Firmware now recovers from USB disconnection without halting. Needs
changes to Arduino core library.
Added a timeout in the Spin() functions, which causes diagnostic info to
be stored and the system to be reset if a Spin() function takes more
than 20 seconds.
Completed changes to support multiple concurrent HTTP file requests.
Added support for new poll response for future support of additional
heaters and multiple extruders. Fixed a bug in reporting extruder
distance.
Tidied up axis homing tracking.
When checking endstops, wait for move to complete before accepting
further moves, otherwise subsequent moves use the wrong coordinates.
Temperatures and Z probes are now monitored continuously using a tick
interrupt to kick off ADC conversions. ADC is now run in 12-bit mode.
Thermistor readings are passed through averaging filters. Thermistors
are monitored for overheat conditions and bad readings in the tick ISR
and the appropriate heater is turned off (useful because the main loop
sometimes gets suspended while trying to do USB communication).
Use watchdog timer to monitor the tick interrupt - needs patch to
Arduino Due core library. Add facility to test watchdog timer (M111
S1001). Added an error status word to record that errors have occurred
(e.g. over-temperature).
M111 command changes so that S0 turns debug off, S1 turns debug on, S2
reports free memory - also now reports the type of the last restart and
the error status word. Fixed problem whereby M111 debug reports were not
sent to the web interface.
Implemented M999 command, which resets the Duet.
Removed an unused variable.
Changed some more "char*" to "const char*".
Changed extruder PID parameters and added more explanation for them.
Increase incoming web gcode buffer size to 1200 chars to allow more
gcodes to be sent in each message
Include free buffer size in poll response
Include response sequence number in poll response
Implement M30 (delete file) via USB interface
Support M503 and M111 commands via web interface
