[time-nuts] Modern motherboard with RS232 port

Bob Camp lists at rtty.us
Mon Aug 20 00:51:09 UTC 2012


There has been a lot of work done on FreeBSD kernel timing and ntp. That and the work PHK has done on some of the drivers makes it a tough thing to beat. Since the pi is ARM hardware, a lot of the 386 specific work isn't going to apply to it. Still that's less of an issue than the USB to Ethernet connection on the pi.


On Aug 19, 2012, at 8:38 PM, Chris Albertson <albertson.chris at gmail.com> wrote:

> On Sun, Aug 19, 2012 at 5:21 PM, Bob Camp <lists at rtty.us> wrote:
>> Hi
>> The pi doesn't have a conventional serial port. It does have a TTL serial
>> on the 28 pin connector. There are also IRQ pins on the same connector.
>> Since they go directly to the CPU chip, hardware latency should be pretty
>> good.
> Is there a PPS device driver on the version of Linux that runs on this
> board?    In theory all you need is the interrupt pin and a high speed
> (usec or nanosec counter) counter that can be captured by the device
> driver.  But even with this hardware has anyone written the device driver?
> I don't understand the comment about no well tuned ntp.
> Chris Albertson
> Redondo Beach, California
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