Empathy List Archives

DJ

Didier Juges

Sun, Dec 1, 2019 9:27 PM

This article indicates: " Average precision was measured (by comparison to
known-good time sources) with 1 ms, or 0.001 seconds "

On Sun, Dec 1, 2019 at 2:01 PM David david@mju.io wrote:

I'd think one of the ESP32's would be a fine choice. They have some good
power management options to wake up periodically to do the work, making for
even lower power consumption.

Looks like someone has already written some code that could be adapted?

https://github.com/DennisSc/PPS-ntp-server/blob/master/README.md

-David

-------- Original Message --------
On Dec 1, 2019, 09:49, Bob kb8tq wrote:

Hi

So something like one of the many ESP32 based boards?

Of course when it comes to the “code from scratch” part there is the

problem that I’m

pretty (most would say very …) lazy :) :) :)

Bob

On Dec 1, 2019, at 12:29 PM, Poul-Henning Kamp phk@phk.freebsd.dk

wrote:

You can do better than RPi, since a NTP server basically
only needs to understand two packets: IP/UDP at port 123
and ARP packets.

There are WiFi enabled microcontrollers that could be taught how
to do that, but you'd have to write up your NTP daemon from scratch
which is not hard when you do not have to do the "sync clock from
remote servers" part.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by

incompetence.

time-nuts mailing list -- time-nuts@lists.febo.com
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This article indicates: " Average precision was measured (by comparison to known-good time sources) with 1 ms, or 0.001 seconds " On Sun, Dec 1, 2019 at 2:01 PM David <david@mju.io> wrote: > I'd think one of the ESP32's would be a fine choice. They have some good > power management options to wake up periodically to do the work, making for > even lower power consumption. > > Looks like someone has already written some code that could be adapted? > > https://github.com/DennisSc/PPS-ntp-server/blob/master/README.md > > -David > > -------- Original Message -------- > On Dec 1, 2019, 09:49, Bob kb8tq wrote: > > > Hi > > > > So something like one of the many ESP32 based boards? > > > > Of course when it comes to the “code from scratch” part there is the > problem that I’m > > pretty (most would say very …) lazy :) :) :) > > > > Bob > > > >> On Dec 1, 2019, at 12:29 PM, Poul-Henning Kamp <phk@phk.freebsd.dk> > wrote: > >> > >> -------- > >> > >> You can do better than RPi, since a NTP server basically > >> only needs to understand two packets: IP/UDP at port 123 > >> and ARP packets. > >> > >> There are WiFi enabled microcontrollers that could be taught how > >> to do that, but you'd have to write up your NTP daemon from scratch > >> which is not hard when you do not have to do the "sync clock from > >> remote servers" part. > >> > >> > >> -- > >> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > >> phk@FreeBSD.ORG | TCP/IP since RFC 956 > >> FreeBSD committer | BSD since 4.3-tahoe > >> Never attribute to malice what can adequately be explained by > incompetence. > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. >

BK

Bob kb8tq

Sun, Dec 1, 2019 10:28 PM

Hi

My target is “a couple of mili seconds” so a microsecond or five is sort of a non-issue.

The whole thing will run over (slow) WiFi. That puts a whole other layer of delay
on top of things. Holding nanoseconds or microseconds with that sort of overhead
seemed to be a bit much.

What I’m doing will be quite happy if the results are typically (=90%) < 10 ms.

Bob

On Dec 1, 2019, at 4:27 PM, Didier Juges shalimr9@gmail.com wrote:

This article indicates: " Average precision was measured (by comparison to
known-good time sources) with 1 ms, or 0.001 seconds "

On Sun, Dec 1, 2019 at 2:01 PM David david@mju.io wrote:

I'd think one of the ESP32's would be a fine choice. They have some good
power management options to wake up periodically to do the work, making for
even lower power consumption.

Looks like someone has already written some code that could be adapted?

https://github.com/DennisSc/PPS-ntp-server/blob/master/README.md

-David

-------- Original Message --------
On Dec 1, 2019, 09:49, Bob kb8tq wrote:

Hi

So something like one of the many ESP32 based boards?

Of course when it comes to the “code from scratch” part there is the

problem that I’m

pretty (most would say very …) lazy :) :) :)

Bob

On Dec 1, 2019, at 12:29 PM, Poul-Henning Kamp phk@phk.freebsd.dk

wrote:

You can do better than RPi, since a NTP server basically
only needs to understand two packets: IP/UDP at port 123
and ARP packets.

There are WiFi enabled microcontrollers that could be taught how
to do that, but you'd have to write up your NTP daemon from scratch
which is not hard when you do not have to do the "sync clock from
remote servers" part.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by

incompetence.

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to

http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com

and follow the instructions there.

time-nuts mailing list -- time-nuts@lists.febo.com
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Hi My target is “a couple of mili seconds” so a microsecond or five is sort of a non-issue. The whole thing will run over (slow) WiFi. That puts a whole other layer of delay on top of things. Holding nanoseconds or microseconds with that sort of overhead seemed to be a bit much. What I’m doing will be quite happy if the results are typically (=90%) < 10 ms. Bob > On Dec 1, 2019, at 4:27 PM, Didier Juges <shalimr9@gmail.com> wrote: > > This article indicates: " Average precision was measured (by comparison to > known-good time sources) with 1 ms, or 0.001 seconds " > > On Sun, Dec 1, 2019 at 2:01 PM David <david@mju.io> wrote: > >> I'd think one of the ESP32's would be a fine choice. They have some good >> power management options to wake up periodically to do the work, making for >> even lower power consumption. >> >> Looks like someone has already written some code that could be adapted? >> >> https://github.com/DennisSc/PPS-ntp-server/blob/master/README.md >> >> -David >> >> -------- Original Message -------- >> On Dec 1, 2019, 09:49, Bob kb8tq wrote: >> >>> Hi >>> >>> So something like one of the many ESP32 based boards? >>> >>> Of course when it comes to the “code from scratch” part there is the >> problem that I’m >>> pretty (most would say very …) lazy :) :) :) >>> >>> Bob >>> >>>> On Dec 1, 2019, at 12:29 PM, Poul-Henning Kamp <phk@phk.freebsd.dk> >> wrote: >>>> >>>> -------- >>>> >>>> You can do better than RPi, since a NTP server basically >>>> only needs to understand two packets: IP/UDP at port 123 >>>> and ARP packets. >>>> >>>> There are WiFi enabled microcontrollers that could be taught how >>>> to do that, but you'd have to write up your NTP daemon from scratch >>>> which is not hard when you do not have to do the "sync clock from >>>> remote servers" part. >>>> >>>> >>>> -- >>>> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 >>>> phk@FreeBSD.ORG | TCP/IP since RFC 956 >>>> FreeBSD committer | BSD since 4.3-tahoe >>>> Never attribute to malice what can adequately be explained by >> incompetence. >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there.

TS

Tim Shoppa

Sun, Dec 1, 2019 10:42 PM

Didier, I'm not sure I saw Bob write that 5uS was his goal.

I don't think anyone would claim that ordinary cheap WiFi can achieve
consistent sub-millisecond variations in latency.

Tim N3QE

On Sun, Dec 1, 2019 at 5:06 PM Didier Juges shalimr9@gmail.com wrote:

You should look at latency. The ESP8266 has serial (SPI) flash and a
relatively small internal cache. When the chip needs to load code from
flash, that can take a while, compared to the 5uS target. Great for cheap
IoT stuff, not so great for time sensitive, in my opinion.

On Sun, Dec 1, 2019 at 2:01 PM David david@mju.io wrote:

I'd think one of the ESP32's would be a fine choice. They have some good
power management options to wake up periodically to do the work, making

for

even lower power consumption.

Looks like someone has already written some code that could be adapted?

https://github.com/DennisSc/PPS-ntp-server/blob/master/README.md

-David

-------- Original Message --------
On Dec 1, 2019, 09:49, Bob kb8tq wrote:

Hi

So something like one of the many ESP32 based boards?

