AT command interface works! The cause of the breakage was the same Nucleus API issue with NU_Create_Timer() which we encountered at the very beginning of this project with Riviera timers: the code in uartfax.c from TCS211 was passing 0 as the initial dummy value for the timer duration, and our FreeNucleus version doesn't like it. The fix is the same: pass 1 as the initial dummy value instead.

# The primary Makefile invokes ${MAKE} with this sub-Makefile
# just like the typical subdirectory Makefiles.
# This invokation happens after the processconf.sh step,
# hence the include below.

include	include/config.mk

default: ${BUILD_DEFAULT_IMAGE}

${BUILD_COMPONENTS}: FRC
	cd $@; ${MAKE} ${MFLAGS}

ramImage flashImage: ${BUILD_COMPONENTS}
	cd finlink; ${MAKE} ${MFLAGS} $@

FRC: