Hahah! My interest has been piqued! I found some interesting stuff in the firmware and I also have another idea to further enhance my enhancement and ultimately improve the tester project!
First things first, bad Gyro
You're BS'ing me!
As expected, the relay protection code is in the current source code trunk. Just search for the TPRELAY macro in the source. However, if you go back 2 versions (2 years ago) and look at ttester_111k, that code doesn't exists. Many manufacturers are behind on using latest firmware and they also modify them heavily. So no, many existing tester cannot be upgraded without new firmware.
Stepping back, a quick disclaimer, I did not want to waste time on the boring relay solution, therefore I did not look at the code carefully. In the event the macro was rename, I will stand corrected!
Here is the source of all the releases going back 5 years.
https://www.mikrocontroller.net/svnbrowser/transistortester/Software/tags/Back to my original enhancement idea, I did a bit more research and thinking and made good progress!
First, I found a 3PDT (9pin) momentary switch on ebay!
http://www.ebay.com/itm/ST9P02LB-3PDT-9Pin-Guitar-Effects-Pedal-Footswitch-Momentary-Switch-AC-125V-4A-/322653255134?hash=item4b1fa1f5de:g:tXUAAOSwOfdZuv7fI needed only 2 poles to short the 3 input pins together. I still have the 3rd pole that can be use as the test button!
Yup! It is possible to operate the tester with 1 fingers and have auto DUT discharge and tester protection! Just one button click and I can break the shorting of the 3 input pin and start the test!
Hon hon hon, unfortunately not so easy mon ami! I wasn't sure how the firmware was trapping for the button event to start the test cycle so I needed to take a quick look at the code first. On a side note Gyro, this was the main reason I looked at the code. I kind of already knew you were BS'ing me when I read your reply
.
What I found is the tester actually distinguish between short click and long click will run in different modes!
So my latest idea to implement a single button click solution may need a simple firmware change for newer testers (also maybe not! TBD). All the existing relay firmware code and the relay circuit can be tossed into the trash bin. No need to waste half or more of the battery on operating the relay. Simpler circuit, simpler code, and higher battery efficiency!
For owners of older testers, I suspect the old firmware will work with the 3PDT button unmodified as describe above since they don't have the new features that could get in the way.
And for those who want a guaranteed solution for all testers, new and old, ebay to the rescue! Just use my original enhancement idea with a DPDT momentary switch and perhaps 10 minutes of rewiring of the input pins to it.
http://www.ebay.com/itm/Red-6-Pin-DPDT-ON-ON-Momentary-Push-Button-Switch-AC-125V-5A-250V-2A-/232276845587?hash=item3614c76413:g:YRYAAOSwv0tVfYW2And use your 2 fingers! For those who don't even want to lift 2 fingers; well use your noggin to come up with something more clever!
Kidding aside, I have a new tester on order. It will take a month to get it in my hand. After I work out the kinks I'll contribute this back to AVR tester. I really like this tester and it will please me a lot that a community solution is superior in every way to the commercial solution.