xDot/mDot UART differences

[Andrew Lindsay]

Hi,

Are there any differences in the mbed Serial library between the xDot and mDot version? I’m using the xDot UART1 to communicate with a serial device at 9600 baud. The same code, with a change in the port pins works fine on the mDot but will not work on the xDot. Code compiles and runs but no data is being received. It is a simple serial passthrough application using the mbed Serial class.

Are there any known issues around this area?

I have tried this on both mbed 2 and mbed-os 5.

Thanks

Andrew

[Mike Fiore]

Andrew,

What pins are you using on both devices? Are the dots on DK boards or on custom boards?

What version of mbed-os are you using?

As I’m sure you well know, the mbed Serial code should work on any mbed device. However, the underlying implementation is a little different between the F4 and L1 families. See the following files:

https://github.com/ARMmbed/mbed-os/blob/master/targets/TARGET_STM/TARGET_STM32L1/serial_api.c

https://github.com/ARMmbed/mbed-os/blob/master/targets/TARGET_STM/TARGET_STM32F4/serial_api.c

Cheers,
Mike

[Andrew Lindsay]

Its the UART1 interface I’m using on the xDot not the USB interface.

[Mike Fiore]

Andrew,

I’m not sure what you meant by your last comment. It’s possible to have a dot on a DK and still use the UART interface.

What pins are you using on both devices? Are the dots on DK boards or on custom boards?

What version of mbed-os are you using?

Did anything else from my previous post help you out at all?

Cheers,
Mike

[Andrew Lindsay]

Yes, xdot is on the dev board, doing some evaluations before committing to a design. So far the xDot is losing out to other manufacturers. Its latest mbed-os and I also tried the latest mbed 2 but that wont compile for xdot anyway.

Pins on both devices are UART_TX and UART_RX on the xDot. I’ll check the rest and try again later. Not able to look just yet.

Thanks

Andrew

[Peter Ferland]

Double check that you’ve soldered your connections on the DK to the correct pad – on the UART_TX and UART_RX pins are not right above each other, TX is the 2nd closest to the USB port on the bottom of the board not the closest.

I only ask because I did it the first time I connected a UART on the xDot…

[Andrew Lindsay]

Thanks Peter, I’ve got it connected fine as I’ve used a regular FTDI cable to test it.

Andrew

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