Serial Console

I am intrigued by the serial console on the HiFive Unmatched. Is it useful for more than just booting without a video card? For example for displaying debug output, or for use as an additional command terminal even when the video card is the primary display?

If so I would like to set up a dedicated serial terminal on it. Can I connect an adapter from the microUSB connector to a standard DB9 RS232 serial port?

It is basically same as Unleashed. There is an FTDI chip on the board that drives the microUSB connector, and you need a driver to convert the result to a serial console. There are actually two serial devices on the single USB connector, one for the serial console and one for JTAG. I don’t know if it can be converted to an RS232 serial port. I don’t think that I have any equipment that can use RS232 directly anymore. I just connect the usb cable to a nearby linux computer and use minicom to access the console. The docs say to use screen which works also.

The serial console shows the boot messages from u-boot and the linux kernel. Linux kernel messages will show up on the serial console. It can be used to log in.