencores (and modified it for our puproses) and it works pretty well. Some other stuff, maybe not so finished and ready for use. It all depends on provenance To blow our horn a bit, we've got some useful building blocks available for free.. We are targeting Xilinx Virtex II, but they're designed to be pretty generic Verilog for any target. If you need a 64 bit timer core with a bunch of latches and a programmable pulse generator, let me know. We've got one at JPL we're happy to distribute (for free). Goddard Space FLight Center has a variety of SpaceWire cores (in VHDL), and we've got a Verilog wrapper for it at JPL. Simple cores to do things like record samples from an ADC into a giant SDRAM buffer or play back samples from SDRAM into a DAC, we've also got. You want that digital oscilloscope or ARB with a 10s of MegaSample buffer.. we've got it. Gaisler has a lot of useful, well debugged, cores for free.. Ethernet, RAM controlkers, various other peripherals. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
On 4/7/12 10:08 AM, Javier Herrero wrote: El 07/04/2012 16:02, Jim Lux escribió: RTEMS wise... It's pretty well supported by the community, it's open source, it does all the stuff you want a RTOS to do. it's NOT a multitasking, dynamic loading OS like Linux. That is it doesn't support an MMU and process space isolation (although that might be possible in newer versions.. there's a lot of configurability). It's basically a statically linked single task with threads. They've got RAM (and disk) file systems, IP stacks, a shell, YAFFS, etc. But there's also a core of users who are serious and rigorous and contribute back, so the main stuff in the distribution from Joel Sherrill at OAR (who make RTEMS) is pretty rock solid. I will learn more about RTEMS. For the application I've (and this links directly to the message from Javier Serrano), the hardware platform is one of the CERN Open Hardware ones, the SPEC. For the purpose and interface needs, really an operating system is not required (no filesystem, no TCP/IP needed, no multitasking, no framebuffer...), and certainly a Linux would have a very large footprint without providing any real help. RTEMS might be just what you need. Kernel, basic OS calls for scheduling, queues, etc. It's nice when you decide you want threading to not have to graft it into a "big loop no-OS" style program. You can use native calls or POSIX style (I like POSIX, because I can develop on Linux and just recompile for the RTEMS target). There's all the usual GDB support as well. And about the processor selection, the trade-off that Javier exposes are the same I'm confronting. Both are open-sourced and well supported, and in one side the LM32 is smaller, in the other the LEON3 has more capabilities that can be implemented or not (like MMU or FPU, and better multi-core support, although not currently needed in my project). I probably will take the LEON3 road, but also because it is more popular in my current field, but for now I usually do not need the FT version since I'm more related with GSEs. And that's good because the FT version costs money, but the regular old LEON2 and LEON3 are free, and pretty bulletproof by now. ESA has several rigorously verified flight qualified versions of RTEMS (in Portugal and Austria, as I recall) Yes, this is one of the reasons to gain experience in that road :) I have some tendency to stay in Linux because I'm very familiarized with it in the non-MMU implementations (for Blackfin) and also with MMU - and I've found that for a small embedded system, to have the MMU is not so important, even sometimes it is a drawback. Device drivers are easy to write for RTEMS, and it has VERY fast ISRs. That's probably one of the big advantages.. It's a small footprint, stripped down RTOS, but because you can work with POSIX API calls, you can do most of your development in Linux (particuarly things like calibration interfaces and computational stuff) and then it ports very easily when you move it to RTEMS on the target. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
Chris Albertson writes: > > On Fri, Apr 6, 2012 at 9:41 PM, Andrew Rodland wrote: > > > Another option would be building something on an FPGA. This would be a > > considerable stretch for me, since I've never done FPGA work, but if I build > > from the ground up, I can have *very* tight control over things that are chosen > > for me with a micro controller. > > A compromise is to find a "soft core" for the FPGA. This is a CPU > implemented in FPGA and then it runs software just like a "real" CPU. > This would let you move your micro controller based be sign over to > the FPGA quickly. After that you can implement some specialized > peripherals that do time stamping > > How does the performance of the Arduino based NTP compare with what > you could do with Linux on (say) and Atom or ARM processor? Pretty well, I think. A PPS generated by my board shows an RMS absolute jitter of 174ns compared to a Spectracom 9183, which is almost impossibly good considering that all the timing is done off of a 2MHz clock. As measured from the NTP side, the performance is diluted a lot by the fact that the W5100 ethernet chip has unknown and unpredictable delays, but it still comes back with a jitter of <20us (possibly better — the box I'm using to measure the NTP is a Linux machine that isn't really a timing champ. Wish I still had my net4801.) Andrew ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
