When Chip is powered on, with GPIO0 pulled up, it enter into firmware downloading mode.

Download / install / git clone esptool.

Example usage:

./esptool.py --port /dev/ttyUSB1 --baud 9600 write_flash 0 ../nodemcu_float_0.9.6-dev_20150704.bin

Connecting...
Erasing flash...
Writing at 0x00001400... (1 %)

Erasing flash...
Wrote 462848 bytes at 0x00000000 in 520.5 seconds (7.1 kbit/s)...

Leaving...

./esptool.py --port /dev/ttyUSB1 --baud 9600 write_flash 0 ../nodemcu_float_0.9.6-dev_20150704.bin

./esptool.py --port /dev/ttyUSB1 --baud 115200 write_flash 0 ../nodemcu_float_0.9.6-dev_20150704.bin

nodemcu-master-14-modules-2016-06-27-15-50-54-float.bin

• 32Mbit (512kB+512kB)
• 32Mbit-C1 (1024kB+1024kB)
  • 0x00000 boot_v1.2+.bin
  • 0x01000 user1.2048.new.5.bin
  • 0x3fc000 (optional) esp_init_data_default.bin
  • 0xfe000 & 0x3fe000 blank.bin