Arm Mbed OS support forum

Strange characters in serial mode

I am getting some strange characters in the serial stream from an LPC1114, example below

þþMeasure Errorþ

is being displayed on Teleterm when it should just be displaying ‘Measure Error’ and not the other garbage.

There is no other hardware connected to the serial port. Funny thing is I can program the device and no errors are reported. I’ve tried swapping devices out - no difference.

Any thoughts?

Thank you


I tested my LPC1114FN28 board with mbed-os-example-blinky-baremetal example and got serial out below without any garbage:

This is the bare metal blinky example running on Mbed OS 6.9.0.

You can probably update the latest firmware for the LPC1114FN28 board.