El 07/04/2012 16:02, Jim Lux escribió: On 4/7/12 4:47 AM, Javier Herrero wrote: I'm very familiar with the LEON and RTEMS, having managed a software development project with it for the last 3 or 4 years at work. http://www.gaisler.com/ for LEON http://www.rtems.org/ for RTEMS I will have a look to RTEMS And yes, there is a port (maybe two) of Linux for the LEON as well (A few years ago, we loaded up the Snapgear port, but since we went RTEMS, I haven't fooled with it). You'd have to check the Gaisler.com website. I've done. The Snapgear port is quite old now, but the other port is actively maintained and updated with current kernel. You can drop a LEON core into a Virtex II in about a day, and judging from the traffic on the LEON yahoo list (where the Gaisler folks hang out), lots of people are doing things like multiple cores and things on all manner of Xilinx eval boards. And also for Altera (for example, the Terasic DE2-115 with a Cyclone IV) and others. I've seen you int that list :) An I've seen implementations for smaller FPGAs like the Spatarn 6LX25 RTEMS wise... It's pretty well supported by the community, it's open source, it does all the stuff you want a RTOS to do. it's NOT a multitasking, dynamic loading OS like Linux. That is it doesn't support an MMU and process space isolation (although that might be possible in newer versions.. there's a lot of configurability). It's basically a statically linked single task with threads. They've got RAM (and disk) file systems, IP stacks, a shell, YAFFS, etc. Like all open source, there's quite a lot of interesting stuff available (not from rtems.org, but others) that is 90% complete. Somebody at Google Summer of Code or for their Masters decides to implement something cool, and gets most of the way done, then wanders away (the summer ended, they got their degree, the usual story). But there's also a core of users who are serious and rigorous and contribute back, so the main stuff in the distribution from Joel Sherrill at OAR (who make RTEMS) is pretty rock solid. I will learn more about RTEMS. For the application I've (and this links directly to the message from Javier Serrano), the hardware platform is one of the CERN Open Hardware ones, the SPEC. For the purpose and interface needs, really an operating system is not required (no filesystem, no TCP/IP needed, no multitasking, no framebuffer...), and certainly a Linux would have a very large footprint without providing any real help. And about the processor selection, the trade-off that Javier exposes are the same I'm confronting. Both are open-sourced and well supported, and in one side the LM32 is smaller, in the other the LEON3 has more capabilities that can be implemented or not (like MMU or FPU, and better multi-core support, although not currently needed in my project). I probably will take the LEON3 road, but also because it is more popular in my current field, but for now I usually do not need the FT version since I'm more related with GSEs. ESA has several rigorously verified flight qualified versions of RTEMS (in Portugal and Austria, as I recall) Yes, this is one of the reasons to gain experience in that road :) I have some tendency to stay in Linux because I'm very familiarized with it in the non-MMU implementations (for Blackfin) and also with MMU - and I've found that for a small embedded system, to have the MMU is not so important, even sometimes it is a drawback. In any case we are running a bit OT (except considering that this general discussion has timing applications, of course ;) ). Also I'm happy to have found a time-nut colleage in other list, and probably I will ask you some things about off-list in order to not increase noise, if possible. Best regards, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
El 07/04/2012 18:17, shali...@gmail.com escribió: When you install the Altera tools, it automatically installs NIOS and gcc. I assume there are no restrictions for private use, but you may have to send $ if you make a commercial product. That remains to be checked. With the Quartus Web, you can use any Nios but in time limited form (1 hour or so) or as long as the debug cable is tied to the PC. The only Nios free for use (commercial or private) is the Nios-II/e version. The only NIOS really useful, NIOS-II/f (with MMU, caches, and faster) is commercial, and the license pack inclding the triple speed ethernet core is $995. Also other IPs are commercial (like memory controllers, etc.) Regards, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
