RAMPS-FD

RAMPS for Arduino Due

Arduino Dueis the new Arduino board that is using an ARM Cortex M3 CPU.

The Atmel SAM3X8E chip used on the Due operates at 3.3V and is not compatible with 5V. Therefore the RAMPS shield will not work with Due, and worse applying 5V to the Due's inputs will likely damage the chip.

Therefore it is proposed to create a new RAMPS variant which is compatible with the Due.

Useful resources

• Due pinout diagram
• SAM3X Series datasheet

Significant differences between Arduino Mega and Arduino Due

• CPU operates at 3.3V
• High-current IO pins are capable of 15 mA source, 9 mA sink
• Low-current IO pins capable of 3 mA source, 6 mA sink
• CPU package has an absolute max of 130mA

Hardware issues

• MOSFETs need to be compatible with threshold voltage of 3.3V or better have a gate driver which allows any MOSFET to be used
• Expansion pins need to be level-translated, but this depends on how they are used
  • Add ons: SD card, thermocouple drivers, LCD boards
• Is heat dissipation of Due ok with RAMPS shield over it?
• Some opto-endstops need 5V power, and return 5V on signal

Hardware features known to be compatible

• The Allegro stepper drivers will run with VDD = 3.3V and the logic signals compatible with 3.3V. This should apply to all the Pololu style drivers.
• Servos "should" be able to operate with +5V power and a PWM signal of 3.3V
• Thermistors will operate at 3.3V but the Analog Ref is also 3.3V, so no changes should be necessary
• Mechanical endstops should be OK, if they do not use external pullup to 5V

Firmware changes

• Firmware needs to be recompiled with ARM compiler (gcc)
• Arduino libraries may be compatible
• Any references to AVR CPU peripherals need to be ported