Rambo

RAMBo

Release status: Working

Description	An all in one RAMPS class motherboard targeting convenience, reliability, and performance
License	GPL
Author	User:johnnyr
Contributors
Based-on	RAMPS
Categories	Electronics
CAD Models
External Link	Github

Summary

RAMBo (RepRap Arduino-compatible Mother Board) is an all in one RAMPS class motherboard targeting convenience, reliability, and performance.

More info coming soon...

• 

  All connectors

• 

  Main connectors

• 

  Auxiliary connectors

• 

  Schematic

• 

  Top/1^st copper layer

• 

  Ground/2^nd copper layer

• 

  Supply/3^rd copper layer

• 

  Bottom/4^th copper layer

Features

Logic

• Arduino MEGA compatible Atmega2560 and Atmega32u2 processors are compatible with all RAMPS class firmwares
• 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 A4984 1/8th microstep motor drivers (2 connectors on Z for Prusa Mendel)
• 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.)

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

Power

• Three independent power rails
  • Heated Bed 14A (Limited to 16V due to fuse rating, see rambo_development for hacks)
  • Extruders 5A (fuse can be exchanged for up to 10A capacity) 10V-26V input voltage
  • Motors and logic 5A (fuse can be exchanged for up to 10A capacity) 10V-26V input voltage
• Built in SMPS for 5V generation from 10V-26V Vin

PCB

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

Firmware

Here https://github.com/tonokip/Marlin is Tonokip's Marlin Fork with RAMBo support. It allows setting of the motor current with M907, and microstep mode with M350. Storing to EEPROM is not yet implemented.

USB Driver for new boards

If you are having problems installing the Arduino MEGA 2560 Rev 3 USB driver, it is likely that you you have a newer RAMBo board. If windows is giving you the error that it is an invalid driver, download this file File:RAMBo USBdriver.zip and unzip it into a known location on your computer. In windows 7, plug in your RAMBo board, and let windows fail to find the driver. Then, go to the start menu, right click on computer and click properties. On the left, click on Device Manager. Scroll down to Unknown Devices, and right click on RAMBo. Choose Update driver. CLick on "Browse my computer for driver software", then click on "Let me pick from a list of device drivers on my computer", then click the button for "Have Disk" and then click browse and point it to the file you downloaded above. Then click OK and it will tell you the driver isn't signed, it's ok, install anyways, and enjoy!

Motor Current

The current for the stepper motors is set by firmware controlling the digipot. You can verify the max current for each driver by plugging the reference voltage (V_REF) measured at the X_REF test point (Y_REF,etc for the other drivers) in the following formula:

I_TripMAX = V_REF/0.8

This formula is from the Allegro datasheet : I_TripMAX = V_REF/(8 X R_S). R_S = 0.1, the value of the sense resistors.

Schematic

Devolopment information

There is a page at Rambo_development with the pin assignments, fuses, changelog, etc.