I’ve been making a ton of progress on a project using an Artemis DK and mBed Studio. But at some point over the last 24 hours, the serial monitor stopped printing messages from the dev kit.
I can definitely update the code on the board (verified by changing LED blink rate). I haven’t yet tried to see if I can receive data over the USB serial connection.
Environment is macOS 10.15.17, mBed Studio 1.4.0.2, mBed OS 6.10, and using the mbed_os_blinky_example program (with an added printf). I’ve set the baud rate of the Serial Monitor to 9600, which is what it was set to when things were previously working.
I should add that I also don’t see any output when I directly cat the USB serial port.
Thanks for reaching out to us on this.
Maybe one of the apps updated and changed something back to a default setting? Be sure you can select the correct board (SparkFun apollo3)
Also be sure to see if you can tx/rx data over USB; perhaps save your files and begin over altogether (re-flash to original firmware, update, etc.) one step at a time to find out if there is a ‘breaking point’, or if it just works after starting over…boards can be finnicky!
Hope this helps, and happy sparking!
It is because Mbed Studio V 1.4 updated the bundled compiler to ARMC6.15. For some reason on the Artemis boards printf(), BufferedSerial and UnbufferedSerial stop working when using that compiler. Bug has been reported [here
For now you need to use GCC_ARM as compiler to circumvent this regression. [Here is how to do that.](Switching to GCC - Installing | Mbed Studio Documentation)](Print() and (Un)BufferedSerial do not work on Artemis Thing Plus when compiled with ARMC 6.15 · Issue #14531 · ARMmbed/mbed-os · GitHub)
Upgraded to mBed Studio 1.4.1 (which still uses the 6.15 compiler), did a clean build, and the problem remains.
I’ll have to try the GCC ARM trick when I have a bit more time since my copy isn’t installed in the directory that those instructions point to.
@frankus
Mbed Studio 1.4.2 has been released recently, now it comes with ARMC6.16.
Using Mbed OS 6.15 and Studio 1.4.2 it seems the issue has been fixed even if using ARM as compiler.
Can you also give it a try and confirm my finding?