Simply speaking, I can receive serial data from another device with /dev/ttyMFD1 on mini breakout, ONLY AFTER I connect THE USB CABLE BELOW TO MY COMPUTER:
Otherwise I cann't receive any data. But after I connected the USB cable again, the data showed again! I am totally confused. Pls help, there must be sth I missed. But I cannot find it out through Google.
Thank you for contacting us. I want to make sure I'm understanding your question correctly: you say you can only receive serial data through port J3 of the mini breakout board with the cable connected and that as soon as you disconnect it, you stop receiving data? If that's the case then this behavior is expected, you can only see data in the serial port with the cable connected. Please let us know if we understood your question correctly.
We'll be waiting for your response.
Thanks for your reply. It's J18-pin13 that I used to receive the data from another board. And it worked only with the cable connected to a PC, and when I disconnect it from PC, It also worked. But after I unplug the power (i.e. reboot everything), and without USB cable connected to PC, it didn't work! At this time, as soon as you connect USB cable, it worked again.
I will try another mini breakout board. I doubted that's the hardware bug. And will give the feedback here.
Thank you for letting us know you resolved the issue. If you have other questions don't hesitate to open a new thread to receive help from the community.