So, thanks to very helpful Rickta59 on #43oh IRC channel, I got my Launchpad v1.5 serial communication working. The key piece of information I was missing:
If you are using hardware UART,
you must rotate the RX-TX jumpers by 90 degrees!
you must rotate the RX-TX jumpers by 90 degrees!
This is even drawn on the board, but it just didn’t occur to me that I need to do this simple thing. Most examples seem to use hardware UART, and Energia Serial class also uses hardware UART.
It is still very flaky:
- For the first ten seconds, communication is impossible. Wait for timeout messages to appear in dmesg, then you can start communication.
- When the board is sending data, something must be reading them on the host side. If not, the driver collapses and you need to replug the device.
- The latter might be circumvented by direct USB communication without involving the tty driver.
So, it is rather fragile, but usable! Let’s enjoy our Launchpads for projects where this is not a big issue…