Of course when it comes to the “code from scratch” part there is the

problem that I’m

pretty (most would say very …) lazy :) :) :)

Bob

On Dec 1, 2019, at 12:29 PM, Poul-Henning Kamp phk@phk.freebsd.dk

wrote:

You can do better than RPi, since a NTP server basically
only needs to understand two packets: IP/UDP at port 123
and ARP packets.

There are WiFi enabled microcontrollers that could be taught how
to do that, but you'd have to write up your NTP daemon from scratch
which is not hard when you do not have to do the "sync clock from
remote servers" part.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by

incompetence.

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to

http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com

and follow the instructions there.

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to
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and follow the instructions there.

Didier, I'm not sure I saw Bob write that 5uS was his goal. I don't think anyone would claim that ordinary cheap WiFi can achieve consistent sub-millisecond variations in latency. Tim N3QE On Sun, Dec 1, 2019 at 5:06 PM Didier Juges <shalimr9@gmail.com> wrote: > You should look at latency. The ESP8266 has serial (SPI) flash and a > relatively small internal cache. When the chip needs to load code from > flash, that can take a while, compared to the 5uS target. Great for cheap > IoT stuff, not so great for time sensitive, in my opinion. > > On Sun, Dec 1, 2019 at 2:01 PM David <david@mju.io> wrote: > > > I'd think one of the ESP32's would be a fine choice. They have some good > > power management options to wake up periodically to do the work, making > for > > even lower power consumption. > > > > Looks like someone has already written some code that could be adapted? > > > > https://github.com/DennisSc/PPS-ntp-server/blob/master/README.md > > > > -David > > > > -------- Original Message -------- > > On Dec 1, 2019, 09:49, Bob kb8tq wrote: > > > > > Hi > > > > > > So something like one of the many ESP32 based boards? > > > > > > Of course when it comes to the “code from scratch” part there is the > > problem that I’m > > > pretty (most would say very …) lazy :) :) :) > > > > > > Bob > > > > > >> On Dec 1, 2019, at 12:29 PM, Poul-Henning Kamp <phk@phk.freebsd.dk> > > wrote: > > >> > > >> -------- > > >> > > >> You can do better than RPi, since a NTP server basically > > >> only needs to understand two packets: IP/UDP at port 123 > > >> and ARP packets. > > >> > > >> There are WiFi enabled microcontrollers that could be taught how > > >> to do that, but you'd have to write up your NTP daemon from scratch > > >> which is not hard when you do not have to do the "sync clock from > > >> remote servers" part. > > >> > > >> > > >> -- > > >> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > > >> phk@FreeBSD.ORG | TCP/IP since RFC 956 > > >> FreeBSD committer | BSD since 4.3-tahoe > > >> Never attribute to malice what can adequately be explained by > > incompetence. > > > > > > _______________________________________________ > > > time-nuts mailing list -- time-nuts@lists.febo.com > > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > and follow the instructions there. > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. >

DJ

Didier Juges

Mon, Dec 2, 2019 1:24 AM

"Didier, I'm not sure I saw Bob write that 5uS was his goal."

I realize that now, I saw 5uS in another email thread and wrongly
associated the two :) Happens when doing two things at once...
Anyhow, I mentioned it because I did do some experiments early on the
ESP8266 and the seemingly random flash reload was quite unexpected. It was
in the 10's of uS if I recall, so of course not a real concern for this
application but it could be in other cases. Something to keep in mind when
comparing architectures.

On Sun, Dec 1, 2019 at 5:00 PM Tim Shoppa tshoppa@gmail.com wrote:

Didier, I'm not sure I saw Bob write that 5uS was his goal.

I don't think anyone would claim that ordinary cheap WiFi can achieve
consistent sub-millisecond variations in latency.

