PlatformIO Community

Moving ESP8266 Arduino project to platformio core : reset loop


Dear community,

I’m trying to change the build system of my ESP8266 project from Arduino to PlatformIO core.

The board I use within the Arduino IDE is the “Generic ESP8266 module” that comes shipped with the ESP8266 Arduino Core

I wrote a custom PlatformIO JSON file for my board description that fits the settings I use in Arduino. The flash settings, method, CPU freq, etc, are supposed to be all good - and, in effect, it seemed to work at first: I can build the project, upload it to my board, and I’m also able to flash the SPIFFS using platformio run -t uploadfs. No compilation error or anything.

However, when I try to turn on the board after flashing, the ESP displays a rapidly blinking blue light (which seems to mean panic, or so I’ve been told) outputs this about every second on the serial monitor (at 115200 bds)

ets Jan  8 2013,rst cause:2, boot mode:(3,6)

load 0x4010f000, len 1384, room 16 
tail 8
chksum 0x2d
csum 0x2d

From what I could gather the rst cause:2 on the first line means a software watch dog reset. I must be doing something wrong but I can’t figure out what. Manually flashing the binary with esptool gives the same result (Arduino-generated binary works, PIO’s do not). Flashing the SPIFFS with PlatformIO also works as expected, so it seems the problem is a compilation problem and not about flashing, etc…

When I compare the binaries generated by Arduino and platform IO, Arduino’s .bin is slightly smaller (about 20 KiB difference), and PIO’s ELF file is about 3 times bigger (1,2 MiB PIO vs. 460 KiB Arduino…)

$ ls -l build/WeatherStation.ino.*                    

-rwxr-xr-x 1 erwan erwan 4600587 Feb 13 10:47 build/WeatherStation.ino.elf
-rw-r–r-- 1 erwan erwan 417968 Feb 13 10:47 build/WeatherStation.ino.bin

ls -l .pioenvs/coolboard/firmware.*                                 
-rw-r--r-- 1 erwan erwan  437344 Feb 13 02:02 .pioenvs/coolboard/firmware.bin
-rwxr-xr-x 1 erwan erwan 1211763 Feb 13 02:07 .pioenvs/coolboard/firmware.elf

Here is my board description file:

  "build": {
    "core": "esp8266",
    "extra_flags": "-DESP8266 -DARDUINO_ARCH_ESP8266",
    "f_cpu": "80000000L",
    "f_flash": "40000000L",
    "flash_mode": "dio",
    "ldscript": "eagle.flash.4m1m.ld",
    "mcu": "esp8266",
    "variant": "generic"
  "connectivity": [
  "frameworks": [
  "name": "La COOL Board",
  "upload": {
    "maximum_ram_size": 81920,
    "maximum_size": 4194304,
    "require_upload_port": true,
    "resetmethod": "ck",
    "speed": 115200
  "url": "",
  "vendor": "La COOL Co"

And my platformio.ini:


platform = espressif8266
framework = arduino
board = coolboard
lib_deps =


Could you try to disable OneWire lib?


@ivankravets, as suggested I removed the OneWire lib and all dependent code, started from scratch with a new virtualenv and fresh git clone of the OneWire-free code. Unfortunately, still no luck…

 ets Jan  8 2013,rst cause:2, boot mode:(3,6)

load 0x4010f000, len 1384, room 16 
tail 8
chksum 0x2d
csum 0x2d

I guess I’ll have a look at the compilation command lines and figure out what’s different between gcc or ar calls made by arduino and PIO, then try to find the right compilation flags… Any other pointer would be greatly appreciated, though !


Could you try staging version?