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
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 ------
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
  Subject: Re: [AFMUG] OT Raspberry PI

  Find a 555 timer ... I used many in the olden day when radioshacks were king 

  On 02/22/2018 05:05 PM, 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
    Subject: Re: [AFMUG] OT Raspberry PI

    Other than setting the process priority, you may need a custom kernel. See

    On Feb 22, 2018 4:48 PM, <> 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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