Verifying the timing between relay activations I would like to verify timings of a relay controlled by an arduino (uno R3). There is a lot going on in the sketch and it does not use the delay function but one which is based on counting milliseconds. The arduino then transmits to another arduino using a radio module (nRF24L01). I'd like to confirm the intervals between the relay, so for instance if the relay is acivated 10 times and there are 5 seconds between each actvation.

So what I was wondering was whether anyone had any reccomendations on methods to verify timings using an external source.

Two ideas I came up with were: have another arduino with a very simple script that measures the timings or try and find/write a verilog script to upload to a mojo fpga and measures the timings.

An ideal situation would be where I have a seperate device that hooks up to the relay and then measures and displays the timings between the relay switches and is extremely precise.

I hope that makes sense, if not please let me know and I'll explain further. Thank you for reading and any help is greatly appriciated.
You could use sigrok with one of the many supported devices.
For example, you can find on ebay an 8 channell 24MHz probe for less than $10.

It's a nice tool to have laying around. For example you can use it as less-invasive-than-serial-print way to detect when internal states of a program change value: just toggle some unused GPIO.