When you install the Altera tools, it automatically installs NIOS and gcc. I assume there are no restrictions for private use, but you may have to send $ if you make a commercial product. That remains to be checked. I have not used NIOS either. Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: Azelio Boriani Sender: time-nuts-boun...@febo.com Date: Sat, 7 Apr 2012 13:19:14 To: Discussion of precise time and frequency measurement Reply-To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux) The Xilinx and Altera have their embedded CPUs (Microblaze and Nios) IP. I'm not familiar with them and don't know how much they cost. Until now I have developed on Xilinx 50Kgates FPGA and 128 cells CPLD with the Xilinx's free tools. On Sat, Apr 7, 2012 at 7:53 AM, Chris Albertson wrote: > On Fri, Apr 6, 2012 at 9:41 PM, Andrew Rodland > wrote: > > > Another option would be building something on an FPGA. This would be a > > considerable stretch for me, since I've never done FPGA work, but if I > build > > from the ground up, I can have *very* tight control over things that are > chosen > > for me with a micro controller. > > > A compromise is to find a "soft core" for the FPGA. This is a CPU > implemented in FPGA and then it runs software just like a "real" CPU. > This would let you move your micro controller based be sign over to > the FPGA quickly. After that you can implement some specialized > peripherals that do time stamping > > > How does the performance of the Arduino based NTP compare with what > you could do with Linux on (say) and Atom or ARM processor? > > > > > Chris Albertson > Redondo Beach, California > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
On Sat, Apr 7, 2012 at 1:47 PM, Javier Herrero wrote: > RTEMS also (see www.milkymist.org , an open source hardware and > software project with an LM32 implementation on a Spartan 6 FPGA using > RTEMS. We use the LM32 (http://www.ohwr.org/projects/lm32) in the White Rabbit and other projects. Here's a LibreOffice presentation on why it was chosen: http://www.ohwr.org/attachments/download/559 It's smaller than the LEON3 and more capable than the ZPU. We found it to be a good compromise. The guys in GSI (a German Physics lab) developed a good debugging tool for it (http://www.ohwr.org/projects/phase). Our PTP stack (http://www.ohwr.org/projects/ppsi/wiki) will soon run on it. Cheers, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
If you are looking for free soft core CPUs for use in an FPGA then look here: http://opencores.org/projects Look under "processors" for many CPU cores. They also have some Eithernet controllers you'd need. On Sat, Apr 7, 2012 at 6:35 AM, cfo wrote: > On Sat, 07 Apr 2012 13:19:14 +0200, Azelio Boriani wrote: > >> The Xilinx and Altera have their embedded CPUs (Microblaze and Nios) IP. >> I'm not familiar with them and don't know how much they cost. Until now >> I have developed on Xilinx 50Kgates FPGA and 128 cells CPLD with the >> Xilinx's free tools. >> > Maybe ZPU > http://opensource.zylin.com/zpuref.html > http://opencores.org/project,zpu > > http://embdev.net/articles/ > ZPU:_Softcore_implementation_on_a_Spartan-3_FPGA > > /Cfo > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
OK, taken a look: it seems that the smallest Spartan3 usable is the 400Kgates. I don't need the ZPU now but good to know. On Sat, Apr 7, 2012 at 3:35 PM, cfo wrote: > On Sat, 07 Apr 2012 13:19:14 +0200, Azelio Boriani wrote: > > > The Xilinx and Altera have their embedded CPUs (Microblaze and Nios) IP. > > I'm not familiar with them and don't know how much they cost. Until now > > I have developed on Xilinx 50Kgates FPGA and 128 cells CPLD with the > > Xilinx's free tools. > > > Maybe ZPU > http://opensource.zylin.com/zpuref.html > http://opencores.org/project,zpu > > http://embdev.net/articles/ > ZPU:_Softcore_implementation_on_a_Spartan-3_FPGA > > /Cfo > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
On 4/7/12 4:47 AM, Javier Herrero wrote: El 07/04/2012 13:19, Azelio Boriani escribió: The Xilinx and Altera have their embedded CPUs (Microblaze and Nios) IP. I'm not familiar with them and don't know how much they cost. Until now I have developed on Xilinx 50Kgates FPGA and 128 cells CPLD with the Xilinx's free tools. Mostly expensive for amateur use, although reduced free versions exists (for Nios-II it is Nios-II/e without MMU and no cache, I suppose that something similar for Microblaze). But both are closed-source. There are open-source soft processors like LatticeMico32 and LEON3. I'm moving to one of these for a next project (not yet decided which one, since in this case it will be a bare-metal application, with no operating system, but I would like to use a processor that is supported by Linux distribution for the future). Linux is ported to both, and for LM32 (not sure if for LEON3), RTEMS also (see www.milkymist.org , an open source hardware and software project with an LM32 implementation on a Spartan 6 FPGA using RTEMS. Also there is a plethora of soft implementation of several processors in OpenCores (ranging from 6502 to OpenRISC) and also somewhere I read about an implementation of a Cray-1 in a Spartan-3 :) I'm very familiar with the LEON and RTEMS, having managed a software development project with it for the last 3 or 4 years at work. http://www.gaisler.com/ for LEON http://www.rtems.org/ for RTEMS And yes, there is a port (maybe two) of Linux for the LEON as well (A few years ago, we loaded up the Snapgear port, but since we went RTEMS, I haven't fooled with it). You'd have to check the Gaisler.com website. You can drop a LEON core into a Virtex II in about a day, and judging from the traffic on the LEON yahoo list (where the Gaisler folks hang out), lots of people are doing things like multiple cores and things on all manner of Xilinx eval boards. Gaisler's GPL library of assorted cores (pretty much all using AMBA) make life pretty easy from a hardware interface standpoint. Their basi strategy is that source and documentation is free, but that if you want the fault tolerant versions, or the versions intended for spaceflight, or the testbenches for the cores, you have to go with a license ( a few thousand bucks per core, depending on what it is). Gaisler's basic business model (hopefully I'm summarizing correctly..) is that they do custom FPGA/ASIC designs for people, putting together pieces of their library, possibly adding new modules, targeted to platforms like the Actel AX2000 (or Xilinx, or FPGA->ASIC). SO you have products like the Atmel AT697 (A LEON-FT with memory controllers and peripherals) which we use in JPL's space radios) or the Aeroflex UT699 (another LEON core with various peripherals). RTEMS wise... It's pretty well supported by the community, it's open source, it does all the stuff you want a RTOS to do. it's NOT a multitasking, dynamic loading OS like Linux. That is it doesn't support an MMU and process space isolation (although that might be possible in newer versions.. there's a lot of configurability). It's basically a statically linked single task with threads. They've got RAM (and disk) file systems, IP stacks, a shell, YAFFS, etc. Like all open source, there's quite a lot of interesting stuff available (not from rtems.org, but others) that is 90% complete. Somebody at Google Summer of Code or for their Masters decides to implement something cool, and gets most of the way done, then wanders away (the summer ended, they got their degree, the usual story). But there's also a core of users who are serious and rigorous and contribute back, so the main stuff in the distribution from Joel Sherrill at OAR (who make RTEMS) is pretty rock solid. ESA has several rigorously verified flight qualified versions of RTEMS (in Portugal and Austria, as I recall) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
On Sat, 07 Apr 2012 13:19:14 +0200, Azelio Boriani wrote: > The Xilinx and Altera have their embedded CPUs (Microblaze and Nios) IP. > I'm not familiar with them and don't know how much they cost. Until now > I have developed on Xilinx 50Kgates FPGA and 128 cells CPLD with the > Xilinx's free tools. > Maybe ZPU http://opensource.zylin.com/zpuref.html http://opencores.org/project,zpu http://embdev.net/articles/ ZPU:_Softcore_implementation_on_a_Spartan-3_FPGA /Cfo ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
The Cray-1 implementation is here http://chrisfenton.com/homebrew-cray-1a/ On Sat, Apr 7, 2012 at 1:47 PM, Javier Herrero wrote: > El 07/04/2012 13:19, Azelio Boriani escribió: > >> The Xilinx and Altera have their embedded CPUs (Microblaze and Nios) IP. >> I'm not familiar with them and don't know how much they cost. Until now I >> have developed on Xilinx 50Kgates FPGA and 128 cells CPLD with the >> Xilinx's >> free tools. >> >> Mostly expensive for amateur use, although reduced free versions exists > (for Nios-II it is Nios-II/e without MMU and no cache, I suppose that > something similar for Microblaze). But both are closed-source. > > There are open-source soft processors like LatticeMico32 and LEON3. I'm > moving to one of these for a next project (not yet decided which one, since > in this case it will be a bare-metal application, with no operating system, > but I would like to use a processor that is supported by Linux distribution > for the future). Linux is ported to both, and for LM32 (not sure if for > LEON3), RTEMS also (see www.milkymist.org , an open source hardware and > software project with an LM32 implementation on a Spartan 6 FPGA using > RTEMS. Also there is a plethora of soft implementation of several > processors in OpenCores (ranging from 6502 to OpenRISC) and also somewhere > I read about an implementation of a Cray-1 in a Spartan-3 :) > > Regards, > > Javier > > > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
