This calls out for an FPGA solution. On Thu, Feb 22, 2018 at 10:45 PM, Forrest Christian (List Account) < [email protected]> wrote:
> You can get a fpga board which might be suitable for this project (after > adding appropriate clocks) for around $20 anymore. One example: > http://tinyfpga.com/ > > > > On Thu, Feb 22, 2018 at 6:42 PM, Lewis Bergman <[email protected]> > wrote: > >> They aren't cheap but you could always use an fpga. >> >> On Thu, Feb 22, 2018, 7:35 PM Chuck McCown <[email protected]> wrote: >> >>> No, I saw it, but I already had the Pi so I ignored it and hoped for the >>> best. >>> I tried it first with arduino. Just not enough speed. And it had the >>> jitter problem too. >>> >>> I have a method using three TTL/CMOS chips that is going to work... I >>> think... >>> >>> The only thing separating the gps disciplined signal and the T1 will be >>> a D flip flop and a few AND/NAND gates. So that ought to get me super low >>> jitter. >>> >>> Trying for stratum I with rubidium hold-over isochronous performance at >>> the end of the day. For cheap. >>> >>> *From:* Forrest Christian (List Account) >>> *Sent:* Thursday, February 22, 2018 6:27 PM >>> *To:* af >>> *Subject:* Re: [AFMUG] OT Raspberry PI >>> >>> Ok, I think you missed this portion of my email last time: >>> >>> >>> *"I'm skeptical that you'll be able to generate a bitstream with enough >>> accuracy under Linux, without extreme programming measures.I'd suggest a >>> digilent chipkit wifire and the arduino ide for this. You should be able >>> to bitbang at least a T1 with this processor (500mhz)"* >>> >>> Generally the raspberry pi is great for 'tiny server stuff', or 'user >>> interface' stuff, and the arduino and/or microcontrollers will work better >>> for what you're looking at, since there isn't an operating system in the >>> way. All arduino really is is a c++ ide with some simplified libraries. >>> >>> The wifire product I mentioned is really a PIC32MZ dev board, optimized >>> for arduino. If you've had enough of the arduino ide, you can download the >>> microchip ide and program it with a full development kit. >>> >>> Honestly for what you are talking about a EUSART in even a low end PIC >>> might be able to handle this. If you program the EUSART into synchronous >>> mode you'll just have to stuff a byte into it every 8 bit times and it will >>> clock it out for you. Not sure if the clock rate is adjustable enough for >>> you, but if you get a PIC with the NCO peripheral you might be able to >>> dynamically adjust the frequency enough to make it work. >>> >>> NCO app sheet: http://ww1.microchip.com/downl >>> oads/en/AppNotes/90003131A.pdf >>> >>> >>> >>> >>> On Thu, Feb 22, 2018 at 3:48 PM, <[email protected]> wrote: >>> >>>> Anyone know how to get my program to run on bare metal? >>>> >>>> Or at the very least tell Linux that my program is the most important >>>> thing in the world and service it above all other things. >>>> >>>> I am trying to create a timing signal with the Pi. It is doing it but >>>> the jitter is pretty bad. >>>> >>>> I have researched trying to use an interrupt but there is a pretty low >>>> limit on how many times per second you can fire a hardware interrupt. >>>> Too low for my application. >>>> >>> >>> >>> >>> -- >>> *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.* >>> Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 >>> <https://maps.google.com/?q=3577+Countryside+Road,+Helena,+MT+%0D+59602&entry=gmail&source=g> >>> [email protected] | http://www.packetflux.com >>> <http://www.linkedin.com/in/fwchristian> >>> <http://facebook.com/packetflux> <http://twitter.com/@packetflux> >>> >>> > > > -- > *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.* > Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 > <https://maps.google.com/?q=3577+Countryside+Road,+Helena,+MT+59602&entry=gmail&source=g> > [email protected] | http://www.packetflux.com > <http://www.linkedin.com/in/fwchristian> <http://facebook.com/packetflux> > <http://twitter.com/@packetflux> > >
