FIM for 2nd serial port on Connect ME 9210, Linux

Using Digi EL vers 2, Digi EL 5.2, and the Connect ME 9210 module, booting over NFS.

I’d like to use the serial port provided by FIM0 in addition to the regular Port A (and I’ll leave the console on Port A), but can’t seem to get the FIM serial port to show up as a device in /dev.

In a project that includes UBoot, kernal, app, and rootfs, my configuration is as follows:

(No change to U-Boot)

Linux Kernal Configuration / System Type / NS9xxxx Implementations:
–Digi Connect ME 9210 on Devboard
----2-wire (TX/RX)
Linux Kernal Configuration / Device Drivers / Character devices:
–Unix98 PTY support is the only one checked
–Serial drivers: Just Digi NS921x serial port support, and console on Digi NS921x serial
Linux Kernal Configuration / Device Drivers / FIM drivers support:
–FIM 0
----Serial driver 2-wires
----(nothing else selected–e.g., serial console)

Everything boots fine, but I’m expecting to see /dev/ttyFIM0 listed, but the only serial ports I see via “ls /dev/tty*” are those associated with port A.

I do not have this on a development board. It’s not even a development (i.e., jtag) module. I read through the documentation and I think by configuring Port A as 2-wire (RX/TX), I have the pins available for FIM0 to work (as 2-wire TX/RX).

A few questions:

  1. When I pick the system type “Digi Connect ME 9210” (that is, without “on devboard”), I don’t get any options for the type of serial port–or even enabling a serial port at all. It seems like I’m missing what these two system types mean. But it really sounds like I need to configure the serial port as TX/RX only, so I went with the “on devboard.”

  2. I want a second serial port I can use (2-wire is fine), e.g. “ttyFIM0”. Can I really do this on a (non-jtag) ME 9210 via the FIM?

  3. If so, what else do I need to do? It sounded like enabling the FIM in the project configuration would automatically do everything I needed. I thought I was building a “built-in”, vs. loadable module.



And the answer seems to be:

The enable boxes in the configuration utility are tri-state (see section 6.2 of the Digi ESP for Embedded Linux documentation). Blank is not built at all; check mark for built directly into the kernal (which is preferred); and a black circle which means build as a module (which would then need to be loaded, etc.).

I had inadvertently built the FIM as a module, not into the kernal as I wanted. But didn’t notice the distinction between checkmark and black dot.

I’m not sure I like tri-state checkboxes as a user interface. Too subtle.

But the FIM0 serial port is now in /dev.