Martin Heine

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9 years, 5 months ago.

USBSerial blocking when Powered by a external USB Power Supply

I am working on a kind of datalogger, based on the KL25Z plattform. The device uses USBserial to access data and to communicate. It works like charm as long as USB is connected to a PC. However, USBSerial blocks the code execution as soon no PC connection is present and its powered only (USB Powersupply or Battery). VBUS detection won't work here. I have seen others with the same problem, but nobody seems to have any solution. ? Thanks a lot in advance for your help!

2 Answers

Manel Marin
8 years, 5 months ago.

Hi,

I used the connect_blocking argument and a watchdog for blocking when closing the serial terminal

Take a look to this example: https://developer.mbed.org/users/Manel_Marin/code/KL25Z_WATCHDOG_USBSERIAL/

Zapta Z.
9 years, 2 months ago.

Have you solved this problem?

Looking at USBSerial.h, it has a connect blocking argument

https://github.com/mbedmicro/mbed/blob/master/libraries/USBDevice/USBSerial/USBSerial.h

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Edit: initializing USBSerial in non blocking mode looks like this:

USBSerial usb_serial(0x1f00, 0x2012, 0x0001, false);

The first 3 values are the default values of the USBSerial constructor.

Unfortunately no :(. Would be great if someone knows a solution. In the meantime, I just use an external FTDI Serial to USB cable. Its a shame!

posted by Martin Heine 25 Feb 2015