Console (Debug) Port¶
Access the controller debug interface via the connector table below1.
Controller Board |
Debug Interface Connector |
|---|---|
This is an RS-232 level serial port that runs at 115.2k Baud, 8-bit, no parity, 1 stop bit. This port should always be connected during product development. You will need a terminal emulator program or shell that understands ANSI color escape sequences. Examples include Tera Term or PuTTY2 (Windows) or picocom in a bash shell (Linux).
Important
If using Windows 10 as your development host (with or without the
Reach Technology G3 Developer VM) the single most common problem you will run into is non-deterministic
enumeration of USB->serial converters (like the Reach Technology debug interface
cable mentioned in the footnotes). The observable symptom is the Windows COM
port number changes, and the path to the device special file in the VM
(/dev/ttyUSB<n>) will also change. This makes it challenging to use a
single config file for your favorite terminal emulation program to access
the console.
This is especially problematic when flashing and booting a new SD card or eMMC image for the first time! Because the u-boot DTB variable is not set, the display will not illuminate. So if you can’t see the boot messages scrolling on the debug interface, you will likely and erroneously think the image is bad or the device is toast.
If you don’t see messages scrolling on the debug interface during boot, it’s most likely due to one of the following:
Connected to the wrong COM port or COM port parameters are wrong.
eMMC boot jumper is not in and no SD card is in the socket.
eMMC boot jumper is in, eMMC not flashed with a valid image and no SD card inserted.
Footnotes: