Pretty sure you need  RTOS to accomplish this.That will get pretty close to
bare metal.

-bp

--
bp
part15sbs{at}gmail{dot}com

On Thu, Feb 22, 2018 at 3:36 PM, <ch...@wbmfg.com> wrote:

> Had the command syntax wrong.
> But got nice to work.  Have to sudo if you use negative nice numbers.
>
> It made zero difference in my jitter.  I went from 19 to –20 on nice and
> no change.
>
> *From:* ch...@wbmfg.com
> *Sent:* Thursday, February 22, 2018 4:29 PM
> *To:* af@afmug.com
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> The problem is there is a crap ton of stuff out there that needs network
> sync.  And it all has a T1 as an input.
> But most T1 trunking circuits are getting replaced with SIP.
>
> So, I am building a cheap and dirty T1 signal generator that is GPS and
> rhubidium referenced.  The hard part is easy.  The easy part should be easy
> but all the T1 framing chips that used to exist no longer exist.
>
> The ones that are out there have massive CPU interfaces and tons of
> registers that need to get set to get them fired up and running....
>
> Where is Exar when you need them....
>
> *From:* Adam Moffett
> *Sent:* Thursday, February 22, 2018 4:21 PM
> *To:* af@afmug.com
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> Tell whoever's got the T1 that 1967 is way behind us and get a new
> interface.
> Problem eliminated LOL
>
>
> ------ Original Message ------
> From: ch...@wbmfg.com
> To: af@afmug.com
> Sent: 2/22/2018 6:16:45 PM
> Subject: Re: [AFMUG] OT Raspberry PI
>
>
> I have to generate an alternate mark inversion signal on 1.544 MHz with
> every 193rd bit following a t1 framing sequence.
> Sure wish a 555 could do that.
>
> *From:* Dave
> *Sent:* Thursday, February 22, 2018 4:10 PM
> *To:* af@afmug.com
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> Find a 555 timer ... I used many in the olden day when radioshacks were
> king LOL!
>
>
> On 02/22/2018 05:05 PM, ch...@wbmfg.com wrote:
>
> I am thinking of using some shift registers instead of using the PI output
> directly as the timing signal.
>
> Use the PI to load them.
>
> I love me some hardware design anyhow....
>
>
> *From:* Colin Stanners
> *Sent:* Thursday, February 22, 2018 3:59 PM
> *To:* af@afmug.com
> *Subject:* Re: [AFMUG] OT Raspberry PI
>
> Other than setting the process priority, you may need a custom kernel. See
> https://medium.com/@metebalci/latency-of-raspberry-pi-3-on-
> standard-and-real-time-linux-4-9-kernel-2d9c20704495
>
>
> On Feb 22, 2018 4:48 PM, <ch...@wbmfg.com> 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.
>>
>
> --
>
>

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