ESP8266 Community Forum

Posted: **Fri Feb 02, 2018 3:25 pm**

Hello everyone. I have a very noob question and I need your help.

I want to write to the ESP a program that blinks in some random pattern, but I also want to monitor the number of blinks with serial monitor.

For example,

Code: Select all

Let x be a random number
For (int i=0;i<x;i++) { digitalWrite(LED_builtin,0); delay(500); digitalWrite(LED_builtin,1); }
Serial.println (x);

How could I do something like this?

It seems that I can only use either the Serial Monitor or the blue LED, and I can't use both.

In most other responses to other people's questions, they suggest wiring up another LED instead. But this isn't the proper solution is it?

From my searches and reading, the Serial Monitor depends on the TX pin (GPIO3). And the LED is on GPIO0 (or GPIO2?). So technically they're independent lines, the TX for the Serial Monitor and the GPIO0 is for the blue LED. But this doesn't seem to be happening this way.

I have also read people suggesting "switch RX/TX". What does this mean exactly? Does it mean I set GPIO3 to input and set GPIO1 to output?

Will the Serial Monitor know to listen to GPIO1 for the serial debugging logs?

Thanks for reading!

Posted: **Sat Feb 03, 2018 4:26 am**

Hi,
they most likely mean "swap uart0/1", see
http://arduino-esp8266.readthedocs.io/e ... tml#serial

The serial monitor is not bothered at all. It just listens to the pin you connect to the Rx of your usb/serial converter.

Posted: **Sat Feb 03, 2018 10:51 am**

I've tried the serial.swap()
I don't think it did anything, I am still not seeing anything on the Serial Monitor when the digitalOutput is set to GPIO1.

I also tried the others, Serial1.begin, and also

Code: Select all

Serial.begin(115200)
Serial.set_tx(2);

From what I understand, this sets the TX pin to GPIO2.
but still, the LED blinks fine but the Serial Monitor is not receiving anything on its display.

Maybe it's important to mention that I am using the CH340 USB adapter to connect the ESP to the USB ?

Posted: **Sat Feb 03, 2018 5:21 pm**

The ESP-01 has very limited access to the GPIO. The header pins are hard wired to RX,TX, GPIO01 so you can't swap serial lines around to the other pins like you can with other ESP modules.

You will have better luck using an ESP-12F or a nodemcu with built in usb which give full access to all the GPIO pins available on a esp8266

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