El 07/04/2012 13:19, Azelio Boriani escribió: The Xilinx and Altera have their embedded CPUs (Microblaze and Nios) IP. I'm not familiar with them and don't know how much they cost. Until now I have developed on Xilinx 50Kgates FPGA and 128 cells CPLD with the Xilinx's free tools. Mostly expensive for amateur use, although reduced free versions exists (for Nios-II it is Nios-II/e without MMU and no cache, I suppose that something similar for Microblaze). But both are closed-source. There are open-source soft processors like LatticeMico32 and LEON3. I'm moving to one of these for a next project (not yet decided which one, since in this case it will be a bare-metal application, with no operating system, but I would like to use a processor that is supported by Linux distribution for the future). Linux is ported to both, and for LM32 (not sure if for LEON3), RTEMS also (see www.milkymist.org , an open source hardware and software project with an LM32 implementation on a Spartan 6 FPGA using RTEMS. Also there is a plethora of soft implementation of several processors in OpenCores (ranging from 6502 to OpenRISC) and also somewhere I read about an implementation of a Cray-1 in a Spartan-3 :) Regards, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
The Xilinx and Altera have their embedded CPUs (Microblaze and Nios) IP. I'm not familiar with them and don't know how much they cost. Until now I have developed on Xilinx 50Kgates FPGA and 128 cells CPLD with the Xilinx's free tools. On Sat, Apr 7, 2012 at 7:53 AM, Chris Albertson wrote: > On Fri, Apr 6, 2012 at 9:41 PM, Andrew Rodland > wrote: > > > Another option would be building something on an FPGA. This would be a > > considerable stretch for me, since I've never done FPGA work, but if I > build > > from the ground up, I can have *very* tight control over things that are > chosen > > for me with a micro controller. > > > A compromise is to find a "soft core" for the FPGA. This is a CPU > implemented in FPGA and then it runs software just like a "real" CPU. > This would let you move your micro controller based be sign over to > the FPGA quickly. After that you can implement some specialized > peripherals that do time stamping > > > How does the performance of the Arduino based NTP compare with what > you could do with Linux on (say) and Atom or ARM processor? > > > > > Chris Albertson > Redondo Beach, California > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
On Fri, Apr 6, 2012 at 9:41 PM, Andrew Rodland wrote: > Another option would be building something on an FPGA. This would be a > considerable stretch for me, since I've never done FPGA work, but if I build > from the ground up, I can have *very* tight control over things that are > chosen > for me with a micro controller. A compromise is to find a "soft core" for the FPGA. This is a CPU implemented in FPGA and then it runs software just like a "real" CPU. This would let you move your micro controller based be sign over to the FPGA quickly. After that you can implement some specialized peripherals that do time stamping How does the performance of the Arduino based NTP compare with what you could do with Linux on (say) and Atom or ARM processor? Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)
Azelio Boriani writes: > > >>On a side note, speaking of deterministic systems, why has no one built a > GPSDO with an FPGA yet? Or an NTP server? :) > > Yes, I have: I have a GPSDO entirely on a 50Kgates FPGA (Spartan3 XC3S50) > without microprocessor. GPS is the iLotus M12M and OCXO is a Morion MV201, > the DAC is... well, not exactly the best choice but it is an AD5660 16bit > only, anyway it works. I'd be interested in hearing more about this. For about the past year I've been building an NTP server on an Arduino (ATMega2560 microcontroller, WizNet W5100 ethernet/TCP/IP offload engine, boring off-the-shelf 16MHz quartz crystal). Nowadays it's nearing completion (meaning I've hit the limits of the accuracy I can get with this setup) and I've been thinking about what I can do next to make it better. One option is keeping the AVR platform, but building a custom board instead of using the Arduino, and disciplining an OCXO in proper GPSDO fashion instead of the digital frequency synthesis that I'm doing now. This would be interesting for the pure timekeeping aspect, although it wouldn't improve the accuracy of the NTP server very much. Another option would be building something on an FPGA. This would be a considerable stretch for me, since I've never done FPGA work, but if I build from the ground up, I can have *very* tight control over things that are chosen for me with a microcontroller. I can timestamp Ethernet frames while they're still coming in from the wire, and timestamp outgoing NTP packets at the last possible moment; I can make delays pretty much as deterministic as I want; I can control counter widths and divisors, and interrupt priorities, etc. It's really fascinating and I think at some time I'd like to try it. Andrew ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
