ESP8266-01s keeps getting damaged after programming through Arduino UNO

I've been using the UNO board to program the ESP8266-01s and it works the first couple of times. However the chips just keep getting broken after while. I say this because they overheat after powering them up and I can't program them anymore.
The connection I've been using to program is the following:
UNO -> ESP8266
Rx -> Rx
Tx -> Tx
3,3V -> 3,3V
3,3V -> EN

I've read some things on the internet but nothing precise. I would be thankful for any help you can give me.


Could the fact that the Uno is a 5V device and the ESP is a 3.3V device have anything to do with it ?

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DON'T do this! You are pumping 5V in to a 3.3V tollerant pin. If you MUST do this, place a 10K resistor in line.

Also, Rx to Rx and Tx to Tx is kinda different. I typically transmit from one device to be received on the other device.

Uno Tx to esp8266 Rx.
esp8266 Tx to Uno Rx.

RX,TX are the labels from the MCU's point of view, not from the USB<>Serial chip.

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I will try this next time.
thank you

I'm not communicating the MUC on the UNO board with the ESP, I'm just using the USB to TTL on the board to program the ESP8266.

The ESP8266 expects 3.3volt TTL. 5volt TTL from the Uno could fry it.

I use a NodeMCU to program ESP8266 modules.
There are also special (3.3volt) programmers for these modules.

Edit: Watch this.

To program the ESP-01, you use a purpose-built USB programming adapter:
Aliexpress item
At least, that is the manual switching version; here is the automatic version which while it does have the reset button, initiates the programming directly from the Arduino IDE:
Aliexpress item
Similarly, to actually use the ESP-01 in a project, a very convenient way is with the cheaper adapter board, plugged into a USB "phone charger" so you have both the 5 V and 3.3 V conveniently and adequately supplied.
Aliexpress item
You have three GPIO conveniently available by soldering to the adapter, and the fourth - serial Rx - can be separated from the USB chip if necessary by cutting a track. Using those I/O you can connect port expanders for many more I/O connections and a variety of sensors.

Just being really safe actually, not supposing that 1 mA is actually desirable.

As long as the input capacitance of the ESP does not slow logic transitions, the 10k, mounted close to the ESP, will be just fine.

But I say - get the proper programmer, much more practical if you are going to seriously do this stuff.

By the way, on a **real** UNO, there is already a 1k resistor in series with the output of the 16U2 USB interface chip which is producing 5 V levels, while on a fake UNO, the USB chip may be generating 3.3 V levels anyway. As mentioned, the "328" chip is disabled.
Whoah! Where did Raschemmel's comment, to which I was responding, go?

DON'T do this! You are pumping 5V in to a 3.3V tollerant pin. If you MUST do this, place a 10K resistor in line."

The "L" word is not allowed.
My calculation.
Assuming the max current per pin of the ESP
is 1mA/per pin,
Dropping Resistor value =
= 1.7k
Let Iin=0.010A
.'. (5V-3.3V)/10000 ohms=0.000170A (170uA)

Don't see the logic or justification for 10k.
Where's the data to support that ?
Can you show your work ?

Time to check the stock market while you still operating in the future WRT alla us. :wink:


Hi, thanks for the advice. I did as you said and programmed the esp with a nodeMCU. For the ones interested I followed the steps on this video (#7 Flash ESP-01 easily with your NodeMCU - YouTube).
Thank you all.

I occasionally use raw ESP8266 modules (ESP12-E or ESP12-F) and I have a pile of 5 waiting to be used. For programming at 5 volts, I always use a circuit design copied from the Adafruit Huzzah breakout and a normal USBTTL adapter.

One way to do it, but I suggest you order - say a couple of - the modules I cited in #9. The links I gave are the cheapest on Aliexpress at this time and i am sure you can afford them.

A month or two down the track when they arrive, it will be much easier to play around with the ESP-01s. I received my order a week back, presently looking for a USB A to A extender cable to get going on trying out all the ESP-1s I have been collecting. :grin: