esp8266/doc/generic.md

Upload via serial port

Pick the correct serial port. You need to put ESP8266 into bootloader mode before uploading code.

Power Supply

For stable use of the ESP8266 a power supply with 3.3V and >= 250mA is required.

• Note

• Using the Power available from the USB to Serial adapter is not reccomended, these adapters typically do not supply enough current to run the ESP8266 reliably in every situation, an external supply or regulator is preferred.

Serial Adapter

There are many different USB to Serial adapters / boards.

• Note

• for full upload management you need RTS and DTR
• the chip need to have 3.3V TTL (5V may damage the chip)
• not all board have all pins of the ICs as breakout (check before order)
• CTS and DSR are not useful for upload (they are Inputs)

• Working ICs

• FT232RL
• CP2102
• may others (drop a comment)

Minimal Hardware Setup for Bootloading and Usage

ESPxx Hardware

PIN	Resistor	Serial Adapter
VCC		VCC (3.3V)
GND		GND
TX or GPIO2*		RX
RX		TX
GPIO0	PullUp	DTR
Reset*	PullUp	RTS
GPIO15*	PullDown
CH_PD	PullUp

• Note

• GPIO15 is also named MTDO
• Reset is also named RSBT or REST (adding PullUp improves the stability of the Module)
• GPIO2 is alternative TX for the boot loader mode
• Directly connecting a pin to VCC or GND is not a substitute for a PullUp or PullDown resistor, doing this can break upload management and the serial console, instability has also been noted in some cases.

ESP to Serial

Minimal Hardware Setup for Bootloading only

ESPxx Hardware

PIN	Resistor	Serial Adapter
VCC		VCC (3.3V)
GND		GND
TX or GPIO2		RX
RX		TX
GPIO0		GND
Reset		RTS*
GPIO15	PullDown
CH_PD	PullUp

• Note
  • if no RTS is used a manual power toggle is needed

Minimal Hardware Setup for Running only

ESPxx Hardware

PIN	Resistor	Power supply
VCC		VCC (3.3V)
GND		GND
GPIO0	PullUp
GPIO15	PullDown
CH_PD	PullUp

Minimal

Improved Stability