So what the @#$ is your problem?
I guess every forum needs at least one over-the-top protocol nazi.
You know, I've been called a lot of things here on the forum, but I think you're the first to actually nail it.
Yeah, protocol nazi, that would be me. ;D
As I was soldering them back on, I noticed that there was a row of solder connectors on the other side,
The correct term is "through-hole solder pads" (="solder connectors").
They're not called solder connectors because the word "connector" , in electronics, means some "thing",
(as opposed to some "hole")
I then included a link to a source with a photo that had a close-up of the tx/rx pins.
They are not connected. I though it would be nice if they output serial data - but they don't when I checked.
It looks like Paul already checked those pins and they aren't connected.
Yeah I need some spare time to figure out how a scope even works. I picked up one of those pocket ones shaped like a small cell phone but have never really used one before so I'm wallowing any time I pick it up.
And yes, the electronics are under the LED
I suppose you could try your scope to see if there is anything on those pins.
If there had been , the following describes how one might read it. Since there probably isn't any serial data on those pins, you can disregard the following , unless you have nothing else to do and want to read it for future reference.
Good news/Bad news:
The bad news first:
The tx/rx pins of the meter are probably the interface between the meter circuit and the display circuit.
It's probably a microprocessor meter with a serial display. One way to find out is to solder a couple of wires to it and connect it to a PC running a terminal program. The bad news is your going to need to convert that to RS232 to connect it to a PC. Then you can run the terminal program and hopefully see the ASCII sent by the meter circuit to the display.
If you're the hacker type and have the patience and are up to the challenge, you , or your electronics friends (who weren't much help) can hack those three wires and connect them to a PC to see what's going on there.
The Good news: , that part should actually be easy.
Those holes look to be designed for a male header connector. You can use them to connect some 20 guage solid wire to plug into a breadboard.
You have two options:
Option-A: Order the ebay converter and make your serial cable to plug the DB9 of the converter to the DB9 of your PC. You'll have to experiment with all the different baud rates but I would try 9600 first.
I think we can assume the start bits , stop bits and parity are all 1.
Option-B: Buy a MAX232 chip and breadboard the converter circuit and make a cable with 20 guage solid wire at one end and a female DB9 at the other end and connect the RS232 side of the circuit to the PC with that custom cable. The TTL serial side of the chip would connect to the two wires + GND that you soldered to the back side of the PCB. If you had access to a scope, the first thing you would want to do is look at the signals on those pins to verify it is 5V TTL serial. Someone who really knows C++ could probably read the data but without knowing the correct baud rate that could be a tedious process of trying all of them. A terminal program is much easier because you just try everyone until you get to the right one and then the garbage turns into readable characters.
Do you have any terminal programs like Clear Terminal or Hyperterminal ?
The serial is probably TTL 5V level, not RS232 so you need some way to connect those pins to your pc or laptop but the problem is the DB9 RS232 connector on a PC is rs232 so you would need an RS232 to TTL SERIAL converter like this.
This converter has a femaie DB9. The PC has a male. if you can't find a male-female cable you can modify whatever you find by adding the appropriate male -male or female - female gender changer.
Don't waste any time trying to use an arduino to communicate with it. It can be done, but only if your specialty is software, particularly C++. It's much faster to just connect it to a PC and run a terminal emulation program. I have one called Clear Terminal, one called Real Term and one called Hyperterminal.
I'm running Win 7 so I don't have the Hyperterminal that everyone is familiar with from XP. There is a company that has a free download program called HyperTerminalÒ Private Edition 6.4
by Hilgraeve Inc., that does a pretty good job of emulating the XP Hyperterminal we're all familiar with.
I tested it and it works. You need to connect the tx of your lcd meter to the rx of your RS232 converter on the TTL side and the rx of your meter to the tx of the converter on the TTL side. Run the terminal program to see if there is any data on those pins. If you don't get anything you could try hitting the enter key to see if anything comes back. I seriously doubt those pins were intended for the end user to mess with so don't be surprised if all you wind up with is a serial output for your meter voltage.
Good Luck Mr. Phelps.
As always, should you be captured the Secretary will disavow any knowledge of your mission.
This tape will self destruct in 5 seconds.....
Something about porcine avionics comes to mind.
I think "When PIGS FLY !" sounds better ...(but that's just me)
I wouldn't call " notes in my program code" "documentation".
"Documentation is hard copy kept in an alphabetcally sorted file or copy kept in an alphabetically sorted folder of subfolders ;
ie: Meters/panel/ modules/7-segment
It sounds like you are saying all your documentaion is scattered through your program code files. What good is that if it is not all located in one central location ? I'm not seeing the usefulness of storing hardware reference documentation in software files. How could you remember which software file it was stored in?
Wallowing is bad. Don't do that. Post on this topic for the pocket scope with the vendor link.
I can name two senior members that have something similar who could probably help you.
That's the "protocol".
I would know, wouldn't I ?