[time-nuts] Thought experiment on a low cost timing board

Paul Boven p.boven at chello.nl
Sun Feb 26 18:24:42 EST 2006

Hi everyone,

Poul-Henning Kamp wrote:

> You don't even need 32bits for that:
> 	http://phk.freebsd.dk/pubs/timecounter.pdf
> And doing it in hardware would be more expensive than in software, hardware
> access is much slower than memory access.

How about taking one of the bigger FPGA's, that can hold a complete 
stand-alone microcontoller, running a Unix-like OS? You could implement 
several fast, wide synchronous counter/latches in the same FPGA fabric, 
so there would be no need to bother with things like PCI busses. Does 
FreeBSD run on any of these chips?

With a serial (for NMEA) and PPS input, and ethernet output, you'd have 
an NTP-server-on-a-chip. Add a D/A-converter to discipline a TCXO, and 
you're all set. An FPGA with relatively few pins, hence no BGA, would 
suffice. Building such a device would be within the capabilities of some 
of the more dedicated timenuts in here.

Regards, Paul Boven - PE1NUT

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