Tim N3QE

On Sun, Dec 1, 2019 at 5:06 PM Didier Juges shalimr9@gmail.com wrote:

You should look at latency. The ESP8266 has serial (SPI) flash and a
relatively small internal cache. When the chip needs to load code from
flash, that can take a while, compared to the 5uS target. Great for cheap
IoT stuff, not so great for time sensitive, in my opinion.

On Sun, Dec 1, 2019 at 2:01 PM David david@mju.io wrote:

I'd think one of the ESP32's would be a fine choice. They have some

good

power management options to wake up periodically to do the work, making

for

even lower power consumption.

Looks like someone has already written some code that could be adapted?

https://github.com/DennisSc/PPS-ntp-server/blob/master/README.md

-David

-------- Original Message --------
On Dec 1, 2019, 09:49, Bob kb8tq wrote:

Hi

So something like one of the many ESP32 based boards?

Of course when it comes to the “code from scratch” part there is the

problem that I’m

pretty (most would say very …) lazy :) :) :)

Bob

On Dec 1, 2019, at 12:29 PM, Poul-Henning Kamp phk@phk.freebsd.dk

wrote:

You can do better than RPi, since a NTP server basically
only needs to understand two packets: IP/UDP at port 123
and ARP packets.

There are WiFi enabled microcontrollers that could be taught how
to do that, but you'd have to write up your NTP daemon from scratch
which is not hard when you do not have to do the "sync clock from
remote servers" part.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by

incompetence.

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to

http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com

and follow the instructions there.

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

"Didier, I'm not sure I saw Bob write that 5uS was his goal." I realize that now, I saw 5uS in another email thread and wrongly associated the two :) Happens when doing two things at once... Anyhow, I mentioned it because I did do some experiments early on the ESP8266 and the seemingly random flash reload was quite unexpected. It was in the 10's of uS if I recall, so of course not a real concern for this application but it could be in other cases. Something to keep in mind when comparing architectures. On Sun, Dec 1, 2019 at 5:00 PM Tim Shoppa <tshoppa@gmail.com> wrote: > Didier, I'm not sure I saw Bob write that 5uS was his goal. > > I don't think anyone would claim that ordinary cheap WiFi can achieve > consistent sub-millisecond variations in latency. > > Tim N3QE > > On Sun, Dec 1, 2019 at 5:06 PM Didier Juges <shalimr9@gmail.com> wrote: > > > You should look at latency. The ESP8266 has serial (SPI) flash and a > > relatively small internal cache. When the chip needs to load code from > > flash, that can take a while, compared to the 5uS target. Great for cheap > > IoT stuff, not so great for time sensitive, in my opinion. > > > > On Sun, Dec 1, 2019 at 2:01 PM David <david@mju.io> wrote: > > > > > I'd think one of the ESP32's would be a fine choice. They have some > good > > > power management options to wake up periodically to do the work, making > > for > > > even lower power consumption. > > > > > > Looks like someone has already written some code that could be adapted? > > > > > > https://github.com/DennisSc/PPS-ntp-server/blob/master/README.md > > > > > > -David > > > > > > -------- Original Message -------- > > > On Dec 1, 2019, 09:49, Bob kb8tq wrote: > > > > > > > Hi > > > > > > > > So something like one of the many ESP32 based boards? > > > > > > > > Of course when it comes to the “code from scratch” part there is the > > > problem that I’m > > > > pretty (most would say very …) lazy :) :) :) > > > > > > > > Bob > > > > > > > >> On Dec 1, 2019, at 12:29 PM, Poul-Henning Kamp <phk@phk.freebsd.dk> > > > wrote: > > > >> > > > >> -------- > > > >> > > > >> You can do better than RPi, since a NTP server basically > > > >> only needs to understand two packets: IP/UDP at port 123 > > > >> and ARP packets. > > > >> > > > >> There are WiFi enabled microcontrollers that could be taught how > > > >> to do that, but you'd have to write up your NTP daemon from scratch > > > >> which is not hard when you do not have to do the "sync clock from > > > >> remote servers" part. > > > >> > > > >> > > > >> -- > > > >> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > > > >> phk@FreeBSD.ORG | TCP/IP since RFC 956 > > > >> FreeBSD committer | BSD since 4.3-tahoe > > > >> Never attribute to malice what can adequately be explained by > > > incompetence. > > > > > > > > _______________________________________________ > > > > time-nuts mailing list -- time-nuts@lists.febo.com > > > > To unsubscribe, go to > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > > and follow the instructions there. > > > _______________________________________________ > > > time-nuts mailing list -- time-nuts@lists.febo.com > > > To unsubscribe, go to > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > and follow the instructions there. > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. >

