Lessons Learned with ESP-201

I recently ordered several more ESP8266 modules, and of that set, I decided to get a couple of ESP-201’s. These were appealing because they’re still fairly bare-bones (and therefore extremely cheap – about $4US each), lacking an on-bard regulator or serial chip, but they also bring out a lot more IO lines to pin pads, and seemed more convenient for plugging into a prototyping breadboard.

UPDATE : Note that, as noted on another blog, “Compared to ESP-12 this module has 6 more pins broken out – D0, D1, D2, D3, CLK, CMD (GPIO6-GPIO11). But only two of them (D2, D3) can be used as regular GPIOs after slight hardware modification.” Yuck! Looking forward to the ESP32!

I encountered a couple of issues that took a fair amount of googling to figure out, so I figured I’d pass them on.

First, as others have pointed out, the pin labels are on the underside, which is really annoying.  like most ESP8266’s, you have to pull CH_EN high, and to flash it, you have to pull GPIO0 low. You ALSO have to pull GPIO15 LOW, though, which is different from other ESP variants. Once I pulled 15 low, GPIO2 high, and GPIO0 low, I was able to flash the module.

However…I was flashing a NodeMCU image onto them, intending to keep it consistent with the other modules I’ve been playing with for my Light Suit V2 project. But it turns out, the ESP-201 is specifically designed to work with the SDK and it does NOT work with NodeMCU flash images. You pretty much much need to use the SDK or, as I do, use the Arduino plugin to handle the compiling and flashing for you.

CORRECTION: ESP-201 WORKS FINE with NodeMCU, you just have to have the pin levels
right a boot to get it into a mode where you can load .lua files and run on boot – specifically, pull CH_EN high, as you normally do, and pull their pin “IO15” (really pin 13 on the chip, I guess?) LOW. To flash, pull GPIO0 low, as usual. This wound up working and now I’m much happier 🙂

The Arduino plugin makes coding with ESP’s really easy since it builds and flashes your code to the module in one easy step without requiring you to go learn complex code build chain crap. Once I switched to that environment, the usual process of pulling GPIO0 high, followed by programming, worked well.  I haven’t really done much with it yet, but I presume it will work pretty much like any other variant using the Arduino toolset.

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