Invalid characters after UART reinitialization

[aashishc1988]

Target:
NUCLEO_F103RB
Toochain:
Arm
MbedOS:
mbed-os-5.9.0-rc3
Test case:
mbedmicro-mbed\call_before_main

While running one of the mbed tests on the NUCLEO_F103RB, we noticed an issue where htrun complained about receiving a byte it cannot decode. The test ran fine on other targets. Narrowing it down further, it seemed like the problem is on the host target. Whenever we flush out the stdout using '\n' or fflush, and the uart gets reinitialized for next stream of data, the very first character it sends is something unusual ('255', or '254') which is causing the issue.

I am attaching snapshots of the data captured from logic analyzer, and you can see the decay on analog during reinitialization.

In this snapshot, you can see the ascii value of the character sent right after reinitialization ('255')

This behavior is reproducible each time.

Steps to reproduce
mbed test -m NUCLEO_F103RB -t ARM -n tests-mbedmicro-mbed-call_before_main -v

[ ] Question
[ ] Enhancement
[X ] Bug

@ARMmbed/team-st-mcd
@screamerbg

See, ARMmbed/greentea#278, once this issue is fixed for all partners, revert the change made for greentea

[bcostm]

I looked in our internal CI test history and didn't see any problem with this test from mbed-os-5.6.6 to mbed-os-5.9.1.

I tested the NUCLEO_F103RB on master and I confirm that the test fails now:

Exception in thread Thread-3:
Traceback (most recent call last):
  File "c:\python27\lib\threading.py", line 801, in __bootstrap_inner
    self.run()
  File "c:\python27\lib\threading.py", line 754, in run
    self.__target(*self.__args, **self.__kwargs)
  File "c:\python27\lib\site-packages\mbed_greentea\mbed_greentea_cli.py", line 489, in run_test_thread
    verbose=verbose)
  File "c:\python27\lib\site-packages\mbed_greentea\mbed_test_api.py", line 318, in run_host_test
    returncode, htrun_output = run_htrun(cmd, verbose)
  File "c:\python27\lib\site-packages\mbed_greentea\mbed_test_api.py", line 134, in run_htrun
    htrun_output += line.decode('utf-8')
  File "c:\python27\lib\encodings\utf_8.py", line 16, in decode
    return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode byte 0xfe in position 63: invalid start byte

[Mirrored to Jira]

[jeromecoutant]

Hi

I also tried this test, and result is depending on greentea version...

The exception that @bcostm has, comes with greetea version 1.4.0

With greentea version 1.3.3 test is OK even with the issue during greentea synchro:

[1531725281.70][CONN][RXD] MBED: mbed_main() call before main(▒mbedmbedmbedmbedmbedmbedmbedmbed

With #7512 , test is OK with all greentea versions

[Mirrored to Jira]

[jeromecoutant]

@pan-
[Mirrored to Jira]

[bcostm]

Seems related to PR ARMmbed/greentea#271

[Mirrored to Jira]

[0xc0170]

@cmonr Please review
[Mirrored to Jira]

[cmonr]

@aashishc1988 @jeromecoutant @bcostm Could y'all post the output of the following commands?

python --version
pip list --verbose

I think htrun recently underwent a release, so it's possible the versions that y'all have installed are out of date since the Py3 fixes are really recent.
[Mirrored to Jira]

[jeromecoutant]

I am still using python 2.7

mbed-cli 1.7.5 c:\python27\lib\site-packages pip
mbed-greentea 1.4.0 c:\python27\lib\site-packages
mbed-host-tests 1.4.0 c:\python27\lib\site-packages
mbed-ls 1.4.6 c:\python27\lib\site-packages

[Mirrored to Jira]

[aashishc1988]

Here is the output
Python: 2.7.11
mbed-cli 1.7.3
mbed-host-tests 1.3.1
mbed-greentea 1.4.0
mbed-ls 1.4.6

I have tried updating htrun to latest release but still saw the failures.
[Mirrored to Jira]

[bcostm]

Python 2.7.13

$ pip list --verbose | grep mbed
mbed-cli 1.7.3 c:\python27\lib\site-packages
mbed-greentea 1.4.0 c:\python27\lib\site-packages
mbed-host-tests 1.3.1 c:\python27\lib\site-packages
mbed-ls 1.4.5 c:\python27\lib\site-packages

[Mirrored to Jira]

[bentcooke]

I have also experienced this issue on the MAX32625MBED and MOTE_L152RC platforms in the past week.

Python 2.7.13
mbed-cli (1.7.5)
mbed-cloud-sdk (1.2.8.970)
mbed-flasher (0.8.0)
mbed-greentea (1.4.0)
mbed-host-tests (1.4.0)
mbed-ls (1.4.6)

[Mirrored to Jira]