Updated firmware for K20 mBed usb-serial

[carl_cog]

We have TWR-LS1021a with Rev1 CPUs which we run our automated CI software regression tests on. The uart is accessed on USB via the onboard K20 mcu running mBED firmware. Every few days, the serial-port crashes the USB hub or Host PC root port and serial console breaks. Sometimes re-plugging the board will fix it, however often a full hardware reset is required. There are lots of other USB_serial converters we use continuously for months, the TWR is the only one that crashes.

Are there any firmware updates to increase the reliability of mBED USB serial on the TWR-LS1021a ?

[carl_cog]

Ok, sorry I should elaborate. The problem occurs on our Linux servers (we don't run any Windows machines).

This is most likely a firmware not a driver issue (combined with poor USB handling on hubs and PC's which we have no chance of fixing). On Linux there are no special drivers to install, the MBED device enumerates a standard USB ACM device. The fact that it's buggy and can kill the hub it is connected to and often the USB root hub on the PC motherboard, leads us to believe its a protocol issue with bad packets or voltage spikes etc from the K20 micro. Note our automated regression power-cycles the TWR board frequently, but the K20 is bus powered and never resets in the process.

My question relates to whether there is a firmware update for the K20 micro on the TWR-LS1021a (original board) [not TWR-LS1021a-PB].

Thanks

[skhasanujjaman]

Has your problem been resolved?

I am developing the BSP for an RTOS for the board TWR-LS1021A-PB. I am also having the same kind of issue with UART. I believe the K20 micro stops responding frequently. There might be the firmware issue. Do you know how can I get the latest firmware for K20 for this board?

[yipingwang]

Please refer to the attached k20 firmware.

[skhasanujjaman]

Hi Wang,

Thank you very much for providing the firmware. But I am sorry to inform you that my problem is not resolved by using this firmware. Serial works fine as long as you don't stress it by sending lots of data to the target. In the situation when serial communication stops, if I reset the MBED controller (by plug in/plug out the USB cable), serial seems to work again. In my understanding the problem may be in the Windows driver (mbedWinSerial_16466.exe) or in the MBED firmware (k20dx128_if_mbed.bin). Please find below the details of my test environment.

Host PC: Windows x86

Serial Driver: mbedWinSerial_16466.exe

Serial Port Configuration: 115200-8-N-1

Host application: Send/receive data to/from the target board (TWR-LS1021A-PB). 

Target board: TWR-LS1021A-PB

UART controller: DUART1

Clock input to the UART controller : 150 MHz (Platform clock / 2, where Platform clock is 300 MHz)

Baud rate set : 115200 bps

During debugging, I have observed that the UART driver in the target board is alive when the communication fails between the host and the target. That means if I reset the MBED controller the communication gets established again.

Could you please guide me how to recover from this situation? 

[Pavel]

The latest version of this driver is available on the following page:

http://mbed.org/handbook/Windows-serial-configuration

Install this MBED USB driver.

NXP does not own the MBED documents.

Have a great day,
Pavel

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