DK

David Kern

Mon, Dec 2, 2019 4:18 AM

I did some testing against an ESP32 this evening to see how feasible it would be to use this platform. Unfortunately there is extremely high jitter on the wifi interface of the ESP32 (between 4ms to 90ms) - even after adjusting some settings and disabling all power management. This was testing against a quiet wifi network with consistent 1ms pings between my workstation to the router.

I believe that high jitter would make it difficult to get a good result with NTP over wifi.

I'm not sure if the 8266 has the same issue.

Shame, because with the ultra low power processor you could do some interesting things.

-David (AD7WZ)

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Sunday, December 1, 2019 5:24 PM, Didier Juges shalimr9@gmail.com wrote:

"Didier, I'm not sure I saw Bob write that 5uS was his goal."

I realize that now, I saw 5uS in another email thread and wrongly
associated the two :) Happens when doing two things at once...
Anyhow, I mentioned it because I did do some experiments early on the
ESP8266 and the seemingly random flash reload was quite unexpected. It was
in the 10's of uS if I recall, so of course not a real concern for this
application but it could be in other cases. Something to keep in mind when
comparing architectures.

On Sun, Dec 1, 2019 at 5:00 PM Tim Shoppa tshoppa@gmail.com wrote:

Didier, I'm not sure I saw Bob write that 5uS was his goal.
I don't think anyone would claim that ordinary cheap WiFi can achieve
consistent sub-millisecond variations in latency.
Tim N3QE
On Sun, Dec 1, 2019 at 5:06 PM Didier Juges shalimr9@gmail.com wrote:

You should look at latency. The ESP8266 has serial (SPI) flash and a
relatively small internal cache. When the chip needs to load code from
flash, that can take a while, compared to the 5uS target. Great for cheap
IoT stuff, not so great for time sensitive, in my opinion.
On Sun, Dec 1, 2019 at 2:01 PM David david@mju.io wrote:

I'd think one of the ESP32's would be a fine choice. They have some
good

power management options to wake up periodically to do the work, making
for
even lower power consumption.
Looks like someone has already written some code that could be adapted?
https://github.com/DennisSc/PPS-ntp-server/blob/master/README.md
-David
-------- Original Message --------
On Dec 1, 2019, 09:49, Bob kb8tq wrote:

Hi
So something like one of the many ESP32 based boards?
Of course when it comes to the “code from scratch” part there is the
problem that I’m
pretty (most would say very …) lazy :) :) :)
Bob

On Dec 1, 2019, at 12:29 PM, Poul-Henning Kamp phk@phk.freebsd.dk
wrote:

You can do better than RPi, since a NTP server basically
only needs to understand two packets: IP/UDP at port 123
and ARP packets.
There are WiFi enabled microcontrollers that could be taught how
to do that, but you'd have to write up your NTP daemon from scratch
which is not hard when you do not have to do the "sync clock from
remote servers" part.

Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by
incompetence.

time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

time-nuts mailing list -- time-nuts@lists.febo.com
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I did some testing against an ESP32 this evening to see how feasible it would be to use this platform. Unfortunately there is extremely high jitter on the wifi interface of the ESP32 (between 4ms to 90ms) - even after adjusting some settings and disabling all power management. This was testing against a quiet wifi network with consistent 1ms pings between my workstation to the router. I believe that high jitter would make it difficult to get a good result with NTP over wifi. I'm not sure if the 8266 has the same issue. Shame, because with the ultra low power processor you could do some interesting things. -David (AD7WZ) ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Sunday, December 1, 2019 5:24 PM, Didier Juges <shalimr9@gmail.com> wrote: > "Didier, I'm not sure I saw Bob write that 5uS was his goal." > > I realize that now, I saw 5uS in another email thread and wrongly > associated the two :) Happens when doing two things at once... > Anyhow, I mentioned it because I did do some experiments early on the > ESP8266 and the seemingly random flash reload was quite unexpected. It was > in the 10's of uS if I recall, so of course not a real concern for this > application but it could be in other cases. Something to keep in mind when > comparing architectures. > > On Sun, Dec 1, 2019 at 5:00 PM Tim Shoppa tshoppa@gmail.com wrote: > > > Didier, I'm not sure I saw Bob write that 5uS was his goal. > > I don't think anyone would claim that ordinary cheap WiFi can achieve > > consistent sub-millisecond variations in latency. > > Tim N3QE > > On Sun, Dec 1, 2019 at 5:06 PM Didier Juges shalimr9@gmail.com wrote: > > > > > You should look at latency. The ESP8266 has serial (SPI) flash and a > > > relatively small internal cache. When the chip needs to load code from > > > flash, that can take a while, compared to the 5uS target. Great for cheap > > > IoT stuff, not so great for time sensitive, in my opinion. > > > On Sun, Dec 1, 2019 at 2:01 PM David david@mju.io wrote: > > > > > > > I'd think one of the ESP32's would be a fine choice. They have some > > > > good > > > > > > > power management options to wake up periodically to do the work, making > > > > for > > > > even lower power consumption. > > > > Looks like someone has already written some code that could be adapted? > > > > https://github.com/DennisSc/PPS-ntp-server/blob/master/README.md > > > > -David > > > > -------- Original Message -------- > > > > On Dec 1, 2019, 09:49, Bob kb8tq wrote: > > > > > > > > > Hi > > > > > So something like one of the many ESP32 based boards? > > > > > Of course when it comes to the “code from scratch” part there is the > > > > > problem that I’m > > > > > pretty (most would say very …) lazy :) :) :) > > > > > Bob > > > > > > > > > > > On Dec 1, 2019, at 12:29 PM, Poul-Henning Kamp phk@phk.freebsd.dk > > > > > > wrote: > > > > > > > > > > > You can do better than RPi, since a NTP server basically > > > > > > only needs to understand two packets: IP/UDP at port 123 > > > > > > and ARP packets. > > > > > > There are WiFi enabled microcontrollers that could be taught how > > > > > > to do that, but you'd have to write up your NTP daemon from scratch > > > > > > which is not hard when you do not have to do the "sync clock from > > > > > > remote servers" part. > > > > > > -- > > > > > > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > > > > > > phk@FreeBSD.ORG | TCP/IP since RFC 956 > > > > > > FreeBSD committer | BSD since 4.3-tahoe > > > > > > Never attribute to malice what can adequately be explained by > > > > > > incompetence. > > > > > > > > > > time-nuts mailing list -- time-nuts@lists.febo.com > > > > > To unsubscribe, go to > > > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > > > and follow the instructions there. > > > > > > > > time-nuts mailing list -- time-nuts@lists.febo.com > > > > To unsubscribe, go to > > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > > and follow the instructions there. > > > > > > time-nuts mailing list -- time-nuts@lists.febo.com > > > To unsubscribe, go to > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > and follow the instructions there. > > > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there.

BK

Bob kb8tq

Mon, Dec 2, 2019 11:55 AM

Hi

Indeed, if you get up into the “many tens” of ms, that rules it out in my application.
A consistent 90 ms would be ok, you could compensate for that. Random flopping
from 4 to 90 … not so much.

It seems like that sort of jitter would get in the way of a lot of things. I guess that just
shows how little I know about a lot of things :)

Bob

On Dec 1, 2019, at 11:18 PM, David Kern david@mju.io wrote: