Sorry for leaving you guys hanging for a while, I didn't get the notification that someone had responded.
Hi,
Don't it has anything to do with probing the circuit, looks to me like two outputs are connected together.
Maybe it's caused by poor power supply decoupling, put a low esr capacitor across the power supply pins of the ESP8266-05.
Tried the cap, same.
Your scope isn't an a 50 Ohm input mode, is it?
What happens if, say, you keep the scope set up the same way, but probe across a AA battery? Does it read a sensible voltage then?
What if you then put a 10k resistor between the battery + terminal and the tip of the probe? Does it read the same, or something wildly different?
I made the 50 Ohm mistake before on a different project (I really think they should hide that more, or have a confirmation box or something, its dangerous...) but no, that was one of the first things I checked. Battery test works as expected.
Maybe it is a floating ground problem. Try using differential probing. (A-B)
I don't have a differential probe, unless you mean just use two and then use math, but even without connecting the ground it starts screwing up, I can't imagine how connecting another channel to another pin will reverse that, but if you insist I could try that.
Some things I noticed based on the pictures.
That's not the normal probes for the ds4k. Make sure you have 1x/10x configured. On those probes and in the scope.
Is the rs232 signal TTL 5v/3.3v or the "real rs232" ~15v
Good eye, I sold the probes on eBay and bought cheaper ones because I wanted 1x and didn't need high bandwidth capabilities (probably not my smartest move because I think I pretty much gave them away but thats another story). The scope is set for 1x just like the probe, and 10x doesn't change anything.
The RS323 is 3.3V, I've never heard of 15V, but nothing like that is coming out of my USB port.
This house may or maynot have grounding issues (it's just some cheap student apartment) but I thought the ground line is independent from earth ground?