REPL Pyboard over serial not USB

[tsjoiner]

I'm working on a project that requires I communicate with my Pyboard over a serial port (tx, rx) not the built in USB.
I hope to have access to REPL, rshell functionality and perhaps DFU-util. I have had success with an ESP32-dev_board because it has tx and rx pins exposed behind usb-serial chip. Looking at the schematic for Pyboard all the USB stuff is handled by the MCU. Please tell me this can be done as I need good quality Pyboard hardware for this project.

[Roberthh]

That's possible. Look in the manual for uos.dupterm().http://docs.micropython.org/en/latest/p ... os.dupterm

[tsjoiner]

Many thanks to Roberthh for some direction here. I put this code in my boot.py and rebooted - instant results.

Code: Select all

import pyb
import uos
from pyb import UART

uart = UART(6)
uart.init(baudrate=115200, bits=8, parity=None, stop=1)
uos.dupterm(uart)

This may be crude but I'm pleased the Pyboard USB connection is now duplicated on UART 6.
Enter REPL from Raspberry Pi over serial adapter in picocom:

Code: Select all

$ picocom -b115200 /dev/ttyUSB0

Enter
>>>

[tsjoiner]

Ran in to a small snag. It seems REPL can't break out of a while loop using ctrl-c. REPL is not responding to keyboard interrupt. Is this something to do with sys.stdin perhaps? What if anything can be done to remedy this?

[pythoncoder]

Might this issue be with picocom? I've used rshell with several targets over a serial interface and not encountered this.

[tsjoiner]

Thank you pythoncoder, the issue does not seem to be with picocom. I tested rshell and it connects to the pyboard over serial no problem I can enter REPL and ctrl-x out of REPL. Ctrl-a, ctrl-b, ctrl-d and ctrl-e work as expected in REPL but ctrl-c will not break or interrupt a running loop. Also, I have attached an LED indicator to the UART rx pin and see it flash on keyboard strokes including ctrl-c. The message appears to arrive at the rx pin but is ignored somehow. Perhaps I have initiated the UART incorrectly.

Pyboard: MicroPython v1.9.2 on 2017-08-23; PYBLITEv1.0 with STM32F411RE.

[Roberthh]

This is just to confirm the issue, that Ctrl-C on dupterm does not interrupt code. A first glance into the code shows, that, in contrast to USB, Ctrl-C for UART is indeed not handled by the interrupt routine, but only when getting characters form the buffer.
This is an open issue since two years: https://github.com/micropython/micropython/issues/1568

[pythoncoder]

Ah, apologies - this issue is specific to dupterm. My testing was on devices where the interface is serial only rather than USB.

[tsjoiner]

Thank you both. The apollogies are all mine to make because RT*M. Issue #1568 describes the same problem

[EasyRider]

Bumping this thread.

Looking for solution to Pyboard Repl over UART, where Ctrl-C break doesn't work.
Been a recognized problem for a long time.
https://github.com/micropython/micropython/issues/1568

Need to have REPL access to remote pyboards via wireless minicom UART terminal, have this working but without CTRL-C program break.

Is there a non blocking equivalent of scanning for keyboard key-press?

sys.stdin.read(1), this is blocking waiting for keypress