Espressif Systems ESP8266 Beginner's Manual page 3

1. Connect the ground (GND) of the USB-to-Serial converter to the ground of the ESP8266.
2. Connect the RX-pin of the USB-to-Serial converter to the TXD pin of the ESP8266. (On some boards, it's labelled TX instead of
TXD, but it's the same pin.)
3. Connect the TX-pin of the USB-to-Serial converter to the RXD pin of the ESP8266. (On some boards, it's labelled RX instead of
RXD, but it's the same pin.)
4. If your ESP8266 board has a DTR pin, connect it to the DTR pin of the USB-to-Serial converter. This enables auto-reset when
uploading a sketch, more on that later.
Enabling the chip
If you're using a bare-bone ESP-## board by AI Thinker, you have to add some resistors to turn on the ESP8266, and to select the right
boot mode.
1. Enable the chip by connecting the CH_PD (Chip Power Down, sometimes labeled CH_EN or chip enable) pin to V
resistor.
2. Disable SD-card boot by connecting GPIO15 to ground through a 10KΩ resistor.
3. Select normal boot mode by connecting GPIO0 to V
4. Prevent random resets by connecting the RST (reset) pin to V
5. Make sure you don't have anything connected to GPIO2 (more information in the next chapter).
Adding reset and program buttons
If your ESP8266 board doesn't have a reset button, you could add one by connecting a push button to between the RST pin and
ground.
To put the chip into programming mode, you have to pull GPIO0 low during startup. That's why we also need a program button.
Because it's possible to use GPIO0 as an output, we can't directly short it to ground, that could damage the chip. To prevent this,
connect 470Ω resistor in series with the switch. It's important that this resistance is low enough, otherwise, it will be pulled high by the
10KΩ resistor we added in the previous paragraph.
Connecting the power supply
If the ESP8266 module you have doesn't have a 3.3V voltage regulator on board, you have to add one externally. You could use an
LM1117-3.3 for example.
1. Connect the first pin of the regulator to ground.
2. Place a 10µF capacitor between pin 2 (V
3. Place a 10µF capacitor between pin 3 (V
4. Connect pin 2 to the 3.3V or V
5. Connect pin 3 to a 5V power source, a USB port, for example.
through a 10KΩ resistor.
CC
) and ground. Watch the polarity!
out
) and ground.
in
of the ESP8266.
CC
through a 10KΩ resistor.
CC
through a 10KΩ
CC