Just a quick note here to raise a flag concerning module compatability, functionality and design.
I would guess that most people reading this probably know already that the company Espressif is the manufacturer of the ESP8266 chip and the producer of a couple of the reference designs to support it. Most (though not all) of the actual modules (the PCBs with the ESP8266 chip and additional components required to support it) are produced by other companies. The most prolific producer is “AI Thinker” and we (the hobbyist community) have a lot to thank them for — the low retail cost of the modules for one thing and the wide variation of different available designs for another. Equally so, there have been some fairly big bumps along the road, with modules getting into the supply chain with magic smoke issues (the “self healing” LED current limiting resistor problem) and confusion from both the vendors and recipients of various modules when the item received was markedly different from the item ordered (to be specific, I’m talking about the ESP-12 variants here, not odd vendor miss-ships).
The lack of useful documentation has been one of the main bugbears with the ESP8266 from the very start and AI Thinker have been a fairly major player in that particular field, even if you do happen to read Chinese.
Well, unfortunately it looks rather as though it’s happening again. Danny Von Lintzgy has left a couple of comments over at Pete Scargill’s blog noting that his product is pretty much dead in the water for the time being, as the latest batch of ESP-06 modules has different connections from all of those which he had received previously (the ESP-12 all over again). Danny says “It seems the new variant has three of the corner pads connected to pins, where previously all four corner pads were connected to ground“. That’s a pretty major change to have happen without any notification or hints (even the ESP12E at least had visible, extra pads).
So, if you’re using ESP-06 modules, please take note of Danny’s warning and be very careful with any new modules you purchase. It doesn’t sound like a magic smoke issue, but if your new ESP-06 won’t boot and won’t program, this could be the reason.
Update – Danny has reported that AI Thinker support got back to him with the news that there are currently three versions of the ESP-06 out there. The first is the older original, then (most worrying) there’s a not-quite-right version of the new design (which apparently has a problem with one of the resistors — but no news yet as to what sort of issues, if any, this errant resistor causes) and the last is the new design with the resistor problem corrected. Apparently, the original and the newer versions have a slightly different AI Thinker logo on the outside of the RF shielding with (I believe) the newer versions having WiFi-style radio waves radiating from the head of the character which makes up the stylized “I” of the “AI”.