For Arduino MEGA compatible Atmega2560 and Atmega32u2 processors are compatible with all RAMPS class firmware
Crystals for both usb and mcu (timing accurate to 10ppm)
3 Thermistor jacks + 4th Thermistor circuit on ZProbe.
Motor Drivers
4 Trinamic TMC2130 1/256th microstep motor drivers(2 connectors on Z for Prusa Mendel and other dual Z printer designs)
SPI Control of stepper current instead of PWM.
Microstep mode configured by MCU through firmware (SPI, no jumpers needed)
PWM DC outputs (Extruders, Fans, Etc.)
4 outputs (1 Extruder, 1 BED, 2 low power (fan, etc.)
Low resistance mosfets for cool running
Indicator led for each channel
FANS have 3pin fan connector.
FANS have 5V instead of 12-24V power source.
FAN connectors have tachometer feedback pin to the MCU to measure fan speed in capable firmware.
Power
2 power input rails
Heated Bed, 15A 12-24V (15A dedicated fuse)
Primary Power 10A 12-24V: Motors, Logic & Fans (5A dedicated fuse) + Extruder (5A dedicated fuse)
Built in SMPS for 5V generation from the Motors, Logic & Fans rail
Provides 5V power to FANS
Connectors
4-pin motor, zprobe plug-Molex 5057-9404
3-pin fan plug-Molex 5057-9403
2-pin thermistor, mech. endstop plug-Molex 5057-9402