Requirements
- USB ESP01 Programmer Adapter (Hardware)

- CP201x driver (Windows)
- ESP-01 MCU (4Mbit / 512 Kb flash size)
- Expressif Flash Tool (flash_download_tool.exe and version 3.9.0)
- Expressif Firmware
- NONOS SDK 2.1
- Version 1.6.2
Mount the EPS01 module (Blue board, Flash 4MBit / 512 Kb) on the header of USB ESP01 Programmer Adapter
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Download the Espressif’s Flash Download Tool (zip compress)
https://www.espressif.com/en/support/download/other-tools
Extract the compressed file from your download folder
Download the ESP8266 Firmware for 4MBit( 512 Kb) and SDK V2.0 (AT Bin V1.6.2)
https://www.espressif.com/en/support/download/at

Setup the Expressif’s Flash Tool (flash_download_tool.exe) version 3.9.0
SPI SPEED | 40MHz |
SPI MODE | QIO |
FLASH SIZE | 4Mbit |

blank.bin | 0x7B000 |
esp_init_data_default.bin | 0x7C000 |
blank.bin | 0x7E000 |
boot.bin | 0x00000 |
user1.bin | 0x01000 |
user2.bin | 0x41000 |
COM | COM3 (a Port value from Device Manager) |
BAUD | 115200 |

Verify firmware was sucessfuly flash
Putty (Serial Terminal Software)

AT+GMR command to check the SDK version installed.
Type AT+GMR then follow by CTRL+M CTRL+J

Resources
Expressif Quick Start Guide
https://www.espressif.com/sites/default/files/documentation/esp8266_quick_start_guide_en.pdf