UART does not return to REPL

[microbit-mark]

micro:bit support: 44148

from microbit import *
def uart_test():
    uart.init(baudrate=115200,tx=pin0,rx=pin1)
    display.scroll("UART")
    uart.init(baudrate=115200)
    return ('done son')

On v1 program displays 'UART' and returns the string 'done son' in the REPL

on V2 program displays 'UART' but does not return the string 'done son' in the REPL

Tested in https://python.microbit.org/v/beta

Flash the script then open a serial connection. Call the uart_test() function

>>>print(uart_test())

Notice the program works as expected on V1 but hangs V2.

Clicking on on send CTRC-C or CTRL-D does not reset the REPL

[microbit-carlos]

Removing the display.scroll() and the function shows the same issue:

from microbit import *

print("this prints normally")
sleep(1000)
uart.init(baudrate=115200,tx=pin0,rx=pin1)
print("this goes to the edge connector pins")
sleep(1000)
uart.init(baudrate=115200)
print("this doesn't print on serial")
sleep(1000)

I can replicate this as well in MakeCode (the stable deployment with CODAL 0.2.25):

serial.writeLine("this prints normally")
basic.pause(1000)
serial.redirect(SerialPin.P0, SerialPin.P1, BaudRate.BaudRate115200)
serial.writeLine("this goes to the edge connector pins")
basic.pause(1000)
serial.redirect(SerialPin.USB_TX, SerialPin.USB_RX, BaudRate.BaudRate115200)
serial.writeLine("this doesn't print on serial")
basic.pause(1000)

@martinwork could you try to create a test in C++ to see if this is reproducible in the CODAL side?

If a normal call to uBit.serial.redirect() with the edge connector pins, and then with the internal pins doesn't work we can try to replicate the MicroPython uart.init call:

micropython-microbit-v2/src/codal_port/microbit_uart.c

Lines 86 to 87 in e0f3e60

	microbit_hal_uart_init(tx, rx, args[ARG_baudrate].u_int,
	args[ARG_bits].u_int, parity, args[ARG_stop].u_int);

micropython-microbit-v2/src/codal_app/microbithal.cpp

Lines 210 to 221 in b7a76e4

	int microbit_hal_uart_init(int tx, int rx, int baudrate, int bits, int parity, int stop) {
	// TODO set bits, parity stop
	int ret = uBit.serial.redirect(*pin_obj[tx], *pin_obj[rx]);
	if (ret != DEVICE_OK) {
	return ret;
	}
	ret = uBit.serial.setBaud(baudrate);
	if (ret != DEVICE_OK) {
	return ret;
	}
	return 0;
	}

[martinwork]

Created lancaster-university/codal-microbit-v2#92

[microbit-carlos]

@martinwork thanks for looking into this!
Is PR lancaster-university/codal-nrf52#31 the only thing pending for this being fixed in CODAL, or are there more?

[martinwork]

@microbit-carlos I believe that PR on its own should fix this issue, but I haven't tested it in a micropython build.

[dpgeorge]

This is now waiting on a tag in codal-microbit-v2

[microbit-mark]

Latest tagged release is in https://github.com/lancaster-university/codal-microbit-v2/releases/tag/v0.2.26 which I think should resolve this issue.

[dpgeorge]

Fixed by 291e05c