Raw REPL crashing

[eighthree]

It's possible for Raw REPL to stop working properly if main.py contains code that looks like what I whipped up below:

main.py contents

import time
from machine import ADC

x = True
while True:
  startMillis = time.monotonic()
  signalMax = 0
  signalMin = 1023
while time.monotonic() - startMillis < 10:
  adc = ADC(0)
  sample = adc.read()
if sample < 1024:
  if sample > signalMax:
      signalMax = sample
  elif sample < signalMin:
      signalMin = sample
peakToPeak = signalMax - signalMin
print(peakToPeak)

Normally, I'd get something like:
ampy.pyboard.PyboardError: ('exception', '', 'Traceback (most recent call last):\r\n File "<stdin>", line 14\r\nSyntaxError: invalid syntax\r\n')
but running this main.py code through ampy causes terminal to hang.

To reproduce

1. ) Flash CP 2.0.0 rc2 on an ESP8266
2. ) Run main.py (hangs)
3. ) Put main.py (works ok!)
4. ) Reset/Unplug unit
5. ) Try running main.py through ampy (hangs) *
6. ) screen /dev/ttyUSB0 115200 (see video for behaviour)
7. ) Try running -or- putting file via ampy returns File "/usr/local/lib/python2.7/dist-packages/ampy/pyboard.py", line 202, in enter_raw_repl raise PyboardError('could not enter raw repl') ampy.pyboard.PyboardError: could not enter raw repl

Observed on an ESP8266 running CP 2.0.0-rc.2 / Ubuntu 16
Latest ampy & esptools

I've attached a screen captured video (webm format) demonstrating this issue:
ESP Development Environment-2017-09-12T01-24-24-828588200Z.zip

Here's the error when trying to use ampy when the Raw REPL fails:

Traceback (most recent call last):
  File "/usr/local/bin/ampy", line 11, in <module>
    sys.exit(cli())
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 722, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 697, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 1066, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 895, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python2.7/dist-packages/click/core.py", line 535, in invoke
    return callback(*args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/ampy/cli.py", line 271, in run
    output = board_files.run(local_file, not no_output)
  File "/usr/local/lib/python2.7/dist-packages/ampy/files.py", line 221, in run
    self._pyboard.enter_raw_repl()
  File "/usr/local/lib/python2.7/dist-packages/ampy/pyboard.py", line 202, in enter_raw_repl
    raise PyboardError('could not enter raw repl')
ampy.pyboard.PyboardError: could not enter raw repl

What fixes the issue
Re-flash the firmware.

[jerryneedell]

Your first "while" loop will never exit. It just executes the next 3 lines repeatedly. You need to revise your indentation.

[jerryneedell]

something more like:

import time
from machine import ADC

x = True
while True:
  startMillis = time.monotonic()
  signalMax = 0
  signalMin = 1023
  while time.monotonic() - startMillis < 10:
    adc = ADC(0)
    sample = adc.read()
  if sample < 1024:
    if sample > signalMax:
      signalMax = sample
    elif sample < signalMin:
      signalMin = sample
  peakToPeak = signalMax - signalMin 
  print(peakToPeak)

[jerryneedell]

RE your comment #6 , #7
You can't run ampy if you have a screen session open. Either ampy or screen can access the USB port at a time, not both at the same time

[eighthree]

Thanks Jerry! Will revise the indentation.

To clarify No. 6 and No. 7: I'm not trying to have ampy and screen running at the same time. I could reset the unit , unplug it from power -- and Raw REPL will exhibit the same behaviour as shown in the video.

No. 5 when it hangs, I abort the process (Ctrl + C) before opening a screen session.
sudo ampy -- port /dev/ttyUSB0 run 'home/timothyDocuments/development/circuitpython/analog-read/main.py' ^C Aborted!

Edit: Folks from the discord server also suggested to check if an instance was running in the background. I was able to recreate the bug and then checked whether or not a screen session was running using screen -list and it wasn't.

[tannewt]

Ok, so I took a look at this. I don't think its a CircuitPython bug. I think you've found a state where the code in AMPY to get into raw REPL isn't enough. (It does two CTRL-Cs but thats not enough.)

Please re-file it here: https://github.com/adafruit/ampy/issues