Rambo v1.1

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RAMBo Pages: RAMBo .:. RAMBo v1.0-1.1 .:. RAMBo v1.2 .:. RAMBo v1.3 .:. RAMBo v1.4 .:. RAMBo Firmware .:. RAMBo Development .:. MiniRambo .:. MiniRambo Development .:. EinsyRambo .:. EinsyRambo Development

This page is applicable for RAMBo version 1.0 through 1.1

See RAMBo for general RAMBo details including firmware, configuration, drivers, etc. See RAMBo v1.2 for information applicable to version 1.2.



  • Arduino MEGA compatible Atmega2560 and Atmega32u2 processors are compatible with all RAMPS class firmware
  • Crystals for both usb and mcu (timing accurate to 10ppm)
  • 4 Thermistor jacks
  • All extra pins broken out on both processors (allows using the 32u2 for LUFA AVR programmer, etc.)
  • 2 channel SDRAMPS compatible SPI breakout

Motor Drivers

  • 5 A4982 1/16th microstep motor drivers (A4984 1/8th prior to v1.1) (2 connectors on Z for Prusa Mendel and other dual Z printer designs)
  • Digital Trimpot for stepper current control
  • Current limit on driver IC VCC to prevent permanent latchup
  • Microstep mode configured by MCU through firmware (no jumpers needed)
  • Test points for driver control signals
  • Step and Direction pins are on their own ports for synchronous movement capability
  • Extra driver ports broke out for up to 3 additional drivers (some of the motor extension pins are shared with max endstop and a pin allocated for SPI-SS extensions)

PWM DC outputs (Extruders, Fans, Etc.)

  • 6 outputs
  • Low resistance mosfets for cool running
  • Indicator led for each channel


  • Three independent power rails for flexible input power configurations
    • Heated Bed, 15A 12-24V (version earlier than 1.1 limted to 14A 16V due to fuse rating, see rambo_development for hacks)
    • Extruders and fans, 5A 12-24V (fuse can be exchanged for up to 10A capacity) 10V-26V input voltage
    • Motors and logic, 5A 12-24V (fuse can be exchanged for up to 10A capacity) 10V-26V input voltage
  • Built in SMPS for 5V generation from Motor Power Input2


  • 4 layer
  • 2oz copper on all layers
  • High quality, High temperature FR4-TG130 PCB
  • Gold ENIG finishing


This is the RAMBo schematic.


RAMBo v1.1 has 3 replaceable fuses. The small white fuse holders are Little Fuse OMNI-BLOCK fuse holders. They are compatible with NANO2 Fuses. Fast or very fast acting are recommended. An example part number for replacement fuses is 0448005.MR

  • F2 supplies the motors and on-board power supply.
  • F3 supplies the extruder heater and fan outputs.
  • F4 is a 15A ATO (the type found in many automotives). F4 supplies the heated bed output. (Version 1.0 has 11A PTC self resetting fuse)