[time-nuts] inexpensive, black box, GPS or NTP based TTL time capture?

jimlux jimlux at earthlink.net
Wed Oct 18 18:56:08 EDT 2017

On 10/18/17 2:09 PM, Adrian Godwin wrote:
> On Wed, Oct 18, 2017 at 9:11 PM, Gary E. Miller <gem at rellim.com> wrote:
>> Yo Hal!
>> On Wed, 18 Oct 2017 12:26:27 -0700
>> Hal Murray <hmurray at megapathdsl.net> wrote:
>>> For getting started, you also need:
>>>    SD card reader/writer
>>>    keyboard and mouse (Pi has USB)
>>>    display adapter (Pi is HDMI)
>>>    display
>> Yeah, just for setup.  Shall we include the price of the desk it sits
>> and the building it is in?
> You can set a Pi up headless from scratch by putting an empty file called
> 'ssh' in the boot directory of the raspbian SD card. It then enables the
> ssh daemon on startup.

This is one of the reasons I use beaglebone greens - soldered in eMMC so 
no need for SD card, no HDMI interface - the expectation is that you're 
using it headless/serial console style. And the eMMC is preloaded with 
Debian Jessie (or perhaps something newer)

The only ugly thing is the USB Gadget interface, which works fine, but 
always seems a bit weird - The USB serves triple duty - disk access to 
part of the file system, IP network interface, serial console port.

So on a Mac, you can mount it as a disk, ssh or "screen" to it via 
either ip or the /dev/cu.usbmodem

There's also a standard ethernet interface. Which by default comes up 
using DHCP and zeroconf, so you can plug it in to your network at home, 
and then look for it with "ping beaglebone.local".

And the beaglebone has lots of GPIO.

> Of course, then you need another computer to talk to it with ..

Unless you're a real hardcore embedded person, in which case you just 
make and break a connection between two wires on the TxD line to send 
ascii, and you use the blinks of an LED or the intermittent tingle on 
your tongue from the RxD to decode it.

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