Edit - Arduino Stack Exchange

You are not logged in. Your edit will be placed in a queue until it is peer reviewed.

We welcome edits that make the post easier to understand and more valuable for readers. Because community members review edits, please try to make the post substantially better than how you found it, for example, by fixing grammar or adding additional resources and hyperlinks.

Required fields*

Rev

Required fields*

How to I make the Tx and Rx pins on an ESP-8266-01 into GPIO pins?

When programming an ESP-01 with Arduino IDE, how can I make the Tx and Rx into a generic I/O pins reliably? I think there's a command to swap the Tx and Tx with other pins. I tried serial.swap() but it didn't work. So how to get done with Arduino IDE or is it even possible?. I am using an ESP-01, which means there will be four GPIO pins once this question in answered.

I want to achieve same as in the video, How to add more GPIOs to ESP8266 (ESP-01), but without soldering wire.

Answer*

Add this to your code at the beginning of set `void setup()`:

 //********** CHANGE PIN FUNCTION TO GPIO **********
 //GPIO 1 (TX) swap the pin to a GPIO.
 pinMode(1, FUNCTION_3); 
 //GPIO 3 (RX) swap the pin to a GPIO.
 pinMode(3, FUNCTION_3); 
 //**************************************************

You will no longer be able to use the Serial Monitor as TX will now be a GPIO pin and not transmit Serial data. You can still Flash your device as when you boot the device in flash mode it converts GPIO1 and GPIO3 back to TX/RX. Once you reboot into regular running mode GPIO1 and GPIO3 will go back to being GPIO pins. 

To change GPIO1 and GPIO3 back to being TX/RX for regular Serial Monitor use add this to your code at the beginning of set `void setup()`:

 //********** CHANGE PIN FUNCTION TO TX/RX **********
 //GPIO 1 (TX) swap the pin to a TX.
 pinMode(1, FUNCTION_0); 
 //GPIO 3 (RX) swap the pin to a RX.
 pinMode(3, FUNCTION_0); 
 //***************************************************

If I understand the ESP-01 correctly the pins CANNOT be both TX/RX and GPIO pins at the same time.

Draft saved

Draft discarded

Edit Summary*

Cancel

For more info about pin functions see esp8266.com/wiki/doku.php?id=esp8266_gpio_pin_allocations

kleptog
– kleptog

2019年10月12日 10:38:50 +00:00
Commented Oct 12, 2019 at 10:38
5

And don’t forget ‚pinMode(1/3, OUTPUT/INPUT)‘

LaborEtArs
– LaborEtArs

2020年01月11日 09:10:13 +00:00
Commented Jan 11, 2020 at 9:10

Add a comment |

How to Edit

Correct minor typos or mistakes
Clarify meaning without changing it
Add related resources or links
Always respect the author’s intent
Don’t use edits to reply to the author

How to Format

create code fences with backticks ` or tildes ~
```
like so
```
add language identifier to highlight code
```python
def function(foo):
print(foo)
```
put returns between paragraphs
for linebreak add 2 spaces at end
_italic_ or **bold**
indent code by 4 spaces
backtick escapes `like _so_`
quote by placing > at start of line
to make links (use https whenever possible)

<https://example.com>

[example](https://example.com)

<a href="https://example.com">example</a>

formatting help »
answering help »

How to Tag

A tag is a keyword or label that categorizes your question with other, similar questions. Choose one or more (up to 5) tags that will help answerers to find and interpret your question.

complete the sentence: my question is about...
use tags that describe things or concepts that are essential, not incidental to your question
favor using existing popular tags
read the descriptions that appear below the tag

If your question is primarily about a topic for which you can't find a tag:

combine multiple words into single-words with hyphens (e.g. arduino-uno), up to a maximum of 35 characters
creating new tags is a privilege; if you can't yet create a tag you need, then post this question without it, then ask the community to create it for you

popular tags »