Connecting with a breadboard

You can use one of the following things to connect ESP8266 with a breadboard:

Using female/male extension jumper wires (https://www.adafruit.com/product/1954)
Using a 10-pin IDC breakout helper (https://www.adafruit.com/product/2102)

Power supply

The ESP8266 works only with regulated 3.3V. You can build a simple regulated power supply with an LD1117-3.3 linear voltage regulator. It can provide 3.3V at 800 mA. You can purchase a TO-220 package of the LD1117-3.3 for use with a breadboard. Figure 1.5 shows the circuit diagram for 3.3V output. You can supply 4-15V DC to V_in using one of the following sources:

7V LiPo battery
5V power bank
9V battery
5V "wall wart" power supply

Figure 1.5: 3.3V regulated power supply circuit diagram

Now, you can connect the power supply to ESP-01:

Connect Vout to the V_cc pin of ESP-01.
Connect GND to the GND pin of ESP-01.

Connecting through USB for flashing

ESP8266 ESP-01 doesn't have a built-in USB to serial conversion chip to directly connect to your computer through a USB cable for flashing programs. As a solution, you can use a USB to TTL serial console cable to connect ESP8266 to a computer. Figure 1.6 shows a USB TTL serial console cable from Adafruit (https://www.adafruit.com/product/954):

Figure 1.6: A USB to TTL serial console cable. Image courtesy of Adafruit Industries (https://www.adafruit.com)

The type A USB plug includes a USB to serial conversion chip and provides four wires to connect to your ESP8266ESP-01 board. Table 1.1 shows the functions of the four wires:

Color	Function
Red	Power
Black	Ground
White	RX
Green	TX

Table 1.1: Color codes and functions of wires

You can use the following steps to connect the USB to TTL serial cable with your ESP8266:

Connect the white RX wire of the cable to the TX pin of ESP8266
Connect the green TX wire of the cable to the RX pin of ESP8266
Connect the black ground wire of the cable to the GND pin of ESP8266
Connect the CH_PD pin of ESP8266 to the V_cc wire of the power supply

Don't connect the red power wire because it is 5V.

Using a serial terminal program

The following steps will guide you how to use a serial terminal program to communicate and execute AT commands with ESP-01. In this example, you will use PuTTY, SSH, and a Telnet client for Windows to run AT commands through a serial port:

First, download the latest PuTTY MSI installer or binary from the following sources:
- MSI (Windows installer):
  - 32-bit: putty-0.70-installer.msi (https://the.earth.li/~sgtatham/putty/latest/w32/putty-0.70-installer.msi)
  - 64-bit: putty-64bit-0.70-installer.msi (https://the.earth.li/~sgtatham/putty/latest/w64/putty-64bit-0.70-installer.msi)
- Binary:
  - 32-bit: putty.exe (https://the.earth.li/~sgtatham/putty/latest/w32/putty.exe)
  - 64-bit: putty.exe (https://the.earth.li/~sgtatham/putty/latest/w64/putty.exe)

Open the PuTTY Configuration window by double clicking on putty.exe or the putty shortcut.
In the Serial line text box, type the COM port that is assigned to your ESP8266 board (Figure 1.7).
In the Speed text box, type 115200 as the baud rate.

Click on the Open button to make a serial connection:

Figure 1.7: The PuTTY configuration window

If you have provided the correct settings, the serial connection will establish between ESP8266 and your computer.
You can use the serial terminal window to issue AT commands for ESP8266 from your computer.

AT commands

Table 1.2 shows the complete set of AT commands that you can use with ESP8266:

AT command	Manual
`AT`	Attention.
`AT+RST`	Resetting the unit.
`AT+GMR`	Retrieving the firmware version ID.
`AT+CWMODE=?` `AT+CWMODE?` `AT+CWMODE=<mode>`	Setting operation mode: Client Access point Client and access point The access point functionality does not have a DHCP function and has only minimum functionalities. However, it will assign an IP address to the client and there is no way to do a manual IP, manual DNS, and other advanced IP functionalities. This unit only provides minimal functionalities.
`AT+CWJAP=<ssid>,<pwd>` `AT+CWJAP?`	Joining a network or just an access point.
`AT+CWLAP`	Retrieving the list of the visible network.
`AT+CWQAP`	Disconnecting from the current network connection.
`AT+CWSAP=<ssid>,<pwd>,<chi>,<ecn>` `AT+CWSAP?`	Setting up access point SSID, password, RF channel, and security scheme. The following is the security scheme: `0`: Open. No security. `1`: `WEP`. `2`: `WPA_PSK`. `3`: `WPA2_PSK`. `4`: `WPA_WPA2_PSK`.
`AT+CWLF`	Retrieving a list of assigned IP addresses.
`AT+CIPSTATUS`	Retrieving the current connection as socket client or socket server.
`AT+CIPSTART=?` `AT+CIPSTART=<type>,<addr>,<port> (AT+CIPMUX=0)` `AT+CIPSTART=<id>,<type>,<port> (AT+CIPMUX=1)`	Connecting to socket server (TCP or UDP).
`AT+CIPSEND=<length> (AT+CIPMUX=0 & AT+CIPMODE=0)` `AT+CIPSEND=<id>,<length> (AT+CIPMUX=1 & AT+CIPMODE=0)` `AT+CIPSEND (AT+CIPMUX=0 & AT+CIPMODE=1)`	Sending by connection channel and by specific length.
`AT+CIPCLOSE`	Closing the socket connection.
`AT+CIFSR`	Retrieving the assigned IP address when the unit is connecting to a network.
`AT+ CIPMUX=AT+CIPMUX?`	Setting a single connection (`AT+CIPMUX=0`) or multi-channel connection (`AT+CIPMUX=1`).
`AT+CIPSERVER= [,] (AT+CIPMUX=1)`	Starting at the specified port or stopping the server. The default port is `333`. `<mod>` is as follows: `0`: Close the socket server `1`: Open the socket server
`AT+CIPMODE=<mode>` `AT+CIPMODE?`	Setting transparent mode (data from the socket client will be sent to the serial port as is) or connection channel specific mode (`+IPD`,`<connection channel>`,`<length>`) segments. Data sent from the socket client will be broken into multiple unsolicited (`+IPD`,`<connection channel>`,`<length>`) segments. `<mode>`is as follows: `0`: Data received will be sent to the serial port with a `+IPD`,`<connection channel>`,`<length>` format. (`AT+CIPMUX=[0,1]`) `1`: Data received will be sent to the serial port as a data stream. (`AT+CIPMUX=0`)
`AT+CIPSTO=<time>` `AT+CIPSTO?`	Setting the automatic socket client disconnection timeout from `1` to `28800` seconds due to inactivities.
Packetized data from the unit	Unsolicited data packet (`+IPD`, `<connection channel>`,`<length>`).