NUMAKER_PFM_M2351 serial communication is broken on linux.

[studavekar]

Description

NUMAKER_PFM_M2351 serial communication is broken on linux. It works well on windows 10

Host machine info
lsb_release -a

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.2 LTS
Release:        16.04
Codename:       xenial

uname -a
Linux austin-ci-linux-002 4.15.0-24-generic #26~16.04.1-Ubuntu SMP Fri Jun 15 14:35:08 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

NUMAKER_PFM_M2351

Toolchain:
ARMC6

mbed-os sha:
e9e1ff9 Merge pull request #7302 from OpenNuvoton/nuvoton_m2351_v1.1

Steps to reproduce
Use blinky program with uart logging, expect to see led blink and incremental counter value on uart.

#include "mbed.h"

DigitalOut led1(LED1);
int main() {
    uint32_t counter = 0;
    while (1) {
        led1=!led1;
        wait(0.5);
        printf("counter : %d \n\r",++counter);
    }
}

Logs

Tool used : Beagle USB 480 Protocol Analyzer , software is availabe for free https://www.totalphase.com/products/beagle-usb480/

Please rename the files from .txt to .tdc to view it

• linux_failure.tdc.txt

• windows_success.tdc.txt

[ ] Question
[ ] Enhancement
[ X] Bug

cc : @deepikabhavnani @SenRamakri @c1728p9 @ccli8

[deepikabhavnani]

CC @cyliangtw @ccli8

[ciarmcom]

ARM Internal Ref: MBOTRIAGE-1309

[ccli8]

@studavekar @deepikabhavnani We can now reproduce on Ubuntu 16.04. Our tool team is looking into it.

[samchuarm]

@studavekar @deepikabhavnani Has this issue been verified with the latest M2351 interface firmware binary provided by Nuvoton Chris? Thanks.

[studavekar]

@samchuarm this is been fixed in the latest interface binary provided.

Thanks @ccli8.