Testing if ubinascii.unhexlify exists ...

[davef]

Following another thread I tried:

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rshell -d -p /dev/ttyUSB0 --editor nano --buffer-size=30 -a

and got:

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Trying to connect to REPL .

Stalled, so I then tried:

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sudo screen /dev/ttyUSB0 115200

and got:

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FAT filesystem appears to be corrupted. If you had important data there, you
may want to make a flash snapshot to try to recover it. Otherwise, perform
factory reprogramming of MicroPython firmware (completely erase flash, followed
by firmware programming).

The program I was running has a while loop, is there a problem at which point you break out of a while loop when re-booting? It could have been writing to a file at that point in time.

Appreciate any suggestions.
Dave

[dhylands]

rshell sends 20 Control-C's (one every 100 msec) and looks for the >>> prompt. If it doesn't find it, then it gives up.

You need to fix the:

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FAT filesystem appears to be corrupted. If you had important data there, you
may want to make a flash snapshot to try to recover it. Otherwise, perform
factory reprogramming of MicroPython firmware (completely erase flash, followed
by firmware programming).

before rshell will connect properly.

[davef]

I have fixed that.

Before the ESP32 ends up with a corrupted file system again when I do a re-boot when my while loop is running, I wondered if there was a proper method of closing the files before shutting it down.

I guess something like <shutdown -h> on a RaspberryPi.

Thanks,
Dave

[pythoncoder]

If you have a loop that writes to a file you need to use exception trapping to close the file. Alternatively use a context manager.

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with open(myfile, 'w') as f:
   while True:
       f.write(something)  # write to file

Then if a KeyboardInterrupt occurs the context manager will close the file.

The same thing can be done with try...finally.

[davef]

Hi Peter,

I always use:

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 try:
      with open ... 

for reading and writing files. I haven't had any issues using Crtl-C to stop execution.

Perhaps the smart thing to do is to do a Ctrl-C before pushing the reset button!

Thanks,
Dave

[pythoncoder]

That will work with a finally clause that closes the file, which I believe is exactly what a context manager does.

The reset button is kinda fatal

[davef]

I didn't put in the full coding for a typical file read statement. Following an example I found somewhere:

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try:
    with open('/batt_voltage_values', 'r') as infile:
        batt_voltage_values_lines = infile.readlines()
except IOError:
    print('oops!')

I re-read https://realpython.com/read-write-files-python/ and it suggests either a try ... finally or a with open

Hopefully, one can put something more useful in the

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except IOError:

statement.