for programming my ESP-01 chip I bought an "USB Uart", but it looks different to all the ones in all tutorials. I don't know how to connect the uart to the esp. The uart i bought has following pins: 3V3, DTR, RXI, TX0, GND, +5V. The ESP01 has the known layout (http://www.esp8266.com/wiki/doku.php?id=esp8266-module-family#esp-01).

Once connected: Do I need an external power source, or do i just connect the usb uart to my computer?

Many thanks

  • A Beginner's Guide to the ESP8266 Yes, you need an external power supply. Note that programming it would be much easier if you bought a USB-to-Serial adapter that breaks out both the DTR and RTS control lines. Or even better, get a WeMos D1 mini or similar.
    – tttapa
    Jan 7, 2018 at 15:58
  • @tttapa, why external power supply? I don't use one if connected to USB to UART.
    – Juraj
    Jan 7, 2018 at 16:08
  • 1
    @Juraj, the ESP8266 draws a lot of current, especially during WiFi transmission. The 3.3V from the USB to UART is just for the output drivers and maybe some external logic, it's not meant for driving any real loads. For instance, the 3.3V output from an FT232R is only rated for 50 mA. It can't handle the peak currents needed for RF communication. The ESP8266 can draw up to 300mA peak. Many people experience instability because of an incapable power supply.
    – tttapa
    Jan 7, 2018 at 16:21
  • Thanks so far for the answers. Recording to the "Beginner's Guide" i have connected the pins tx, rx and gnd to the esp01. Understanding this guide correctly i now need to connect the CH_PD and GPIO0 with a 10k resistor to Vcc, So after adding a power source i can start programming, right?
    – sporc
    Jan 7, 2018 at 16:34
  • @tttapa, but for flashing is the 50 mA enough.
    – Juraj
    Jan 7, 2018 at 17:13

2 Answers 2


Just to give an anwser for users struggling with the same problem I will sum up what helped me.

To connect the UART to the ESP the Beginner's Guide to the ESP8266 from @tttapa was very helpful. Another helpful link was this one: https://www.allaboutcircuits.com/projects/flashing-the-ESP-01-firmware-to-SDK-v2.0.0-is-easier-now/

So in my case I just needed the GND, 3V3, RXI and TX0 pins from my UART.

I needed no external powersupply for the flashing process and some simple examples.


You can program the ESP-01 whith described method in this page:


Its works fine!

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