How to use UART

[MikaelNissen]

Hi

I have a little bet hard time to figur out if UART is implementerede in the firmware....

What I'm trying to do is reading from UART and send the data via socket to a server...

I'm tryin to init the UART port via REPL without luck;

Code: Select all

from machine import UART 
uart = UART(1, 115200)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: extra positional arguments given

Thanks!

[wendlers]

Hi,

first: I have not tried UART myself on the ESP. That being said, from the MP code I could tell the following:

The "UART" constructor only takes a single argument, the UART ID. All the settings then should be done by calling the "init" method I think. The "init" allows a set of "kwargs", but to my understanding, only "timeout" and "timeout_char" are allowed at the moment. Baudrate I think is fix (https://github.com/micropython/micropyt ... phal.c#L51)

So just using:

Code: Select all

from machine import UART
uart = UART(1)

Might give you a UART object working at 115200 ....

[MikaelNissen]

Thanks for the info

I get an error if I use UART(1):

Code: Select all

from machine import UART
uart = UART(1)
test = uart.readline()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OSError: UART(1) can't read

But it is working on UART0:

Code: Select all

from machine import UART

uart = UART(0)

[wendlers]

Hi,

yes, seams like UART(1) is only for writing (the exception you see is thrown from the UART code when you call "read" for UART with ID 1). Writing so far works for me. I think using UART 0 is not an option I think since it is the one the REPL uses.

Also it seams that my board (NodeMCU) has no HW pin for RX on UART ID 1:

[aleskeyfedorovich]

Anyone that tested it?
If I understood the reply, it is mandatory to use D0 for reading/writing from/to devices communicating through uart?
thank you

[kevinkk525]

I used UART one for TX in one application and it works fine.

[aleskeyfedorovich]

Which pin do you mean?
In the above schema I can't see any pin named "UART1".
I have an ESP-12e (actually a nodeMCU lolin)
I'm a beginner.
Thank you

[kevinkk525]

I think it was pin D4. It was a work project and I don't have the files at the moment.