ESP8266 Community Forum

- Sun Feb 04, 2018 7:12 am #73689 Ok I see. So the header pins are hardwired to the Tx pins, that is why if I set the serial.swap() I still won't be able to see serial outputs because the pins (GPIO15?) aren't going to be connected to the USB plug?

Thanks

- Sun Feb 04, 2018 9:42 am #73692 Because of the limited user accessible pins on the ESP-01 board most of the GPIO lines of the ESP8266 can't be used. They still are on the chip but they don't go anywhere. You can do a swap function, and the ESP8266 chip will switch GPIO pin mapping, but there are no connections on the board to make this accessible.

I have never used the ESP-01 (too limiting) so I was not sure of what GPIO pin the blue led is connected to. But I found this.

viewtopic.php?f=13&t=13659

The one marked "ESP-01S" does not have a red power LED, only one larger, blue LED. It also has far more chip capacitors than the other one. And using the Arduino IDE, addressing LED_BUILTIN does not work. I found the LED to be connected to GPIO2, and not the usual GPIO1 = LED_BUILTIN.

This was what I thought. The blue led is connected to GPIO1, which is the TX pin. There is no way to have them controlled separately with the ESP-01.

The ESP-12 has the blue led connected to the GPIO2 pin. From the quote above, the ESP-01S has the blue led connected on GPIO2 and it therefor can be controlled independently since it is not tied to the TX pin.

- Mon Feb 05, 2018 1:46 am #73708 let me sum it up for you:

on a standard ESP-01:
with

Code: Select allSerial.begin(115200)
Serial.set_tx(2);

you should see output but ofcourse you have to move the wire to your ch340 from Tx-pin to gpio2 pin of the esp-01 header. Then you should be able to toggle gpio1 to flash led. uploading new sketch still has to be done via original Rx/Tx pins!

on the new ESP-01s:
you don't have to swap serial, led can be flashed via gpio2 while using serial as always.