How to setup and configure PlatformIO for Tasmota compilation and upload.
Download PlatformIO from http://platformio.org/
Install PlatformIO to a known folder.
Download the latest Tasmota Source code from https://github.com/arendst/Tasmota and unzip to another known folder.
Copy all files from the Tasmota Source code into your PlatformIO base folder.
The default environment configuration can be used to easily generate Tasmota firmware variants (sonoff, sensors, display, etc.). If you're not sure which binary is the right one for you, consult the builds table or just start with tasmota.bin. To build and/or flash exactly one of these, uncomment (i.e., remove the leading ;) the env_default line for the variant you need. To compile more than one binary variant, uncomment all of the desired env_default lines in the platformio.ini file.
Select Build from the menu.
PlatformIO uses the serial interface to upload the firmware to your device. On Windows these interfaces are named COM ports (COM1, COM2, etc.). On Linux these interfaces are named TTY ports (e.g., /dev/ttyUSB0, /dev/ttyUSB1, etc.).
When performing a firmware upload do not connect the device to AC. Use a 3.3v DC power supply such as that provided by your serial programming adapter.
Put the device in programming mode by grounding pin GPIO0 and then applying power (e.g., connecting your computer to the serial adapter). Grounding pin GPIO0 can often be achieved by pressing the button on the device or using a wire between GPIO0 and GND if the button is not available. Deviations may apply.
Select Upload from the menu.
NOTE: For a proper device initialization after first firmware upload power down and power up the device.