Re: AVR Scope Clock

John Clark

Another small update on this. I found the clock was running fast, somewhere around 30-60 seconds per day. So I set out for a solution (low cost, of course.) I found an old GlobalSat BT-359 in a box that I used back in the day for bluetooth GPS to some small Fujitsu laptops we used in our company airplanes during the early days of going to paperless nav charts (before iPads.) Only problem is, it's bluetooth and the scope clock needs serial data. However, I opened it up and found loads of test points on the board so I figured there might be some hope! I started probing around with my 314 and found some points that looked like the right data but I wasn't sure. I then found this thread on the Arduino forums. See specifically post #3:

So, probing TP4 showed a 3.3v data signal with some kind of additional pulse on it at that appeared about once per second. So, I gave it a shot. I soldered a wire to TP4, as well as a ground wire and hooked TP4 up to the middle pin of the RXRoute header on the clock board and the other wire to ground on the clock board. I set my local Zulu offset in the clock's GPS settings , as well as the proper baud rate and voila! The time updated! Just as the Arduino forum post said, I had to use 38400 baud rather than the 4800 that Dutchtronix recommended but within a few seconds the clock flashed "G" for about 4-5 seconds and reset the time.

Now the scope clock updates itself automatically from the small bluetooth GPS


From: <> on behalf of John Clark <>
Sent: Thursday, December 20, 2018 5:02 PM
Subject: Re: [TekScopes] AVR Scope Clock

If anyone else is interested it looks like he has these AVR clock kits back in stock and available to order online. Every time I've looked they've been out of stock.

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