As a work-around, tweaked the firmware process_g_code:
// Get a command and process it
//read in characters if we got them.
c = Serial.read();
if(c == '\r' || c == '.')
if(c == '\r')
c = '\n';
Example of how you can test the firmware by entering the appropriate command, terminated by a dot, in the Arduino Serial Monitor:
M105. ; read the temperature
G1X10. ; position X
G0 X-99. ; X go home
G0 X-99. ; Y go home
See the RepRap wiki for more on G-Codes.
The minimum stops are seen now, for the maximum endstops I have yet to find out why these are not seen by the FW.
To conclude today with the reassuring (?) knowledge that the firmware seems to be ok so the Java Host is next in line.