Introduction: Flash AT Command Firmware to ESP01 Module (requires a USB to TTL Adapter)

About: fb @ geeameal

By Jay Amiel Ajoc

Gensan PH

Step 1: Get the Necessary Files

Step 2: Preparations for Flashing

1. Open "esp8266_flasher.exe"

2. Load the BIN File “ai-thinker-v1.1.1.bin”. You may check this link if you want a different version :

3. Type in the proper COM port, if you don’t know what’s the COM Port, head over to Device Manager >> Ports (COM & LPT), it should be there. If not, then there’s something wrong with your adapter.

To fix it, click here(There’s a part there that’ll guide you on how to reinstall the driver or you can google on your own, whatever suits you)

Step 3: Make the Connections

1. Make the following connections

a. USB to TTL Tx - ESP Rx

b. USB to TTL Rx - ESP Tx

c. USB to TTL 3.3V - ESP VCC & CH_PD (ESP01 is 5V intolerant!)

d. USB to TTL GND - ESP GND & GPIO0 (Take note of this pin, it should be removed when sending AT commands later on, for now just keep it plugged)

Then click Download

Step 4: Downloading

1.You should have something like this. If in the end it says, “failed to leave flash mode”, don’t worry. The flashing is already done by that time.

Step 5: Testing

1. After it’s done, open Arduino IDE. Select the proper COM Port in Tools >> Port

2. Before anything else, redo the connections by simply unplugging the GPIO0 (only this pin has to be removed)

a. USB to TTL Tx - ESP Rx

b. USB to TTL Rx - ESP Tx

c. USB to TTL 3.3V - ESP VCC & CH_PD


3. Open the Serial Monitor (Both NL & CR, 115200 baud or sometimes trial and error will work, just try different combinations)

4. Type in “AT” (not case sensitive), then press Enter, it should return “Ok”

5. Done!