Timing capabilities UNO, RTC, Ethernet Advice Please

I am about to tackle a project where I need to send a time stamp over ethernet to a terminal when the controller receives an event input on its I/O.

The hope is to get 1mS resolution and I am asking you guys who are experts at arduino process timing if it is possible, or do I just go to 1/100 Sec.
Of course an RTC of this resolution would also be needed.

The idea of going to a DUE is not out of the question either, but thought I'd try here before appearing to double up in the DUE section of the forum.

Tom...... :slight_smile:
(No I don't have a circuit diagram, but all my gnds are connected.. :D)

Why do you need 1ms resolution ? Sending it over ethernet is a lot slower than 1ms.
The normal RTC modules are not that accurate after an hour.

Do you know an RTC with that accuracy ?
Perhaps you have to use a 1kHz output of an RTC and connect that to the input of a 16-bit timer of the microcontroller (The ATmega chip on the Arduino board).

Does the timestamp have to be accurate only for the Arduino board itself, or also with other devices ?
If the time has to be accurate for example with something from the outside, I do not know how to match the Arduino to that external time.

What if it is allowed to have 2ms resolution ? If that was the case, you could use the timing of the Arduino. You could tune the crystal with capacitors of a few pF, and keep the crystal at the same temperature with a PID controlled heater. A timestamp could be simply the millis() function.

Hi, thanks for the reply, we are just throwing things around at the moment.
The stamp only has to be accurate at the arduino, it may in fact only be sent when an ethernet inquiry is made.
We even have thought of using a GPS in each arduino so that time is syncronised.

Thanks again for your input..Tom.... :slight_smile:

I need to send a time stamp over ethernet to a terminal

That depends on the terminal.

Most PC terminals can pick up the time from the local clock, which is likely to be a lot more accurate than an Arduino clock.

Usually, the only time you really need an on-board RTC is when you you are doing on-board recording.

No comment on the 1ms resolution, why you need it, how you get it, or how you broadcast it, other than that it may also be easier to do that at the other end than on the Arduino, if only by virtue of there being less data to send.